Axis of upper limb passes through ?

Ans. is 'a' i.e., Capitulum The mechanical axis of the upper limb is formed by the line joining the center of the humeral head with the the centre of the lower aicular surface of the ulna approximately. The center of the elbow joint lies 3-4 mm medial to the mechanical axis of the upper limb. Thus mechanical axis passes through capitulum (Trachlea is medial to mechanical exis).