Lumbricals (Hand)
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Lumbricals (Hand)
- Comprise the Central Compartment of the Hand
- Contrasting movements at the digit joints allow for fine motor control, such as in writing.
Lumbricals 1 and 2:
- Unipennate
- Originate on the lateral sides of their tendons
Lumbricals 3 and 4:
- Bipennate
- Originate on the medial and lateral sides of their tendons
Muscle Group
Median nerve - Terminal group
Ulnar nerve - Intrinsic hand group
Nerve
Deep branch (of ulnar nerve)
Median nerve
Ulnar nerve
Nerve Root
C8
T1
Plexus
Brachial plexus
Brachial Plexus Trunk
Lower trunk
Brachial Plexus Division
Anterior division
Brachial Plexus Cord
Medial cord
Anatomical Site
Central palmar hand
Articulation Site
Finger
Muscle Action
Metacarpalphalangeal flexion with proximal interphalangeal extension
Other Information
Median n. innervates lumbricals 1 & 2
Ulnar n. innervates lumbricals 3 & 4
Lumbricals insert into the extensor expansions of digits 2-5 (dorsally).
Flex the metacarpophalangeal joints (aka, MCP joints) while extending the interphalangeal joints (aka, IP joints).