Lumbrical muscles of the hand
The lumbrical muscles of the hand are intrinsic muscles of the hand associated with the flexor digitorum profundus (FDP) tendon.
On this page:
Summary
- origin: tendons of flexor digitorum profundus in the palm
- insertion: extensor expansion on the dorsum of proximal phalanx after passing along the lateral side of metacarpophalangeal joints
- innervation: following the parent tendon, i.e. ulnar two lumbricals by ulnar nerve (C8, T1), radial two lumbricals by median nerve
- action: provide motor and proprioceptive functions, flex metacarpophalangeal joints, when closing fist extend terminal phalanx
Gross anatomy
The four lumbricals arise from the tendons of the flexor digitorum profundus (FDP). The first and second lumbricals arise from the radial side of the FDP tendons of the index and middle fingers. The third lumbrical arises from the adjacent tendons of the middle and ring finger while the fourth arises from the adjacent tendons of the ring and little finger.
Each lumbrical travels on the radial side of its corresponding finger and attaches to the lateral edge of the extensor expansion complex on the dorsum of each finger.
Variant anatomy
Variation in the muscles bellies and attachments of the lumbricals are common with any being possibly unipennate or bipennate. Accessory lumbrical slips have been described as also attaching to the tendons of the flexor digitorum superficialis.
History and etymology
The name comes from the Latin 'lumbricus' meaning 'worm' 5 describing the gross appearance of the muscle.
Related Radiopaedia articles
Anatomy: Upper limb
-
skeleton of the upper limb
- clavicle
- scapula
- humerus
- radius
- ulna
- carpal bones (mnemonic)
- metacarpals
- phalanges
- accessory ossicles of the upper limb
- accessory ossicles of the shoulder
- accessory ossicles of the elbow
-
accessory ossicles of the wrist (mnemonic)
- os centrale carpi
- os epilunate
- os epitriquetrum
- os styloideum
- os hamuli proprium
- lunula
- os triangulare
- trapezium secondarium
- os paratrapezium
- os radiostyloideum (persistent radial styloid)
- joints of the upper limb
-
pectoral girdle
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shoulder joint
- articulations
- associated structures
- joint capsule
- bursae
- ligaments
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movements
- scapulothoracic joint
- glenohumeral joint
- arm flexion
- arm extension
- arm abduction
- arm adduction
- arm internal rotation (medial rotation)
- arm external rotation (lateral rotation)
- circumduction
- blood supply - scapular anastomosis
- ossification centers
-
shoulder joint
-
elbow joint
- proximal radioulnar joint
- ligaments
- associated structures
- movements
- alignment
- blood supply - elbow anastomosis
- development
-
wrist joint
- articulations
-
ligaments
- intrinsic ligaments
- extrinsic ligaments
- radioscaphoid ligament
- dorsal intercarpal ligament
- dorsal radiotriquetral ligament
- dorsal radioulnar ligament
- volar radioulnar ligament
- radioscaphocapitate ligament
- long radiolunate ligament
- Vickers ligament
- short radiolunate ligament
- ulnolunate ligament
- ulnotriquetral ligament
- ulnocapitate ligament
- ulnar collateral ligament
- associated structures
- extensor retinaculum
- flexor retinaculum
- joint capsule
- movements
- alignment
- ossification centers
-
hand joints
- articulations
- carpometacarpal joint
-
metacarpophalangeal joints
- palmar ligament (plate)
- collateral ligament
-
interphalangeal joints
- palmar ligament (plate)
- collateral ligament
- movements
- ossification centers
- articulations
-
pectoral girdle
- spaces of the upper limb
- muscles of the upper limb
- shoulder girdle
- anterior compartment of the arm
- posterior compartment of the arm
- anterior compartment of the forearm
-
posterior compartment of the forearm (extensors)
- superficial
- deep
- hand (mnemonic)
- accessory muscles
- blood supply to the upper limb
-
arteries
- subclavian artery (mnemonic)
- axillary artery
- brachial artery (proximal portion)
- ulnar artery
- radial artery
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arteries
- innervation of the upper limb
- intercostobrachial nerve
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brachial plexus (mnemonic)
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- medial cord
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- lymphatic drainage of the upper limb