Scapulohumeral muscles (JO)

Question 1

Name this muscle:
State its Origin(s), Insertion(s), Innervation(s), and Action(s)

Answer 1

Deltoid
Origin: Lateral ⅓ of the clavicle, acromion and spine of the scapula
Insertion: Deltoid tuberosity of the humerus
Innervation: Axillary nerve
Action: Anterior: flexes and medially rotates the GH joint; middle: abducts the GH joint; posterior: extends and laterally rotates the GH joint

Question 2

Name this muscle:
State its Origin(s), Insertion(s), Innervation(s), and Action(s)

Answer 2

Subscapularis
Origin: Scapular fossa (costal surface) of scapula
Insertion: Lesser tubercle of the humerus and medial lip of intertubercular sulcus of the humerus
Innervation: Upper and lower subscapular nerves
Action: Medially rotates the GH joint; helps to hold the humeral head in the glenoid cavity

Question 3

Name this muscle:
State its Origin(s), Insertion(s), Innervation(s), and Action(s)

Answer 3

Supraspinatus
Origin: Supraspinous fossa of the scapula
Insertion: Superior facet of greater tubercle of humerus
Innervation: Suprascapular nerve
Action: Initiates and assists the deltoid in abduction of GH joint and acts with other rotator cuff muscles to stabilize the shoulder joint

Question 4

Name this muscle:
State its Origin(s), Insertion(s), Innervation(s), and Action(s)

Answer 4

Infraspinatus
Origin: Infraspinous fossa of the scapula
Insertion: Middle facet of greater tubercle of humerus
Innervation: Suprascapular nerve
Action: Laterally (externally) rotates the GH joint; helps hold humeral head in glenoid cavity of the scapula

Question 5

Name this muscle:
State its Origin(s), Insertion(s), Innervation(s), and Action(s)

Answer 5

Teres Minor
Origin: Superior part (2/3rds) of the lateral border of the scapula
Insertion: Inferior facet of greater tubercle of the humerus
Innervation: Axillary nerve
Action: Laterally (externally) rotates the GH joint; helps hold humeral head in glenoid cavity of the scapula

Question 6

Name this muscle:
State its Origin(s), Insertion(s), Innervation(s), and Action(s)

Answer 6

Teres Major
Origin: Inferior part of the lateral border and dorsal surface of the inferior angle of the scapula
Insertion: Medial lip of intertubercular sulcus of the humerus
Innervation: Lower subscapular nerve
Action: Adducts and medially rotates the GH joint