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Intrinsic Muscles of Hand – Origin, Nerve Supply, Functions

Intrinsic Muscles of Hand/ The thenar muscles are three short muscles located at the base of the thumb. The muscle bellies produce a bulge, known as the thenar eminence. They are responsible for the fine movements of the thumb. The median nerve innervates all the thenar muscles.

Intrinsic Muscles of Hand

Thenar muscles

Opponents policies

Function: Opposition of the thumb
Origin: Flexor retinaculum and tubercle of trapezium
Insertion: Lateral aspect of first metacarpal
Innervation: Recurrent branch of median nerve (C8, T1)

Abductor policies Brevis

Function: Abduction of the thumb at the metacarpophalangeal joint
Origin: Flexor retinaculum and tubercle of scaphoid
Insertion: Lateral aspect of proximal phalanx of first finger
Innervation: Recurrent branch of median nerve (C8, T1)

Flexor pollicus brevis

Function: Flexion of the thumb at the metacarpophalangeal joint
Origin: Flexor retinaculum and tubercle of trapezium
Insertion: Lateral aspect of proximal phalanx of first finger
Innervation: Recurrent branch of median nerve (C8, T1)

Adductor Compartment

Adductor pollicus

Function: Adduction of the thumb
Origin: Second, third metacarpal, and capitate
Insertion: Proximal phalanx and extensor expansion of 1st finger
Innervation: Deep branch of ulnar nerve (C8, T1)

Hypothenar Muscles

Abductor digiti minimi

Function: Abduction of the little finger at the metacarpophalangeal joint
Origin: Pisiform
Insertion: Medial aspect of proximal phalanx of fifth finger
Innervation: Deep branch of ulnar nerve (C8, T1)

Flexor digiti minimi brevis

Function: Flexion of the little finger at the metacarpophalangeal joint
Origin: Flexor retinaculum and hook of hamate
Insertion: Medial aspect of proximal phalanx of fifth finger
Innervation: Deep branch of ulnar nerve (C8, T1)

Opponens digiti minimi

Function: Opposition of the little finger
Origin: Flexor retinaculum and hook of hamate
Insertion: Medial aspect of fifth metacarpal
Innervation: Deep branch of ulnar nerve (C8, T1)

Short Muscles

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Lubricants

Function: Flexion of the metacarpophalangeal joints with extension of the interphalangeal joints
Origin: Arise from tendons of flexor digitorum profundus. First 2 are unipennate, and the third and fourth are bipennate
Insertion: Extensor expansions of second, third, fourth, and fifth finger
Innervation: Median nerve (C8, T1) for the lateral 2 lumbricals, deep branch of ulnar nerve (C8, T1) for the medial 2 lumbricals

Dorsal interossei

Function: Abduction of the second, third, and fourth finger away from the axial line
Origin: Adjacent metacarpals
Insertion: Extensor expansions and proximal phalanges of the second, third, and fourth fingers
Innervation: Deep branch of ulnar nerve (C8, T1)

Palmar interossei

Function: Adduction of the second, third, and fourth finger towards the axial line
Origin: Palmar surfaces of second, fourth, and fifth metacarpals
Insertion: Extensor expansions and proximal phalanges of the second, fourth, and fifth fingers
Innervation: Deep branch of ulnar nerve (C8, T1)

Surgical Considerations

The deltoid is a significant factor when considering the anterior surgical approach to gain access to the shoulder joint. Some of these technical procedures include, but are not limited to the following:

Open Bankart repair/capsular reconstructions – indicated in the setting of recurrent anterior (or other directional) instability of the shoulder
Shoulder arthroplasty – indicated for cases of post-traumatic deformity, advanced degenerative arthritis, and/or avascular necrosis includes hemiarthroplasty, total shoulder arthroplasty (TSA), reverse total shoulder arthroplasty (TSA)
The long head of the biceps tendon (LHBT) – repair versus tenotomy versus tenodesis procedures indicated in the setting of either LHBT/bicipital groove instability or advanced/end-stage LHBT tendinopathy and degeneration[rx][rx]
Rotator cuff repair contemporary – indications remain somewhat controversial although most of these procedures are now being performed arthroscopically popular approaches (as opposed to the deltopectoral approach) include the mini-open approach (lateral deltoid-splitting approach)