Palmaris brevis muscle is a thin, quadrilateral

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

, placed beneath the integument of the

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

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 (which has two opposable thumbs on each "h ...

. It acts to fold the skin of the

hypothenar eminence The hypothenar muscles are a group of three muscles of the hand, palm that control the motion of the little finger. The three muscles are: * Abductor minimi digiti muscle (hand), Abductor digiti minimi * Flexor digiti minimi brevis (hand), Flexor ...

transversally.

Structure

Origin and insertion

Palmaris brevis muscle is located on the

ulnar The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

side of the

. It arises from the tendinous

fasciculi Fascicle or ''fasciculus'' may refer to: Anatomy and histology * Muscle fascicle, a bundle of skeletal muscle fibers * Nerve fascicle, a bundle of axons (nerve fibers) ** Superior longitudinal fasciculus *** Arcuate fasciculus ** Gracile fas ...

from the

transverse carpal ligament The flexor retinaculum (transverse carpal ligament, or anterior annular ligament) is a fibrous band on the palmar side of the hand near the wrist. It arches over the carpal bones of the hands, covering them and forming the carpal tunnel. Structur ...

and

palmar aponeurosis The palmar aponeurosis (palmar fascia) invests the muscles of the palm, and consists of central, lateral, and medial portions. Structure The central portion occupies the middle of the palm, is triangular in shape, and of great strength Its apex i ...

. 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 ''pisifomis'', 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 The palmar metacarpal arteries (volar metacarpal arteries, palmar interosseous arteries) are three or four arteries that arise from the convexity of the deep palmar arch. Structure The palmar metacarpal arteries arise from the convexity of the ...

of the

deep palmar arch The deep palmar arch (deep volar arch) is an arterial network found in the palm. It is usually primarily formed from the terminal part of the radial artery. The ulnar artery also contributes through an anastomosis. This is in contrast to the supe ...

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 Matteo Realdo Colombo (c. 1515 – 1559) was an Italian professor of anatomy and a surgeon at the University of Padua between 1544 and 1559. Early life and education Matteo Realdo Colombo or Realdus Columbus, was born in Cremona, Lombardy, the ...

before being pushed to general acceptance in the works of

Andreas Vesalius Andreas Vesalius (Latinized from Andries van Wezel) () was a 16th-century anatomist, physician, and author of one of the most influential books on human anatomy, ''De Humani Corporis Fabrica Libri Septem'' (''On the fabric of the human body'' '' ...

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 In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. 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 bone, so injury is ...

and

ulnar artery The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspects of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial ar ...

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