anatomy

AnatomyLertcharernrit J.,MD.

Bony pelvis

Bony pelvisformed by sacrum coccyx paired hipbone its ligament & foramina

Sacrum&Coccyx

Bone : Sacrum & Coccyx

Bone : Sacrum & Coccyx1. Sacral promontory landmark for insert laparoscope & for sacrocolpopexy just below the level of bifurcate of common iliac arteries2. Four paired anterior & posterior sacral foramina exit sites for sacral nerve3. sacral hiatus clinically important for caudal anesthesia

Bone : Hip bones/Os coxas have 3 components : ilium, ischium and pubis

Bone : Hip bones

Bony pelvis The pelvis is conceptually divided into false and true components. The false pelvis lies above the linea terminalis. The true pelvis is below the linea terminalis.

Bony pelvisboundary of False pelvis boundary of True pelvis posterior : lumbar vertebrae superior : linea terminalis lateral : iliac fossa inferior : pelvic outlet in front : lower portion of posterior : anterior surface of anterior abdominal wall sacrum lateral : ischial bone, sacrosciatic notch and ligament in front : pubic bone, superior rami of ischial bone, obturator foramina

Bony pelvisThe true pelvis is the portion important in childbearing.The sidewalls of the true pelvis of an adult woman converge somewhat.ischial spines These are of great obstetrical importance because the distance between them usually represents the shortest diameter of the true pelvis. landmarks in assessing the level to which the presenting part of the fetus has descended into the true pelvis landmarks for pudendal nerve block placement

Plane & Diameters of pelvis the plane of pelvic inlet : superior strait the plane of the mid pelvis : the least pelvic dimensions the plane of pelvic outlet : inferior strait

Pelvic inlet Pelvic inlet (superior strait) is superior plane of the true pelvis Boundary posterior : promontory and alae of the sacrum lateral : linea terminalis anterior : horizontal pubic rami & symphysis pubis During labor, metal head engagement is defined by the fetal head’s biparietal diameter passing through this plane.

Pelvic inlet

Pelvic inlet 4 diameters anteroposterior diameter transverse diameter 2 oblique diameters

Anteroposterior diameter True conjugate : extends from the upper margin of the symphysis pubis to the sacral promontory. >> Normal : 10 cm or more for clinical purposes, the true conjugate is estimated indirectly by subtracting 1.5 to 2 cm from the diagonal conjugate.

Oblique diameter Each of the two oblique diameters extends from one sacroiliac synchondrosis to the contralateral iliopubic eminence. Diameters average less than 13 cm.

Midpelvis also called the midplane or plane of least pelvic dimensions. is measured at the level of the ischial spines. During labor, the degree of fetal head descent into the true pelvis may be described by station. ischial spines serve to mark zero station Interspinous diameter is 10 cm or slightly greater. (the smallest pelvic diameter)

Midpelvis

Pelvic outlet formed by the descending inferior rami of the pubic bones. Angle of 90 to 100 degrees to form a rounded arch under which the fetal head must pass. Unless there is significant pelvic bony disease, the pelvic outlet seldom obstructs vaginal delivery.

Pelvic shapes The Caldwell-Moloy anatomical classification of the pelvis The greatest transverse diameter of the inlet and its division into anterior and posterior segments are used to classify

Bone : Pelvic bone articulation Pelvic bone are joined by 4 articulation 2 cartilaginous symphyseal joints Sacrococcygeal joint Symphysis pubis 2 synovial joints Sacroiliac joints

Bone : Pelvic bone articulationPelvic bone are joined by 4 These joints are surrounded byarticulation strong ligaments anteriorly and posteriorly, which are responsive 2 cartilaginous symphyseal joints to the effect of relaxin and Sacrococcygeal joint facilítate parturition Symphysis pubis 2 synovial joints Sacroiliac joints

Bone : Pelvic bone articulationPelvic bone are joined by 4 these joints are stabilized byarticulation - sacroillac ligaments - iliolumbar ligament 2 cartilaginous symphyseal joints - lateral lumbosacral ligament Sacrococcygeal joint - sacrotuberous ligament Symphysis pubis - sacrospinous ligament. 2 synovial joints Sacroiliac joints

Bone : Pelvic bone articulation These joints in general have a limited degree of mobility. However, during pregnancy, there is remarkable relaxation of these joints at term, caused by upward gliding of the sacroiliac joint. The displacement, which is greatest in the dorsal lithotomy position, may increase the diameter of the outlet by 1.5 to 2.0 cm. The squatting position may increase the interspinous diameter and the pelvic outlet diameter. These latter observations are unconfirmed, but this position is assumed for birth in many societies.

Bone : Ligament Inguinal ligament Cooper’s ligament Sacrospinous ligament sacrotuberous ligament

Bone : Foramina Greater sciatic foramen Lesser sciatic foramen Obturator forramen

Bone : ForaminaGreater sciatic foramen Lesser sciatic foramen- Piriformis m. - Internal pudendal n. & v.- Superior & Inferior gluteal n. & - n. of obturator internus v.- Internal pudendal n. & v.- sciatic n.- posterior cutaneous n. of thigh- n. of obturator internus

Bone : Foramina Obturator foramen transmits the obturator nerves and vessels. The obturator neurovascular bundle can be injuries during transobturator tape placement.

Muscle

Abdominal wall Boundary Superior : Xyphoid process & costal cartilage of the 7th to 10th ribs Inferior : iliac crest & anterosuperior iliac spine & inguinal ligament & pubic bone consists of skin, muscle, fascia, nerve, vessel

Abdominal wall Skin Langer lines describe the orientation of dermal fibers within the skin. Lower abdominal skin may exhibit striae or “stretch mark” and hyper pigmentation in parous women. Subcutaneous tissue contains a variable amount of fat.

Abdominal wallMuscle consists of 5 muscle & their fibrous aponeuroses

The fibrous aponeurosesof these three lattermuscles form the primaryfascia of the anteriorabdominal wall.These fuse in the midline atthe linea alba (10-15 mm).



Abdominal wallFascia Superficial fascia consist of 2 layers ; Camper fascia : superficial layer contains a variable amount of fat. is continuous with the superficial fatty layer of the perineum. Scarpa fascia : a deeper membranous layer continuous in the perineum with Colles fascia (superficial perineal fascia) and with the deep fascia of the thigh (fascia lata).



Abdominal wall : Blood supply

Abdominal wallBlood supply Superficial epigastric a. Superficial circumflex iliac a. Superficial external pudendal a. Inferior “deep” epigastric a. Deep circumflex iliac a.

Abdominal wallSupply at : Skin Subcutaneous layers of the anterior abdominal wall Mons pubis When Pfunnenstiel incision is used, the superficial epigastric a. may be lacerated

Abdominal wallBlood supply Superficial epigastric a. Superficial circumflex iliac a. Superficial external pudendal a. Inferior “deep” epigastric a. Deep circumflex iliac a.

Abdominal wallSupply at : Muscles and fascia of the anterior abdominal wall When a Maylard incision is used, the inferior epigastric artery may be lacerated

Abdominal wallInnervation by intercostal nerves (T7–11) subcostal nerve (T12) iliohypogastric and ilioinguinal nerves (L1) iliohypogastric n. provide sensation to the skin over the suprapubic area. ilioinguinal n. supplies the skin of the mons pubis, upper labia majora, and medial upper thigh.

External generative organs Vulva Vagina & Hymen Perineum

Vulvaincludes all structures visible externally from symphysis pubis toperineal body.mons pubis urethral openinglabia majora and minora greater vestibular or Bartholin glandsclitoris minor vestibular glandshymen paraurethral glandsvestibule

mons pubislabia majora and minoraclitorishymenvestibuleurethral openinggreater vestibular or Bartholinglandsminor vestibular glandsparaurethral glands

Mons pubis called the mons veneris is a fat-filled cushion overlying the symphysis pubis. After puberty the mons pubis skin is covered by curly hair that forms the escutcheon. In women : hair is distributed in a triangle (covers the upper margin of the symphysis pubis to the clitoris). In men and some hirsute women : the escutcheon is not so well circumscribed and extends onto the anterior abdominal wall toward the umbilicus.

Labia majora labia majora are homologous with the male scrotum. amount of fat contain. Size : 7 - 8 cm in length, 2 - 3 cm in depth, and 1 - 1.5 cm in thickness. apocrine, eccrine, and sebaceous glands are abundant. dense connective tissue layer, which is nearly void of muscular elements but is rich in elastic fibers and adipose tissue.

Labia majoraLabia majora is supplied with a rich venousplexus.During pregnancy this vasculature commonly develops varicosities (from increased venous pressure created by the enlarging uterus). They appear as engorged tortuous veins or as small grapelike clusters, but they are typically asymptomatic.

Labia minora In males, its homologue forms the ventral shaft of the penis. Size : lengths 2 - 10 cm. and widths 1 - 5 cm. composed of connective tissue with numerous vessels, elastin fibers, and very few smooth muscle fibers. supplied with many nerve endings >> extremely sensitive lack hair follicles, eccrine glands, and apocrine glands. However, there are many sebaceous glands.