**Question:** True statement about upper half of anal canal is:

A. Upper half of anal canal is lined by simple columnar epithelium
B. Lower half of anal canal is lined by simple columnar epithelium
C. Upper half of anal canal is lined by stratified squamous epithelium
D. Upper half of anal canal is lined by stratified squamous epithelium

**Core Concept:** Anal canal is a part of the digestive system, and its lining determines its function and susceptibility to diseases. The stratified epithelium is found in areas exposed to friction or wear and tear, while simple columnar epithelium is seen in areas with a protective role.

**Why the Correct Answer is Right:** The upper half of the anal canal is exposed to friction and mechanical stress during defecation. Therefore, its lining consists of stratified squamous epithelium, which provides resistance to friction and mechanical damage.

**Why Each Wrong Option is Incorrect:**

A) The correct answer disproves this option as stratified squamous epithelium is not found in the anal canal.
B) The correct answer disproves this option as stratified squamous epithelium is found in the upper half of the anal canal, not the lower half.
C) This option is incorrect as stratified squamous epithelium is found in the upper half of the anal canal, not stratified squamous epithelium.
D) This option is incorrect as stratified squamous epithelium is found in the upper half of the anal canal, not stratified squamous epithelium.

**Clinical Pearl:** The stratified squamous epithelium in the upper half of the anal canal makes it resistant to mechanical stress during defecation, protecting the underlying tissues from damage. Understanding these anatomy details is crucial in identifying potential complications like anal fissure, which may occur due to mechanical stress on anal canal epithelium.