Trochlea of which bone fits in the sigmoid notch of ulna ?

Options

A. Humerus
B. Radius
C. Femur
D. Scaphid

Answer

To answer the question "Trochlea of which bone fits in the sigmoid notch of ulna?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Key Terms**: The question mentions two key anatomical features: the "trochlea" and the "sigmoid notch of ulna".

2. **Understand the Sigmoid Notch**: The sigmoid notch, also known as the semilunar notch, is a large depression located at the upper extremity of the ulna. This notch is specifically designed to accommodate another bone.

3. **Identify the Trochlea**: The trochlea is a structure found on the humerus bone. It is a spool-shaped surface that articulates with the ulna.

4. **Determine the Relationship**: The sigmoid notch of the ulna fits the trochlea of the humerus. This means that the ulna and humerus work together at the elbow joint, allowing for movement.

5. **Eliminate Other Options**: The other options provided are radius, femur, and scaphoid. The radius is a bone of the forearm but does not fit into the sigmoid notch. The femur is a thigh bone and does not relate to the ulna, and the scaphoid is a wrist bone. Therefore, they can be eliminated.

6. **Conclude the Answer**: Based on the anatomical relationship, the trochlea of the humerus fits into the sigmoid notch of the ulna.

### Final Answer:
The trochlea of the **humerus** fits in the sigmoid notch of the ulna.

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