Opponens Pollicis Muscle Anatomy

The opponens pollicis is a quadrangular muscle that lies deep to the abductor pollicis brevis and lateral to the flexor pollicis brevis.

The thenar eminence of the hand is made up of four muscles: These muscles make up what is considered the “ball” of the palm:

• The opponens pollicis muscle,
• The adductor pollicis muscle,
• The abductor pollicis brevis muscle,
• The flexor pollicis brevis muscle.

Opponens Pollicis Muscle Anatomy

The opponens pollicis muscle is a muscle originates from the tubercle of the trapezium bone and the transverse carpal ligament (flexor retinaculum). The muscle then inserts onto the entire length of the first metacarpal bone. 

See Also: Hand Anatomy, Bones & Muscles

It receives its blood supply mainly from the superficial palmar arch. The superficial palmar arch derives from the radial artery.

The opponens pollicis muscle is innervated by spinal levels C8 and T1. These spinal levels make up the recurrent branch of the median nerve.

The opponens pollicis opposes the thumb, the most important thumb movement. It flexes and rotates the 1st metacarpal medially at the carpometacarpal joint during opposition; this movement occurs when picking up an object. During opposition, the tip of the thumb is brought into contact with the pulp (pad) of the little finger.

The thumb opposition occurs at the carpometacarpal joint and results in a “cupping” of the palm. Bringing the tip of the thumb into contact with the 5th finger, or any of the other fingers, involves considerably more movement than can be produced by the opponens pollicis alone.

Muscle Variants

The nerve innervation of the opponens pollicis muscle may come from the ulnar nerve in some cases. The ulnar nerve is made up of spinal roots C8 and T1. The attachment and insertion of the opponens pollicis muscle may vary from person to person, but the action of opposition is constant.

Clinically

The compression of the median nerve in carpal tunnel syndrome may cause atrophy of the thenar muscles and pain in the first three digits.

References & More

1. Cael, C. (2010). Functional anatomy: Musculoskeletal anatomy, kinesiology, and palpation for manual therapists. Philadelphia, PA: Wolters Kluwer Health/Lippincott, Williams & Wilkins.
2. Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
3. Clinically Oriented Anatomy – 8th Edition
4. Nguyen JD, Duong H. Anatomy, Shoulder and Upper Limb, Hand Opponens Pollicis Muscle. [Updated 2023 Aug 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: Pubmed