Part 4: Shoulder Region

Question 1

Name the 6 muscles that attach scapular to humerus

Answer 1

Supraspinatus, Infraspinatus, subscapularis, teres major, teres minor, deltoid

Question 2

Supraspinatus origin, insertion and action and nerve supply

Answer 2

Arises from med 3/4 of supraspinous fossa and upper surface of spine. Attaches to sup facet of greater tuberosity of humerus and capsule of shlder joint.
Action: abducts and stabilses joint.
Suprascapular N (C5,6) from upper trunk

Question 3

Infraspinatus origin, insertion, action and nerve supply

Answer 3

Medial 3/4 of inspinatous fossa and fibrous intermuscular septa. Inserts middle facet of gtr tuberosity of humerus and capsule.
Action: Lat rotation and stabilses
Supplied by suprascapular N (C5,6) from upper trunk

Question 4

Teres minor origin, insertion, action and nerve supply

Answer 4

O: Middle 3rd lat border of scapular above teres maj.
I: Inf facet of gtr tuberosity of humerus and capsule
A: Lat rotates and stablises. Weak adductor.
N: Axillary N (C5,6) posterior cord

Question 5

Deltoid origin, insertion, action and nerve supply

Answer 5

O: Lat 3rd clavicle, acromion and spine of scapular to deltoid tubercle.
I: Middle of lat surface of humerus (deltoid tuberosity)
A: Abducts, ant fibres flex and med rotate, post fibres extend and lat rotate
N: Axillary N (C5,6) from posterior cord

Question 6

Describe the scapular anastomosis

Answer 6

Transverse cervical art from subclav has a deep descending branch (dorsal scapular) runs down vert border. Suprascapular (from subclav) runs through supraspinous fossa around the spine into infraspinous fossa. Subscapular supplies subscap fossa and gives off circumflex A which supplies infraspinous fossa. All vessels anastomose.

Question 7

Describe the shoulder capsule

Answer 7

Attached to scapular, margins of labrum and head of humerus. Thick and strong but lax. Thickened at humerus by muscle tendons

Question 8

Transverse humeral ligament

Answer 8

At the upper end of the intertubercular groove the capsule bridges the gap. This is known as the transverse humeral ligament

Question 9

Coracohumeral ligament

Answer 9

Strong. Under surface of corocoid to grt tuberosity.

Question 10

Coracoacromial ligament

Answer 10

Strong flat triangular band. Increases the surface by which the head of the humerus is supported (prevents superior dislocation). Separated from RCby bursa

Question 11

Glenohumeral ligaments

Answer 11

Slight thickenings of capsule above and below subscap bursa opening

Question 12

Bursa of shoulder joint

Answer 12

Subacromial: Beneath coracoacromial ligament, Not connected with capsule.
Subscapularis bursa - allows movement of subscap. Connects with joint

Question 13

Rotator cuff role in stability

Answer 13

Shoulder is shallow joint. Stability achieved by muscles and tendons pulling humerus tight against glenoid fossa. RC fuses with capsule and prevents lax capsule/synovial membrane being nipped in joint.

Question 14

Which arm muscles aid shoulder stability?

Answer 14

Long head of biceps - sinks through capsule. Strong support over head of humerus.
Long head of Triceps is important in abduction as it lies directly behind humerus in this position - gives posterior support

Question 15

Describe movements of shoulder joint

Answer 15

Abduction - to 90’, then to 120’ with lat rotation - remainder is scapula.
Flexion is free
about 90’ of lateral rotation available and 70’ of medial rotation