Extrinsic muscles of the hand
Located in the anterior and posterior compartments of the forearm. They control crude movement and produce a strong grip.
Intrinsic muscles of the hand
Located within the hand itself. They are responsible for he fine motor functions of the hand.
What are the thenar muscles?
Opponens Pollicis, Abductor Pollicis Brevis, Flexor Pollicis Brevis
What are the thenar muscles responsible for?
Fine movements of the thumb
Innervation of the thenar muscles
Opponens pollicis actions
Opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium
Opponens pollicis innervation
Abductor pollicis brevis actions
Abducts the thumb
Abductor pollicis brevis innervation
Flexor pollicis brevis actions
Flexes the metacarpophalangeal (MCP) joint of the thumb.
Flexor pollicis brevis innervation
Median nerve. The deep head is innervated by the deep branch of the ulnar nerve.
What are the hypothenar muscles of the hand?
Opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis
Innervation of the hypothenar muscles
Opponens Digiti Minimi actions
It rotates the metacarpal of the little finger towards the palm, producing opposition.
Abductor Digiti Minimi actions
Abducts the little finger.
Flexor Digiti Minimi Brevis actions
Flexes the MCP joint of the little finger.
There are four lumbricals in the hand, each associated with a finger. They are very crucial to finger movement, linking the extensor tendons to the flexor tendons.
Denervation of the lumbricals leads to:
Ulnar claw and hand of benediction
Each lumbrical originates from a tendon of the flexor digitorum profundus. They pass dorsally and laterally around each finger, and inserts into the extensor hood.
The flex at the MCP joint, and extend at the interphalangeal (IP) joints of each finger.
The lateral two lumbricals (of the index and middle fingers) are innervated by the median nerve. The medial two lumbricals (of the little and ring fingers) are innervated by the ulnar nerve.
Dorsal interossei attachments
Each interossei originates from the lateral and medial surfaces of the metacarpals. They attach into the extensor hood and proximal phalanx of each finger.
Dorsal interossei actions
Abduct the fingers at the MCP joint
Dorsal interossei innnervation
Palmar interossei attachments
Each interossei originates from a medial or lateral surface of a metacarpal, and attaches into the extensor hood and proximal phalanx of same finger.
Palmar interossei actions
Adducts the fingers at the MCP joint.
Palmar interossei innervation