Palmaris Brevis

Origin, Insertion, Action & Nerve

Attachments explained

The Palmaris Brevis is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.

Action & function

When the Palmaris Brevis contracts, it produces the following movement: Wrinkles the skin of the hypothenar palm and deepens the cup of the hand, improving grip.

As part of the Hand group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.

Nerve supply & clinical relevance

The Palmaris Brevis receives its nerve supply from the Superficial branch of the ulnar nerve (C8–T1). This nerve carries fibres from spinal segment(s) C8, T1.

Because a muscle can only contract when its nerve is intact, injury to the Superficial branch of the ulnar nerve or to its spinal roots (C8, T1) can weaken or paralyse the Palmaris Brevis, impairing the movements it normally produces (wrinkles the skin of the hypothenar palm and deepens the cup of the hand, improving grip). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Palmaris Brevis (the OIANS method)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Palmaris Brevis, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.

Most students remember the Palmaris Brevis fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.

Palmaris Brevis quick facts

Region

Upper Limb

Group

Hand

Origin

Flexor retinaculum and medial (ulnar) border of the palmar aponeurosis

Insertion

Skin of the medial (ulnar) border of the palm

Action

Wrinkles the skin of the hypothenar palm and deepens the cup of the hand, improving grip

Nerve

Superficial branch of the ulnar nerve (C8–T1)

Spinal roots

C8, T1

Frequently asked questions

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