Upper Arm/Scapular Muscles

Question 1

Rhomboid minor

Answer 1

O: Spinous processes of C7-T1

I: Upper portion of medial border of scapula, across from spine of scapula

N: Dorsal scapular (C4-C5)

A: Adduct the scapula (scapulothoracic joint), elevate the scapula (S/T joint), downwardly rotate scapula (S/T joint)

Question 2

Trapezius

Answer 2

O: External occipital protuberance, medial portion of superior nuchal line of the occiput, ligamentum nuchae, and spinous processes of C7-T12

I: Lateral 1/3 of clavicle, acromion, and spine of the scapula

N: Spinal portion of Cranial nerve XI (accessory) and ventral ramus of C2-4

A: Upper fibers
Bilaterally - Extend the head and neck
Unilaterally - Ipsilateral lateral flexion of head/neck; Contralateral rotation of head/neck; elevate the scapula (scapulothoracic joint); upwardly rotate the scapula (S/T joint)

Middle fibers - Adduct the scapula (S/T joint); Stabilize (S/T joint)

Lower fibers - Depress the scapula (S/T joint); upwardly rotate the scapula (S/T joint)

Question 3

Serratus Anterior

Answer 3

O: External surfaces of upper 8-9 ribs

I: Anterior surface of medial border of scapula

N: Long thoracic (C5-C8)

A:
With the origin fixed - Abducts the scapula (scapulothoracic joint), upwardly rotates the scapula (S/T joint), Depress the scapula (S/T joint), Hold the medial border of the scapula against the rib cage

With the scapula fixed - May act to elevate the thorax during forced inhalation

Question 4

Subscapularis

Answer 4

O: Subscapular fossa of scapula

I: Lesser tubercle of humerus

N: Upper and lower subscapular (C5-C7)

A: Medially rotate shoulder (glenohumeral joint), stabilize head of humerus in glenoid cavity

Question 5

Biceps Brachii

Answer 5

O: Short head - Coracoid process of scapula
Long head - Supraglenoid tubercle of scapula

I: Tuberosity of the radius and aponeurosis of the biceps brachii

N: Musculocutaneous (C5, C6)

A: Flex the elbow (humeroulnar joint), supinate the forearm (radioulnar joints), flex the shoulder (glenohumeral joint)

Question 6

Infraspinatus

Answer 6

O: Infraspinous fossa of scapula

I: Greater tubercle of humerus

N: Suprascapular (C4-C6)

A: Laterally rotate the shoulder (glenohumeral joint), adduct shoulder (G/H joint), stabilize head of humerus in glenoid cavity

Question 7

Brachialis

Answer 7

O: Distal half of anterior surface of humerus

I: Tuberosity and coronoid process of ulna

N: Musculocutaneous (C5, C6)

A: Flex the elbow (humeroulnar joint)

Question 8

Pectoralis Major

Answer 8

O: Medial half of clavicle, sternum, and cartilage of ribs 1-6

I: Crest of greater tubercle of humerus

N: Lateral and Medial Pectoral nerve (C5-T1)

A: All fibers - Adduct the shoulder (glenohumeral joint), medially rotate the shoulder (G/H joint), Assist to elevate the thorax during forced inhalation (with arm fixed)
Upper fibers - Flex the shoulder (G/H joint), Horizontally adduct the shoulder (G/H joint)
Lower fibers - Extend the shoulder (G/H joint)

Question 9

Teres Major

Answer 9

O: Inferior angle and lower 1/3 of lateral border of scapula

I: Crest of lesser tubercle of the humerus

N: Lower subscapular (C5-C7)

A: Extend the shoulder (glenohumeral joint), adduct the shoulder (G/H joint), medially rotate the shoulder

Question 10

Subclavius

Answer 10

O: First rib and cartilage

I: Inferior surface of middle one-third of clavicle

N: Subclavian (C5-C6)

A: Depress the clavicle and draw it anteriorly, elevate the first rib (to assist during inhalation), stabilize the sternoclavicular joint

Question 11

Latissimus Dorsi

Answer 11

O: Inferior angle of scapula, spinous processes of last six thoracic vertebrae, last 3-4 ribs, thoracolumbar fascia, and posterior iliac crest

I: Intertubercular groove of humerus

N: Thoracodorsal (C6-C8)

A: Extend the shoulder (glenohumeral joint), adduct the shoulder (G/H joint), medially rotate the shoulder (G/H joint)

Question 12

Levator Scapulae

Answer 12

O: Transverse processes of C1-C4 vertebrae

I: Medial border of scapula, between superior angle and superior portion of spine of scapula

N: Cervical 3, 4, and dorsal scapular (C4-C5)

A: Unilaterally - Elevate the scapula (scapulothoracic joint), downwardly rotate the scapula (S/T joint), Laterally flex head/neck, ipsilateral rotation of head/neck

Question 13

Rhomboid Major

Answer 13

O: Spinous processes of T2-T5

I: Medial border of the scapula between the spine of scapula and inferior angle

N: Dorsal scapular (C4-C5)

A: Adduct the scapula (scapulothoracic joint), elevate the scapula (S/T joint), downwardly rotate scapula (S/T joint)

Question 14

Coracobrachialis

Answer 14

O: Coracoid process of scapula

I: Medial surface of mid-humeral shaft

N: Musculocutaneous (C6, C7)

A: Shoulder flexion and adduction (G/H joint)

Question 15

Deltoid

Answer 15

O: Lateral 1/3 of clavicle, acromion, and spine of scapula

I: Deltoid tuberosity

N: Axillary (C5-C6)

A:
All fibers - Abduct the shoulder (Glenohumeral joint)

Anterior fibers - Flex the shoulder (G/H joint), medially rotate the shoulder (G/H joint), horizontally adduct shoulder (G/H joint)

Posterior fibers - Extend the shoulder (G/H joint), laterally rotate the shoulder (G/H joint), horizontally abduct shoulder (G/H joint)

Question 16

Teres Minor

Answer 16

O: Upper 2/3 of lateral border of scapula

I: Greater tubercle of humerus

N: Axillary (C5-C6)

A: Laterally rotate shoulder (glenohumeral joint), adduct shoulder (G/H joint), stabilize head of humerus in glenoid cavity

Question 17

Triceps Brachii

Answer 17

O: Long head - Infraglenoid tubercle of scapula
Lateral head - Posterior surface of proximal half of humerus
Medial head - Posterior surface of distal half of humerus

I: Olecranon process of ulna

N: Radial (C6-T1)

A: All heads - Extend the elbow (humeroulnar joint)
Long head - Extend the shoulder (G/H joint), Adduct the shoulder (G/H joint)

Question 18

Supraspinatus

Answer 18

O: Supraspinous fossa of scapula

I: Greater tubercle of humerus

N: Suprascapular (C4-C6)

A: Abduct shoulder (glenohumeral joint), stabilize head of humerus in glenoid cavity

Question 19

Pectoralis Minor

Answer 19

O: Ribs 3-5

I: Medial surface of coracoid process of scapula

N: Medial pectoral, with fibers from a communicating branch of the lateral pectoral C6-T1

A: Depress the scapula (scapulothoracic joint), abduct the scapula (S/T joint), downwardly rotate the scapula (S/T joint)
With scapula fixed - Assists to elevate thorax during forced inhalation