Shoulder Joint, Posterior Arm and Forearm

Question 1

What does the axillary nerve supply?

Answer 1

The deltoid and teres minor

Question 2

Where does the deltoid attach proximally?

Answer 2

To the lateral third of the clavicle and the inferior aspects of the scapular spine and acromion

Question 3

Where does the deltoid attach distally?

Answer 3

Deltoid tuberosity of the humerus

Question 4

What rotator cuff muscle strengthens the fibrous capsule of the shoulder superiorly?

Answer 4

Supraspinatus

Question 5

What rotator cuff muscles strengthen the fibrous capsule of the shoulder inferiorly?

Answer 5

Infraspinatus, teres minor

Question 6

Where is the subacromial bursa located?

Answer 6

Between the supraspinatus tendon and the acromion process of the scapula

Question 7

What nerves innervate the posterior arm medially?

Answer 7

Anterior rami of spinal nerves C8, T1 and T2

Question 8

Why is the medial aspect of the posterior arm a common sit for cardiac referred pain?

Answer 8

Due to the intercostobrachial nerve, the medial and posterior cutaneous nerves of the arm, and the medial cutaneous nerve of the forearm

Question 9

What nerves supply the posterior arm laterally?

Answer 9

Anterior rami of spinal nerves C5 and C6 via the axillary nerve

Question 10

What is the only muscle of the posterior arm?

Answer 10

Triceps brachi

Question 11

What innervates triceps brachi?

Answer 11

Radial nerve

Question 12

Where are the proximally attachments of triceps brachi?

Answer 12

Infraglenoid tubercle of the scapula (long head), superior (lateral head) and inferior (medial head) to the radial groove of the humerus

Question 13

What is the distal attachment of the triceps brachi?

Answer 13

All three heads combine to form the triceps tendon, which attaches to the olecranon process of the ulna

Question 14

What action does the triceps brachi perform?

Answer 14

Weak extension of the arm at the shoulder, extension of forearm at elbow

Question 15

Where is the axillary nerve located?

Answer 15

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

Question 16

Where is the badge patch?

Answer 16

Lateral aspect of arm supplied by the axillary nerve

Question 17

What is the badge patch used for?

Answer 17

Testing axillary nerve function after an inferior shoulder dislocation by assessing sensation in the badge patch

Question 18

How is function of the axillary nerve assessed?

Answer 18

Ask patient to abduct the upper limb beyond 15 degrees

Question 19

Where is the radial nerve located?

Answer 19

Passes from axilla into posterior arm where it is found in the radial groove of the humerus

Question 20

Where does the radial nerve pass once it has supplied triceps brachi?

Answer 20

Leaves posterior arm to enter lateral aspect of cubital fossa before returning to posterior forearm

Question 21

When may the radial nerve be damaged?

Answer 21

In mid-shaft fracture to humerus (test function in hand)

Question 22

What are the muscle groups of the posterior forearm?

Answer 22

Groups A-D

Question 23

What nerve supplies the muscles of the posterior forearm?

Answer 23

Radial nerve

Question 24

What muscle groups make up the superficial and deep layers of muscle in the posterior forearm?

Answer 24

Superficial layer = Groups A and B

Deep layer = Groups C and D

Question 25

Where do groups A and B of the posterior forearm attach?

Answer 25

Attach proximally to the common extensor tendon on the lateral epicondyle of the humerus

Question 26

Where do groups C and D of the posterior forearm attach?

Answer 26

Attach proximally to the shafts of the radius and ulna, and the interosseous membrane

Question 27

What action does group A of the posterior forearm perform?

Answer 27

Extension, abduction and adduction of the wrist (carpus)

Question 28

What action does group B of the posterior forearm perform?

Answer 28

Extension of the fingers (digitorum)

Question 29

What action does group C of the posterior forearm perform?

Answer 29

Extension and abduction of the thumb (pollicis)

Question 30

What action does group D of the posterior forearm perform?

Answer 30

Supination of the forearm at the proximal and distal radioulnar joints

Question 31

Where are groups A-C of the posterior forearm located?

Answer 31

Their muscle bellies are only found within the posterior forearm, while their tendons pass to the wrist and fingers

Question 32

What holds the tendons of groups A-C of the posterior forearm in place as they cross the wrist?

Answer 32

The extensor retinaculum

Question 33

Why is brachioradialis also categorised as a muscle of the posterior forearm?

Answer 33

It is also supplied by the radial nerve

Question 34

Where is brachioradialis located?

Answer 34

At the boundary between the anterior and posterior compartments of the forearm

Question 35

What is the main action of brachioradialis?

Answer 35

Flexion of the semi-pronated forearm

Question 36

Where does the radial nerve divide into its deep and superficial branches?

Answer 36

Just anterior to the lateral epicondyle of the humerus

Question 37

Where is the deep branch of the radial nerve located?

Answer 37

Passes into posterior forearm by winding around the neck of the radius and passing through the supinator muscle, which is supplies

Question 38

Where does the deep branch of the radial nerve become the posterior interosseous nerve?

Answer 38

After passing through the supinator (supplies muscles of posterior forearm)