Dr. med. Dirk Manski



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Anatomy of the Pelvic Cavity

Muscles of the Pelvic Floor

The pelvic floor muscles may be separeted into the pelvic diaphragm, urogenital diaphragm and superficial perineal muscle layer. Fibers of all three layers have contact (are inserting) at the perineal body (central tendon of perineum).

Pelvic Diaphragm

The pelvic floor muscle consists of the levator ani and coccygeus muscle.

Levator Ani:

Funnel-shaped flat pelvic floor muscle originating from the symphysis and fascia obturatoria (parts are called tendinous arc). The muscle fibers of both sides pass downward and backward to the middle line of the pelvic floor, where they meet their contralateral counterpart to form the levator sling, which surrounds the rectum. Ventral to the rectum remains a muscle gap of the levator ani, through which the urogenital organs pass [Fig. pelvic floor muscles].

Coccygeus Muscle

The coccygeus muscle is located dorsally to the levator ani. Origin: sacrospinous ligament and ischial spine. Insertion: coccyx.


Urogenital Diaphragm

The urogenital diaphragm is located caudal to the pelvic diaphragm and closes the ventral gap of the levator ani. The urogenital organs pass through this flat muscle plate. The muscles of the urogenital diaphragm are the external urethral sphincter, superficial and deep transverse perineal muscles [Fig. pelvic floor muscles]. The urogenital diaphragm is surrounded by fascias: the perineal membrane (inferior layer) and superior fascia of the urogenital diaphragm.

Superficial Perineal Muscles of the Pelvic Floor

External Anal Sphincter

The external anal sphincter surrounds circularly the anus and measures about 8–10 cm in length.

Bulbospongiosus Muscle

The bulbospongiosus muscle is a superficial perineal muscle covering the bulb of the penis (in men) and surrounding the vestibulum (in women). The external anal sphincter and the bulbospongiosus muscle form a figure-eight-shaped muscle loop, especially in women, with the central tendon of the perineum in the middle.

Ischiocavernosus Muscle

The ischiocavernous muscle is a superficial perineal muscle covering the crus of the penis (in men) or the crus of the clitoris (in women). In the female the vestibular vaginae is surrounded. The muscle fibers run from ischium to the corpus cavernosum of the penis or clitoris [Fig. pelvic floor muscles].

Pelvic floor muscles. Fig. modified from Gray’s Anatomy, Lea and Febinger 1918, Philadelphia, USA.
figure pelvic floor muscles

Arteries of the Pelvic Cavity

figure arteries of the pelvic cavity

Arteries of the pelvic cavity: A. iliolumbalis (1), A. sacralis mediana (2), A. rectalis media der Gegenseite (3), A. iliaca externa (4), A. epigastrica inferior (5), A. obturatoria (6), A. vesicalis superior (7), A. vesicalis inferior (8), A. rectalis media (9), A. pudenda interna (10), A. glutealis inferior (11), A. glutealis superior (12), A. umbilicalis und Lig. umbilicale (13). Fig. modified from Gray’s Anatomy, Lea and Febinger 1918, Philadelphia, USA.



The common iliac artery divides after a short distance into the external iliac and internal iliac artery [Fig. arteries of the pelvic cavity].

Parietal Branches of the Internal Iliac Artery

The parietal branches supply the wall of the pelvis cavity and reach structures outside of the pelvic cavity through bone and muscle gaps.

Visceral Branches of the Internal Iliac Artery

Branches of the External Iliac Artery

Shortly before the entering the lacuna vasorum (then named femoral artery), the following branches are released:

Veins of the Pelvic Cavity

The veins of the pelvis cavity follow above mentioned arteries and drain into the internal iliac veins. The common iliac vein is formed by the internal and external iliac veins. The confluence of the left and right common iliac vein at the level of the fifth lumbar vertebra gives rise to the inferior vena cava.

Lymphatic Drainage from the Pelvic Cavity

The lymphatic vessels largely follow the course of the veins. Lymph node groups exist as: external iliac lymph nodes, internal iliac lymph nodes, common iliac lymph nodes, obturator lymph nodes, pararectal and sacral lymph nodes. The pelvic lymph nodes drain into the lumbar lymph nodes and reach via the left and right lumbar lymph trunk the cysterna chyli [Fig. pelvic lymph nodes].

figure pelvic lymph nodes

Lymphatic drainage from the pelvic cavity: common iliac artery (1), common iliac lymph nodes (2), external iliac lymph nodes (3), obturator lymph nodes (4), internal iliac lymph nodes (5), pararectal and sacral lymph nodes (6). Fig. modified from Gray’s Anatomy, Lea and Febinger 1918, Philadelphia, USA.







Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z





References

Benninghoff 1993 BENNINGHOFF, A.:
Makroskopische Anatomie, Embryologie und Histologie des Menschen.
15. Auflage.
München; Wien; Baltimore : Urban und Schwarzenberg, 1993


  Deutsche Version: Anatomie der Beckenhöhle