Palmaris brevis muscle is a thin, quadrilateral

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

, placed beneath the integument of the

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

r side of the

hand A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the Koala#Characteristics, koala (which has two thumb#O ...

. It acts to fold the skin of the hypothenar eminence transversally.

Structure

Origin and insertion

Palmaris brevis muscle is located on the

r side of the

. It arises from the tendinous fasciculi from the transverse carpal ligament and palmar aponeurosis. The muscle fibres are inserted into the skin on the ulnar border of the palm of the hand, and occasionally on the

pisiform bone The pisiform bone ( or ), also spelled pisiforme (from the Latin ''pisiformis'', pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel. Structure The pisiform is a sesamoid bone ...

Innervation

Palmaris brevis muscle is the only muscle innervated by the superficial branch of the ulnar nerve (C8, T1).

Blood supply

Palmaris brevis muscle is supplied by the palmar metacarpal artery of the deep palmar arch.

Discovery

The first recorded observation of the muscle is by Italian anatomist Giambattista Canano sometime before 1543. The muscle was independently discovered a few years later by Realdo Colombo before being pushed to general acceptance in the works of

Andreas Vesalius Andries van Wezel (31 December 1514 – 15 October 1564), latinized as Andreas Vesalius (), was an anatomist and physician who wrote '' De Humani Corporis Fabrica Libri Septem'' (''On the fabric of the human body'' ''in seven books''), which is ...

Function

Palmaris brevis muscle tenses the skin of the palm on the ulnar side during a grip action. It also deepens the hollow of the palm. The palmaris brevis may protect the

ulnar nerve The ulnar nerve is a nerve that runs near the ulna, one of the two long bones in the forearm. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or ...

and

ulnar artery The ulnar artery is the main blood vessel, with oxygenated blood, of the Human Anatomical Terms#Anatomical directions, medial aspects of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins ...

from compressive forces during repetitive grasping actions. The muscle has a fatigue-resistant fiber type profile, which supports the idea of a protective function to the ulnar neurovasculature during repetitive intermittent grasping tasks.

Additional images

References

{{Authority control Muscles of the upper limb