Flexor digitorum superficialis (''flexor digitorum sublimis'') is an extrinsic flexor

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 mus ...

of the

finger A finger is a limb of the body and a type of digit, an organ of manipulation and sensation found in the hands of most of the Tetrapods, so also with humans and other primates. Most land vertebrates have five fingers ( Pentadactyly). Chamber ...

s at the proximal interphalangeal joints. It is in the anterior compartment of the forearm. It is sometimes considered to be the deepest part of the superficial layer of this compartment, and sometimes considered to be a distinct, "intermediate layer" of this compartment. It is relatively common for the Flexor digitorum superficialis to be missing from the little finger, bilaterally and unilaterally, which can cause problems when diagnosing a little finger injury.

Structure

The muscle has two classically described heads – the humeroulnar and radial – and it is between these heads that the

median nerve The median nerve is a nerve in humans and other animals in the upper limb. It is one of the five main nerves originating from the brachial plexus. The median nerve originates from the lateral and medial cords of the brachial plexus, and has cont ...

and ulnar artery pass. The ulnar collateral ligament of elbow joint gives its origin to part of this muscle. Four long

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

s come off this muscle near the wrist and travel through the

carpal tunnel In the human body, the carpal tunnel or carpal canal is the passageway on the palmar side of the wrist that connects the forearm to the hand. The tunnel is bounded by the bones of the wrist and flexor retinaculum from connective tissue. Normall ...

formed by the flexor retinaculum. These tendons, along with those of

flexor digitorum profundus The flexor digitorum profundus is a muscle in the forearm of humans that flexes the fingers (also known as digits). It is considered an extrinsic hand muscle because it acts on the hand while its muscle belly is located in the forearm. Togeth ...

, are enclosed by a common flexor sheath. The tendons attach to the anterior margins on the bases of the

intermediate phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

of the four fingers. These tendons have a split (Camper's Chiasm) at the end of them through which the tendons of flexor digitorum profundus pass.

Innervation

The Flexor digitorium superficialis muscle is innervated by the

(C7, C8, T1).

Function

The primary function of flexor digitorum superficialis is flexion of the middle phalanges of the four fingers (excluding the thumb) at the proximal interphalangeal joints, however under continued action it also flexes the

metacarpophalangeal joints The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow ...

and wrist joint. To test flexor digitorum superficialis, one finger is flexed at the proximal interphalangeal joint against resistance, while the remaining three fingers are held fully extended (to inactivate flexor digitorum profundus).

Additional images

File:Gray416.png, Tendons of forefinger and vincula tendina. File:Gray417_color.PNG, Cross-section through the middle of the forearm. File:Gray422.png, Transverse section across the wrist and digits. File:Gray423.png, The mucous sheaths of the tendons on the front of the wrist and digits. File:Gray427.png, The muscles of the left hand. Palmar surface. File:Gray527.png, The radial and ulnar arteries. File:Musculusflexordigitorumsuperficialis.png File:Muscles of forearm.jpg, Flexor digitorum superficialis muscle File:Slide9r.JPG, Flexor digitorum superficialis muscle File:Slide5q.JPG, Flexor digitorum superficialis muscle File:Slide3GGG.JPG, Flexor digitorum superficialis muscle File:Slide7RRR.JPG, Flexor digitorum superficialis muscle File:Muscles of upper limb.(cross section - human cadaver).jpg, Muscles of upper limb. Cross section.

References

External links

* {{Authority control Muscles of the upper limb Forearm