MSK - Muscles of the Hand Flashcards
Images reproduced, with permission, from teachmeanatomy.info
How many groups can the hand muscles be divided into?
What are the names of these groups?
2
Intrinsic
Extrinsic
What is the function of the extrinsic muscles of the hand?
Where are they located?
Produce crude movements and a forceful grip
Located in the anterior and posterior compartments of the forearm
What is the function of the intrinsic muscles of the hand?
Where are they located?
Responsible for the fine motor functions of the hand
Located within the hand
What is the grouped name of the three short muscles located at the base of the thumb?
Thenar muscles
What is the thenar eminance?
The bulge at the base of the thumb produced by the muscle bellies
What is the function of the Thenar hand muscles?
Fine movements of the thumb
What nerve innervates each thenar muscle?
All of them are innervated by the median nerve
What is the muscle highlighted in green?
What is it’s attachments?
What is it’s actions?
Oppenens Pollicis
Originates from the tubercle of the trapezium and flexor retinaculum and inserts into the lateral margin of the metacarpal of the thumb
Opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium
What is the muscle highlighted in blue?
What is it’s attachments?
What is it’s actions?
Abductor Pollicis Brevis
Originates from the tubercles of the scaphoid and trapezium and from flexor retinaculum and attaches to lateral side of proximal phalanx
Abducts the thumb
What is the muscle highlighted in red?
What is it’s attachments?
What is it’s actions?
Flexor Pollicis Brevis
Originates from the tubercle of the trapezium and flexor retinaculum and attaches to the base of the proximal phalanx of the thumb
Abducts the thumb
What is the muscle highlighted in green?
What is it’s attachments?
What is it’s actions?
Flexor Digiti Minimi Brevis
Originates from the hook of hamata and adjacent flexor retinaculum and inserts into the base of the proximal phalanx of the little finger
Flexes the MCP joint of the little finger
What is the muscle highlighted in blue?
What is it’s attachments?
What is it’s actions?
Opponens Digiti Minimi
Originates from the hook of hamate and associated flexor retinaculum and inserts into the medial margin of metacarpal V
Rotates the metacarpal of the little finger towards the palm, producing opposition
What is the muscle highlighted in red?
What is it’s attachments?
What is it’s actions?
Abductor Digiti Minimi
Originates from the pisiform and the tendon of the flexor carpi ulnaris and attaches to the base of the proximal phalanx of the little finger
Abducts the little finger
What is the grouped name for the following muscles?
Opponens Digiti Minimi
Abductor Digiti Minimi
Flexor Digiti Minimi Brevis
What are they all innervated by?
The **Hypothenar **Muscles
Innervate by the Ulnar nerve
What group do these muscles belong to?
The Lumbricals
What is the function of the lumbricals?
Crucial to finger movement, linking the extensor tendons to the flexor tendons
How would denervation of the lumbricals clinically present?
Ulnar claw/Hand of benediction
Which lumbricals are unipennate and which are bipennate?
I and II - unipennate
III and IV - bipennate
What are the attachments of the lumbricals?
Each lumbrical originates from a tendon of the flexor digirorum profundus before passing dorsally and laterally around each finger and inserting into the extensor hood
What are the actions of the lumbricals?
The flex at the MCP joint, and extend at the IP joints of each finger
What are the innvervations of the lumbricals?
Medial two lumbricals (little and ring fingers) - ulnar nerve
Lateral two lumbricals (index and middle fingers) - median nerve
What muscles are located between the metacarpals?
The interossei muscles
How many groups can the interossei muscles be divided into?
Name them
2
Dorsal and Palmar interossei
What else do the interossei muscles do in addition to their own actions?
Assist the lumbricals in flexion at the MCP joints and extension at the IP joints
Which ones are dorsal and which ones are palmar?
Yellow - Dorsal
Green - Palmar
How many dorsal muscles are there?
What are their attachments?
What are their individual actions?
What are their innervations?
4
Each interossei originates from the lateral and medial surfaces of the metacarpals before attaching into the extensor hood and proximal phalanx of each finger
Abduct the fingers at the MCP joint
Ulnar Nerve
How many palmar muscles are there?
What are their attachments?
What are their individual actions?
What are their innervations?
3
Each interossei originates from a medial or lateral surface of a metacarpal before attaching into the extensor hood and proximal phalanx of the same finger
Adducts the fingers at the MCP joint
Ulnar Nerve
There are two other muscles in the palm that do not fit the hypothenar or thenar compartments. What are their names?
Where is the Palmaris Brevis found?
Very superficially in the subsutaneous tissue of the hypothenar eminence
What are the attachments of the Palmaris Brevis?
What is its actions?
What is it innervated by?
Originates from the palmar aponeurosis and flexor retinaculum before attaching to the dermis of the skin on the medial margin of the hand
Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand which improves grip
Ulnar nerve
What structure passes anteriorly to this muscle between its two heads and what does it form?
What is it’s attachments?
What is it’s actions?
What is it innervated by?
Radial artery, forming palmar arch
One head originates from metacarpal III, the other from the capitate, and adjacent areas of metacarpals II and III. They both attach into the base of the proximal phalanx of the thumb
Adductor of the thumb
Ulnar nerve
