Muscles of the Hand Overview

Muscles of the Hand

• Hand muscles are categorized as extrinsic and intrinsic.
• Extrinsic muscles are located in the forearm, controlling gross movements and providing a strong grip.
• Intrinsic muscles are found within the hand, responsible for fine motor skills.

Intrinsic and Extrinsic Muscles

• Intrinsic muscles are contained within the hand region.
• Extrinsic muscles are positioned outside the hand region but move the fingers.

Hand Compartments

• The hand has four muscle compartments: thenar, hypothenar, adductor, and central.
• Thenar compartment: moves the thumb (digit 1), includes abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis brevis.
• Hypothenar compartment: moves the pinky (digit 5), includes abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi.
• Adductor compartment: includes adductor pollicis.
• Central compartment: includes lumbrical, palmar interossei, and dorsal interossei muscles.

Thenar Compartment

• Made of three short muscles at the base of the thumb (thenar eminence).
• Responsible for precise thumb movements.
• Innervated by the median nerve.

Abductor Pollicis Brevis

• Originates from the scaphoid and trapezium tubercles.
• Attaches to the lateral side of the proximal phalanx and thumb extensor hood.
• Abducts the thumb at the metacarpophalangeal joint.
• Innervated by the recurrent branch of the median nerve (C8, T1).

Flexor Pollicis Brevis

• Originates from the trapezium tubercle and flexor retinaculum.
• Attaches to the base of the proximal thumb phalanx.
• Flexes the thumb at the metacarpophalangeal joint.

Opponens Pollicis Brevis

• Originates from the trapezium tubercle and flexor retinaculum.
• Attaches to the medial margin of the thumb metacarpal.
• Rotates the thumb medially.

Hypothenar Compartments

• Located on the medial side of the palm, at the base of the little finger (hypothenar eminence).
• Similar to the thenar muscles in structure and function.
• Innervated by the ulnar nerve.

Abductor Digiti Minimi

• Originates from the pisiform, pisohamate ligament, and flexor carpi ulnaris tendon.
• Attaches to the proximal phalanx of the little finger.
• Abducts the little finger at the metacarpophalangeal joint.
• Innervated by the deep branch of the ulnar nerve (C8, T1).

Flexor Digiti Minimi

• Originates from the hook of the hamate and flexor retinaculum.
• Attaches to the proximal phalanx of the little finger.
• Flexes the little finger at the metacarpophalangeal joint.
• Innervated by the deep branch of the ulnar nerve.

Opponens Digiti Minimi

• Originates from the hook of the hamate and flexor retinaculum.
• Attaches to the medial side of the little finger metacarpal.
• Rotates the little finger laterally.
• Innervated by the deep branch of the ulnar nerve

Adductor Compartment

• Contains the adductor pollicis muscle
• It has two heads: transverse and oblique
• Originates from metacarpal 3(transverse) and capitate and bases of metacarpals 2 and 3(oblique)
• Inserts into the base of proximal phalanx and extensor hood of thumb
• Action: Adducts thumb
• Innervation: deep branch of ulnar n (C8, T1)

Central Compartment

• Contains the lumbrical and interossei muscles.
• Lumbricals: four muscles crucial for finger movement, connecting extensor and flexor tendons. Essential for ulnar claw and benediction hand poses. Innervated by the ulnar and median nerves.
• Interossei : Located between metacarpals, Dorsal and Palmar types, assist lumbricals in flexion/extension at MCP and IP joints, responsible for abduction and adduction.

Interossei

• Dorsal interossei: situated between metacarpals, responsible for abduction of the index, middle, and ring fingers.
• Palmar interossei: positioned between metacarpals, responsible for adduction of the index, ring, and little fingers.

This quiz explores the anatomy of the hand muscles, focusing on the distinction between intrinsic and extrinsic muscles. It covers the various compartments of the hand, detailing their functions and the specific muscles involved. Test your knowledge on how these muscles contribute to movements and motor skills.