Lab 2 - Posterior Shoulder & Upper Limb

Question 1

triceps brachii

action, innervation, proximal / distal attachment?

what 3 heads comprise the triceps brachii?

Answer 1

triceps brachii = long head, lateral head, medial head

action

elbow joint extension

innervation

radial nerve

proximal attachment

long head attaches to scapula (infraglenoid tubercle)

lateral head attaches to humerus (lateral shaft)

medial head attaches to humerus (medial shaft)

distal attachment

ulna (olecranon process)

Note: triceps brachii is only muscle in posterior brachial compartment

Question 2

anconeus

action, innervation, proximal / distal attachment?

Answer 2

action

elbow joint extension (small muscle, known as the “tennis” muscle bc assists w/ antebrachial pronation)

innervation

radial nerve

proximal attachment

humerus (lateral epicondyle)

distal attachment

ulna (olecranon process)

Question 3

brachioradialis

action, innervation, proximal / distal attachment?

Answer 3

action

elbow joint flexion

innervation

radial nerve

proximal attachment

humerus (lateral supraepicondylar ridge)

distal attachment

radius (styloid process)

Question 4

extensor carpi radialis longus

action, innervation, proximal/distal attachment?

Answer 4

action

wrist joint extension and radial deviation (abduction)

innervation

radial nerve

proximal attachment

humerus (lateral epicondyle)

distal attachment

metacarpal 2 (base)

Question 5

extensor carpi radialis brevis

action, innervation, proximal/distal attachment?

Answer 5

action

wrist joint extension and radial deviation (abduction)

innervation

radial nerve (deep branch)

proximal attachment

humerus (lateral epicondyle)

distal attachment

metacarpal 2 (base)

Question 6

extensor digitorum

action, innervation, proximal/distal attachment?

Answer 6

action

1) wrist joint extension
2) digit 2-5 extension (MCP, PIP, and DIP joints)

innervation

radial nerve (posterior interosseous branch)

proximal attachment

humerus (lateral epicondyle)

distal attachment

digit 2-5 extensor expansions

Note: MCP = metacarpophalangeal, PIP = proximal interphalangeal, DIP = distal interphalangeal

Question 7

extensor digiti minimi

action, innervation, proximal/distal attachment?

Answer 7

action

1) wrist joint extension
2) joint digit 5 (pinky) extension (MCP, PIP, and DIP joints)

innervation

radial nerve (posterior interosseous branch)

proximal attachment

humerus (lateral epicondyle)

distal attachment

digit 5 extensor expansion

Question 8

extensor carpi ulnaris

action, innervation, proximal/distal attachment?

Answer 8

action

1) wrist joint extension
2) ulnar deviation (adduction)

innervation

radial nerve (posterior interosseous branch)

proximal attachment

humerus (lateral epicondyle)

distal attachment

metacarpal 6 (base)

Question 9

supinator

action, innervation, proximal / distal attachment?

Answer 9

action

radioulnar joint supination

innervation

radial (deep branch)

proximal

humerus (lateral epicondyle)

ulna (proximal medial shaft)

distal attachment

radius (proximal anterior shaft)

Question 10

abductor pollicis longus

action, innervation, proximal / distal attachment?

Answer 10

action

digit 1 (thumb) CMC joint abduction and extension

innervation

radial (posterior interosseous branch)

proximal attachment

ulna (midshaft)

radius (midshaft)

interosseous membrane

distal attachment

metacarpal 1 (base)

Note: abduction = thumb moves away from and perpendicular to plane of palm ; extension = thumb moves away radially from plane of palm ; CMC = carpometacarpal joint

Question 11

extensor pollicus longus

action, innervation, proximal / distal attachment?

Answer 11

action

digit 1 (thumb) extension (CMC, MCP, PIP and DIP joints)

innervation

radial (posterior interosseous branch)

proximal attachment

ulna (distal shaft)

interosseous membrane

distal attachment

distal phalanx 1 (base)

Note: DIP = distal interphalangeal joint

Question 12

extensor pollicis brevis

action, innervation, proximal / distal attachment?

Answer 12

action

digit 1 (thumb) extension (CMC and MCP joints)

innervation

radial (posterior interosseous branch)

proximal attachment

radius (distal shaft)

interosseous membrane

distal attachment

proximal phalanx 1 (base)

Question 13

extensor indicis

action, innervation, proximal / distal attachment?

Answer 13

action

digit 2 extension (MCP, PIP and DIP joints)

innervation

radial (posterior interosseous branch)

proximal attachment

ulna (posterior distal shaft)

interosseous membrane

distal attachment

digit 2 extensor expansion

Question 14

identify the carpals, metacarpals, proximal phalanges, intermediate phalanges and distal phalanges on your hand

Answer 14