Muscles of the Hand Flashcards
Instrinsic muscles of the hand are responsible for
Fine motor functions of the hand
Instrinsic Muscles of the hand
Adductor pollicus Palmaris Brevis Interossei Lumbricals Thenar Hypothenar muscles
Thenar Muscles
These 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.
Nerve innervation of the thenar muscles
Median Nerve
Opponens Pollicus
The largest of the thenar muscles. This lies underneath the other two thenar muscles.
Opponens Pollicus Attachements
Originates from the tubercle of the trapezium and the associated flexor retinaculum. It inserts into the lateral margin of the metacarpal of the thumb
Opponens Pollicus Action
Opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium
Aductor Pollicus Brevis
This muscle is found anteriorly to the opponens pollicus and proximal to the pollicus brevis
Attachments of Abductor Pollicus Brevis
Originates from the tubercles of the scaphoid and the trapezium, and from the associated flexor retinaculum. Attache to the lateral side of the proximal phalanx of the thumb.
Action of Abductor Pollicus Brevis
Abducts the thumb
Flexor Pollicus Brevis
This is the most distal of the thenar muscle
Attachements of Flexor Pollicus Brevis
Originates from the tubercle of the trapezium and the associated flexor retinaculum. Attaches to the base of the proximal phalanx of the thumb.
Actions of Flexor Pollicus Brevis
Flexes the metacarpophalangeal joint of the thumb.
Hypothenar Eminence
This is is produced by the hypothenar muscles and is a muscular protrusion on the medial side of the palm, at the base of the little finger.
Innervation of Hypothenar Muscles
The Ulnar Nerve
Opponens Digiti Minimi attachments
Originates from the hook of the hamate and associated flexor retinaculum, inserts into the medial margin of metacapral 5.
Actions of opponens digiti minimi
It rotates the metacarpal of the little finger towards the palm, producing opposition.
Abductor Digiti Minimi attachments
Originates from the pisiform and the tendon of the flexor carpi ulnaris. It attaches to the base of the proximal phalanx of the little finger.
Actions of abductor digiti minimi
Abducts the little finger
Flexor Digiti Minimi Brevis attachments
Originates from the hook of hamate and adjacent flexor retinaculum, and inserts into the base of the proximal phalanx of the little finger
Actions of Flexor Digiti Minimi Brevis attachments
Flexes the MCP joint of the little finger
Lumbricals
These 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
Attachments of the lumbricals
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.
Actions of the Lumbrical muscles
The flex at the MCP joint, and extend at the interphalangeal (IP) joints of each finger.
Innervation of the Lumbrical Muscles
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.
Interossei
The interossei muscles are located between the metacarpals. They can be divided into two groups: the dorsal and palmar interossei
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.
Actions of the dorsal interossei
Abduct the fingers at the MCP joint
Innervation of the dorsal interossei
Ulnar nerve
Attachments of the Palmar Interossei
Each interossei originates from a medial or lateral surface of a metacarpal, and attaches into the extensor hood and proximal phalanx of same finger.
Actions of the Palmar Interossei
Adducts the fingers at the MCP joint
Innervation of the palmar interossei
Ulnar nerve
Palmaris Brevis
A small thin muscles, found in the subcutaenous tissue of the hypothenar eminence
Attachments of Palmaris Brevis
Originates from the palmar aponeurosis and flexor retinaculum, attaches to the dermis of the skin on the medial margin of the hand.
Actions of Palmaris Brevis
Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand, improving grip.
Innervation of Palmaris Brevis
Ulnar Nerve
Adductor Pollicus
This is large triangular muscle with two heads. The radial artery passes anteriorly through the space between the two heads, forming the deep palmar arch
Attachments of Adductor Pollicus
One head originates from metacarpal III. The other head originates from the capitate and adjacent areas of metacarpals II and III. Both attach into the base of the proximal phalanx of the thumb
Actions of Adductor Pollicus
Adductor of the thumb
Innervation of adductor pollicus
Ulnar nerve
Radial artery
contributes mainly to supply of the thumb and the lateral side of the index finger. As it tends to enter the hand dorsally it contributes mainly to the deep palmar arch.
Ulnar Artery
contributes mainly to the supply of the rest of the digits, and the medial side of the index finger. The main contributor of the superficial arch.
