Flexor Digitorum Superficialis (FDS)
Other Name: Flexor digitorum sublimis (FDS)
Palpation: Palpate the flexor digitorum superficialis tendon at the volar wrist ulnar to the palmaris longus or flexor carpi radialis tendons. The long and ring finger tendons lie superficial to the index and small finger tendons.
Strength Testing: Position ““ wrist and hand in neutral with palm up; keep the distal interphalangeal joints of the three fingers you are not testing in full extension. Stabilize ““ metacarpal-phalangeal joint in extension. Resist ““ flexion at proximal interphalangeal joint by applying force at palmar middle phalanx (in the direction of extension). Test each finger individually (holding the other fingers not being testing in full extension as noted).
Note: Many patients do not have a flexor digitorum superficialis of the small finger.
Origin of Humeral Head: Common flexor tendon from the medial epicondyle of the humerus, ulnar collateral ligament of the elbow joint, and deep antebrachial fascia.
Origin of Ulnar Head: Medial side of the coronoid process of the ulna.
Origin of Radial Head: Anterior surface of radius by providing a smaller more tendinous contribution.
Insertion: By four separate tendons to each corresponding finger into the ulnar and radial aspect of the palmar middle phalanx.