Flexor digitorum superficialis muscle

Flexor digitorum superficialis
	Transverse section across distal ends of radius and ulna. (Flexor dig. subliminis labeled at center top.)
Details
Latin	musculus flexor digitorum superficialis
Origin	medial epicondyle of the humerus (common flexor tendon) as well as parts of the radius and ulna.
Insertion	anterior margins on the bases of the middle phalanges of the four fingers
Artery	ulnar artery
Nerve	median nerve
Actions	flexor of fingers (primarily at proximal interphalangeal joints)
Antagonist	Extensor digitorum muscle
Identifiers
Dorlands; /Elsevier	m_22/12549098
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TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
	Anatomical terms of muscle [[[d:Lua error in Module:Wikidata at line 863: attempt to index field 'wikibase' (a nil value).\|edit on Wikidata]]]

Flexor digitorum superficialis (flexor digitorum sublimis) is an extrinsic flexor muscle of the fingers 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,^[1]^[2] and sometimes considered to be a distinct, "intermediate layer" of this compartment.^[3] 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.^[4]

Structure

The muscle has two classically described heads - the humeroulnar and radial - and it is between these heads that the median nerve and ulnar artery pass. The ulnar collateral ligament of elbow joint gives its origin to part of this muscle.

Four long tendons come off this muscle near the wrist and travel through the carpal tunnel formed by the flexor retinaculum. These tendons, along with those of flexor digitorum profundus, are enclosed by a common flexor sheath. The tendons attach to the anterior margins on the bases of the intermediate phalanges 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 median nerve (C7, C8, T1).^[5]

Function

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