Lecture 16: Perineum Flashcards
Urogenital and Anal triangles
Made from muscles of the perineum
Anal: more posterior
Urogenital: more anterior
What makes up the Pelvic Outlet?
- Pubic Symphysis
- Ischiopubic Ramus
- Ischial Tuberosity
- ST lig.
- Coccyx
*Roughly diamond shape
What is the Perineal Body?
Made of fibrous CT, an attachment point!
Attaching is?
- Levator ani
- Bulbospongiosus
- External anal sphincter
- Perineal Muscles
What two main muscles make up the pelvic floor?
- Levator ani
- Coccygeus
Levator Ani divisions and supply
- Iliococcygeus
- Pubococcygeus
Forms a V shaped structure
Pudendal nerve (S2-4) and nerve to levator ani (S3-4)
Levator Ani: Pubococcygeus
- Levator Prostatae/pubovaginalis
- Pubococcygeus
- Puborectalis; helps maintain fecal continence, forms sling around the rectum (creates angulation)
Levator divisions: Iliococcygeus
Attaches to fascia of Obturator internus, prevents prolapse of pelvic viscera
Label Levator Ani muscles
What is the External Anal sphincter? Function and innervation?
Made of skeletal muscle, it closes the anus (accompanied by puborectalis) and is also under partial voluntary control!
From perineal body to anococcygeal ligament
supplied by Pudendal Nerve (S2-4) - inferior rectal branch
Internal Anal sphincter
Smooth Muscle (involuntary control (ANS))
Deep to External Anal Sphincter (seperated by CT)
Label
Landmarks of the urogenital and anal Sphincters
Laterally: ischial Tuberosity
Posteriorally: Coccyx
Midline: Perineal Body
**avoid the lateral apex (where the nerves are) → impotence or incontinence
The Anal Canal
Where the rectum pierces the pelvic floor it becomes the Anal canal (once passed the puborectalis)
Arterial and Lymphatics of the rectum
- *Superior rectal artery (inf mesenteric)**
- Pre-aortic nodes @ L3*
- *Middle rectal artery (int iliac)**
- Internal iliac nodes*
- *Inferior rectal artery (int pudendal)**
- Internal Iliac nodes*
** anal canal inferior to pectinate line (SF inguinal nodes)
Rectal/anal venous drainage
Superior and inferior recal vein meet at portal-systemic anastomosis
These drain the internal and external venous plexuses
The perineal membrane
Has an anterior deficiency (where the deep dorsal vein of penis/clitoris moves through)
- Attachment site for nearly all perineal muscles eg; deep transverse perineal muscles and compressor urethra
- Forms inferior layer of urogenital diaphragm/ Deep perineal pouch
Urogenital Diaphragm
What’s the male/female variation of the Deep Perineal Pouch
Female:
- Compressor urethrae
- DOrsal n. of the clitoris
- **Bartholins glands in SF pouch
Male:
- ‘membranous’ urethra
- Bulbospongiosus
- DOrsal n. of the penis
Superficial Perineal Pouch
Structures between the perineal membrane and skin
- Nerves + vessels
- Erectile tissues
- Perineal muscles
- Bartholins gands (females)
Internal Pudendal artery important branches. Draw.
Pudendal Nerve
Mirrors the artery. (S2-4) motor and sensory
Perineal muscles, ext. urethral sphincter, skin of genitalia, erectile muscles
Sex- the nervous system
Saddle anasthesia
Compression of cauda equina (S5 to anus) → numb butt thighs and perineum
