Anatomy & Physiology of the Intrinsic Muscles of the Hand

A set of 40 vocabulary flashcards covering the intrinsic muscles of the hand, their origins, insertions, actions, and innervations.

Opponens pollicis

Muscle that originates from carpal bones and the transverse carpal ligament, inserting at metacarpal 1, enabling opposition of digit 1 to digits 2-5.

Abductor pollicis brevis

Muscle originating from carpal bones and transverse carpal ligament, inserting at the proximal phalanx of digit 1, facilitating abduction of digit 1.

Flexor pollicis brevis

Muscle originating from carpal bones and transverse carpal ligament, inserting at the proximal phalanx of digit 1, allowing flexion of digit 1 at the metacarpophalangeal joint.

Adductor pollicis

Muscle originating from metacarpals 2 & 3, inserting at the proximal phalanx of digit 1, enabling adduction of digit 1.

Abductor digiti minimi

Muscle from carpal bones and flexor retinaculum, inserting at the base of the proximal phalanx of digit 5, allowing abduction and flexion of digit 5.

Flexor digiti minimi brevis

Muscle originating from carpal bones and flexor retinaculum, inserting at proximal and middle phalanx of digit 5, facilitating flexion of digit 5 at MCP and PIP joints.

Opponens digiti minimi

Muscle originating from carpal bones and flexor retinaculum, inserting at the 5th metacarpal, opposing digit 5.

Palmar interossei

Muscle that originates from metacarpals, inserting at proximal phalanx of digits 2, 4, and 5, enabling adduction of these digits.

Dorsal interossei

Muscle originating from metacarpals, inserting at proximal phalanx of digits 2, 3, and 4, facilitating abduction of these digits.

Lumbricals

Muscles originating from tendons of the flexor digitorum profundus, inserting at tendons of extensor digitorum for digits 2-5, allowing MCP flexion with PIP and DIP extension.

Action of Opponens pollicis

Opposition of digit 1 to digits 2-5.

Innervation of Abductor pollicis brevis

Median nerve.

Action of Flexor pollicis brevis

Flexion of digit 1 at the metacarpophalangeal joint.

Innervation of Adductor pollicis

Ulnar nerve.

Origin of Abductor digiti minimi

Carpal bones and flexor retinaculum.

Insertion of Flexor digiti minimi brevis

Proximal and middle phalanx of digit 5.

Action of Opponens digiti minimi

Opposes digit 5 slightly.

Function of Palmar interossei

Adduction of digits 2, 4, and 5.

Function of Dorsal interossei

Abduction of digits 2, 3, and 4.

Innervation of Lumbricals for digits 2 & 3

Median nerve.

Innervation of Lumbricals for digits 4 & 5

Ulnar nerve.

Intrinsic plus position

MCP flexion with PIP and DIP extension, achieved by the lumbricals.

Carpal bones

Bones at the base of the hand from which many intrinsic muscles originate.

Transverse carpal ligament

A fibrous band in the wrist from which intrinsic muscles of the thenar eminence originate.

Flexor retinaculum

A fibrous band from which intrinsic muscles of the hypothenar eminence originate.

Opponens pollicis innervation

Median nerve.

Abductor pollicis brevis innervation

Median nerve.

Flexor pollicis brevis innervation

Median and ulnar nerves.

Adductor pollicis action

Adduction of digit 1.

Abductor digiti minimi action

Abduction and flexion of digit 5.

Opponens digiti minimi action

Opposes digit 5.

Palmar interossei origin

Metacarpals.

Dorsal interossei insertion

Proximal phalanx digits 2, 3, and 4.

Lumbricals action

MCP flexion with PIP and DIP extension.

Intrinsic muscles of the hand

Muscles that originate and insert within the hand, controlling fine motor movements.

Thenar eminence

The muscular bulge at the base of the thumb.

Hypothenar eminence

The muscular bulge at the base of the little finger.

Digital flexors

Muscles that enable flexion at MCP joints.

Digital extensors

Muscles that enable extension at PIP and DIP joints.

Median nerve function

Innervates most intrinsic muscles of the thenar eminence.

Ulnar nerve function

Innervates intrinsic muscles of the hypothenar eminence and some lumbricals.

Flexion at the MCP joint

Movement of a finger towards the palm at the metacarpophalangeal joint.

Abduction of a digit

Movement of a finger away from the midline of the hand.

Adduction of a digit

Movement of a finger towards the midline of the hand.

Opposition of the thumb

The ability of the thumb to touch the tips of the other fingers.