The perineum (perineum) is a structure that covers the exit from the pelvic cavity. It has a rhomboid shape and has the following borders: the pubic symphysis anteriorly, the apex of the coccyx inferiorly, the lower branches of the pubis and ischium bones, as well as ischial tuberosities bilaterally.
In the center of the perineum, the so-called central tendon of the perineum (centrum tendineum) is located. The median perineal raphe (raphe perinei) runs along the perineum in the anteroposterior direction.
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The structure of the perineum includes a fairly large number of muscles. The line that connects the ischial tuberosities divides the perineum into two important zones:
The urogenital diaphragm (regio urogenitalis)
The pelvic diaphragm / anal triangle (region analis)
Next, we will cover the muscles of the pelvic diaphragm. The rectum passes through the pelvic diaphragm in both men and women.
The muscles of the pelvic diaphragm are divided into superficial and deep.
The superficial muscles include the following:
The external anal sphincter (m. sphincter ani externus)
(m. sphincter ani externus)
Origin: skin in the anus region, as well as on the apex of the coccyx (deeper fasciculi)
Insertion: perineal body
Function: narrows / squeezes the anus, strengthens the perineal body
Innervation: inferior anal branch of the pudendal nerve (S2-S4)
Blood supply: inferior rectal artery, perineal artery
The deep muscles include:
The levator ani muscle (m. levator ani)
(m. levator ani)
Origin:
Puborectal part: posterior surface of the pubis body
Pubococcygeal part: posterior surface of the pubis body (lateral to the part described previously)
Iliococcygeal part: ischial spine, tendinous arch of the internal obturator fascia
Insertion: the muscle covers the rectum, forming a loop, and is partially woven into the wall of the urinary bladder; in men, it is also woven into the prostate, and in women — into the wall of the vagina
Function: promotes retention of urine and feces, strengthens the pelvic floor, and increases intra-abdominal pressure. In women, it also narrows the vaginal opening
Innervation: nerve of the levator ani muscle (S4), inferior anal nerves (S3-S4), coccygeal plexus
Blood supply: inferior gluteal artery
The coccygeus muscle (m. coccygeus)
(m. coccygeus)
Origin: ischial spine
Insertion: inferior part of the sacrum, coccyx
Function: strengthens the pelvic floor, holds the coccyx
Innervation: anterior branches of spinal nerves (S4, S5)
Blood supply: deep pudendal artery, perineal artery
Muscles of the perineum. Diaphragm of the pelvis.
- Perineum
- perineum
- Central tendon
- centrum tendineum perinei
- Perineal raphe
- raphe perinei
- Urogenital diaphragm
- regio urogenitalis
- Pelvic diaphragm / anal triangle
- regioanalis
- External anal sphincter
- m. sphincter ani externus
- Levator ani muscle
- m. levator ani
- Coccygeus muscle
- m. coccygeus
