21 Internal Organs

Rectum & Canalis Analis

Fig. 21.1 Rectum: Location

Fig. 21.2 Closure of the rectum
Left lateral view. The m. puborectalis acts as a muscular sling that kinks the junctio anorectalis. It functions in the maintenance of fecal continence.

Fig. 21.3 Rectum in situ
Coronal section, anterior view of the female pelvis. The upper third of the rectum is covered with peritoneum viscerale on its anterior and lateral sides. The middle third is covered only anteriorly and the lower third is inferior to the peritoneum parietale.

Fig. 21.4 Rectum and canalis analis
Coronal section, anterior view with the anterior wall removed.

Table 21.1 Regions of the rectum and canalis analis

Region		Epithelium
Rectum		Colon-like with crypts; simple columnar with goblet cells
Canalis analis	Columnar zone	Stratified squamous, nonkeratinized
	Pecten analis
	Cutaneous zone	Stratified squamous, keratinized with sebaceous glands
Perianal skin (pigmented)		Stratified squamous, keratinized with sebaceous glands, hairs, and sweat glands

Ureteres

The ureteres cross the a. iliaca communis at its bifurcation into the aa. iliacae externa and interna.

Fig. 21.5 Ureteres in situ
Anterior view, male abdomen. Removed: Nonurinary organs and rectal stump. The ureteres are retroperitoneal.

Fig. 21.6 Ureter in the male pelvis
Superior view.

Fig. 21.7 Ureter in the female pelvis
Pelvis viewed from above. Removed from left side: Peritoneum and lig. latum uteri. The partes pelvicae ureterum pass under the a. uterina approximately 2 cm lateral to the cervix.

Vesica Urinaria & Urethra

Fig. 21.8 Female vesica urinaria and urethra

Fig. 21.9 Urethral sphincter mechanism in the female
Anterolateral view.

Fig. 21.10 Male vesica urinaria and urethra

Fig. 21.11 Urethral sphincter mechanism in the male
Lateral view.

Overview of the Genital Organs

The genital organs can be classified topographically (external versus internal) and functionally (Tables 21.2 and 21.3).

Fig. 21.12 Female genital organs

Fig. 21.13 Male genital organs

Uterus & Ovaria

Fig. 21.14 Female internal genitalia
The uterus and ovaria are suspended by the mesovarium and mesometrium (portions of the lig. latum uteri).

Fig. 21.15 Ovarium
Right ovarium, posterior view.

Fig. 21.16 Curvature of the uterus
Midsagittal section, left lateral view. The position of the uterus can be described in terms of flexion () and version ().

Fig. 21.17 Uterus and tuba uterina

Clinical box 21.1

Ectopic pregnancy

After fertilization in the ampulla tubae uterinae, the ovum usually implants in the wall of the cavitas uteri. However, it may become implanted at other sites (e.g., the tuba uterina or even the cavitas peritonealis). Tubal pregnancies, the most common type of ectopic pregnancy, pose the risk of tubal wall rupture and potentially life-threatening bleeding into the cavitas peritonealis. Tubal pregnancies are promoted by adhesion of the tubal tunica mucosa, mostly due to inflammation.

Ligaments & Fasciae of the Deep Pelvis

Fig. 21.18 Ligaments of the female pelvis
Superior view. Removed: Peritoneum, neurovasculature, and superior portion of the vesica urinaria to demonstrate only the fascial condensations (ligamenta). Deep pelvic ligaments support the uterus within the cavitas pelvis and prevent uterine prolapse, the downward displacement of the uterus into the vagina.

Fig. 21.19 Ligaments of the deep pelvis in the female
Superior view. Removed: peritoneum, neurovasculature, uterus and vesica uterina. Uterosacral ligaments and the paracolpium support, and help maintain the positions of, the cervix and vagina in the pelvis.

Fascia pelvis plays an important role in the support of pelvic viscera. On either side of the diaphragma pelvis, where the fascia visceralis of the pelvic organs is continuous with the fascia parietalis of the muscular walls, thickenings called arcus tendinei fasciae pelvis are formed. In females, the paracolpium—lateral connections between the fascia visceralis and the arcus tendinei—suspends and supports the vagina. Ligg. pubovesicalia (and ligg. puboprostatica in the male) are extensions of the arcus tendinei that support the vesica urinaria and prostata. Endopelvic fascia, a loose areolar (fatty) tissue that fills the spaces between pelvic viscera, condenses to form “ligaments” (ligg. cardinalia, ligg. lateralia vesicae, ligg. recti lateralia; see Fig. 21.20) that provide passage for the ureteres and neurovascular elements within the pelvis.

Fig. 21.20 Fascia and ligaments of the female pelvis
Transverse section, through cervix uteri, superior view.

Vagina

Fig. 21.21 Location of vagina
Midsagittal section, left lateral view.

Fig. 21.22 Structure of vagina
Posteriorly angled coronal section, posterior view.

Fig. 21.23 Female genital organs: Coronal section
Anterior view. The vagina is both pelvic and perineal in location. It is also retroperitoneal.

Fig. 21.24 Vagina: Location in the perineum
Inferior view.

Female External Genitalia

Fig. 21.25 Female external genitalia
Lithotomy position with labia minora pudendi separated.

Fig. 21.26 Vestibulum vaginae and vestibular glands
Lithotomy position with labia minora pudendi separated.

Fig. 21.27 Erectile tissue and muscles of the female
Lithotomy position. Removed: Labia and skin. Removed from left side: Mm. ischiocavernosus and bulbospongiosus.

Clinical box 21.2

Episiotomy
Episiotomy is a common obstetric procedure used to enlarge the birth canal during the expulsive stage of labor. The procedure is generally used to expedite the delivery of a baby at risk for hypoxia during the expulsive stage. Alternately, if the perineal skin turns white (indicating diminished blood flow), there is imminent danger of perineal laceration, and an episiotomy is often performed. More lateral incisions gain more room, but they are more difficult to repair.

Penis, Testis & Epididymis

Fig. 21.28 Penis

Fig. 21.29 Testis and epididymis
Left lateral view.

Fig. 21.30 Blood vessels of the testis
Left lateral view.

Male Accessory Sex Glands

The accessory male sex glands consist of the gll. vesiculosae, prostata, and gll. bulbourethrales, which contribute fluid to the ejaculate that provides nourishment for the spermatozoa as well as neutralizes the pH of the male urethra and the vaginal environment.

Fig. 21.31 Accessory sex glands
Posterior view. The ducts of the gl. vesiculosa and ductus deferens combine to form the ductus ejaculatorius.

Fig. 21.32 Anatomic divisions of the prostata

Fig. 21.33 Clinical divisions of the prostata

Fig. 21.34 Prostata in situ
Sagittal section through the male pelvis, left lateral view.

Clinical box 21.3

Prostatic carcinoma and hypertrophy
Prostatic carcinoma is one of the most common malignant tumors in older men, often growing at a subcapsular location (deep to the capsula prostatica) in the peripheral zone of the prostata. Unlike benign prostatic hyperplasia, which begins in the central part of the gland, prostatic carcinoma does not cause urinary outflow obstruction in its early stages. Being in the peripheral zone, the tumor is palpable as a firm mass through the anterior wall of the rectum during rectal examination.

In certain prostatic diseases, especially cancer, increased amounts of a protein, prostate-specific antigen or PSA, appear in the blood. This protein can be measured by a simple blood test.