Upper arm

Question 1

What type of joint is the sternoclavicular?

Answer 1

Saddle, is biaxial thus allows movement in two planes.

Question 2

What is notable about the sternoclavicular joint?

Answer 2

It is the only joint connecting the upper limb and axial skeleton.

Question 3

What muscles stabilize the pectoral girdle?

Answer 3

Posterior: Trapezious (attaches to clavicle and scapula), rhomboid major/minor, levator scapulae (attach to scapula).
Anterior: Pec major (attaches to clavicle and humerus), pec minor (attaches to scapula and ribs), subclavious (attaches to first rib to stabilize scapula), serratus anterior (medial border or scapula to anterior ribs).

Question 4

What are the main movements that occur around the scapula, as most upper limb movements occur indirectly by movement of the scapula?

Answer 4

Elevation: Traps, levator scapulae, rhomboids
Depression: Gravity, traps
Protraction: Serratus anterior
Retraction: Traps, rhomboids
Upward rotation: Traps, serratus anterior (glenoid fossa points up)
Downward rotation: Levator scapulae, rhomboids

Question 5

What type of joint is the acromioclavicular, and where is it?

Answer 5

Plane between the acromion (lateral end of scapular spine) and lateral end of clavicle.

Question 6

What stabilizes the acromioclavicular joint?

Answer 6

The coracoclavicular ligament, which connects the coracoid process of the scapula to the clavicle.

Question 7

What type of joint is the glenohumeral joint?

Answer 7

Ball and socket between the glenoid fossa or the scapula and the humerus.

Question 8

What is a common issue of the glenohumeral joint? What attempts to resolve this?

Answer 8

Poor congruence of bones (sizes at articulation site do not match up well) leads to less stability. Partially resolved by the glenoid labrum, or fibrocartilage rim surrounding the outside of the glenoid fossa.

Question 9

What stabilizes the glenohumeral joint?

Answer 9

The rotator cuff muscles:
1. Supraspinatus
2. Infraspinatus
3. Teres major
4. Subscapularis
Note first three attach to the greater tubercle of the humerus, fourth to the lesser tubercle.

Question 10

Describe common glenohumeral joint dislocation.

Answer 10

No reinforcement exists inferiorly, so dislocations happens inferiorly, and then often pop anteriorly into axilla after.

Question 11

What is the glenoid fossa?

Answer 11

A section of the scapula that articulates with the humeral head.

Question 12

What is the basic concept of blood supply throughout the upper limb?

Answer 12

1. Originates from subclavian artery.
2. Subclavian becomes axillary at outer border of first rib.
3. Axillary becomes brachial at inferior edge of teres major.
4. Brachial bifurcates near elbow to radial and ulnar.
5. Radial and ulnar contribute to three hand artery arches, the superficial palmar (mostly ulnar), deep palmar (mostly ulnar), and dorsal carpal (mostly radial).
6. Arches give off metacarpal and then digital branches.

Question 13

What are the three anterior arm compartment muscles? What are their functions?

Answer 13

Biceps brachii, brachialis, and coracobrachialis.
All three lead to flexion at the joint/joints they cross. Biceps brachii additionally causes flexed forearm supination, coracobrachialis additionally causes shoulder adduction.

Question 14

What supplies the anterior arm muscles with blood?

Answer 14

Brachial artery

Question 15

What does the biceps tendon reflex test do?

Answer 15

Tests integrity of C5/C6 spinal cord segments, as they are major contributors to branch of MC nerve that innervated biceps brachii.

Question 16

What are the muscles of the posterior arm compartment, and what innervates them? What is their blood supply?

Answer 16

Triceps brachii (three heads meet at elbow, only long head crosses shoulder) and anconeus.
Innervated by the radial nerve.
Blood supply is the deep brachial artery.