Posterior Forearm and Dorsal Hand Flashcards
Which group of the posterior compartment of the forearm crosses the elbow?
the SF group, the deep group does not
What is the innervation rule for the posterior forearm?
radial nerve (C5-C8)
What are the actions of the posterior compartment of the forearm?
extend wrist and fingers
Abduct and adduct the wrist
supinate forearm
Extend, abduct and reposition the thumb
What is the extensor retinaculum?
band of deep fascia that holds long extensor tendons in place as they cross the wrist, tendons are surrounded by synovial sheaths for movement
What are synovial “ganglionic” cysts?
fluid filled swellings that can develop within the synovial sheaths, unknown cause
movement enlarges cysts
most common: synovial sheath of extensor carpi radialis brevis
What is the origin for the superficial group of the posterior compartment of the forearm?
lateral epicondyle of the humerus
What is lateral epicondylitis (tennis elbow)?
inflammation of common extensor origin and periosteum of the lateral epicondyle
What are the muscles of the SF group of the posterior compartment of the forearm?
brachioradialis
extensor carpi radialis longus
extensor carpi radialis brevis
extensor carpi ulnaris
extensor digiti minimi
Insertion of brachioradialis? Action?
distal radius
flex elbow joint*
What does the brachioradialis reflex test assess?
radial nerve and the C6 spinal level
Insertion of extensor carpi radialis longus and extensor carpi radialis brevis? Action?
radial side of hand
extend and abduct wrist joint
Insertion of extensor carpi ulnaris? Actions?
ulnar side of hand
extend wrist, adduct wrist
Insertion of extensor digitorium? actions?
forms extensor expansions of digits 2-5
extend digits (MCP, PIP and DIP) extend wrist joint
insertion of extensor digiti minimi? action?
helps form extensor expansion of digit 5
extend digit 5 (MCP, PIP, DIP)
Origins of the deep group of the posterior compartment of the forearm?
ulna, radius, interosseous membrane
most do not cross elbow
What are the muscles of the deep group of the posterior compartment of the forearm?
abductor pollicis longus
extensor pollicis brevis
extensor pollicis longus
extensor indicis
supinator
Insertion of abductor pollicis longus? Actions?
base of MC1
abduct and extend thumb at CMC joint
Insertion of extensor pollicis brevis? Action?
proximal phalanx of pollux
extend thumb at CMC and MCP joints
Insertion of extensor pollicis longus? Action?
distal phalanx of pollux
extend thumb at CMC, MCP and IP joints
Insertion of extensor indicis? action?
extensor expansion of digit 2
extend digit 2 (MCP, PIP and DIP joints)
Insertion of supinator? Action?
proximal radius
supinate forearm
Name the pronators. What innervates them?
pronator teres
pronator quadratus
both innervated by median nerve
Name the supinators. What innervates them?
supinator- radial n.
biceps brachii-musculocutaneous n.
What resides in the dorsal hand?
long extensor tendons only
no intrinsic muscles
Anatomical stuff box
depression proximal to thumb on dorsal hand
Lateral border: tendons of abductor pollicis longus & extensor pollicis brevis
Medial border: tendon of extensor pollicis longus
What makes up the floor of the anatomical snuff box? What are its contents?
scaphoid and trapezium
contents: radial artery
Why is the anatomical snuff box clinically relevant?
pain and tenderness of the snuff box may indicate a scaphoid fracture
Where does the radial nerve travel?
in the radial groove with the deep artery and vein of the arm
posterior cutaneous nerve of the forearm
branch off the radial nerve, innervates the skin on the posterior forearm
Deep branch of the radial nerve (posterior interosseous n.)
motor to posterior compartment of the forearm
What does the superficial branch of the radial n. innervate?
sensory to skin of lateral wrist (snuff box) and lateral aspect of dorsal hand
What would happen if you severe your radial nerve in the axilla (proximal lesion)?
- extension of elbow lost
- flexion of elbow weakened (biceps brachii and brachialis intact)
- supination weakened (biceps brachii intact)
- extension of wrist loss (wrist drop)
- extension of MCP joints lost
- weakened abduction/adduction of wrist
- weakened extension of PIP and DIP joints digits 2-5
- abduction of thumb weakened
- extension of thumb lost
- sensory deficits of posterior arm, forearm and dorsolateral wrist/hand
How can you test the radial nerve?
extension of elbow, wrist and MCP joints
cutaneous sensation of dorsolateral hand
