Intermediate Internal Anal Sphincter Quiz

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

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

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

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

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

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

Q4. What is the rectoanal inhibitory reflex?

• Contraction of the urinary bladder after rectal distension
• Voluntary contraction of the external anal sphincter after rectal distension
• Relaxation of the pelvic diaphragm during inspiration
• Relaxation of the internal anal sphincter 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 sympathetic fibers
• The internal sphincter is somatic, while the external sphincter is autonomic
• Both sphincters are controlled exclusively by the pudendal nerve
• Internal sphincter control is autonomic, while external sphincter control is somatic

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

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

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

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

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

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

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

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

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