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Please view the main muscle page to learn about foundational information relating to muscles (such as origins, insertions, actions, innervations):
Types of Muscles in the Hand
Intrinsic muscles:
Muscles that are solely in the hand (originate and insert in the hand)
Consist of different groups of muscles:
Thenar muscles (thumb side): include the abductor pollicis brevis, flexor pollicis brevis, opponens pollicis
Hypothenar muscles (pinky side): include the abductor digiti minimi, flexor digiti mini brevis, opponens digiti minimi
Lumbricals: muscles that flex the MCP joints, along with extended the PIP and DIP joints
Interossei: there are two groups within the interossei muscles in the palmar interossei and dorsal interossei
The palmar interossei adduct the fingers
The dorsal interossei abduct the fingers
The adductor pollicis is another intrinsic muscle that brings the thumb toward the palm but doesn't fit into any of the above groups
Extrinsic muscles:
Muscles that originate in the forearm and insert onto the hand
Can be divided into two groups:
Flexors: Include the flexor digitorum superficialis, flexor digitorum profundus, and flexor pollicis longus
Extensors: Include the extensor digitorum, extensor indicis, extensor pollicis longus, and extensor pollicis brevis
Palmar view of superficial muscles
Palmar view of superficial muscles
Note the typo in the text for the left picture, as it is actually the flexor retinaculum that is also referred to as the transverse carpal ligament
Palmar view of superficial and middle layer muscles
Palmar view of superficial and middle layer muscles
Palmar view of middle and deep layer muscles
Palmar view of middle and deep layer muscles
Palmar and dorsal view of origins and insertions
Palmar and dorsal view of origins and insertions
Quiz Questions - please watch the videos and view the Kenhub link before taking
What are intrinsic muscles?
A. Muscles that originate in the forearm and insert in the hand
B. Muscles that are solely in the hand
C. Muscles that only function in the wrist
D. Muscles that connect the elbow to the hand
What is the primary action of the dorsal interossei?
A. Flexes the MCP joint
B. Adducts the fingers
C. Abducts the fingers
D. Extends the PIP and DIP joints
What is the primary action of the palmar interossei?
A. Abducts the fingers
B. Adducts the fingers
C. Flexes the PIP joints
D. Extends the MCP joints
What is the primary function of the thenar muscles?
A. To control movements of the pinky
B. To control movements of the thumb
C. To extend the wrist
D. To stabilize the hand during gripping
What action do the lumbricals of the hand perform?
A. Flex the MCP joints and extend the PIP/DIP joints
B. Abduct the fingers
C. Adduct the thumb
D. Extend the wrist
Which muscles are responsible for flexion of the fingers?
A. Intrinsic muscles of the hand
B. Extrinsic flexors from the forearm
C. Abductor pollicis brevis
D. Extensor digitorum
Where do the interossei muscles lie in the hand?
A. Between the metacarpals
B. Between the phalanges
C. On the palm side only
D. On the back of the hand
Which nerve innervates the thenar muscles?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Musculocutaneous nerve
Which nerve innervates the hypothenar muscles?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Musculocutaneous nerve
Which nerve innervates the extensor muscles of the hand?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Musculocutaneous nerve
Quiz Answers
B
C
B
B
A
B
A
A
B
C
References
Images from: Atlas of Anatomy 4th Edition, Gilroy et al., 2020, Thieme Medical Publishers
Information based on lecture content from professor Dr. Earl Mayhew, DPT, BIO 634 - Human Anatomy course, University of Michigan-Flint, Fall 2022
Page updated
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