Netter Concise Orthopaedic Anatomy 2nd Edition

2 Spine • TRAUMA Subluxation with angulation Ͼ3.5 mm greater than 11° and/or anterior displacement greater than 3.5 mm generally indicative of instability Ͼ11˚ Subluxation with angulation Anterior displacement greater than 11˚ greater than 3.5 mm Facet dislocation Anterior facet dislocation of C5 on C6 with X-ray (lateral view) shows bilateral facet tear of interspinous ligament, facet capsules, dislocation at C5–C6 and posterior fibers of intervertebral disc DESCRIPTION EVALUATION CLASSIFICATION TREATMENT SUBAXIAL CERVICAL FRACTURES • Compression fx: involve Hx: High-energy trauma, By mechanism (each class • Compression fx: collar (e.g., MVA, fall, diving), is subclassified by severity) • Burst fx: ACDF (anterior ant. half of vertebral body ϩ/Ϫ pain, numbness, tin- 1. Flexion-compression [#1] gling or weakness 2. Vertical compression corpectomy, diskec- • Burst fx: involve whole PE: Stabilize head & neck 3. Flexion-distraction [#2] tomy, and fusion Palpate neck for “step off.” 4. Extension-compression [ant. plate]) vs vertebral body & have ret- Neuro exam: CN’s, UE & 5. Extension-distraction decompression/post. LE motor/sensory/ 6. Lateral flexion fusion) ropulsion into spinal canal reflexes • Flexion-compression: XR: Lateral, odontoid, AP Descriptive ‫ ؠ‬Stable: collar or halo; • Instability (White & Panjabi) Evaluate for stability Compression ‫ ؠ‬Unstable: ant. or ‫ ؠ‬Ͼ3.5mm of translation criteria Burst ‫ ؠ‬Ͼ11° kyphotic Flexion/extension views: Facet dislocation post. fusion angulation to evaluate dynamic Unilateral • Flexion-distraction/ ‫ ؠ‬ϩ stretch test instability Bilateral ‫ ؠ‬Neuro (cord or root) CT: Best study for all facet dx: Closed (acute, injury fractures awake pt) vs open ‫ ؠ‬Ant. elements destroyed MR: Assess posterior liga- (unconscious or late ‫ ؠ‬Post. elements ments & for disc hernia- presentation) reduction destroyed tion on cord with anterior (ACDF) or ‫ ؠ‬Narrow spinal canal posterior spinal fusion ‫ ؠ‬Disc space narrowing • Heavy loads anticipated COMPLICATIONS: Neurologic: quadriplegia, paraplegia, radiculopathy. Vascular: vertebral artery. Immobilization: halo. 40 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Three-Column Concept of Spinal Stability TRAUMA • Spine 2 Posterior Middle Anterior Posterior Middle Anterior Burst fracture column column column column column column Three-column concept. If more than Lateral view. Note that lateral facet Burst fracture of unstable vertebral one column involved in fracture, (zygapophyseal) joints in posterior body involving both anterior and then instability of spine usually column, with intervertebral foramina middle columns resulted in instability results in middle column and spinal cord compression Chance fracture Flexion Distraction results in complete transverse fracture through entire vertebra. Note hinge effect of anterior longitudinal ligament Fracture/Dislocation: All 3 columns are involved DESCRIPTION EVALUATION CLASSIFICATION TREATMENT THORACOLUMBAR FRACTURES • Mechanism: MVA or fall Hx: High-energy trauma, Compression: 1 (anterior) • Compression: observation (lap belt can be fulcrum pain ϩ/Ϫ numbness or column only, stable fx or orthosis 12wk to cause flexion- weakness Stable burst: 2 columns distraction fx) PE: Palpate for “step off” 1. Ͻ25º kyphosis • Stable burst: TLSO or hy- Neuro exam: LE motor/ 2. Ͻ50% body ht loss perextension brace for • Thoracolumbar junction sensory/reflexes 3. Ͻ50% canal 12wk (f/u x-rays to con- is most common site (including anal wink retropulsion firm stability) of fracture/injury & bulbocavernosus) Unstable burst: 2-3 col- XR: Lateral (body ht, umns fail above criteria • Unstable burst: decom- • Determining stability kyphosis) or have neurologic com- pression & posterior is key to treatment AP (pedicle widening) promise spinal fusion Flexion/extension views: Flexion-distraction: • 3-column theory to evaluate dynamic 2-3 columns; columns • Flexion-distraction: most (Denis): Ͼ1 column in- instability fail posterior to anterior require posterior fusion jured ϭ unstable CT: Best study for all Translation (fx/dx): All fractures 3 columns fail: unstable • Translation: needs reduc- • Burst fx: caused by Evaluate for retropulsion tion and stabilization/ 1. flexion and 2. axial MR: Discs & post. ligaments fusion compression • Chance fx: flexion- distraction fx, all 3 col- umns fail in tension COMPLICATIONS: Neurologic: Spinal cord/cauda equina injury. Immobilization: DVT, PE. Surgical: Infection, dural tears. NETTER’S CONCISE ORTHOPAEDIC ANATOMY 41

2 Spine • TRAUMA Central cord syndrome Central cord hemorrhage and edema. Parts of 3 main tracts involved on both sides. Upper limbs more affected than lower limbs Anterior spinal artery syndrome Artery damaged by bone or cartilage spicules (shaded area affected). Bilateral loss of motor function and pain sensation below injured segment; position sense preserved Brown-Sequard syndrome One side of cord affected. Loss of motor function and position sense on same side and of pain sensation on opposite side Posterior column syndrome (uncommon) Position sense lost below lesion; motor function and pain sensation preserved DESCRIPTION EVALUATION CLASSIFICATION TREATMENT SPINAL CORD TRAUMA • Young males most Hx: High-energy trauma • Complete: no function • Methylprednisolone IV common (MVA, fall), ϩ/Ϫ numbness below the injured level given within 8hr of in- or weakness (spinal shock must be re- jury may improve func- • High association PE: Find lowest functional solved to diagnose) tional level w/C-spine fractures neurologic level (easily missed) Central: UEϾLE motor loss • Incomplete: partial spar- • Most patients recover Anterior: LEϾUE motor and ing of distal function 1 (or 2) levels of func- • Central: #1, hyperexten- sensory, proprioception ‫ ؠ‬Central: central gray tion in complete sion mechanism, seen intact matter injuries in elderly, with cervical B-S: Ipsilateral motor loss, ‫ ؠ‬Anterior: Spinothalamic spondylosis contralateral pain/temp & corticospinal tracts • Decompression of cord loss out, posterior columns (reduce dislocations or • Anterior: #2, worst XR: r/o C-spine fx spared remove bone frag- prognosis CT: r/o or evaluate C-spine fx ‫ ؠ‬Brown-Sequard: lat- ments) with internal or MR: Shows cord, disc herni- eral half of spinal cord external (e.g., collar or • Brown-Sequard: usually ation (on cord), posterior (“hemisection”) halo) immobilization penetrating trauma, rare ligaments ‫ ؠ‬Posterior: posterior col- injury, best prognosis umns • Posterior: very rare; this pattern may not exist COMPLICATIONS: Neurologic; autonomic dysreflexia (treat with urinary catheter/rectal disimpaction); spinal instability. • Spinal shock: Paralysis/areflexia from physiologic cord injury. Return of bulbocavernosus reflex is end of spinal shock. • Neurogenic shock: Hypotension with bradycardia. Decreased sympathetic (unopposed vagal) tone. Treat with vasopressors. • Hypovolemic shock: Hypotension with tachycardia. Treat with fluid/volume resuscitation. 42 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Spine 2 Alar ligaments Cruciate Superior longitudinal band Atlas (C1) ligament Transverse ligament of atlas Axis (C2) Inferior longitudinal band Deeper (accessory) part of tectorial membrane Principal part of tectorial membrane removed to expose deeper ligaments: posterior view Atlas (C1) Apical ligament of dens Axis (C2) Alar ligament Posterior articular facet of dens (for transverse ligament of atlas) Alar ligament Anterior tubercle of atlas Synovial cavities Cruciate ligament removed to show deepest ligaments: posterior view Dens Transverse ligament of atlas Median atlantoaxial joint: superior view LIGAMENT ATTACHMENTS COMMENTS OCCIPITOATLANTAL JOINT • Articulation between convex occipital condyles and concave superior facets of atlas (C1). This articulation is horizontal (especially in pediatrics) allowing for rotation, but is inherently horizontally unstable. ROM: flexion/extension 25°; lat- eral bending 5° (each side); rotation 5° (each side). Capsule Surrounds joints (condyle & facet) Loose tissue provides minimal stability Ant. atlantooccipital Ant. atlas arch to ant. foramen mag. Continuation of ALL Tectorial membrane Post. axis to ant. foramen magnum Primary stabilizer. Continuation of PLL, limits extension Post. atlantooccipital Post. arch to post. foramen magnum Homologous to ligamentum flavum ATLANTOAXIAL JOINT (C1-2) • Made up of 3 articulations: Central (median) atlantoaxial joint (pivot type): between the odontoid and anterior arch. Lat- eral atlantoaxial joints [2] (plane type): between the articulating facets of atlas and axis, allow for rotation. ROM: flex/ extend 20º; lateral bending 5º (each side); rotation 40º (each side). Supplies 50% of cervical rotation. Capsule Surrounds lateral facet joints Loose capsule allows for rotation Cruciate Posterior odontoid to anterior arch Has 3 components, is anterior to tectorial membrane Transverse atlantal Strongest ligament, holds odontoid to atlas. ADI Odontoid to ant. foramen magnum Ͻ3mm. Injury results in C1-2 instability. (TAL) Odontoid to body of axis Posterior to apical ligament, secondary stabilizer. Superior longitudinal Secondary stabilizer Inferior longitudinal Alar Odontoid to occipital condyles Strong, stabilizing ligaments, limit rotation & lateral bending. Injury results in C1-2 instability. Apical Odontoid to ant. foramen magnum Thin ligament provides minimal stability Accessory Axis body to occipital condyles Secondary stabilizers NETTER’S CONCISE ORTHOPAEDIC ANATOMY 43

2 Spine • JOINTS Clivus (surface feature) Tectorial Anterior view Basilar part of of basilar part of occipital bone membrane occipital bone Capsule of Atlas (C1) Pharyngeal atlantoocci- tubercle pital joint Capsule of lateral atlantoaxial joint Anterior Deeper atlantooccipital (accessory) part Axis (C2) membrane of tectorial Capsule of zygapophyseal membrane joint (C2—3) Posterior atlanto- Capsule of zygapophyseal occipital mem- Posterior joint (C3—4) brane longitudinal ligament Capsule of atlantooccipital joint Lateral atlantoaxial joint (opened up) Anterior longitudinal ligament Vertebral artery Hypoglossal canal Tectorial membrane Posterior margin Basion of foramen magnum Apical ligament of dens (opisthion) Posterior atlanto- Superior longitudinal band of occipital membrane cruciate ligament of atlas Posterior arch of atlas (C1) Anterior atlantooccipital membrane Ligamentum nuchae Anterior arch of atlas (C1) Posterior atlantoaxial membrane Articular cavity Spinous process of axis (C2) Dens (odontoid process) of axis (C2) Ligamentum flavum Transverse ligament of atlas Inferior longitudinal band of cruciate ligament of atlas Anterior longitudinal ligament Posterior longitudinal ligament LIGAMENT ATTACHMENTS COMMENTS INTERVERTEBRAL ARTICULATION Adjacent vertebrae are joined by a complex of smaller joints/articulations, ligaments, muscles, & connecting structures. • An intervertebral disc lies between the vertebral bodies (except b/w C1-2 and b/w the fused sacral segments). • Paired facet (apophyseal) joints connect the posterior elements. Their orientation dictates that intervertebral motion. • Uncovertebral joints (of Luschka) add stability between vertebral bodies in the cervical spine. Intervertebral disc To adjacent vertebral bodies Annulus gives strong connection b/w adjacent bodies Anterior longitudinal Adjacent anterior vertebral bodies Strong, thick ligament. Resists hyperextension. ligament (ALL) and discs Posterior longitudi- Adjacent posterior vertebral bodies Weak, limits hyperflexion. Disc herniates around nal ligament (PLL) & discs (full length of spine) ligament. Tectorial membrane is the superior continuation. Ligamentum flavum Anterior lamina (superior vert.) to Strong, yellow, not a long continuous structure. posterior lamina (inferior vert.) Hypertrophy may contribute to nerve root impingement. Ligamentum nuchae Occipital protuberance to C1 post. Continuation of supraspinous ligament arch & C2-C6 spinous processes Supraspinous Dorsal spinous processes to C7 Strong. Ligamentum nuchae is its superior continuation. Interspinous Between spinous processes Weak. Torn in ligamentous flexion-distraction injuries. Intertransverse Between transverse processes Weak ligament, adds little support. Iliolumbar L5 transverse process to ilium May avulse in pelvic fracture (e.g., vertical shear fx). 44 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Left lateral view JOINTS • Spine 2 (partially sectioned in median plane) Inferior articular process Anterior Capsule of zygapophyseal longitudinal ligament (facet) joint (partially opened) Superior articular process Lumbar vertebral body Transverse process Spinous process Intervertebral disc Ligamentum flavum Interspinous ligament Anterior Supraspinous ligament longitudinal ligament Intervertebral foramen Posterior longitudinal ligament L1 Conus medullaris Cauda equina Intervertebral disc Pedicle (cut) Intervertebral disc L5 Posterior longitudinal S1 ligament Superior articular processes; facet tropism (difference in facet axis) on right side Lumbar MRI, sagittal view Spinous process Pedicle Lamina Pars inter- Transverse process articularis Inferior articular process Ligamentum flavum Iliolumbar ligament Iliac crest Posterior view NETTER’S CONCISE ORTHOPAEDIC ANATOMY 45

2 Spine • JOINTS Facet joint Superior Facet joint Facet joint and articular Joint capsule capsule innervated process by dorsal rami Bilevel from two spinal Inferior innervation levels articular of synovial process membrane Annulus and capsule fibrosis Facet joint, composed of articular of facet joint processes of adjacent vertebrae, Vertebral body limits torsion and translation Facet joints Nucleus pulposus Anterior longitudinal ligament Annulus fibrosus Nucleus pulposus Intervertebral disc LIGAMENT ATTACHMENTS COMMENTS FACET ([ZYG]APOPHYSEAL) JOINT Paired (L & R) articulations between the inferior & superior articular processes of adjacent vertebrae. • Orientation changes from semi-coronal (cervical) to sagittal (lumbar) and allows/dictates motion of that segment. • Inferior articular process is anterior & inferior (C-spine) and anterior & lateral (L-spine) to the superior articular process. • Joint innervation is from dorsal rami of two adjacent nerve root levels. • Hypertrophic changes in degenerative disease can cause/contribute to nerve root impingement. Capsule Surrounds the articular pro- Weak structure, adds little support. May hypertrophy in degen- cesses erative joints and narrow neural foramen. Meniscus/disc Within joint b/w processes Can be injured or degenerate and be source of pain INTERVERTEBRAL DISCS Stabilize and maintain spine by anchoring adjacent vertebral bodies. Allow flexibility and absorb/distribute energy. • The discs make up 25% of the spine height. Disc degeneration with age results in loss of spinal column height. Annulus fibrosus Strong attachments to end • Two layers: 1. outer annulus: dense fibers (type 1 collagen); plates of adjacent vertebral 2. inner annulus: fibrocartilage, looser type 2 collagen fibers bodies (via “outer annulus”) • Fibers are obliquely oriented and resist tensile loads • Outer layer innervated, tears can cause back pain (esp. LBP) Nucleus pulposus Contained within the annulus • Gelatinous mass of water, proteoglycans, & type 2 collagen • Resists compressive loads (highest when sitting forward) • Water & proteoglycan content decrease with advancing age • Can herniate out of annulus & compress nerve root (L4-5 #1) 46 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Spine 2 Anterior longitudinal Transverse costal facet (for tubercle ligament of rib of same number as vertebra) Inferior costal facet (for head of Lateral costotransverse ligament rib one number higher) Intertransverse ligament Interarticular ligament of Superior Superior articular head of rib costotransverse facet of rib head Superior costal ligament facet (for head of Intraarticular ligament rib of same Radiate number) ligament Synovial of head cavities Radiate of rib ligament of head of rib Superior costotransverse Left lateral view ligament (cut) Articular cartilage on dens for median Atlas (C1) Costotransverse ligament atlantoaxial joint complex Axis (C2) Lateral costotransverse ligament Transverse section: superior view Lateral atlantoaxial joint Facet (zygapophyseal) joint between C2 and C3 Foramen transversarium Uncinate processes Annulus fibrosus Uncovertebral joints (clefts) of Luschka LIGAMENT ATTACHMENTS COMMENTS UNCOVERTEBRAL JOINTS • “Joints of Luschka”: articulation in cervical spine b/w the uncinate process on the concave superior end plates of the in- ferior vertebral body & the articulating portion of the convex inferior end plate of the superior adjacent vertebral body. • Articular cartilage at this joint can degenerate and contribute to cervical spondylosis. COSTOVERTEBRAL JOINTS Articulation between the head of the rib and the thoracic vertebra (body and transverse process) Capsule Surround head of rib/joint Weak support of joint Intraarticular Head of rib to body/disc Deep to radiate Radiate Head of rib to bodies & disc Fan shaped, reinforces joint anteriorly Costotransverse Transverse process to rib Superior costotransverse attaches to TP of superior vertebrae OTHER Neural foramen: Boundaries: superior & inferior: pedicles; anterior: body & disc (uncinate process in C-spine); poste- rior: facet joint & capsule. Osteophytes, discs, facet hypertrophy, and ligamentum flavum can all narow foramen. NETTER’S CONCISE ORTHOPAEDIC ANATOMY 47

2 Spine • HISTORY Radicular symptons Lower back Paresthesias and/or pain radiating pain Head-on collision with stationary object or oncoming vehicle may, if seat belts not used, drive forehead against windshield. This sharply hyperextends neck, resulting in dislocation with or without fracture of cervical vertebrae QUESTION ANSWER CLINICAL APPLICATION 1. Age Young Disc injuries, spondylolisthesis 2. Pain Middle age Sprain/strain, nucleus pulposis/disc (HNP), degenerative a. Character disc disease (DDD) b. Location Elderly Spinal stenosis, herniated disc, DDD, spondylosis c. Occurrence Radiating (shooting) Radiculopathy (herniated nucleus pulposis [HNP]) d. Alleviating Diffuse, dull, non radiating Cervical or lumbar strain e. Exacerbating Unilateral vs bilateral Unilateral: herniated nucleus pulposis; Bilateral: systemic 3. Trauma or metabolic disease, space-occupying lesion 4. Activity Neck Cervical spondylosis, neck sprain or muscle strain 5. Neurologic Arms (ϩ/Ϫ radiating) Cervical spondylosis (ϩ/Ϫ myelopathy), HNP symptoms Lower back DDD, back sprain/muscle strain, spondylolisthesis Legs (ϩ/Ϫ radiating) Herniated nucleus pulposis, spinal stenosis 6. Systemic Night pain Infection, tumor complaints With activity Usually mechanical etiology Arms elevated Herniated cervical disc (HNP) Sit down Spinal stenosis (stenosis relieved) Back extension Spinal stenosis (going down stairs), DJD/facet hypertrophy MVA (seatbelt?) Cervical strain (whiplash), cervical fractures, ligamentous injury Sports (stretching injury) “Burners/stingers”(esp. in football), fractures Pain, numbness, tingling Radiculopathy, neuropathy, cauda equina syndrome Spasticity, clumsiness Myelopathy Bowel/bladder symptoms Cauda equina syndrome Fever, weight loss, night Infection, tumor sweats 48 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Inspection PHYSICAL EXAMINATION • Spine 2 Range of motion Scoliosis Gauging Spinal column trunk movements: alignment with plumb Flexion line Extension Side bending Malalignment Rotation of spine Palpate for: Palpation Palpate for local Muscle spasm tenderness or spasm Trigger zones Myofascial nodes Sciatic nerve tenderness Compress iliac crests for sacroiliac tenderness EXAM TECHNIQUE CLINICAL APPLICATION Gait INSPECTION Alignment Posture Leaning forward Spinal stenosis Skin Wide-based Myelopathy Bony structures Malalignment Dislocation, scoliosis, lordosis, kyphosis Soft tissues Head tilted Dislocation, spasm, spondylosis, torticollis Flexion/extension: cervical Pelvis tilted Loss of lordosis: spasm Flexion/extension: lumbar Lateral flexion: cervical Disrobe patient Cafe-au-lait spots, growths: possibly neurofibromatosis Lateral flexion: lumbar Port wine spots, soft masses: possibly spina bifida Rotation: cervical Rotation: lumbar PALPATION Spinous processes Focal/point tenderness: fracture; step-off: dislocation/ spondylolisthesis Cervical facet joints Tenderness: osteoarthritis, dislocation Coccyx, via rectal exam Tenderness: fracture or contusion Paraspinal muscles Diffuse tenderness: sprain/muscle strain; trigger point: spasm RANGE OF MOTION Chin to chest/occiput back Normal: Flexion: chin within 3-4cm of chest; ext. 70° Touch toes with legs straight Normal: 45-60° in flexion, 20-30° in extension Ear to shoulder Normal: 30-40° in each direction Bend to each side Normal: 10-20° in each direction Stabilize shoulders: rotate Normal: 75° in each direction Stabilize hip: rotate Normal: 5-15° in each direction NETTER’S CONCISE ORTHOPAEDIC ANATOMY 49

2 Spine • PHYSICAL EXAMINATION Level Motor Reflex Sensory C5 Deltoid Biceps brachii Biceps brachii C6 Brachioradialis Triceps brachii Triceps brachii C7 Interossei None C8 EXAM TECHNIQUE CLINICAL APPLICATION C5 NEUROVASCULAR C6 C7 Lateral shoulder Cervical C8 Thumb T1 Middle finger Sensory Ring & small fingers C5 Ulnar forearm & hand Deficit indicates a corresponding cervical root compression/lesion C6 Deficit indicates a corresponding cervical root compression/lesion C7 Deltoid: resisted abduction Deficit indicates a corresponding cervical root compression/lesion C8 Biceps: resisted elbow flexion Deficit indicates a corresponding cervical root compression/lesion T1 Triceps: resisted elbow ext. Deficit indicates a corresponding cervical root compression/lesion Intrinsics: resisted finger C5 abduction Motor C6 C7 Biceps Weakness indicates corresponding cervical root compression/lesion Inverted radial Brachioradialis (BR) Weakness indicates corresponding cervical root compression/lesion Triceps Weakness indicates corresponding cervical root compression/lesion Hoffman’s Tap BR tendon in distal Weakness indicates corresponding cervical root compression/lesion forearm Weakness indicates corresponding cervical root compression/lesion Flick MF DIPJ into flexion Reflexes Brachial, radial, ulnar Hypoactive/absent indicates C5 radiculopathy Hypoactive/absent indicates C6 radiculopathy Hypoactive/absent indicates C7 radiculopathy Hypoactive brachioradialis & hyperactive finger flexion: myelopathy Pathologic if thumb IPJ flexes: myelopathy Pulses Diminished/absent ϭ vascular injury or compromise 50 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

PHYSICAL EXAMINATION • Spine 2 Level Motor Reflex Sensory L4 Quadriceps Patella tendon Medial L5 Tibialis (”knee jerk”) calf/ankle anterior Dorsal foot L4 and 1st web space Extensor hallucis longus None S1 Plantar and Achilles tendon lateral foot (“ankle jerk”) S1 Gastroc- nemius EXAM TECHNIQUE CLINICAL APPLICATION L3 NEUROVASCULAR L4 L5 Anterior & medial thigh Lumbar S1 Medial leg & ankle S2-4 Dorsal foot & 1st web space Sensory Lateral & plantar foot L3-4 Perianal sensation Deficit indicates corresponding lumbar root compression/lesion L4 Deficit indicates corresponding lumbar root compression/lesion L5 Quadriceps: knee extension Deficit indicates corresponding lumbar root compression/lesion S1 Tibialis anterior: ankle DF Deficit indicates corresponding lumbar root compression/lesion S2-4 Extensor hallucis longus: toe DF Deficit indicates corresponding lumbar root compression/lesion Gastrocnemius: ankle PF L4 Anal sphincter: anal squeeze Motor S1 S2-3 Patellar tendon (“knee jerk”) Weakness indicates corresponding lumbar root compression/lesion Babinski Achilles tendon (“ankle jerk”) Weakness indicates corresponding lumbar root compression/lesion Ankle clonus Bulbocavernosus Weakness indicates corresponding lumbar root compression/lesion Run stick along plantar foot Weakness indicates corresponding lumbar root compression/lesion Rapidly flex & extend ankle Weakness indicates corresponding lumbar root compression/lesion Posterior tibial, dorsalis pedis Reflexes Hypoactive/absent indicates L4 radiculopathy Hypoactive/absent indicates S1 radiculopathy Hypoactive/absent indicates S2-3 radiculopathy or spinal shock Upgoing great toe: upper motor neuron/myelopathy Multiple beats of clonus: upper motor neuron/myelopathy Pulses Diminished/absent ϭ vascular injury or compromise NETTER’S CONCISE ORTHOPAEDIC ANATOMY 51

2 Spine • PHYSICAL EXAMINATION Spurling maneuver Forward bending test Hyperextension and flexion of neck ipsilateral to the side of Estimation of rib hump lesion cause radicular pain and evaluation of curve in neck and down the unwinding as patient turns affected arm trunk from side to side Straight leg test Passively flex hip. Stop when pain occurs. Lower leg until pain re- solves, then dorsiflex foot. Extend knee, hip relaxed EXAM TECHNIQUE CLINICAL APPLICATION Spurling SPECIAL TESTS Distraction Kernig Cervical Brudzinski Axial load, then laterally flex & rotate Radiating pain indicates nerve root compression Straight leg neck Straight leg 90/90 Bowstring Upward distracting force Relief of symptoms indicates foraminal compression of Sitting root (flip nerve root sign) Supine: flex neck Pain in or radiating to legs indicates meningeal irritation/ Forward bending infection Hoover Waddell signs Supine: flex neck, hip flex Pain reduction with knee flexion indicates meningeal irritation Lumbar Flex hip to pain, dorsiflex foot Symptoms reproduced (pain radiating below knee) indica- tive of radiculopathy Supine: flex hip & knee 90°, extend Ͼ20° of flexion ϭ tight hamstrings: source of pain knee Raise leg, flex knee, popliteal press Radicular pain with popliteal pressure indicates sciatic nerve cause Seated: distract patient, passively Patient with sciatic pain will arch/flip backward when extend knee knee extended Standing, bend at waist Asymmetry of back (scapula/ribs) is indicative of scoliosis Supine: hands under heels, patient Pressure should be felt under opposite heel. No pressure then raises one leg indicates lack of effort, not true weakness Presence indicates nonorganic pathology: 1. Exaggerated response/overreaction, 2. Pain to light touch, 3. Nonanatomic pain localization, 4. Negative flip sign with positive straight leg test 52 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

MUSCLES • Spine 2 Superficial (investing) layer of deep cervical fascia Platysma muscle Sternohyoid muscle Infrahyoid fascia Trachea Pretracheal (visceral) fascia Sternothyroid muscle Thyroid gland Buccopharyngeal Esophagus (visceral) fascia Omohyoid muscle Carotid sheath Sternocleidomastoid muscle Subcutaneous tissue Recurrent laryngeal Superficial nerve (investing) layer of deep cervical Common carotid artery fascia roofing Internal jugular vein posterior triangle Vagus nerve (X) Phrenic nerve Fat in Anterior scalene muscle posterior Sympathetic trunk triangle Spinal nerve Prevertebral layer of (deep) Middle and posterior cervical fascia scalene muscles Longus colli muscle Alar fascia Retropharyngeal Subcutaneous Levator scapulae muscle Cross section space tissue Trapezius muscle Deep cervical muscles Cervical vertebra (C7) Sagittal section Mandible Geniohyoid muscle Pharynx Geniohyoid fascia Buccopharyngeal (visceral) Investing layer of (deep) fascia cervical fascia Retropharyngeal Fascia of infrahyoid muscles space Pretracheal (visceral) fascia Alar fascia Thyroid gland Prevertebral fascia Subcutaneous tissue Trachea Suprasternal space (of Burns) Esophagus Manubrium of sternum Aorta Pericardium LAYER CONTENTS COMMENT Platysma FASCIA LAYERS Deep cervical fascia Pretracheal fascia Thin superficial muscle Highly vascular, must be split to access cervical spine Carotid sheath Invests sternocleidomastoid Incised in anterior cervical approach Prevertebral fascia Invests thyroid, trachea Incised off of carotid sheath to access cervical spine Carotid artery, internal jugular vein, Left intact and used to retract structures laterally unless vagus nerve (CN 10) access to contents of sheath is needed Covers A.L.L. & longus colli Deepest fascial layer, incised to access vertebral body and disc NETTER’S CONCISE ORTHOPAEDIC ANATOMY 53

2 Spine • MUSCLES Hyoid bone Digastric muscle (anterior belly) Mylohyoid muscle Thyrohyoid membrane Hyoglossus muscle External carotid artery Stylohyoid muscle Digastric muscle Internal jugular vein (posterior belly) Thyrohyoid muscle Fibrous loop for inter- mediate digastric tendon Thyroid cartilage Omohyoid muscle Sternohyoid and omohyoid (superior belly) muscles (cut) Sternohyoid muscle Thyrohyoid muscle Median cricothyroid Oblique line of ligament thyroid cartilage Cricoid cartilage Cricothyroid muscle Scalene muscles Sternothyroid muscle Trapezius Omohyoid muscle muscle (superior belly) (cut) Omohyoid muscle Thyroid gland (inferior belly) Sternohyoid muscle (cut) Clavicle Trachea MUSCLE ORIGIN INSERTION ACTION NERVE Platysma Sternocleidomastoid ANTERIOR NECK CN 7 Digastric Fascia: deltoid/pecto- Mandible; skin Depress jaw CN 11 ralis major Mylohyoid Anterior: mylohy- Stylohyoid Manubrium & clavicle Mastoid process Turn head opposite side oid (CN 5) Geniohyoid Post: facial (CN 7) ANTERIOR CERVICAL TRIANGLE Mylohyoid (CN 5) Sternohyoid Facial nerve (CN 7) Omohyoid Suprahyoid Muscles C1 via CN 12 Thyrohyoid Sternothyroid Anterior: mandible Hyoid body Elevate hyoid, depress Ansa cervicalis Posterior: mastoid mandible Ansa cervicalis notch C1 via CN 12 Mandible Raphe on hyoid Same as above Ansa cervicalis (C1-3) Styloid process Body of hyoid Elevate hyoid Genial tubercle of Body of hyoid Elevate hyoid mandible Manubrium & clavicle Infrahyoid Muscles Depress hyoid Superficial Body of hyoid Suprascapular notch Body of hyoid Depress hyoid Thyroid cartilage Deep Depress hyoid/larynx Greater horn of hyoid Manubrium Thyroid cartilage Depress/retract hyoid/ larynx 54 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Epicranial aponeurosis MUSCLES • Spine 2 (galea aponeurotica) Occipital belly (occipitalis) of Rectus capitis posterior minor muscle occipitofrontalis muscle Rectus capitis posterior major muscle Semispinalis capitis muscle Greater occipital nerve (cut and reflected) (dorsal ramus of C2 Vertebral artery spinal nerve) (atlantic part) Obliquus capitis Occipital artery superior muscle Suboccipital nerve 3rd (least) occipital nerve (dorsal ramus of C1 (dorsal ramus of C3 spinal nerve) spinal nerve) Posterior arch of atlas (C1 vertebra) Semispinalis capitis and splenius capitis Occipital artery muscles in posterior triangle of neck Obliquus capitis inferior muscle Posterior auricular artery Great auricular nerve Greater occipital (cervical plexus C2, 3) nerve (dorsal ramus Lesser occipital nerve of C2 spinal nerve) (cervical plexus C2, 3) Splenius capitis muscle Sternocleidomastoid muscle (cut and reflected) Trapezius muscle 3rd (least) occipital nerve (dorsal ramus of C3 Posterior cutaneous branches spinal nerve) of dorsal rami of C4, 5, 6 spinal nerves Longissimus capitis muscle Splenius cervicis muscle Semispinalis cervicis muscle Semispinalis capitis muscle (cut) Splenius capitis muscle (cut) MUSCLE ORIGIN INSERTION ACTION NERVE POSTERIOR NECK Laterally flexes neck C5-C8 nerve roots and elevates 1st or Scalene muscles C3-6 transverse process 1st rib 2nd rib Suboccipital nerve Anterior C2-7 transverse process 1st rib Suboccipital nerve Middle C4-6 transverse process 2nd rib Extend, rotate, laterally Suboccipital nerve Posterior flex head Suboccipital nerve Extend, laterally flex Suboccipital Triangle Extend, rotate, laterally Rectus capitis posterior Spine of axis Inferior nuchal flex major line Extend, laterally rotate Rectus capitis posterior Posterior tubercle of Occipital bone minor atlas Obliquus capitis Atlas transverse process Occipital bone superior Obliquus capitis inferior Spine of axis Atlas transverse process Semispinalis, see page 58; Splenius, see page 57. NETTER’S CONCISE ORTHOPAEDIC ANATOMY 55

2 Spine • MUSCLES Semispinalis capitis muscle Superior nuchal line of skull Splenius capitis muscle Spinous process of C2 vertebra Spinous process of C7 vertebra Sternocleidomastoid muscle Splenius cervicis muscle Posterior triangle of neck Levator scapulae muscle Trapezius muscle Rhomboid minor muscle (cut) Spine of scapula Supraspinatus Deltoid muscle muscle Infraspinatus fascia Serratus posterior Teres minor superior muscle muscle Rhomboid Teres major major muscle muscle (cut) Latissimus Infraspinatus dorsi muscle fascia (over infraspinatus Spinous process muscle) of T12 vertebra Teres minor and major Thoracolumbar fascia muscles External Latissimus dorsi muscle (cut) oblique muscle Serratus anterior muscle Internal oblique muscle in lumbar triangle Serratus posterior inferior (Petit) muscle Iliac crest 12th rib Gluteal aponeurosis Erector spinae muscle (over gluteus medius muscle) External oblique muscle Internal oblique muscle MUSCLE ORIGIN INSERTION ACTION NERVE Trapezius Spinous process SUPERFICIAL (EXTRINSIC) CN 11 C7-T12 Thoracodorsal Latissimus dorsi Clavicle; scapula Rotate scapula Dorsal scapular, C3, Spinous process (spine, acromion) Levator scapulae T6-S5 C4 (dorsal rami) Humerus Extend, adduct, IR arm Dorsal scapular Rhomboid minor Transverse process Dorsal scapular C1-4 Scapula (medial) Elevate scapula Intercostal n. (T1-4) Rhomboid major Intercostal n. (T9-12) Spinous process Scapula (spine) Adduct scapula Serratus posterior C7-T1 superior Scapula (medial border) Adduct scapula Serratus posterior Spinous process inferior T2-T5 Ribs 2-5 (upper border) Elevate ribs Spinous process Ribs 9-12 (lower Depress ribs C7-T3 border) Spinous process T11-L3 56 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Superior nuchal line of skull MUSCLES • Spine 2 Posterior tubercle of atlas (C1) Rectus capitis posterior minor muscle Longissimus capitis muscle Obliquus capitis superior muscle Semispinalis capitis muscle Rectus capitis posterior major muscle Obliquus capitis inferior muscle Splenius capitis and Longissimus capitis muscle splenius cervicis muscles Semispinalis capitis muscle (cut) Serratus posterior superior muscle Spinalis cervicis muscle Iliocostalis muscle Spinous process of C7 vertebra Longissimus cervicis muscle Erector Iliocostalis cervicis muscle spinae Longissimus muscle muscle Iliocostalis thoracis muscle Hook Spinalis muscle Spinalis thoracis muscle Longissimus thoracis muscle Serratus posterior Iliocostalis lumborum muscle inferior muscle Spinous process of T12 vertebra Transversus abdominis Tendon of origin of muscle and tendon transversus abdominis muscle of origin Thoracolumbar fascia Internal oblique (cut edge) muscle External oblique muscle (cut) Iliac crest MUSCLE ORIGIN INSERTION ACTION NERVE DEEP (INTRINSIC) Dorsal rami of inferior cervical nerves Superficial Layer: Spinotransverse Group Dorsal rami of spinal Splenius capitis Ligamentum nuchae Mastoid & nuchal line Both: laterally flex & nerves Splenius cervicis Spinous process T1-6 Transverse process rotate neck to same C1-4 side Intermediate Layer: Sacrospinalis Group (Erector Spinae) Iliocostalis Common origin: sa- Ribs Laterally flex, extend, Longissimus crum, iliac crest, and T & C spinous process, and rotate head (to lumbar spinous pro- mastoid process same side) and ver- Spinalis cess T-spine: spinous tebral column process All have three parts: thoracis, cervicis, and capitus NETTER’S CONCISE ORTHOPAEDIC ANATOMY 57

2 Spine • MUSCLES Rectus capitis posterior minor muscle Obliquus capitis superior muscle Superior nuchal line of skull Rectus capitis posterior major muscle Mastoid process Transverse process of atlas (C1) Obliquus capitis inferior muscle Posterior tubercle of atlas Longus (C1 vertebra) Brevis Rotatores cervicis muscles Interspinalis cervicis muscle Spinous process of axis (C2 vertebra) Levator costae muscle Semispinalis capitis muscle Longus Rotatores Brevis thoracis muscles Spinous process Brevis Levatores of C7 vertebra Longus costarum muscles External intercostal muscles Interspinalis lumborum muscle Lateral intertransversarius muscle Semispinalis thoracis muscle Quadratus lumborum muscle Multifidi muscles Iliac crest Multifidi muscles (cut) Thoracolumbar fascia (anterior layer) Thoracolumbar fascia (posterior layer) (cut) Transversus abdominis muscle and tendon of origin Multifidi muscles Erector spinae muscle (cut) MUSCLE ORIGIN INSERTION ACTION NERVE Semispinalis capitus DEEP (INTRINSIC) Dorsal primary rami Semispinalis (C&T) Dorsal primary rami Multifidus (C2-S4) Deep Layers: Transversospinalis Group Dorsal primary rami Rotatores Dorsal primary rami Levator costarum Transverse process Nuchal ridge Extend head Dorsal primary rami Interspinales T1-6 Dorsal primary rami Intertransversarii Dorsal primary rami Transverse process Spinous process Extend, rotate opposite side Transverse process Spinous process Flex laterally, rotate opposite Transverse process Spinous process ϩ1 Rotate superior verte- brae opposite Transverse process Brevis: rib Ϫ1 Elevate rib during Longus: rib Ϫ2 inspiration Spinous process Spinous process ϩ1 Extend column Tranverse process Transverse process ϩ1 Laterally flex column 58 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

NERVES • Spine 2 Cervical Spine Injury: Incomplete Spinal Syndromes Spinal cord orientation Posterior columns (position sense) Lower limb Trunk Lateral corticospinal tract (motor) Upper limb Lower limb Lateral spinothalamic tract Trunk (pain and temperature); fibers Upper limb decussate before ascending Anterior spinal artery Ventral root of spinal n. Dorsal root of spinal n. Spinal sensory (dorsal root) ganglion White and gray rami communicantes to and from sympathetic trunk Ventral ramus of spinal n. Dorsal ramus of spinal n. Dura mater Arachnoid mater Subarachnoid space Filaments of dorsal root Pia mater overlying spinal cord TRACT FUNCTION COMMENT SPINAL CORD • Runs from brain stem to conus medullaris (termination at L1) within the spinal canal where it is protected. • Terminale filum and cauda equina (lumbar and sacral nerve roots) continue in the spinal canal. • It has a layered covering (membranes): dura mater, arachnoid mater, pia mater. • It is made up of multiple ascending (sensory) and descending (motor) tracts and columns. • It is wider in the cervical and lumbar spines, where the roots form plexus to innervate the upper and lower extremities. • Paired (R & L) nerve roots emerge from each level. Nerve roots made up of ventral (motor) and dorsal (sensory) roots. • Injury can be either complete or incomplete (see page 42 for spinal cord injuries). Descending (Motor) Anterior corticospinal Innervates motor neurons—voluntary motor Minor motor pathway, injured in anterior cord syndrome Lateral corticospinal Innervates motor neurons—voluntary motor Major motor pathway, injured in Brown- Sequard syndrome Ascending (Sensory) Anterior spinothalamic Light touch sensation Injured in anterior cord syndrome Lateral spinothalamic Pain and temperature sensation Injured in Brown-Sequard syndrome Dorsal columns Proprioception and vibratory sensation Usually preserved, injured in posterior cord syndrome NETTER’S CONCISE ORTHOPAEDIC ANATOMY 59

2 Spine • NERVES Base C1 C1 C1 spinal nerve exits L4 of skull above C1 vertebra Cervical C2 enlargement C2 C3 L4 C3 C4 Lumbar C4 L5 enlargement C5 L5 C5 C6 C8 spinal nerve Filum terminale C6 C7 exits below internum C7 C8 C7 vertebra (there are 8 cervical S1 Filum T1 nerves but only terminale T1 7 cervical vertebrae) externum (coccygeal T2 ligament) T3 T2 T3 S2 T4 T5 T4 Conus medullaris Disc protrusion at disc level L4–5 affects L5 T6 T5 (termination of spinal nerve, not L4 spinal nerve. spinal cord) T6 Lumbar Vertebra T7 T7 T8 Dura mater T8 Sympathetic Arachnoid mater ganglion T9 T9 T10 T10 Gray ramus Ventral root communicans Spinal nerve T11 T11 Fat in Ventral ramus T12 epidural (contributes to T12 space lumbar plexus) L1 L1 Dorsal and ventral Dorsal L2 roots of lumbar and ramus sacral spinal nerves Spinal sensory L2 forming cauda equina (dorsal root) ganglion L3 Dorsal root L3 Conus medullaris L4 L4 Exiting spinal nerve roots Cauda equina L5 L5 Sacrum S1 Vertebral Terminal S2 body spinal cord and cauda S3 Termination of Lamina equina within S4 dural sac Spinous thecal sac S5 process Coccygeal nerve Cervical nerves Thoracic nerves MRI lumbar spine, axial Coccyx Lumbar nerves Sacral and coccygeal nerves SPINAL NERVES • Spinal nerves are made up of a ventral (motor) root and a dorsal (sensory) root. There are 31 pairs (L & R). • Cell bodies for sensory nerves are in dorsal root ganglia. Motor nerve cell bodies are in ventral horn of spinal cord. • Roots exit spinal column via the intervertebral (neural) foramen (under pedicle); (C1-7 exit above their vertebrae, C8-L5 exit below their vertebrae [C7 exits above and C8 exits below C7 vertebra]). • They can be compressed by herniated discs, osteophytes, and hypertrophied soft tissues (ligamentum flavum, facet capsule). In lumbar spine the traversing nerve is usually affected, and exiting root is not (except in far lateral compression). • The lumbar and sacral nerves form the cauda equina (“horse’s tail”) in the spinal canal before exiting. • Spinal nerve divides into dorsal and ventral rami. Dorsal rami innervate local structures (neck and back musculature, overlying skin, facet capsules, etc). Ventral rami contribute to plexus (e.g., cervical, brachial, lumbosacral) and become peripheral nerves to the extremities. • Ventral rami of spinal nerve commonly referred to as a spinal “roots.” The roots combine to form the various plexus. 60 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

NERVES • Spine 2 Schematic demarcation of dermatomes C2 (according to Keegan and Garrett) shown as distinct segments. There is C3 actually considerable overlap between C4 any two adjacent dermatomes. C5 C6 C2 C6 C6 C7 T1 C3 T1 C7 C8 T2 C4 C8 T3 C5 C7 C8 T4 C5 T5 T1 C6 T6 T2 C8 T7 T3 T8 T4 C7 T9 T5 T10 T6 T11 T7 T12 T8 L1 T9 L2 L3 T10 L4 L5 T11 S1 S2 T12 S3 L1 S4 S2, 3 S5 S1 L2 L5 S2 L3 L4 L1 L2 L3 L5 S1S2 S1 L4 L5 S1 L4 L5 L4 Levels of principal dermatomes T10 Level of umbilicus L1 Inguinal or groin regions C5 Clavicles L1, 2, 3, 4 Anterior and inner surfaces of lower limbs C5, 6, 7 Lateral parts of upper limbs L4, 5, S1 Foot C8, T1 Medial sides of upper limbs L4 Medial side of great toe C6 Thumb S1, 2, L5 Posterior and outer surfaces of lower limbs C6, 7, 8 Hand S1 Lateral margin of foot and little toe C8 Ring and little fingers S2, 3, 4 Perineum T4 Level of nipples NETTER’S CONCISE ORTHOPAEDIC ANATOMY 61

2 Spine • NERVES C6 C2 C3 C7 C6 Anterior view C8 C4 C5 C5 C2 T1 C8 T1 C3 Posterior view C6 C4 C7 C5 C8 C6 C7 C8 T1 LEVEL MOTOR SENSORY REFLEX COMMENT C1 Geniohyoid CERVICAL ROOTS Part of cervical plexus, contributes to Thyrohyoid ansa cervicalis C2 Rectus capitus None None C3 Longus colli/capitis Muscle innervation via the dorsal rami C4 Diaphragm Parietal scalp None Contributes to phrenic & dorsal C5 Occipital scalp None C6 Diaphragm scapular nerves C7 Base of neck None Branches to phrenic and dorsal scap- C8 Deltoid T1 Lateral shoulder and arm Biceps ular nerves & levator scapula muscle Biceps brachii Dorsal scapular n. branches from ECRL, ECRB Lateral forearm and Brachioradialis C5 root Triceps brachii thumb Triceps Most commonly compressed cervical FCR, FCU None FDS, FDP Posterior forearm, central None nerve root hand, and middle finger Exits above C7 vertebra Interosseous Medial forearm, ulnar Exits below C7 vertebra fingers Only thoracic root in brachial plexus Medial arm 62 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

NERVES • Spine 2 Schematic T10 L1 T12 demarcation of T11 L2 dermatomes T12 L3 (according to L1 L4 Keegan and L5 Garrett) shown as S2 S1 distinct segments. L2 S3 S2 There is actually S3 considerable L3 S4 S2 overlap between Autonomous S5 any two adjacent L4 sensory zones Co dermatomes. L3 L1 L4 S2 S1 L2 L3 L5 L5 L5 L5 S1 L4 S1 Anterior view Posterior view L4 L5 S1 Segmental innervation of lower limb movements Knee Extension Hip L3, 4 L5, S1 Dorsiflexion Flexion L4, 5 L5, S1 L4, 5 Inversion Eversion Foot L2, 3 L5, S1 S1, 2 Ankle Flexion Extension Plantar flexion LEVEL MOTOR SENSORY REFLEX COMMENT L1 Transversus abdominis LUMBOSACRAL ROOTS Rarely injured nerve root Internal oblique L2 Psoas Inguinal region None Test with hip flexion L3 Quadriceps L3 & L4 tested with quadriceps L4 Tibialis anterior Upper thigh None Test with ankle dorsiflexion L5 Extensor hallux longus Most commonly compressed lumbar Anterior and medial thigh None root; test with hallux dorsiflexion S1 Gastrocnemius Test with ankle plantar flexion/toe Medial leg, ankle, foot Patellar walking Test tone to evaluate for cauda equina Dorsal/plantar foot, 1st Hamstring syndrome web space, lateral leg Lateral foot, posterior leg Achilles S2-4 Sphincter Perianal sensation Anal wink NETTER’S CONCISE ORTHOPAEDIC ANATOMY 63

2 Spine • NERVES Parotid gland Great auricular nerve Facial artery and vein Lesser occipital nerve Submandibular gland Sternocleidomastoid muscle (cut, turned up) Mylohyoid muscle Stylohyoid muscle Digastric muscle (posterior belly) Hypoglossal nerve (XII) C2 spinal nerve (ventral ramus) Accessory nerve (XI) Digastric muscle C3 spinal nerve (ventral ramus) (anterior belly) Levator scapulae muscle Middle scalene muscle Lingual artery Anterior scalene muscle External carotid artery C5 spinal nerve (ventral ramus) Internal carotid artery Transverse cervical artery Phrenic nerve Thyrohyoid muscle Omohyoid muscle (inferior belly) (cut) Superior thyroid artery Brachial plexus Omohyoid muscle (superior belly) (cut) Dorsal scapular artery Ansa cervicalis Superior root Suprascapular artery Inferior root Sternohyoid muscle Sternothyroid muscle Internal jugular vein Common carotid artery Inferior thyroid artery Vagus nerve (X) Vertebral artery Thyrocervical trunk Subclavian artery and vein Accessory nerve (XI) Great auricular nerve Cervical plexus: schema Hypoglossal nerve (XII) S Lesser occipital nerve C1 (S = gray ramus from superior cervical sympathetic ganglion) To rectus capitis lateralis, longus capitis, and rectus To geniohyoid muscle S C2 capitis anterior muscles To thyrohyoid muscle Communication to vagus nerve Transverse cervical nerves S C3 S C4 To omohyoid muscle To longus capitis and (superior belly) longus colli muscles Ansa cervicalis Superior root Inferior root To sternothyroid muscle To sternohyoid muscle To omohyoid muscle (inferior belly) Supraclavicular nerves Phrenic nerve To scalene and levator scapulae muscles CERVICAL PLEXUS C1-C4 ventral rami (behind IJ and SCM) Lesser Occipital Nerve (C2-3): arises from posterior bor- Supraclavicular (C2-3): splits into 3 branches: anterior, der of sternocleidomastoid middle, posterior Sensory: Superior region behind auricle Sensory: Over clavicle, outer trapezius and deltoid Motor: None Motor: None Great Auricular Nerve (C2-3): exits inferior to lesser oc- Ansa Cervicalis (C1-3): superior (C1-2) & inferior (C2-3) cipital nerve, ascends on SCM roots form loop Sensory: Over parotid gland and behind ear Sensory: None Motor: None Motor: Omohyoid Sternohyoid Sternothyroid Tranverse Cervical Nerve (C2-3): exits inferior to greater Phrenic Nerve (C3-5):On anterior scalene, into thorax be- auricular nerve, then to anterior neck tween subclavian artery and vein Sensory: Anterior triangle of the neck Sensory: Pericardium and mediastinal pleura Motor: None Motor: Diaphragm 64 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Right anterior dissection ARTERIES • Spine 2 Internal jugular vein Common carotid artery Thyroid gland (reflected) Middle cervical sympathetic ganglion Ascending cervical artery Vagus nerve (X) Phrenic nerve Vertebral artery Common carotid artery Anterior scalene muscle Recurrent laryngeal nerve Inferior thyroid artery Brachiocephalic trunk Internal jugular vein (cut) Superficial cervical artery Dorsal scapular artery Right external carotid artery Suprascapular artery Right internal carotid artery Costocervical trunk Ascending cervical artery Thyrocervical trunk Inferior thyroid artery Subclavian artery and vein Superficial cervical artery Right oblique schematic view Right common carotid artery Vertebral artery Thyrocervical trunk Deep cervical artery (ascending to Right subclavian artery (1st part medial anastomose with descending branch to, 2nd part posterior to, 3rd part lateral of occipital artery) to anterior scalene muscle) Superficial cervical artery Brachiocephalic trunk Suprascapular artery Costocervical trunk Aortic arch Supreme (superior) Internal thoracic (mammary) artery intercostal artery 1st, 2nd, and 3rd anterior intercostal arteries Dorsal scapular artery Subscapular artery Superior and inferior transverse scapular ligaments Acromion Dorsal scapular artery Suprascapular artery Axillary artery 1st and 2nd posterior intercostal arteries Circumflex scapular artery Thoracodorsal artery COURSE BRANCHES COMMENT/SUPPLY SUBCLAVIAN ARTERY Branches off aorta (L) or bra- Vertebral arteries (R & L) Main arterial supply to the cervical spine and cord chiocephalic trunk (R) b/w an- Thyrocervical trunk Has 4 primary branches terior and middle scalene Ascending cervical Runs with phrenic nerve on anterior scalene muscles muscles Superficial cervical Crosses posterior triangle of neck (scalenes, etc) Deep cervical Off costocervical trunk, anastomoses w/ occipital artery VERTEBRAL ARTERY Enters foramen transversarium Anterior spinal artery Single midline artery supplies anterior 2⁄3 of spinal cord from C6 through C1 then runs Posterior spinal arteries 2 paired arteries supply posterior 1⁄3 of spinal cord in a groove on the atlas, then Anterior ascending Give primary supply to odontoid to brain stem to form basilar Posterior ascending Give primary supply to odontoid artery Ant. segmental medullary Contribute to anterior spinal artery Post. segmental medullary Contribute to posterior spinal arteries Injury or infarct of the anterior or posterior spinal arteries can result in an anterior/central or posterior cord syndrome. NETTER’S CONCISE ORTHOPAEDIC ANATOMY 65

2 Spine • ARTERIES Posterior spinal arteries Anterior spinal artery Anterior segmental medullary artery Anterior radicular artery Posterior radicular artery Branch to vertebral body and dura mater Spinal branch Dorsal branch of posterior intercostal artery Posterior intercostal artery Paravertebral anastomoses Prevertebral anastomoses Thoracic (descending) aorta Section through thoracic level: anterosuperior view COURSE BRANCHES COMMENT/SUPPLY INTERCOSTAL(THORACIC)/LUMBAR ARTERY Paired arteries (R & L) branch off Ventral branch To vertebral bodies aorta, run posterior along vertebral Dorsal branch To posterior elements and cord bodies (between ribs in thoracic Spinal branch Supplies cord, nerve roots, and body region) Major anterior segmental “Artery of Adamkiewicz”—single medullary artery medullary (radicular) (usually left T10-T12) to ant. spinal artery is pri- mary supply to thoracolumbar cord. Injury can cause cord ischemia/paralysis. SPINAL BRANCH Branches off dorsal branch and en- Anterior radicular Runs on ventral root, anastomoses with anterior ters intervertebral foramen Posterior radicular spinal artery Runs on dorsal root, anastomoses with posterior Postcentral branch spinal artery Prelaminar branch Supplies vertebral body and dura Supplies lamina/posterior elements ANTERIOR SPINAL Single midline artery supplies ante- Central (sulcal) branches Supplies central cord region Supplies peripheral 2⁄3 of spinal cord rior 2⁄3 of spinal cord Pial arterial plexus POSTERIOR SPINAL Paired (R & L) arteries supply poste- Supplied by posterior medullary/radicular arteries rior 1⁄3 of spinal cord 66 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

ARTERIES • Spine 2 Posterior cerebral artery Anterior view Cervical vertebrae Posterior view Superior cerebellar artery Posterior inferior cerebellar artery Thoracic Basilar artery vertebrae Posterior spinal arteries Anterior inferior cerebellar artery Lumbar Vertebral artery vertebrae Posterior inferior Sacrum Posterior segmental cerebellar artery medullary arteries Anterior Deep cervical artery spinal artery Vertebral artery Ascending cervical artery Anterior segmental medullary arteries Subclavian artery Ascending cervical Posterior segmental artery medullary arteries Deep cervical artery Posterior intercostal arteries Subclavian artery Anterior segmental Posterior segmental medullary artery medullary arteries Posterior Anastomotic loops to intercostal anterior spinal artery artery Lumbar arteries Pial plexus Lateral (or medial) sacral arteries Major anterior Note: All spinal nerve roots have segmental medullary associated radicular or segmental artery (artery of medullary arteries. Most roots Adamkiewicz) have radicular arteries. Both types of arteries run along roots, but Posterior radicular arteries end before intercostal reaching anterior or posterior artery spinal arteries; larger segmental medullary arteries continue on to Anterior segmental supply a segment of these arteries. medullary artery Lumbar artery Anastomotic loops to posterior spinal arteries Cauda equina arteries Lateral (or medial) sacral arteries NETTER’S CONCISE ORTHOPAEDIC ANATOMY 67

2 Spine • DISORDERS Spinal stenosis: Laminectomy Lateral recesses and neuroforamina opened Laminectomy defect Postoperative view of decompressed vertebral canal DESCRIPTION Hx & PE WORKUP TREATMENT • Strain or spasm of cervical CERVICAL STRAIN • Rest, NSAIDs, physical musculature therapy, usually 2-6wk Hx: Pain (nonradiating) XR: C-spine series: • Often from MVA (“whip- PE: Decreased ROM, muscle usually normal • Can consider limited soft lash”) or overuse tenderness, normal neuro- MR: Usually not collar immobilization logic exam needed • #2 medical complaint in U.S. • “Red flags” indicate further • Multiple etiologies: muscle LOW BACK PAIN workup: fever/chills, radicu- lopathy, abnormal neuro- strain, annular tear, early Hx: Pain (may radiate to XR: L-spine series: logic exam spondylosis, or degenerative buttocks, not below knee) usually normal disc disease PE: Limited ROM, muscle MR: Usually not • Rest, NSAIDs, physical • Common workman (erector spinae) spasm/ needed therapy, usually 2-6wk compensation/disability tenderness, normal neuro- complaint logic exam; test for Wad- • Can consider lumbar brace dell’s signs • Narrowing of spinal • Activity modification, canal results in cord/root SPINAL STENOSIS NSAIDs compression Hx: Pain, paresthesias XR: L-spine series: • PT— flexion exercises • Causes: hypertrophy of relieved by sitting/forward DDD, facet DJD • Nerve root blocks/ facet capsule or ligamentum leaning (neurogenic CT: Canal narrowing flavum, bulging disc, DDD/ claudication) MR: Evaluate cord/ epidural injection osteophytes PE: Pain with back exten- root compression • Decompression (laminec- sion, do good neurologic exam tomy ϩ/Ϫ partial facetectomy) 68 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Spine 2 Cervical disc herniation Laminae, spinous Herniated disc process, and medial compressing one third of facets nerve root removed Portion of Disc herniation and lamina and nerve compression facet removed Lumbar disc herniation Herniated nucleus pulposus Nerve root compressed by herniated disc Disc material removed Disc material removed to decompress nerve root DESCRIPTION Hx & PE WORKUP TREATMENT • Protrusion of nucleus pulpo- HERNIATED NUCLEUS PULPOSUS (HNP) • Rest, activity modification sus through torn annulus • NSAIDs (limit narcotic use) fibers Hx: Neck/back pain, ϩ/Ϫ XR: Often normal ϩ/Ϫ • Physical therapy extremity (radiating) disc space narrowing • Epidural steroid injections • Lumbar: L4-5 #1, traversing pain, paresthesias, and or spondylosis • Diskectomy ϩ/Ϫ fusion: root affected except in far weakness MR: Best study to show lateral herniation (exiting PE: Variable: decreased protruding disc and ‫ ؠ‬Failed conservative root) ROM, spinal tenderness nerve or cord com- treatment Cervical: ϩ/Ϫ Spurling’s pression • Thoracic: rare Lumbar: ϩ/Ϫ straight ‫ ؠ‬Progressive neurologic • Cervical: associated with deficit leg raise spondylosis Neuro: Radicular find- ‫ ؠ‬Cauda equina syndrome • Can compress cord or roots ings • Emergency surgical de- • Compression of cauda CAUDA EQUINA SYNDROME compression-laminectomy/ equina diskectomy Hx/PE: “Saddle” (perianal) XR: Normal or disc • Usually from large midline anesthesia, lower space narrowing • (Prognosis is still guarded disc herniation or extrusion extremity numbness/ MR: Study of choice: even with prompt diagno- weakness, decreased compression of cauda sis and treatment.) • Bowel & bladder dysfunction rectal tone equina • Surgical emergency NETTER’S CONCISE ORTHOPAEDIC ANATOMY 69

2 Spine • DISORDERS Spine Involvement in Osteoarthritis Atlas (C1) Axis (C2) C7 Extensive thinning of cervical discs and hyperextension deformity with narrowing of intervertebral foramina. Lateral radiograph reveals similar changes Degenerative Disc Disease Radiograph of thoracic spine Degeneration of lumbar intervertebral discs and shows narrowing of interverte- hypertrophic changes at vertebral margins with bral spaces and spur formation spur formation. Osteophytic encroachment on intervertebral foramina compresses spinal nerves DESCRIPTION Hx & PE WORKUP TREATMENT • Degenerative changes in CERVICAL SPONDYLOSIS • NSAIDs, activity modification discs, facets, and unco- • Physical therapy, ϩ/Ϫ vertebral joints Hx: Neck pain, ϩ/Ϫ UE XR: Loss of lordosis/ cer- pain, paresthesias, vical straightening, loss traction • C5-6 #1, C6-7 #2; and/or weakness of disc space • Epidural or facet injections menϾwomen PE: Decreased ROM, ϩ MR: Shows disc degener- • Surgical Spurling’s test, ϩ/Ϫ ation or herniation • Causes axial/neck pain neurologic symptoms ‫ ؠ‬Anterior diskectomy and • Can result in cord or root fusion (ACDF) DEGENERATIVE DISC DISEASE compression: myelo/ra- ‫ ؠ‬Posterior decompression/ diculopathy Hx: Back pain without XR: Can be normal or disc fusion radiculopathy height loss • Disc properties change PE: ϩ/Ϫ decreased MR: Low signal (black • Rest, activity modification, (decr. H2O, proteins al- ROM or painful ROM, disc), decreased height NSAIDs, ϩ/Ϫ muscle tered, etc) leads to decr. normal tension signs Discography: confirms relaxers mechanical properties (straight leg/bowstring disc as pain source tests) (used for preop. eval.) • Physical therapy: stretching, • Ligaments/facets as- strengthening, weight control sume greater load, can be source of pain • Consider lumbar bracing • Surgical: lumbar fusion or • Natural process: unclear why only some have pain disc replacement are options 70 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Spine 2 Spondylolysis and Spondylolisthesis Superior articular process (ear of Scottie dog) Pedicle (eye) Transverse process (head) Isthmus (neck) Lamina and spinous process (body) Inferior articular process (foreleg) Opposite inferior articular process (hind leg) Spondylolysis without spondylolisthesis. Posterolateral view demonstrates formation of radiographic Scottie dog. On lateral radiograph, dog appears to be wearing a collar Isthmic type spondylolisthesis. Anterior subluxation of L5 on sacrum due to fracture of isthmus. Note that gap is wider and dog appears decapitated DESCRIPTION Hx & PE WORKUP TREATMENT • Defect or fracture of pars SPONDYLOLYSIS • Rest, activity modification interarticularis (without slip) • Physical therapy: esp. Hx: Insidious onset of XR: L-spine obliques • Assoc. w/ hyperextension low back pain, worse “Scottie dog has a stretching, flexion exercises sports (gymnasts, linemen) with activities collar/neck” • Lumbar brace PE: Decreased lumbar CT: For subtle lesions • Surgery uncommon without • Common in pediatrics lordosis, ϩ/Ϫ tight SPECT: Indicates if lesion • L5 most common site hamstrings has healing capacity advanced spondylolisthesis • Slippage of one vertebra on SPONDYLOLISTHESIS Low grade (1-2): adjacent vertebrae • Rest, activity modification Hx: Insidious onset of XR: Lateral view used to • Physical therapy • Six types: low back pain, worse determine grade (% of • Lumbar bracing ‫ ؠ‬Dysplastic (congenital) with activities ϩ/Ϫ vertebral body slipped) ‫ ؠ‬Isthmic (#1, L5-S1, radicular symptoms Grade 1: 0-25% High grade (3-4): hyperextension) PE: Decreased ROM, Grade 2: 25-50% • Peds: prophylactic pos- ‫ ؠ‬Degenerative (elderly) often painful (esp. ex- Grade 3: 50-75% terolateral (PL) fusion ‫ ؠ‬Traumatic (acute pars fx) tension) ϩ/Ϫ sensory Grade 4: Ͼ75% • Adults: decompression ‫ ؠ‬Pathologic or motor findings CT/SPECT: For subtle and PL fusion ‫ ؠ‬Post-surgical defects and healing potential NETTER’S CONCISE ORTHOPAEDIC ANATOMY 71

2 Spine • PEDIATRIC DISORDERS Scoliosis Measurement of curvature T5 Upper end vertebrae for thoracic curve (highest (Cobb method) 6 vertebra with superior border inclined toward Vertebrae rotated 7 thoracic concavity) Torticollis (Wryneck) with spinous 8 processes and Transitional vertebra pedicles toward 67˚ 9 (lowest vertebra with 10 inferior border inclined toward thoracic con- concavity cavity and highest vertebra with superior Lower end 63˚ border inclined vertebrae toward lumbar for lumbar concavity) curve (lowest vertebra with inferior border inclined toward lumbar concavity) DESCRIPTION EVALUATION TREATMENT • Incomplete spinal cord development MYELODYSPLASIA (neural tube closure defect) Hx: Can be diagnosed intrauterine • Must individualize for each • 4 types depending on severity PE/XR: Based on type of defect: patient • Associated w/elevated maternal AFP 1. Spina bifida • Prenatal folic acid decreases incidence 2. Meningocele • Most need ambulation aids and/ • Associated with multiple deformities 3. Myelomeningocele or orthoses 4. Rachischisis (spine, hips, knees, and feet) Symptoms/exam based on lowest • Muscle balancing (releases) • Often associated with latex allergy functional level (intact L4 allows for • Individual deformities ambulation) • Lateral bending & rotation of the spine ‫ ؠ‬Scoliosis: most need fusion • Types: ‫ ؠ‬Hips: keep them contained ‫ ؠ‬Feet: release or arthrodesis ‫ ؠ‬I. Congenital (abnormal vertebrae) ‫ ؠ‬II. Idiopathic: #1, often ϩfam hx; SCOLIOSIS ‫ ؠ‬Infantile: Ͻ3y.o., MϾF; Hx: Patient or parents may notice • School screening is effective ‫ ؠ‬Juvenile: 3-10y.o.; asymmetry of back; found on • Congenital: progression & need ‫ ؠ‬Adolescent: #1, FϾM, RϾL; school screening; ϩ/Ϫ pain; neuro ‫ ؠ‬III. Neuromuscular: associated with sx rare for surgery depend on severity/ neuromuscular disease PE: Gross or subtle spinal deformity, type • Curve progression evaluated by: ϩ forward bending test; neurologic • Idiopathic: depends on curve & ‫ ؠ‬Curve magnitude: x-ray/Cobb angle findings rare (increased with left- age ‫ ؠ‬Skeletal maturity: use Risser stage sided curves) ‫ ؠ‬Ͻ25°: observation • Classifications: King & Moe, Lenke XR: Full length spinal films: use ‫ ؠ‬25-40°: bracing Cobb technique to determine ‫ ؠ‬Ͼ40°: spinal fusion • Head tilted, chin rotated opposite side angle • Juvenile type often needs fusion • Sternocleidomastoid (SCM) contracture Bending films used to determine • Neuromuscular: often require • Etiology unknown flexibility of the curve/deformity longer fusions, both anterior & • Associated with intrauterine position posterior • Associated with other disorders TORTICOLLIS Hx: Parents notice deformity, ϩ/Ϫ • Rule out any associated disorders lump in the neck (on sternocleido- • Physical therapy/stretching (SCM) mastoid) • Helmet may be needed for PE: Head tilted/rotated, ϩ/Ϫ SCM lump. ϩ/Ϫ cranial and/or facial cranium asymmetry • Surgical release if persistent • Poor eye development is concern XR: Spine/hips: r/o other deformities 72 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

SURGICAL APPROACHES • Spine 2 Longus Anterior Approach to Cervical Spine colli Transverse incisions at desired level (left side preferred) Prevertebral fascia (opened) Intervertebral disc Vertebral body Longus colli (retracted) Esophagus (retracted) Trachea (retracted) Disc Pretracheal fascia Deep cervical fascia Sternocleidomastoid Carotid sheath Prevertebral fascia USES INTERNERVOUS PLANE DANGERS COMMENT • Anterior cervical dis- ANTERIOR APPROACH • Access C3 to T1 kectomy & fusion • Right recurrent laryngeal nerve (ACDF) for cervical Superficial • Recurrent laryngeal n. spondylosis and/or Deep cervical fascia: SCM • Sympathetic n. more susceptible to injury; HNP goes lateral • Carotid artery many surgeons approach on Pretracheal fascia: carotid • Internal jugular left side • Tumor or biopsy sheath goes lateral • Vagus nerve • Thyroid arteries limit extension Deep • Inferior thyroid artery of the approach Prevertebral fascia be- tween longus collis muscles (right & left) NETTER’S CONCISE ORTHOPAEDIC ANATOMY 73

2 Spine • SURGICAL APPROACHES Posterior Approach to Cervical Spine Incision Paraspinous site muscles (retracted) C-2 Vertebral lamina C-7 Ligamentum flavum Vertebral spine Interspinous ligament Atlantoaxial Paraspinous muscles capsule Vertebral lamina Incision site Posterior Approach to Lumbar Spine Erector spinae Erector spinae muscle (reflected) muscle Vertebral spine Vertebral lamina Vertebral lamina USES INTERNERVOUS PLANE DANGERS COMMENT • Posterior fusion/spondylosis POSTERIOR APPROACH • Most common C-spine • Facet dislocation approach Cervical • Herniated disc (HNP)/nerve • Mark level of pathology with compression & diskectomy Left and right paracervical • Spinal cord radiopaque marker preop to muscles (posterior cervi- • Nerve roots assist finding the appropri- • Lumbar fusion cal rami) • Posterior rami ate level intraoperatively • Vertebral artery • Segmental vessels • Incision is along the spinous processes Lumbar Left and right paraspinal • Segmental vessels muscles (dorsal rami) to paraspinals 74 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Topographic Anatomy CHAPTER 3 Osteology Radiology Shoulder Trauma Joints 76 Minor Procedures 77 History 79 Physical Exam 80 Muscles 85 Nerves 88 Neurovascular Structures 89 Arteries 90 Disorders 94 Pediatric Disorders 98 Surgical Approaches 100 101 102 105 106

3 Shoulder • TOPOGRAPHIC ANATOMY Biceps brachii muscle Triceps brachii muscle Sternocleidomastoid muscle Sternal head Axilla Anterior axillary fold Clavicular head Posterior axillary fold Clavicle (pectoralis major) Acromioclavicular joint Pectoralis major muscle Acromion Clavicular head Sternoclavicular joint Sternal head Deltoid muscle Latissimus dorsi muscle Cephalic vein Serratus anterior muscle Trapezius muscle Deltoid muscle Spine of scapula Deltoid muscle Spine of scapula Infraspinatus muscle Triangle of auscultation Triceps brachii muscle Medial border of scapula Long head Lateral head Inferior angle of scapula Tendon Teres major muscle Latissimus dorsi muscle STRUCTURE CLINICAL APPLICATION Sternoclavicular (SC) joint Uncommon site of infection or dislocation Clavicle Subcutaneous bone: most common bone to fracture Acromioclavicular (AC) joint Common site of “shoulder separation” or degenerative joint disease/pain Acromion Landmark of shoulder (especially for injections, e.g., subacromial) Deltoid muscle Can test muscle function for axillary nerve motor function Trapezius Common site of pain; weakness results in lateral scapular winging Serratus anterior Weakness/palsy results in medial scapular winging Pectoralis major Can rupture off humeral insertion, results in a defect in the axillary fold Cephalic vein Lies in the deltopectoral interval Spine of scapula More prominent with supra/infraspinatus muscle wasting (suprascapular nerve palsy) Inferior angle of scapula May “wing” medially or laterally if muscles are weak (nerve palsies) 76 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

OSTEOLOGY • Shoulder 3 Acromial angle Acromion Coracoid process Clavicle (cut) Superior angle Supraglenoid tubercle Superior border Anatomical neck Suprascapular notch Greater tubercle Neck Lesser tubercle Medial border Surgical neck Intertubercular Subscapular fossa sulcus (bicipital groove) Glenoid Infraglenoid tubercle cavity of Lateral border Crest of scapula Inferior angle greater tubercle Head of Crest of humerus Scapula lesser tubercle Humerus Suprascapular notch Clavicle (cut) Deltoid tuberosity Coracoid process Superior border Acromion Acromial angle Superior angle Spinoglenoid notch (notch connecting supraspinous Supraspinous fossa and infraspinous fossae) Spine Greater tubercle Neck Head of humerus Infraspinous fossa Medial border Anatomical neck Lateral border Groove for Surgical neck Inferior angle circumflex Infraglenoid tubercle scapular Deltoid tuberosity vessels Scapula Humerus Radial groove CHARACTERISTICS OSSIFY FUSE COMMENTS • Flat, triangular bone SCAPULA • Suprascapular nerve can be compressed • Spine posteriorly in suprascapular notch (denervates SS & Primary 8wk fetal 15-20yr IS) or in the spinoglenoid notch (dener- separates two fossae Body vates IS only) (supra/infraspinatus) • Two notches Secondary 1yr All fuse • Suprascapular & spinoglenoid notches • Coracoid process Coracoid 15-18yr between • Coracoid is the “lighthouse” to the anteriorly Glenoid 15-18yr 15-20yr • Glenoid: pear shaped Acromion 15-18yr shoulder • Acromion: hook-shaped Inferior angle • Glenoid: 5-7° retroverted, 5° superior tilt lateral prominence • Unfused acromion results in os acromiale PROXIMAL HUMERUS • Body of scapula is very thin, angle is • Head is retroverted: 35° • Anatomic and surgical Primary 8-9wk Birth thicker Shaft fetal necks • Anatomic neck fxs: risk for osteonecrosis • Head/neck angle: 130° Secondary 17-20yr • Surgical neck: common fx site (especially • Two tuberosities: Proximal (3): Birth in the elderly) Greater is lateral Head 1-2yr • 80% of bone growth from proximal Lesser is anterior Gtr tuberosity 3-4yr • Bicipital groove between Lsr tuberosity physis; proximal fxs in children have gtr and lsr tuberosities: great remodeling potential bicep tendon • Greater tuberosity: insertion site of su- praspinatus, infraspinatus, teres minor • Lesser tuberosity: insertion site of subscapularis NETTER’S CONCISE ORTHOPAEDIC ANATOMY 77

3 Shoulder • OSTEOLOGY Superior surface Acromial Posterior end Anterior Shaft body Sternal end Acromial facet Inferior surface Impression for Anterior costoclavicular ligament Trapezoid line Posterior Sternal facet Conoid tubercle Subclavian groove Clavicle (for subclavius muscle) Acromion Coracoid process X-ray, clavicle Acromion X-ray, clavicle Clavicle Humeral head Coracoid process Clavicle Glenoid Acromioclavicular joint Acromioclavicular Acromion joint Coracoclavicular distance Sternoclavicular joint X-ray, AC joints CHARACTERISTICS OSSIFY FUSE COMMENTS • S-shaped cylindrical bone CLAVICLE • Only link from upper extremity to • Middle 1⁄3 is narrowest, axial skeleton Primary (2) no muscle insertions Medial & lateral 7wk fetal 9wk fetal • Most commonly fractured bone in • Clavicle widens laterally body; middle 1⁄3 is most common • No true medullary canal Secondary 18-20yr 19-25yr location of fracture (80%) Sternal 18-20yr 19-22yr Acromial • First bone to ossify, last to fuse • Starts as intramembranous, then fin- ishes as membranous ossification 78 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Clavicle Acromion RADIOLOGY • Shoulder 3 (slight hook) Coracoid Humeral process Greater head tuberosity Coracoid process Humeral head Glenoid X-ray, scapular X-ray axillary, lateral Acromion Clavicle Acromion Humeral Clavicle Humeral head head Coracoid Greater process tuberosity Glenoid Lesser Glenoid tuberosity X-ray, AP Coronal, CT RADIOGRAPH TECHNIQUE FINDINGS CLINICAL APPLICATION CLAVICLE Clavicle (2 view) AP w/caudal & cephalic tilt Clavicle Fracture, DJD of ACJ Zanca AP (of ACJ) w/10° cephalic tilt Acromioclavicular joint ACJ pathology (DJD, fx) Stress views Both ACJs w/w-out weights Acromioclavicular joints ACJ separation/instability Serendipity 40° cephalic tilt manubrium Sternoclavicular joint Sternoclavicular pathology SHOULDER AP Plate perpendicular to scapula Glenohumeral joint space Trauma (fx/dx), arthritis Axillary lateral Abduct arm, beam into axilla Glenoid/humeral head position Dislocations, Hill-Sachs lesion Scapular Y Beam parallel to scapula Humeral head position Trauma, acromion type Supraspinatus Scapular Y w/10° caudal tilt Acromion morphology Hooked acromion (type 3) is outlet assoc. w/ impingement synd. Stryker notch Hand on head, 10° cephalic tilt Humeral head Hill-Sachs lesion West point Bony Bankart lesion Prone, beam into axilla Anterior inferior glenoid CT Fractures (esp. proximal hu- OTHER STUDIES merus, glenoid/intraarticular) MRI Rotator cuff or labral tears Axial, coronal, sagittal Articular congruity, fx fragment position Sequence protocols vary Soft tissues (tendons, labrum) NETTER’S CONCISE ORTHOPAEDIC ANATOMY 79

3 Shoulder • TRAUMA Fractures of lateral third of clavicle Type I. Fracture with no Type IIA. Fracture is Type IIB. Fracture is Type III. Fracture through disruption of ligaments and medial to ligaments. Both between ligaments; coroid acromioclavicular joint; therefore no displacement. ligaments are intact. is disrupted, trapezoid is no displacement. Often Treated with simple sling intact. Medial fragment missed and may later cause for few weeks may elevate. painful osteoarthritis requir- ing resection arthroplasty DESCRIPTION EVALUATION CLASSIFICATION TREATMENT CLAVICLE FRACTURE • Most common fx Hx: Trauma/fall, pain • Group 1: middle 1/3 • Closed treatment/sling • 80% in middle third PE: Swelling, tenderness. for most groups 1& • Group 2: distal 1/3 3 fxs (group 1) ϩ/Ϫ tenting of skin/ ‫ ؠ‬Type 1: lateral to • 15% group 2, 5% group 3 clinical deformity; do CC ligaments • ORIF for fxs severely • Mechanism: fall onto thorough neurovascular ‫ ؠ‬Type 2a: medial to shortened, tented, exam CC ligaments open, associated with shoulder (e.g., football, XR: 2 views of clavicle ‫ ؠ‬Type 2b: between vascular injuries hockey) (evaluate for shortening) CC ligaments (conoid • Clavicle is unfused until CT: Rarely needed • ORIF for most group early 20’s, periosteal torn, trapezoid intact) 2/type 2 distal fxs sleeve avulsion fx can re- ‫ ؠ‬Type 3: fx into ACJ sult distally • Group 3: proximal 1/3 COMPLICATIONS: Nonunion (esp. distal/group 2 fx); vascular or nerve injury SCAPULA FRACTURE • Mechanism: high-energy Hx: Trauma (e.g., MVA), • Anatomic classification: A-G • Closed treatment with trauma pain in back and/or sling for 2wk for most shoulder • Ideberg (glenoid fx) fxs, then early ROM • Uncommon injury PE: Swelling, tenderness ‫ ؠ‬Type I: anterior avulsion fx • Young males most to palpation, decreased ‫ ؠ‬Type II: transverse/oblique • ORIF for displaced, ROM fx through glenoid; exits unstable, or large common XR: AP/axillary lateral/ (Ͼ25%) intraarticular • Ͼ85% have associated scapular Y; CXR inferiorly or angulated neck fxs CT: Intraarticular/glenoid ‫ ؠ‬Type III: oblique fx through injuries: pulmonary contu- fractures, displaced sion, pneumothorax body fractures glenoid, exits superiorly • Good healing potential ‫ ؠ‬Type IV: transverse fx exits provided by surrounding muscles through the scapula body ‫ ؠ‬Type V: types II ϩ IV COMPLICATIONS: Associated injuries: Rib fracture #1, pulmonary contusion, pneumothorax, vascular or brachial plexus 80 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

TRAUMA • Shoulder 3 Grade 1 Grade 2 Grade 3 Grade 4 Grade 5 Grade 6 DESCRIPTION EVALUATION CLASSIFICATION TREATMENT ACROMIOCLAVICULAR SEPARATION • Mechanism: fall onto Hx: Fall/direct blow, pain, Rockwood grade: • Grades I & II: sling, shoulder (e.g., football, swelling, ϩ/Ϫ popping I. AC ligament sprain rest, physical therapy bicycles, etc) PE: AC tenderness, ϩ/Ϫ II. AC tear, CC intact instability & deformity III. AC & CC ligament tears Յ • Grade III: controversial. • Progression from isolated XR: AC joint (ϩ/Ϫ stress 100% superior displacement Nonoperative for most, AC ligament injury to views, esp. grade II) IV: Grade III w /posterior CC reconstruction for combined AC and CC (measure CC distance) displacement high-level athletes & (coracoclavicular) ligament MR: Evaluate CC V: Grade III Յ 300% superior laborers disruption with varying ligaments displacement clavicle displacement VI: Grade III w/ inferior • Grades IV-VI: CC liga- displacement ment reconstruction • Aka “shoulder separation” COMPLICATIONS: AC arthrosis/DJD; stiffness; associated injuries (pneumothorax, fracture, neurapraxia) NETTER’S CONCISE ORTHOPAEDIC ANATOMY 81

3 Shoulder • TRAUMA Anterior Dislocation Anterior dislocation (most Anteroposterior radiograph common) Anterior dislocation Posterior Dislocation Posterior (subacromial) dislocation Antero- Lateral posterior view view Anteroposterior radiograph. Lateral radiograph (parallel True axillary view. Also shows humeral Difficult to determine if to plane of body of scapula). head posterior to glenoid cavity. humeral head within, Humeral head clearly seen anterior, or posterior to to be posterior to glenoid glenoid cavity. cavity. DESCRIPTION EVALUATION CLASSIFICATION TREATMENT GLENOHUMERAL DISLOCATION • Most common dislocation Hx: Trauma/fall, pain, in- Anatomic (based on loca- • Acute: reduce dislocation • Common in young/athletic ability to move arm tion of humeral head): PE: “Flattened” shoulder, • Anterior (Ͼ90%) • Methods (with sedation): patients (recurrence Ͼ90% no ROM, test axillary • Posterior (often missed) ‫ ؠ‬Hippocratic/traction if Ͻ25y.o.) nerve function • Inferior (luxatio erecta: ‫ ؠ‬Stimson • Associated w/ labral tears XR: 3-view shoulder; abducted arm cannot ‫ ؠ‬Milch (Ͻ40y.o.) and rotator cuff must have axillary lateral be lowered [rare]) ‫ ؠ‬Scapular retraction tears (Ͼ40y.o.) for posterior dislocation • Superior (extremely • Associated with fxs: tuber- CT: To evaluate fxs: tuber- rare) • Immobilize: sling for 2wk osity or glenoid rim (“bony osity or glenoid Bankart”) • Physical therapy • Posterior dislocations asso- ciated w/ seizures • ORIF of displaced fxs • Humeral head impression fracture (Hill-Sachs lesion) • Consider early labral can occur repair in young patients COMPLICATIONS: Recurrent dislocation/instability (esp. in young/Ͻ25y.o.); nerve injury (axillary, musculocutaneous) 82 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

TRAUMA • Shoulder 3 Reduction of Anterior Dislocation of Glenohumeral Joint Stimson maneuver Patient prone on table with affected limb hanging freely over edge; 10–15-lb weight suspended from wrist. Gradual traction overcomes muscle spasm and in most cases achieves reduction in 20–25 minutes. Milch maneuver Patient supine; steady downward traction applied at elbow, combined with slow, gradual external rotation and abduction of limb. Hippocratic maneuver Patient supine on table. Examiner places sole of foot (shoe removed) against patient’s axillary fold for countertraction, grasps patient’s wrist with both hands, and applies steady longitudinal traction. Ancient but occasionally useful method. NETTER’S CONCISE ORTHOPAEDIC ANATOMY 83

3 Shoulder • TRAUMA Supraspinatus and Rotator interval external rotator mm. Anatomic neck Neer four-part classification of 13 Greater fractures of proximal humerus. 2 tuberosity 1. Articular fragment (humeral head). 4 Surgical neck 2. Lesser tuberosity. Lesser Long tendon of 3. Greater tuberosity. tuberosity biceps brachii m. 4. Shaft. If no fragments displaced, fracture considered Subscapularis m. stable (most common) and treated with minimal external immobilization and early range-of-motion exercise. Neer Classification of Proximal Humerus Fractures 2 Part 3 Part 4 Part Anatomical neck Surgical neck Greater tuberosity Greater tuberosity Greater and lesser tuberosities Lesser tuberosity Lesser tuberosity DESCRIPTION EVALUATION CLASSIFICATION TREATMENT PROXIMAL HUMERUS FRACTURE • Common fx, esp. in Hx: Trauma/fall, pain, • Neer: based on number of • 1 part: sling, early motion elderly/osteoporotic difficult to move arm parts (fragments) • 2 part: closed reduction & patients PE: Humeral tenderness, decreased ROM, ϩ/Ϫ • Parts (4): head, GT, LT, coaptation splint, then PT • Proximal humeral cancel- deformity shaft • 3 part: operative: PCP vs lous bone is susceptible XR: 3-view shoulder to fx CT: Identify fragments • Fragment must be Ͼ1cm ORIF (locking plate) and displacement displaced or 45° angula- • 4 part: ORIF vs hemi- • Muscular attachments tion to be considered a determine displacement “part” arthroplasty pattern • Multiple combinations of • Most are minimally fragments/parts possible displaced/1-part fxs • Associated with rotator cuff tears COMPLICATIONS: Shoulder stiffness, AVN (anatomic neck fractures), nerve injury (axillary, brachial plexus), nonunion 84 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Shoulder 3 Anterior sternoclavicular ligament Sternoclavicular Joint Articular disc of Clavicle sternoclavicular joint Interclavicular Subclavius muscle ligament Articular cavities of Costoclavicular ligament sternoclavicular joint 1st rib Costoclavicular ligament Costal cartilages Synchondrosis of 1st rib 2nd rib Manubrium Radiate sternocostal ligament Sternocostal (synovial) joint Manubriosternal synchondrosis LIGAMENT ATTACHMENTS COMMENTS SHOULDER JOINTS General • The shoulder is made up of 4 separate articulations. Shoulder motion is a combined movement from all 4 articula- tions: 1. Sternoclavicular joint, 2. Glenohumeral joint, 3. Acromioclavicular joint, 4. Scapulothoracic articulation • The shoulder joint has the most range of motion in the body. ‫ ؠ‬Forward flexion: 0-170° ‫ ؠ‬Extension: 0-60° ‫ ؠ‬Abduction: 0-170/180° ‫ ؠ‬Internal rotation: to thoracic spine ‫ ؠ‬External rotation: up to 70° • 2:1 ratio of glenohumeral joint to scapulothoracic articulation motion during shoulder abduction • Inherently unstable joint with huge ROM potential. Static and dynamic stabilizers give joint stability. ‫ ؠ‬Static: glenoid, labrum, articular congruity, glenohumeral ligaments & capsule, negative intraarticular pressure ‫ ؠ‬Dynamic: rotator cuff muscles/tendons, biceps tendon, scapular stabilizers (periscapular muscles), proprioception • Shallow glenoid “socket” gives minimal bony stability, but is deepened/stabilized by the fibrocartilaginous labrum. • Labrum serves as a “bumper”/stop to humeral subluxation, as well attachment site for capsuloligamentous structures. Joint instability can result from labral tear/detachment with loss of “bumper” and resultant ligamentous laxity. • Rotator cuff: confluent “horseshoe-” shaped insertion of 4 stabilizing muscle tendons inserting on the proximal hu- merus (greater & lesser tuberosities). RC muscles actively keep humeral head seated into glenoid during all motions. STERNOCLAVICULAR JOINT Diarthrodial/double gliding joint. Only true attachment of upper extremity to axial skeleton. ROM: clavicle rotates in joint up to 50° on the fixed sternum. Capsule Surrounds joint Secondary stabilizer Sternoclavicular Medial clavicle to sternum Primary stabilizer of sternoclavicular joint Anterior and posterior ligaments Posterior stronger, anterior dislocation more common Costoclavicular Inferior clavicle to costal cartilage Strongest sternoclavicular ligament Interclavicular Between medial ends of clavicle Secondary stabilizer Disc Intraarticular disc Fibrocartilage disc within the joint SCAPULOTHORACIC ARTICULATION The articulation is not an actual joint. Scapula slides/rotates along posterior ribs (2-7). Multiple muscles (including serra- tus anterior and trapezius) are involved. 2:1 ratio of GHJ to scapulothoracic motion during flexion & abduction NETTER’S CONCISE ORTHOPAEDIC ANATOMY 85

3 Shoulder • JOINTS Coronal section through joint Joint opened: lateral view Acromion Acromioclavicular Acromion Coracoacromial Coracoid process Synovial membrane joint Supraspinatus ligament Coracohumeral Glenohumeral Glenoid tendon (fused ligament ligament labrum, to capsule) (SGHL) superior Biceps brachii Sub- Subdeltoid tendon deltoid Glenoid bursa (long head) bursa labrum, Infraspinatus tendon Superior Supra- inferior (fused to capsule) glenohumeral spinatus ligament tendon Glenoid Glenoid cavity Deltoid cavity of (cartilage) Subscapularis muscle scapula tendon Axillary recess Teres minor tendon (fused to capsule) (pouch) (fused to capsule) Middle glenohumeral Synovial membrane ligament (cut edge) Inferior glenohumeral Posterior band ligament Openings of subtendinous Anterior band bursa of subscapularis MRI axial, shoulder Key MRI coronal, shoulder Key G^ G Greater tuberosity as D Deltoid L# L Lesser tuberosity D* s Supraspinatus h* h Humeral head +g + Supraspinatus +s ^ Biceps tendon # Subscapularis tendon G tendon g s Subscapularis a Acromion g Glenoid G Greater * Anterior labrum + Posterior labrum tuberosity * Superior labrum g Glenoid LIGAMENT ATTACHMENTS COMMENTS GLENOHUMERAL JOINT Spheroidal (“ball & socket”) joint. Inherently unstable joint stabilized by dynamic and static restraints Glenohumeral Ligaments Superior (SGHL) Anterosuperior glenoid rim/labrum to Resists inferior translation & ER in shoulder adduction proximal lesser tuberosity Resists posterior translation in 90° of forward flexion Middle (MGHL) Anterosuperior glenoid rim/labrum (in- Resists anteroposterior translation in 45° of abduction ferior to SGHL) to just medial to Secondary restraint to translation & ER in adduction lesser tuberosity Buford complex: thickened MGHL & absent anterior/ superior labrum Inferior (IGHL) Most important ligament, forms sling that tightens in abduction & ER (ant. band)/IR (post. band) • Anterior band Anterior glenoid/labrum (3 o’clock) to Resists anterior & inferior translation in abduction & ER; (AIGHL) inferior humeral neck must be tightened/“shifted” in anterior instability or MDI • Posterior band Posterior glenoid/labrum (9 o’clock) to Resists posterior translation in IR & 90° flexion (PIGHL) inferior humeral neck Other Coracohumeral Coracoid base to both LT and GT With SGHL, resists inferior translation in adduction; part of (CHL) (either side of bicipital groove) pulley to stabilize biceps tendon in joint and groove Labrum Circumferentially attached to glenoid Fibrocartilage: deepens glenoid, provides more contact area, adds stability; insertion site for some GH ligaments Capsule Surrounds joint Maintains intraarticular negative pressure, thin posteriorly • Glenohumeral ligaments: Discrete thickenings of anterior and inferior capsule that provide stability to the joint. There are no ligaments posteriorly or superiorly. • Rotator interval: Triangular space between anterior border of supraspinatus and superior border of subscapularis ‫ ؠ‬Contents: SGHL, CHL, and biceps tendon, anterosuperior glenohumeral capsule ‫ ؠ‬Tightening of this interval can decrease the inferior translation in adduction/”sulcus sign” in the unstable shoulder • Biceps pulley: SGHL, CHL, subscapularis form an anterior pulley to keep biceps tendon located in joint/bicipital groove 86 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Arthroscopy of Shoulder JOINTS • Shoulder 3 Labrum Subscapularis Middle glenohumeral ligament MRI sagittal, shoulder tendon Biceps Labrum Acromion tendon Clavicle Glenoid Supraspinatus muscle Glenoid Humerus Inferior glenohumeral Biceps Middle glenohumeral ligament ligament Humerus tendon Subscapularis tendon Supraspinatus tendon Infraspinatus tendon Infraspinatus Teres minor muscle Acromioclavicular joint capsule Anterior view Clavicle (incorporating acromioclavicular ligament) l Trapezoid Coraco- Acromion t ligament clavicular Coracoacromial ligament ligament Supraspinatus tendon (cut) Glenohumeral Conoid Coracohumeral ligament ligaments ligament Greater tubercle and Superior transverse Lesser tubercle scapular ligament and of humerus suprascapular notch Transverse humeral ligament Coracoid process Intertubercular (bicipital) tendon sheath (communicates with synovial cavity) Communications of subtendinous Subscapularis tendon (cut) bursa of subscapularis Biceps brachii tendon (long head) Broken line indicates position of subtendinous bursa of subscapularis LIGAMENT ATTACHMENTS COMMENTS ACROMIOCLAVICULAR JOINT Diarthrodial (plane/gliding) joint. Very limited motion (5° rotation). Common site of injury and/or painful degeneration. Capsule Surrounds joints Weak stabilizer, but sufficient under routine loads Acromioclavicular Thickening of superior capsule Provides anterior to posterior stability and axial stability Injured (to some degree) in all AC separations Coracoclavicular Coracoid base to inferior clavicle Provides vertical stability to the clavicle at the AC joint ‫ ؠ‬Conoid Posteromedial insertion on clavicle Stronger resistance to vertical load than trapezoid ‫ ؠ‬Trapezoid Anterolateral insertion on clavicle Resists axial load to shoulder (more oblique fibers) Disc In joint, between clavicle & acromion Interposed to cushion partially incongruent joint OTHER STRUCTURES Coracoacromial Coracoid tip to anterior and inferior Key component of the coracoacromial arch; prevents acromion humerus migration in rotator cuff–deficient shoulder Superior transverse Crosses suprascapular notch Suprascapular nerve travels under ligament, suprascap- scapular ular artery crosses over it. Transverse humeral Lesser tuberosity to greater tuberos- Stabilizes biceps tendon within the bicipital groove ity (crosses bicipital groove) Lateral aspect of rotator interval NETTER’S CONCISE ORTHOPAEDIC ANATOMY 87

3 Shoulder • MINOR PROCEDURES Acromioclavicular Subacromial injection approach injection/aspiration (posterior approach) Glenohumeral Subacromial (posterior injection/aspiration approach) (lateral approach) STEPS INJECTION OF ACROMIOCLAVICULAR JOINT 1. Ask patient about allergies 2. Palpate clavicle distally to AC joint (sulcus) 3. Prep skin (iodine/antiseptic soap) over AC joint 4. Anesthetize skin with local (quarter size spot) 5. Use 25g needle, insert needle into sulcus vertically (or with slight lateral to medial tilt) and into joint. You should feel a “pop/give” as the needle enters the joint. Inject 2ml of 1:1 local/corticosteroid preparation (the joint may hold Ͻ2ml of fluid). A subcutaneous wheal indicates that the needle tip is superficial to the AC capsule. 6. Dress injection site INJECTION OF THE SUBACROMIAL SPACE 1. Ask patient about allergies 2. Palpate the acromion: define its borders (esp. lateral border & posterolateral corner) 3. Prep skin (iodine/antiseptic soap) over acromial edge 4. Anesthetize skin with local (quarter size spot) 5. Hold finger (sterile glove) on acromion, insert needle under acromion (lateral or posterior) w/ slight cephalad tilt. Aspirate to ensure not in a vessel, then inject 5ml of preparation; will flow easily if in joint. Use: a. diagnostic injection: local only; b. therapeutic injection: local/corticosteroid 6. Dress injection site GLENOHUMERAL INJECTION 1. Ask patient about allergies 2. Palpate the posterior shoulder for the “soft spot” (usually 2cm down, 1cm medial to posterolateral corner of the acro- mion). Also palpate the coracoid process on the anterior aspect of the shoulder. 3. Prepare skin (iodine/antiseptic soap) over the “soft spot” on posterior shoulder 4. Anesthetize the skin overlying the “soft spot” (quarter size spot) 5. With sterile gloves, palpate the “soft spot” and the coracoid process. Then insert the needle into the soft spot and aim it toward the coracoid process. If the needle hits bone it should be redirected (glenoid: move lateral; humerus: move medial). Aspirate to ensure not in a vessel. Inject preparation (local ϩ/Ϫ corticosteroid) into joint (should flow easily if in the joint space) 6. Dress injection site 88 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

HISTORY • Shoulder 3 Injury to acromioclavicular joint. Usually caused Throwing athletes can develop rotator cuff tears, by fall on tip of shoulder, depressing acromion internal impingement, and motion abnormalities (shoulder separation) Shoulder instability is common in swimmers QUESTION ANSWER CLINICAL APPLICATION 1. Age Old Rotator cuff tear, impingement, arthritis (OA), adhesive 2. Pain Young capsulitis (frozen shoulder), humerus fracture (after fall) a. Onset Instability, labral tear, AC injury, distal clavicle osteolysis, b. Location impingement in athletes c. Occurrence d. Exacerbating/ Acute Fracture, dislocation, rotator cuff tear, acromioclavicular relieving injury Chronic Impingement, arthritis/DJD, rotator cuff tear 3. Stiffness On top/AC joint AC joint arthrosis/separation 4. Instability Night pain Classic for RC tear, tumor (rare) Overhead worse Rotator cuff tear, impingement 5. Trauma Overhead better Cervical radiculopathy 6. Work/activity Yes Osteoarthritis (OA), adhesive capsulitis 7. Neurologic sx “Slips in and out” Dislocation (Ͼ90% anterior, esp. in abduction & ER (e.g., 8. PMHx throwing), subluxation, labral tear Direct blow Fall on outstretched hand Acromioclavicular (AC) injury Glenohumeral dislocation (subluxation; fracture) Overhead usage Weight lifting Rotator cuff tear Athlete: throwing type Osteolysis (distal clavicle) Long-term manual labor RC tear/impingement (internal), instability (swimmer’s) Arthritis (OA) Numbness/tingling/”heavy” Thoracic outlet syndrome, brachial plexus injury Cardiopulmonary/GI Referred pain to shoulder NETTER’S CONCISE ORTHOPAEDIC ANATOMY 89