Muscle
Flexor digitorum superficialis
Flexor that stops at the middle phalanges
High-yield
Superficialis acts mainly at the PIP joints; profundus continues farther to act at the DIP joints. Both also contribute to flexion of the more proximal joints.
Overview
This intermediate forearm muscle sends four tendons through the carpal tunnel. In each finger its tendon divides around flexor digitorum profundus before attaching to the middle phalanx.
Reference facts
- Origin
- Humeroulnar head: medial epicondyle, ulnar collateral ligament and coronoid process; radial head: upper anterior radius
- Insertion
- Paired slips on the sides of the middle phalanges of digits 2-5
- Action
- Flexes the PIP joints; also helps flex the MCP joints and wrist
- Innervation
- Median nerve, commonly C7-T1
- Blood supply
- Mainly ulnar artery branches, with radial contributions
Clinical correlation
Clinicians assess PIP flexion separately when examining finger flexor function. The little-finger superficialis tendon is especially variable, so a weak or absent isolated movement does not by itself prove a new tendon injury.
Frequently asked questions
What does the flexor digitorum superficialis do?
Flexes the PIP joints; also helps flex the MCP joints and wrist.
What nerve innervates the flexor digitorum superficialis?
The flexor digitorum superficialis is innervated by the median nerve, commonly C7-T1.
Where does the flexor digitorum superficialis attach?
Origin: Humeroulnar head: medial epicondyle, ulnar collateral ligament and coronoid process; radial head: upper anterior radius. Insertion: Paired slips on the sides of the middle phalanges of digits 2-5.
What is the blood supply of the flexor digitorum superficialis?
Mainly ulnar artery branches, with radial contributions.