Posterior Shoulder Muscles

Question 1

Trapezius

Answer 1

O: medial third of superior nuchal line; external occipital protuberance; ligamentum nuchae, and spinous processes of C7-T12
I: lateral third of clavicle, acromion and spine of scapula
A: elevates, retracts, and rotates the scapula; superior fibers elevates; middle fibers retract, and inferior fibers depress scapula
I: CN XI C3-C4

Question 2

Latissimus dorsi

Answer 2

O: spinous process of T7-T12, thoracolumbar fascia, iliac crest, and inferior three ribs
I: intertubercular groove of humerus
A: extends, adducts, and medially rotates humerus at shoulder
I: C6-C8

Question 3

Levator scapulae

Answer 3

O: transverse process of C1-C4
I: superomedial border of scapula
A: elevates scapula and tilts the glenoid cavity inferiorly by rotating scapula
I: C3-C4 and dorsal scapular nerves

Question 4

Rhomboid minor and major

Answer 4

O: minor- ligamentum nuchae and spinous process of C7 and T1; major- spinous process of T2-T5
I: medial border of scapula from level of spine to inferior angle
A: retracts scapula and rotates it to depress glenoid cavity; fixes scapula to thoracic wall
I: C4-C5

Question 5

Supraspinatus (RC)

Answer 5

O: supraspinous fossa of scapula and deep fossa
I: superior facet on greater tubercle of humerus
A: initiates arm abduction and acts rotator cuff muscles
I: C5-C6

Question 6

Infraspinatus (RC)

Answer 6

O: infraspinous fossa of scapula and deep fascia
I:middle facet on greater tubercle of humerus
A: laterally rotates arm at the shoulder and helps hold head in glenoid cavity
I: C5-C6

Question 7

Teres minor (RC)

Answer 7

O: lateral boarder of the scapula
I: inferior facet of on the greater tubercle
A: laterally rotates arm at shoulder; helps hold head in glenoid cavity
I: axillary nerve (C5-C6)

Question 8

Teres major

Answer 8

O: posterior surface of inferior angle of scapula
I: medal lip of intertubercular grove of humerus
A: extend arms and medially rotates the shoulder
I: lower subscapular nerve (c5-c6)

Question 9

Subscapularis (RC)

Answer 9

O: subscapular fossa of scapula
I: lesser tubercle of humerus
A: medially rotates arm at shoulder and adducts it; helps hold humeral head in glenoid cavity
I:upper and lower subscapular subscapular nerves (c5-c6)