**Question:** Tendon present in third extensor compartment of wrist is

A. thenar
B. thenar
C. hypothenar
D. lumbrical

**Core Concept:**
The wrist is a complex joint with multiple compartments that house tendons responsible for flexing and extending the digits. There are three extensor compartments in the wrist: the triangular, radiocarpal, and distal compartments. Each compartment contains specific tendons that enable precise finger movements.

**Why the Correct Answer is Right:**
The correct answer, D (lumbrical), refers to a group of tendons that extend the little finger and the ring finger. The lumbrical tendons are responsible for the extension of the distal phalanx of the ring finger and little finger. They are essential for maintaining the normal alignment of the digits during pronation or supination of the wrist.

**Why Each Wrong Option is Incorrect:**
A (thenar), B (thenar), and C (hypothenar) are incorrect because they represent tendons associated with the thenar muscles, which extend the thumb. The thenar muscles are responsible for the flexion of the thumb and not its extension.

**Clinical Pearl / High-Yield Fact:**
Understanding the specific tendons within each wrist compartment is crucial for maintaining proper finger positioning during hand movements. Misunderstanding these tendons can lead to functional deficits or deformities, such as mallet fingers.

**Correct Answer:** D. lumbrical

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In summary, the tendon present in the third extensor compartment of the wrist is the lumbrical tendon, which is responsible for extending the ring finger and little finger. The other options represent tendons involved in thumb extension, making them incorrect for the given question. Understanding the specific tendons within each wrist compartment is essential for maintaining proper finger positioning during hand movements.