Shoulder OIA

Question 1

Trapezius

Answer 1

Origin: Superior nuchal line, occipital protuberance, spinous processes of C7-T12 vertebrae

Insertion: Clavicle, acromion and spine of scapula

Innervation: Accessory nerve (CN11)

Action: Superior: elevates. Inferior: depresses. Middle part (or all parts together): retracts scapula

Question 2

Deltoid

Answer 2

Origin: Inferior spine of scapula, lateral margins of acromion, anterior border of lateral clavicle

Insertion: Deltoid tuberosity of humerus

Innervation: Axillary nerve (C5,C6)

Action: Anterior part: flexes and medially rotates arm. Middle part: abducts arm. Posterior part: extends and laterally rotates arm

Question 3

Levator scapulae

Answer 3

Origin: Transverse processes of C1-C4 vertebrae

Insertion: Superior angle of scapula

Innervation: Dorsal scapular (C5) and cervical C3, C4 nerves

Action: Elevates scapula and tilts its glenoid cavity inferiorly by rotating the scapula

Question 4

Rhomboids

Answer 4

Origin: Minor: spinous processes of C7 and T1 vertebrae
Major: spinous processes of T2-T5 vertebrae

Insertion: Minor: medial border of scapula above scapular spine
Major: medial border of scapula below scapular spine

Innervation: Dorsal scapular nerve (C4,C5)

Action: Retract scapula and rotate it to depress glenoid cavity, fix scapula to thoracic wall

Question 5

Supraspinatus

Answer 5

Origin: Supraspinatus fossa of scapula

Insertion: Greater tubercle of humerus

Innervation: Suprascapular nerve (C5,C6)

Main action: Arm abduction / rotator cuff

Question 6

Infraspinatus

Answer 6

Origin: Infraspinous fossa of scapula

Insertion: Greater tubercle of humerus

Innervation: Suprascapular nerve (C5,C6)

Main action: Laterally rotate arm / rotator cuff

Question 7

Teres minor

Answer 7

Origin: Lateral border of scapula

Insertion: Greater tubercle of humerus

Innervation: Axillary nerve (C5,C6)

Main action: Laterally rotate arm / rotator cuff

Question 8

Teres major

Answer 8

Origin: Inferior angle of scapula

Insertion: Intertubercular groove of humerus

Innervation: Lower subscapular nerve (C5,C6)

Main action: Extension, adduction, and internal rotation of arm

Question 9

Long head of triceps

Answer 9

Origin: Infraglenoid tubercle on scapula

Insertion: Olecranon of the ulna

Innervation: Radial nerve (C6 – C8)

Main action: Extension of the elbow and adduction of the shoulder, and extension of arm

Question 10

Pec major

Answer 10

Origin: Clavicular head – anterior surface of clavicle. Sternocostal head – anterior surface of sternum, first 7 costal cartilages

Insertion: Lateral lip of intertubercular sulcus of humerus

Innervation: Clavicular head – medial and lateral pectoral nerves (C5, C6). Sternocostal head – C7 to T1 spinal nerves

Action: Flexion, adduction and medial rotation of arm

Question 11

Subclavius

Answer 11

Origin: First rib and its costal cartilage

Insertion: Middle one-third of clavicle

Innervation: Nerve to subclavius (C5 and C6)

Action: Depresses the clavicle down forward

Question 12

Pec minor

Answer 12

Origin: Ribs 3 to 5

Insertion: Coracoid process of scapula

Innervation: Medial pectoral nerve (C8 – T1)

Action: Elevates the ribs and draws the scapula down and medially

Question 13

Serratus anterior

Answer 13

Origin: 1 – 9 ribs

Insertion: Costal surface of medial border of scapula

Innervation: Long thoracic nerve (C5 - C7)

Action: Protraction and rotation of the scapula

Question 14

Subscapularis

Answer 14

Origin: Subscapular fossa

Insertion: Lesser tubercle of humerus

Innervation: Upper and lower subscapular nerves (C5 & C6)

Action: Medially rotates and adduct arm – rotator cuff

Question 15

Latissimus dorsi

Answer 15

Origin: Spinous processes of T7 – L1 thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs

Insertion: Intertubercular groove of humerus & inferior angle of the scapula

Innervation: Thoracodorsal nerve (C6 - C8)

Action: Adducts, extends, and medially rotates humerus