Question

Sigmoid notch of olecranon process is found in
A. Tibia-fibula
B. Femur
C. Radius-ulna
D. Humerus

Answer 1

Hint:-The olecranon process is found near the upper end of the ulna which forms the pointed portion of the elbow. Sigmoid notch is a large depression in the ulna in which the trochlea of the humerus fits and forms the elbow joint.

Complete step-by-step solution:-
The forelimb of a human is made up of 30 bones. The arm from shoulder to elbow is made up of one bone called humerus. The forearm, from elbow to wrist is made up of two bones, radius and ulna. The wrist is made up of 8 bones called carpals. The palm is made up of 5 metacarpals and the fingers is made up of 14 phalanges. The humerus and ulna meet at the elbow and form the elbow joint. The upper end of the ulna is pointed, it is the pointed portion of the elbow. This pointed portion is called the olecranon process. Sigmoid notch is a large depression or cavity of the olecranon process present in the radius, in which the trochlea of humerus (lower portion of humerus) fits and forms the elbow joint. The elbow joint is made up of the olecranon process of ulna and the coronoid process.

So, the sigmoid notch of the olecranon process is made up of both radius and ulna. The options are
Tibia-fibula, Femur, Radius-ulna and Humerus.
So, the correct option is C. Radius-ulna.

Note:- The articular surface for the ulna is called the sigmoid cavity of the radius. The sigmoid cavity is in the distal radius which is narrow, concave, smooth, and articulates with the head of the ulna and forms the radioulnar joint.