Shoulder Region: Ch. 11

Question 1

Deltoid

Answer 1

Action: abduction of humerus
anterior: flexes and medially rotates humerus
posterior: extends and laterally roatates humerus
middle: pure abduction
N: axillary n.

Question 2

subdeltoid/subacromial bursa

Answer 2

• fluid filled synovial-like sac directly deep to deltoid muscle and acromion process
• facilitates movement

Question 3

Supraspinatus

Answer 3

“over the top position”
A: initiates abduction of humerus
N: suprascapular N.
NOTE: in abduction of humerus, supraspinatus initiates while deltoid is more powerful in it
NOTE: most often ruptured in rotator cuff injuries because of over the top position

Question 4

Infraspinatus

Answer 4

A: lateral rotation of humerus
N: suprascapular n.

Question 5

Teres minor

Answer 5

A: lateral rotation of humerus
N. axillary n.
(works with deltoid b/c they both get axiillary n.)

Question 6

Teres Major

Answer 6

“mini latissimus dorsi”
A: extension, adduction, medial rotation of humerus
N: Lower subscapular n.

Question 7

Subscapularis

Answer 7

A: medial rotation of humerus
N: upper and lower subscapular n.
* really strong multipennate muscle *

Question 8

Rotator Cuff

Answer 8

sub, supra, infra, minor (or SITS)
subscapularis, supraspinatus, infraspinatus, teres minor
- these muscles capture the head of humerus and hold it to cavity so in all ranges of motion the humerus is attached by at least one point to glenoid cavity

Question 9

Serratus anterior

Answer 9

A: protracts scapula, upwardly rotates glenoid cavity, fixates scapula on thoracic wall
N: Long thoracic n.
NOTE: injury of long thoracic nerve can lead to condition whereby scapula is elevated away from body along its medial border and inferior angle (“winged scapula”) - inability to completely abduct the upper limb or to push the upper limb forward against resistance

Question 10

Quadrangular space

Answer 10

Superior: teres minor
Inferior: teres major
Medial: long head, triceps muscle
Lateral: humerus
Contents: axillary nerve, posterior humeral circumflex a.

Question 11

Triangular space

Answer 11

Superior: teres minor
Inferior: Teres major
Lateral: long head of triceps
Contents: circumflex scapular a.

Question 12

Anastomoses of Scapula pattern

Answer 12

Branches of thyrocervical trunk (suprascapular/deep branch of transverse cervical) + circumflex scapular

Question 13

Scapular anastomosis block of axillary artery

Answer 13

blood reaches shoulder through being shunted through thyrocervical trunk to the suprascapular artery and the deep branch of the transverse cervical artery - it further anastomoses with circumflex scapular artery and the thoracodorsal artery –> rejoins with brachial artery