Palmaris Brevis

What is Palmaris Brevis

The palmaris brevis is a small, superficial intrinsic muscle of the hand in the hypothenar region. Despite its location, it is not a hypothenar muscle. The rectangular subcutaneous muscle is vital in tightening the hand’s grip.

Anatomy

Location and Attachments

Origin	Flexor retinaculum and palmar aponeurosis
Insertion	Dermis of the skin on the ulnar side of the palm (hypothenar region)

Origin

Palmaris brevis is a small thin muscle that originates from two points. One is the flexor retinaculum, and the other is the medial border of the palmar aponeurosis.

Insertion

After originating, the muscle fibers course medially for a short distance to insert into the dermis layer of the skin of the hypothenar eminence. It is the fleshy part of the palm at the base of the little finger.

The entire muscle, including its origin, belly, and insertion, remains within the palmar side of the hand.

Relations With Surrounding Muscles and Structures

The palmaris brevis is the most superficial of all the muscles on the ulnar or medial side of the hand. The hypothenar group of muscles, which includes the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi, lie deep to the palmaris brevis.

The palmaris brevis, along with the palmar carpal ligament, make up Guyon’s canal’s roof. It is a tunnel in the carpal area of the hand between the pisiform and the hook of the hamate, that allows passage to the ulnar nerve and artery into the palm.

Function

Action

Strengthens the grip of hand

Contraction of this muscle causes the palmar aponeurosis to tighten, which in turn wrinkles the skin on the hypothenar region, deepening the hollow of the palm. These movements help you to cup your hand and also steadies and strengthen the grip of the hand.

Innervation

Nerve

Superficial branch of the ulnar nerve (C8, T1)

The superficial branch of the ulnar nerve (C8, T1), emerging from the brachial plexus’s medial cord, innervates the palmaris brevis. It is the only muscle this nerve supplies.

Blood Supply

Artery

Superficial palmar arch

The superficial palmar arch, formed by the ulnar artery, provides blood supply to this muscle. Additional supply may come from the princeps pollicis artery or the superficial palmar branch of radial artery.