shoulder joint, posterior arm and forearm

Question 1

what is the deltoid?

Answer 1

muscle supplied by the axillary nerve (along with theres minor)
attaches proximally to the lateral third of the clavicle and the inferior aspects of the scapular spine and acromion
distally to deltoid tuberosity of the humerus

Question 2

what do the rotator cuff muscles do?

Answer 2

strengthen fibrous capsule of the shoulder joint superiorly (supraspinatus) and posteriorly (infraspinatus and theres minor)

Question 3

subacromial bursitis is where

Answer 3

between supraspinatus tendon and acromion process of scapula

pain on abduction

Question 4

sensory innervation to the posterior aspect of the arm

Answer 4

medially: C8, T1 and T2, common site for cardiac referred pain, especially to the left supper limb via the intercostobrachial nerve and medial and posterior cutaneous nerves of arm and medial cutaneous nerve of forearm
laterally: C5 and 6 via axillary nerve

Question 5

the only muscle of the posterior compartment of arm

Answer 5

triceps brachii

Question 6

triceps brachii innervation, attachments, and action

Answer 6

nerve: radial
proximal: infraglenoid tubercle of scapula (long head) superior (lateral head) and inferior (medial head) to the radial groove of humerus
distal: all 3 heads combine to form triceps tendon, attaches to the olecranon process of the ulna
action: weak extension of arm at shoulder joint, and extension of the forearm at the elbow joint

Question 7

where is the axillary nerve found?

Answer 7

quadrangular space between trees minor superiorly, teres major inferiorly, the long head of triceps medially and the humerus laterally

Question 8

what does the axillary nerve supply?

Answer 8

deltoid and teres minor from C5 and 6

area of skin innervated is called “badge patch” (lateral aspect of arm)

Question 9

how to test function of axillary nerve?

Answer 9

abduct upper limb beyond 15 degrees

Question 10

radial nerve

Answer 10

passes from axilla into the posterior compartment of the arm where it is found in the radial groove of the humerus
after supplying triceps brachia the radial nerve leaves posterior compartment of the arm to enter the lateral aspect of the cubital fossa before returning to the posterior aspect of the limb in the posterior compartment of the forearm

Question 11

why is the radial nerve vulnerable to damage?

Answer 11

because of its position in the radial groove, the nerve and accompanying vessels are vulnerable to damage in the (spiral) mid shaft fracture of the humerus

Question 12

groups of the posterior compartment of the forearm

Answer 12

A: extension, abduction and adduction of wrist
B:extension of fingers
C: extension and abduction of thumb (pollicis)
D: supination of the forearm at the proximal and distal radioulnar joints

Question 13

group A and B of the forearm

Answer 13

superficial, muscles attach proximally to the common extensor tendon on the lateral epicondyle of humerus

Question 14

group C and D of forearm

Answer 14

deeper layer, muscles attach proximally to the shafts of the radius and ulna and the interosseous membrane

Question 15

nerve that innervates posterior compartment of forearm

Answer 15

radial

Question 16

how are tendons held in place as they cross wrist

Answer 16

extensor retinaculum

Question 17

radial nerve divides into…

Answer 17

superficial and deep branch just anterior to the lateral epicondyle
deep branch passes into the posterior compartment of the forearm by winding around the neck of the radius and passing through supinator muscle (which it supplies)

Question 18

what does deep branch of radial nerve turn into after passing through supinator

Answer 18

posterior interosseous nerve, which supplies the muscles of the posterior compartment of the forearm

Question 19

brachioradialis?

Answer 19

located at the boundary between anterior and posterior compartments of forearm
flexion of the semi pronated forearm (drinking out of a cup)