Intermediate Internal Anal Sphincter Quiz

Q1. Which neural influence generally promotes contraction of the internal anal sphincter?

• Motor activity through the obturator nerve
• Somatic motor activity through the femoral nerve
• Sympathetic activity
• Motor activity through the sciatic nerve

Q2. Parasympathetic fibers influencing the distal large intestine and anorectal region arise primarily from which spinal levels?

• T5 to T9
• T1 to T4
• L1 to L2
• S2 to S4

Q3. Which nerves carry parasympathetic fibers from S2 to S4 toward the anorectal region?

• Superior gluteal nerves
• Inferior rectal nerves
• Sacral splanchnic nerves
• Pelvic splanchnic nerves

Q4. What is the rectoanal inhibitory reflex?

• Relaxation of the pelvic diaphragm during inspiration
• Relaxation of the internal anal sphincter after rectal distension
• Voluntary contraction of the external anal sphincter after rectal distension
• Contraction of the urinary bladder after rectal distension

Q5. Which feature best distinguishes neural control of the internal anal sphincter from that of the external anal sphincter?

• Both sphincters are controlled exclusively by the pudendal nerve
• Internal sphincter control is autonomic, while external sphincter control is somatic
• Both sphincters are controlled exclusively by sympathetic fibers
• The internal sphincter is somatic, while the external sphincter is autonomic

Q6. Which structure lies immediately external to the internal anal sphincter over much of its course?

• Piriformis
• Urinary bladder
• External anal sphincter
• Obturator internus

Q7. Which property of the internal anal sphincter makes it particularly important for continence at rest?

• Formation of the anorectal angle
• Production of rectal mucus
• Rapid voluntary skeletal muscle contraction
• Tonic smooth muscle contraction

Q8. Which muscle is primarily responsible for maintaining the anorectal angle rather than directly forming the internal anal sphincter?

• Internal anal sphincter
• Muscularis mucosae
• Puborectalis
• Rectal circular muscle

Q9. During normal defecation, which change occurs in the internal anal sphincter?

• It undergoes sustained maximal contraction
• It becomes voluntarily controlled
• It relaxes
• It contracts the puborectalis muscle

Q10. Which statement correctly describes the structural origin of the internal anal sphincter?

• It is derived from the puborectalis muscle
• It is a thickening of the circular smooth muscle of the rectum
• It is formed from the obturator internus muscle
• It is a continuation of the external anal sphincter