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Question 1

Sacrohumeral muscles

Answer 1

1. Deltoid-
O: Anterior- lateral third of clavicle
     Middle- acromion of scapula
      Posterior- spine of scapula
I: deltoid tuberosity of humerus
A: major abductor of the shoulder, anterior flexes, posterior extends
N: Axillary (C5-C6)

SITS

2. Supraspinatus-
   O: supraspinous fossa
   I: superior facet of greater tubercle of humerus
   A: initiates abduction of the arm (helps deltoid)
   N: suprascapular (C5-C6)
3. Infraspinatus-
   O: infraspinous fossa
   I: middle facet of greater tubercle of humerus
   A: lateral (external) rotation of shoulder
   N: suprascapular (C5-C6)

4. Teres Minor-
O: lateral border of scapula
I: inferior facet of greater tubercle of humerus 
A: external rotation of shoulder
N: axillary (C5-C6)

5. Subscapularis-
O: subscapular fossa
I: lesser tubercle of humerus
A: internally (medially) rotate shoulder
N: upper and lower subscapular nerve (C5-C6)

6. Teres Major-
   O: inferior angle of scapula
   I: intertubercular sulcus (bicipital groove) of humerus
   A: internal rotation, adduction, shoulder extension
   N: lower subscapular nerve (C5-C6)

Question 2

Posterior Compartment of the Arm

Answer 2

1. Triceps brachii-
   O: Long head- infraglenoid tubercle
   Lateral head- posterior numeral shaft, above radial groove
   Medial head- posterior numeral shaft, below radial groove
   I: olecranon of ulna
   A: elbow extension, long does extension/adduction of shoulder, lateral recruited primarily against resistance
   N: radial nerve (C5-T1)

2. Anconeus-
O: lateral epicondyle of humerus
I: olecranon
A: assists triceps brachii
N: radial nerve (C5-T1)