Perineum Flashcards
What is the perineum bounded by?
- coccyx
- Pubis
- Ischial tuberosity
What are the 2 divisions of the perineum?
- anal triangle - posterior
2. urogenital triangle- anterior
Describe the anal triangle
contains the anal canal that can be divided into upper and lower halves
contains the ischioanal fossae
Characteristics of the ischioanal fossae
- Full of fat for expansion and cushion
2. Pudendal canal for the pudendal nerve, internal pudendal artery and vein
What are the branches of the pudendal nerve?
- inferior rectal nerves
2. dorsal nerves of penis or clitoris
What are the branches of the internal pudendal artery?
- Inferior rectal artery
2. External genital artery
Upper half of the anal triangle
Above the pectinate line
- No pain receptors
- Derived from endoderm
- Anal columns present
- Involuntary
- Autonomic innervation
- Superior rectal artery and middle rectal artery
Lower half of the anal triangle
Below the pectinate line
- Pain, stretch, and sensation receptors (clinically important for hemorrhoids)
- Somatic innervation from inferior rectal branch of pudendal
- Inferior rectal arteries
Internal anal sphincter
Located next to anal canal
Involuntary
External anal sphincter
Located next to levator ani muscle
Voluntary and innervated by inferior rectal nerve
Male vs. Female urogenital triangle
- Testes = ovaries
- Body of penis = body of clitoris
- Penile raphe and spongy urethra = labium minora
- scrotum = labia majora
- Bulbourethral gland = greater vestibular gland
- Prostate gland = Paraurethral gland/lesser vestibule
- Gubernaculum = round and ovarian ligament
What are the parts to the root of the penis?
- bulb
2. left and right crura
What is the bulbospongiosus muscles job?
- Covers the bulb
2. squeeze to keep the penis erect and empty the urethra
What is the ischiocavernosus muscles job?
- Covers the left and right crura
2. Squeeze to keep the penis erect and push blood distally
What do the bulb and crura become?
Bulb = corpus spongiosum Crura = corpus cavernosum
What does the body contain?
Three cylinders of erectile tissues
- Corpus spongiosum
- Corpus cavernosa x2
What does the corpus spongiosum contain and do?
Contains the urethra and expands to form the glans
Fills with blood to keep the penis erect
Characteristics of the superficial perineal pouch
- Potential space
- bounded laterally by ischiopubic rami
- Proximal spongy urethra and root of penis here
- 3 muscles connect here