LUMBRICALS (HAND)

 

Rotation Gallery

The profundus tendons carry four lumbricals labeled 1st, 2nd, 3rd and 4th lumbricals. They issue from their radial borders and they gain insertion into the distal extensor expansion where they are able to carry out important function in the movement of the fingers. They cross the metacarpophalangeal joint  obliquely to reach their insertion and hence help to flex these joints while acting on the extensor expansion to extend the interphalangeal joints.

They are supplied by two nerves- the lateral two lumbricals are supplied by the median nerve, while the others ,the 3rd and 4th are supplied by the ulnar nerve. Hence in ulnar nerve palsy, two are spared but this is not enough to prevent claw hand formation as a result of paralysis of the interossei which are also players in the action of as a result of the architecture of the extensor expansion.

ORIGIN:  L1 from most lateral tendon of the flexor digitorum profundus for the index finger;

L2 from tendon of the flexor digitorum profundus for the middle finger;

L3 from tendon of the flexor digitorum profundus for the ring finger;

L4 from tendon of the flexor digitorum profundus

 

INSERTION:  Bases of distal phalanges of the medial 4 digit through extensor expansion on the tendons of extensor digitorum

 

ACTION:  Flexor of metacarpophalangeal joints and extensor of interphalangeal joints; this is called the  writing position  or precision grip and it is possible because of the architecture of the extensor expansion

 

NERVE:  Lateral 2 lumbricals (L1 and L2) by median nerve; L3 and 4 by deep branch of ulnar nerve

Action video

 

 

 


Intrinsic muscles of hand

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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