Opponens pollicis muscle
Opponens pollicis is a short intrinsic muscle of the hand. It belongs to a group called thenar muscles, along with adductor pollicis, abductor pollicis and flexor pollicis brevis. Thenar muscles are located on the radial (lateral) aspect of the hand where they form an elevation named the thenar eminence.
Opponens pollicis extends from the trapezium bone and flexor retinaculum to the first metacarpal bone. The main function of this muscle is the opposition of the thumb in the first carpometacarpal joint.
In this article, we will discuss the anatomy and function of the opponens pollicis muscle.
|Origin||Tubercle of trapezium bone, flexor retinaculum|
|Insertion||Radial border of metacarpal bone 1|
|Action||Carpometacarpal joint 1: Thumb opposition|
|Innervation||Recurrent branch of median nerve (C8, T1)|
|Blood supply||Superficial palmar branch of radial artery|
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.
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.
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.
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
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.
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