Opponens pollicis muscle

Origin and insertion

Opponens pollicis muscle originates from the flexor retinaculum and tubercle of the trapezium bone. From its origin point, the muscle belly courses dorsally and laterally to insert onto the anterolateral surface of the first metacarpal shaft.

Relations

Opponens pollicis is a relatively short and slender muscle situated on the radial aspect of the hand. It lies deep to the abductor pollicis brevis and lateral to the flexor pollicis brevis. The superficial head of flexor pollicis brevis is frequently blended with opponens pollicis.

Innervation

Opponens pollicis muscle is innervated by the recurrent (thenar) branch of median nerve (root value C8 and T1) and occasionally by the deep terminal branch of ulnar nerve.

Blood supply

Opponens pollicis muscle is mainly vascularized by the superficial palmar branch that arises from the radial artery. The additional blood supply comes from several other arteries;

• Princeps pollicis artery
• Radialis indicis artery 
• Deep palmar arch

Function

As its name suggests, the main function of opponens pollicis is to produce an opposition of the thumb. Opposition refers to the rather complex movement of the thumb which is a combination of flexion, adduction and medial rotation at the first carpometacarpal joint.

The purpose of this movement is the ability to bring the tip of the thumb in contact with any other fingertip of the same hand. This allows efficient and precise movements of the hand, for example grasping round objects or fine gripping of a pencil.