7. Anorectal Musculature Flashcards
Identify 1
- External anal sphincter (Deep; Superficial; Subcutaneous)
External anal sphincter surrounds the last 2 cm of the (1)___ and consists of (2) ____ (3 portions)
- anal canal
- subcutaneous, superficial, and deep portions.
External anal sphincter
Some fibers attach anteriorly to the (1)___ and posteriorly to the (2)___.
perineal body
anococcygeal ligament
External anal sphincter
Some fibers attach anteriorly to the perineal body and posteriorly to the anococcygeal ligament.
→ Fibers also may join (1)___ (3 muscles)
→ Deep fibers interlace with the (2)___ (a muscle)
- the superficial transverse perineal, the levator ani, and the bulbospongiosus muscles.
- puborectalis muscle.
Identify 1 Action?
External anal sphincter (Deep; Superficial; Subcutaneous)
Action: This muscle is in a tonic state of contraction and has no antagonist.
→It keeps the anal canal closed.
Identify 1. Innervation?
External anal sphincter (Deep; Superficial; Subcutaneous)
Innervation: Supplied by the inferior rectal branches (largely S4) of the pudendal nerve (S2-S4).
An internal sphincter lies deep to (1)___ → just superior to the (2)___
- the external anal sphincter
- external anal sphincter
Internal anal sphincter is a (1) ___(skeletal/smooth) muscle
→ It is under involuntary control.
→ Sympathetic fibers maintain (2)___
→ parasympathetic fibers (3)___ and permit (4)___ during defecation or flatulence.
→ This action also requires that the (5)___
- smooth
- its tonic contraction
- relax muscle tone
- expansion of the anal canal
- external anal sphincter be relaxed simultaneously.
Identify 2 - 3
- Sigmoid colon
- Free taenia
Identify 4
Rectosigmoid junction
Identify 5
- Levator ani muscle (cut)
Identify 6
- Perianal skin
