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Section Ill • Gross Anatomy

Clinical Correlate

Support for pelvic viscera is provided by the pelvic and urogenital diaphragms, perinea! membrane, perinea! body, and the transverse (cardinal) cervical and uterosacral ligaments. Weakness of support structures may result in prolapse of the uterus into the vagina or herniation of the bladder or rectum into the vagina.

Uterus and BroadLigament

Figure III-3-28 illustrates a posteriorview of the female reproductive tract.

 

d

{

 

Broa

 

Mesosalpinx

Round

ligament

Mesovarium

ligaments

 

 

Mesometrium

of uterus

Ovarian

artery

Clinical Correlate

The ureter passes inferior to the uterine artery 1 to 2 centimeters from the cervix ("water under the bridge") and must be avoided during surgical procedures.

Clinical Correlate

A pudenda( nerve block to anesthetize the perineum is performed as the pudenda! nerve crosses posterior to the ischial spine (Figure 111-3-248).

Uterine artery

 

Transverse (cardinal)

("water under bridge")

 

 

Ureter

cervical ligament

 

Uterosacral ligament

 

 

 

Figure 111-3-28. Broad Ligament

 

PERINEUM

The perineum is the diamond-shaped outlet of the pelvis located below the pelvic diaphragm. The perineum is divided by a transverse line between the ischial tuber­ osities into the anal and urogenital triangles (Figure III-3-29).

The sensory and motor innervation to the perineum is provided by the pudenda! nerve (S2, 3, 4) of the sacral plexus.

The blood supply is provided by the internal pudenda! artery, a branch of the internal iliac artery.

The pudendal nerve and vessels cross the ischial spine posteriorly to enter the perineum (Figure III-3-24 B).

AnalTriangle

The anal triangle is posterior and contains the anal canal surrounded by the fat-filled ischioanal fossa.

The anal canal is guarded by a smooth-muscle internal anal sphincter innervated by the ANS and an externalanal sphincter of skeletal mus­ cle innervated by the pudendal nerve.

The pudenda! canal transmitting the pudenda! nerve and internal pudenda! vessels is found on the lateral aspect of the ischioanal fossa (Figure III-3-29) .

272 MEDICAL


Chapter 3 • Abdomen, Pelvis, and Perineum

Complete androgen insensitivity (CAIS, ortesticularfeminization syndrome)

Occurs when a fetus with a 46,)CY genotype develops testes and female external genitalia with a rudimentary vagina; the uterus and uterine tubes are generally absent

Testes may be found in the labia majora and are surgically removed to circumvent malignant tumor formation.

Individuals present as normal-appearing females, and their psychosocial(AR) orientation is female despite their genotype.

Most common cause is a mutation in the androgen receptor gene AR inactive.that renders the

Abnormalities ofthe Penis and Testis

Hypospadias

Occurs when the urethral folds fail to fuse completely, resulting in the external urethral orifice opening onto the ventral surface of the penis.

Generally associated with a poorly developed penis that curves ventrally, known as chordee.

Epispadias

Occurs when the external urethral orifice opens onto the dorsal surface of the penis.

Generally associated with exstrophy of the bladder.

Undescendedtestes (cryptorchidism)

Occurs when the testes fail to descend into the scrotum. Normally occurs within 3 months after birth.

Bilateral cryptorchidism results in sterility.

The undescended testes may be found in the abdominal cavity or in the inguinal canal.

Hydrocele ofthe testes

Occurs when a small patency of the processus vaginalis remains so that perito­ neal fluid can flow into the processus vaginalis. Results in a fluid-filled cyst near the testes.

MEDICAL 277


Section Ill Gross Anatomy

RADIOLOGY OF THE ABDOMEN AND PELVIS

Duodenum Pylorus Stomach Jejunum

Ileum

Figure 111-3-31 . Abdomen: Upper GI, Small Bowel

Hepatic

Transverse

Splenic

Flexure

Colon

Flexure

Descending

Colon

Sigmoid

Colon

Figure 111-3-32. Abdomen: Barium Enema

278 MEDICAL


Chapter 3 • Abdomen, Pelvis, and Perineum

 

Inferior

Liver

Vena Cava Aorta Diaphragm Stomach

Figure 111-3-33. Abdomen: CT, T1 1

Liver

Portal Vein

Descending Colon

Inferior Vena Cava Diaphragm Aorta Stomach Spleen

Figure 111-3-34. Abdomen: CT, T12

MEDICAL 279

Section Ill • Gross Anatomy

Liver

Ascending

Descending

Colon

Aorta Stomach Colon

Spleen

Inferior Vena Cava

Diaphragm

Left Kidney

Figure 111-3-35. Abdomen: CT, T12

 

Superior

 

 

Mesenteric

Splenic

Spleen

Liver Pancreas

Artery

Vein

Left Adrenal Gland

Figure 111-3-36. Abdomen: CT, L1

280 MEDICAL


Chapter 3 • Abdomen, Pelvis, and Perineum

Ascending

Superior

Superior

Mesenteric

Mesenteric

Colon Duodenum

Vein

Artery Jejunum

Right

Renal

Inferior

Aorta

Descending

Kidney

Pelvis

Vena Cava

Colon

Figure 111-3-37. Abdomen: CT, L2

 

Inferior

Superior

 

 

Mesenteric

 

Duodenum

Vena Cava

 

Artery

Aorta

Right Kidney Right Ureter Left Psoas Major

Figure 111-3-38. Abdomen: CT, L3

MEDICAL 281