L36 Extensor Arm and Forearm Flashcards
What is the main nerve and artery in the extensor compartment of the arm?
What is the main action of the extensor arm?
Deep artery of the arm (profunda brachii artery)
Radial nerve
extension
What is the radial groove?
bony feature on the posterior side of the humerus
divides triceps
where the radial nerve and deep artery of the arm course
Triceps brachii
PA: long: infraglenoid tubercle
lateral: humerus superior to radial groove
medial: humerus inferior to radial groove
DA: olecranon process
Act: extends forearm
Inn: radial n
Anconeus
PA: lateral epicondyle of humerus
DA: proximal ulna
Act: extend & stabilize elbow
Inn: radial n
What muscles have PA attachment to the lateral epicondlye of the humerus?
Anconeus
extensor carpi ulnaris
extensor digiti minimi
extensor digitorum
extensor carpi radialis brevis
supinator
What is an Olecranon Fracture?
“fractured elbow”
avulsion of triceps brachii attachment site (muscle breaking bone)
What is bursitis of the elbow?
can be caused by a fall or repeated friction
“student’s elbow”
Deep artery of the arm
main artery of extensor compartment
courses with radial nerve in radial groove
terminates at branching of radial collateral and middle collateral aa.
Radial nerve
main extensor nerve of arm
courses with deep artery of the arm in radial groove
muscular and cutaneous branches
can be damaged with humerus fracture at midshaft
Where do you test radial nerve reflex?
What spinal nerve is this testing?
triceps reflex tested on posterior portion of arm right above elbow
tests C7
What are the main arteries and nerve of the extensor compartment of the forearm?
What are the main actions of the extensor compartment of the forearm?
radial and ulnar aa.
radial n.
supination of the forearm
extension, abduction, adduction of the wrist
extension of the digits
What is a common extensor origin?
lateral epicondyle
What muscles have a PA of the lateral supracondylar ridge?
brachioradialis
extensor carpi radialis longus
Extensor carpi ulnaris
PA: lateral epicondyle of humerus
DA: 5th metacarpal (base)
Act: extends & adducts hand
Inn: radial n (deep branch)
Extensor digiti minimi
PA: lateral epicondyle of humerus
DA: extensor expansion of digit 5
Act: extends hand & digit 5
Inn: radial n (deep branch)
Extensor digitorum
PA: lateral epicondyle of humerus
DA: extensor expansion of digits 2-5
Act: extends hand & digits 2-5
Inn: radial n (deep branch)
Brachioradialis
PA: lateral supracondylar ridge
DA: distal radius
Act: flexion of mid-pronated forearm (drinking water)
Inn: radial n
Extensor carpi radialis longus
PA: lateral supracondylar ridge
DA: 2nd metacarpal (base)
Act: extend & abduct hand
Inn: radial n
Extensor carpi radialis brevis
PA: lateral epicondyle of humerus
DA: 3rd metacarpal (base)
Act: extend & abduct hand
Inn: radial n (deep branch)
Extensor pollicis longus
PA: ulna, interosseous membrane
DA: distal phalanx of digit 1
Act: extends digit 1
Inn: radial n (deep branch)
Extensor indicis
PA: distal ulna
DA: extensor expansion of digit 2
Act: extends hand & digit 2
Inn: radial n (deep branch)
Supinator
PA: lateral epicondyle of humerus, proximal ulna
DA: proximal radius
Act: supinates forearm
Inn: radial n (deep branch)
Abductor pollicis longus
PA: ulna, radius, interosseus membrane
DA: 1st metacarpal (base)
Act: abducts & extends digit 1 (thumb)
Inn: radial n (deep branch)
Extensor pollicis brevis
PA: radius, interosseous membrane
DA: proximal phalanx of digit 1
Act: extends digit 1 (but not at IP joint)
Inn: radial n (deep branch)
What is the bradioradialis reflex?
Where is it tested and what spinal nerve does it test?
C6
What is the extensor retinaculum?
CT that holds down tendons
multiple tunnels, not a single tunnel like carpal tunnel
What do the intertendinous connections do?
limit extension of individual digits
What are synovial cysts?
What tendon is most common?
inflammation of synovial sheath
also called “ganglionic” “myxoid” “mucous” cysts
Most common is Extensor carpi radialis brevis
What are the two branches of the radial nerve in the extensor forearm?
What do they do?
Superficial branch: sensory in hand, digits 1-4.5, fingertips are median nerve
Deep branch: motor to extensor forearm, distal portion often referred to as “posterior interosseous n.” because it travels with the posterior interosseous artery
What is the extensor expansion?
aponeurosis on dorsum of digits
lateral bands go to distal phalanx
median band to middle phalanx
What is lateral band avulsion/rupture?
rupture/avulsion of distal extensor expansion
loss of extension of distal phalanx
“mallet finger” or “baseball finger”
What is central band avulsion/rupture?
PIP flexed, DIP extended
“Boutonniere deformity”
What is a scaphoid fracture?
most frequently broken carpal bone
often misdiagnosed as sprained wrist
poor blood supply: slow healing/avascular necrosis
What is the nerve innervation on the dorsum of the hand?
ulnar n. (dorsal branch): 5th and half of 4th digit
radial n. (superficial branch): 1st to 4.5 digits except fingertips
median n. (proper digital branches): fingertips of digits 1-4.5
no motor n. in dorsal hand
What is the dorsal venous network comprised of?
basilic v on medial side and cephalic vein on lateral side
What is the arterial supply of dorsal hand?
most blood supply in hand comes from palmar arches, but:
dorsal carpal arch, a branch of the radial artery in snuffbox contributes
