0624 - Anatomy of Shoulder and Arm

Question 1

What bones form the shoulder girdle?

Answer 1

Clavicle, articulates with scapula (acromioclavicularjoint). Clavicles also articulate with manubrium of sternum (sternoclavicular joint) at anterior midline, forming a girdle.
Articulates with arm at shoulder (glenorohumoural joint)

Question 2

Describe the clavicle

Answer 2

Link between axial and articular skeletons - strut to support the limb.
S-shaped bone, with a triangular sternal end (sternoclavicular joint), and flat acromial end (acromioclavicular joint)
Superior surface is smooth
Inferior surface contains conoid process for conoid lig. trapezoid line for trapezoid lig. (Together coracoclavicular lig.)

Question 3

Describe the scapula

Answer 3

Roughly triangular shaped bone, with inferior, superior angles. Glenoid cavity allows for glenorohumoural joint), and supraglenoid tubercle, infraglenoid tubercle.

Question 4

Describe the humerus

Answer 4

The only bone in the arm
Proximal hemispheric head with anatomical and surgical necks. Greater and lesser tubercles separated by a bicipital (intertubercular) groove.
Distal end - Trochlea, olecranon fossa posterior, capitulum, epicondyles.

Question 5

Describe the sternoclavicular joint

Answer 5

Only joint between upper limb and axial skeleton.

Synovial saddle joint.

Question 6

Describe the acromiclavicular joint

Answer 6

Synovial, plane type joint, with acromioclavicular ligament over, but trapezoid and conoid (coracoclavicular) ligaments providing stability.

Question 7

Describe the glenohumeral joint

Answer 7

Most important joint in the area. Synovial ball and socket joint.
Allows Fl/Ex, Ab/Ad, Ro, Circumduction movements of shoulder.
Weak stability - 1/3 of humoral head covered by glenoid fossa. Multiple ligaments (thickening of capsule) provide stability.
Muscles of rotator cuff and biceps tendon are the ultimate stabilisers - dynamic restraint as a stabiliser (always drag against movement)

Question 8

What are the main ligaments of the glenohumeral joint?

Answer 8

Glenohumeral lig. anterior
Coracohumeral lig superior
Transverse humeral lig (greater/lesser tubercles)
Coracoacromial ligament and arch.

Question 9

What are the muscles of the rotator cuff? (origin and insertion)

Answer 9

Supraspinatus - Supraspinus fossa of scapula - Greater tubercle of Humerus
Infraspinatus - Infraspinus fossa of scapula - Greater tubercle of humerus
Teres minor - Inferior angle of scapula - Greater tubercle of humerus
Subscapularis - Anterior surface of scapular - Lesser tubercle of humerus

Question 10

What is the function of the rotator cuff?

Answer 10

Hold down humeral head while deltoid abducts arm - without it, deltoid would pull head upward.
Also act in internal (medial) and external (lateral) rotation.

Question 11

What are the muscles of the arm?

(KEY MCQ QUESTION)

Answer 11

Posterior/Inferior Triceps - 3 heads, inferior glenoid tubercle, lateral and medial on humerus (dividing radial groove)
Teres Major - Lower scapula to humerus
Anterior - all flexors
Biceps brachii - long head through glenohumeral joint to subraglenoid tubercle, short head to coracoid process, inserting at radial tuberosity.

Coracobrachialis - Coracoid process to middle humerus.
Brachialis - distal humerus to coranoid process/ulnar tuberosity.

Question 12

What is the location and composition of the brachial plexus?

Answer 12

Extends from anterior and middle scalenes, through anterior triangle of neck, behind clavicle, and into axilla.
Divided into 5 roots, 3 trunks, 6 divisions, 3 cords, and 5 major terminal nerves.

Question 13

Briefly describe the constituent parts of the brachial plexus

Answer 13

Roots
Anterior rami of C5-T1.
Trunks - Top 2 join to join superior, bottom 2 join to become inferior trunk, middle stays alone.
Divisions - Each trunk bifurcates into an anterior and posterior divisions, giving 6 divisions
Cords - Posterior divisions join to form posterior cord. Top 2 anterior divisions join to form lateral cord, anterior division of other forms medial cord.
Nerves - Musculocutaneous, median, ulnar, axillary, radial (most important)

Question 14

Axillary and radial nerves formed by posterior cord

Answer 14

Lateral cord forms musculocutaneous nerve and median nerve (with half of medial cord)
Remainder of medial curve forms ulnar nerve.

Question 15

Draw the brachial plexus.

Answer 15

https://s3.amazonaws.com/classconnection/49/flashcards/6302049/png/brachial_plexus-14917DD31FA048F12F9.png

Question 16

What is the arterial supply to the arm?

Answer 16

Subclavian artery, crosses clavicle to axillary a. then at lower edge of teres major becomes brachial a.
Bifurcates at elbow joint intu ulnar and radial artery.
Branches - Ant and Post circumflex humeral a. Profunda brachii a to muscles of arm.

Question 17

What is the venous drainage from the arm?

Answer 17

Superficial - Medial = basilic, lateral = cephalic.

Deep veins run into basilic.