Question

The trochlea of which bone fits in the trochlear notch of ulna?
a. Humerus
b. Radius
c. Femur
d. Scaphoid

Answer 1

Hint: Trochlea refers to a grooved structure. The trochlear nerve is cranial nerve number four and functions as a motor nerve to control the superior oblique muscles in each eye. The superior oblique muscles control the downward movement of the eyeball within the orbit.

Complete answer:
In the human arm, the trochlea of the humerus articulates with the trochlear notch of the ulna in the forearm, the elbow is a hinge joint which has a rotatory component. The trochlea forms the convex, proximal surface, which articulates with the concave, distal surface of the trochlear notch.

The single bone of the upper arm region is the humerus. At its proximal end is the head of the humerus. This is the large and smooth region that faces medially. The head of the bone articulates with the glenoid cavity of the scapula to form the glenohumeral (shoulder) joint.

In the forearm, the ulna is the medial bone. The proximal end of the ulna is a C-shaped trochlear notch. This notch region articulates with the trochlea of the humerus as part of the elbow joint. The inferior margin of the trochlear notch is formed by bone called the coronoid process of the ulna.

The radius is on the lateral (thumb) side of the forearm. The head of the radius forms the proximal end and is a disc-shaped structure.

The scaphoid bone is present on the wrist, carpal bones. The bone is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel.
Therefore, the Trochlea of the humerus bone fits in the trochlear notch of the ulna.

Hence, the correct answer is option (A).

Note: The trochlear notch fits with the trochlea of the humerus, as part of the elbow joint, is a large depression in the upper extremity of the ulna that there is an indentation in about the middle of either side of this notch, which contracts and indicates the junction of the olecranon and the coronoid process. The notch is further divided into a medial and a lateral portion by a smooth ridge and is concave from above downward. The medial portion is the larger.