Scapulothoracic and Arm Muscles

Scapulothoracic Muscles

Muscles that move and stabilize the scapula and form the borders of axilla

Trapezius

Trapezius Origin

1. Superior nuchal line

2. External occipital protuberance (Lnion)

3. Ligamentum nuchae

4. Spinous process C7-T12

Trapezius Insertion

1. Upper fibers: posteromedial surface of lateral 1/3 of clavicle and acromion

2. Middle fibers: acromion and spine of scapula

3.Lower fibers: medial 1/3 scapular spine

Trapezius Innervation

Spinal Accessory Nerve (CN XI)

Trapezius Action

Retraction and upward rotation of the scapula

Upper fibers: elevates the scapula

Lower fibers: upwardly rotate and depress the scapula

Levator Scapulae

Levator Scapulae Origin

Transverse processes of C1-C4

Levator Scapulae Insertion

Superior angle of scapula

Levator Scapulae Innervation

Dorsal scapular nerve

Levator Scapulae Action

Elevation and downward rotation of scapula

Rhomboid Minor

Rhomboid Major

Rhomboid Minor Origin

spinous processes of C7-T1

Rhomboid Major Origin

spinous processes of T2-T5

Rhomboids Innervation

dorsal scapular nerve

Rhomboids Action

Elevation, retraction, and downward rotation of scapula

Serratus Anterior

Serratus Anterior Origin

lateral aspect of upper 8 or 9 ribs

Serratus Anterior Insertion

Costal surface of vertebral border of scapula

Serratus Anterior Innevation

Long thoracic nerve

Serratus Anterior Action

protraction and upward rotation of scapula

Pectoralis Minor

Pectoralis Minor Origin

anterior surface of ribs 3-5

Pectoralis Minor Insertion

coracoid process of scapula

Pectoralis Minor Innervation

medial and lateral pectoral nerves

Pectoralis Minor Action

Depression of scapula

Pectoralis Major

Pectoralis Major Origin

Clavicular head: Medial clavicle

Sternal head: sternum and costal cartilage of upper 6 ribs the

Pectoralis Major Insertion

lateral lip of intertubercular groove of humerus

Pectoralis Major Innervation

medial and lateral pectoral nerves

Pectoralis Major Action

Adduction and internal rotation of arm

Clavicular head: flexes arm

Sternal head: extends arm from a flexed position

Deltoid Origin

anterior deltoid: lateral 1/3 of clavicle; acromion and scapular spine

Deltoid Insertion

Deltoid tuberosity of humerus

Deltoid Innervation

axillary nerve

Deltoid Action

Abduction of arm

Anterior fibers: flex and internally rotate the arm

Posterior fibers: extend and externally rotate the arm

Teres Major

Teres Major Origin

Dorsal surface of inferior angle of scapula

Teres Major Insertion

Medial lip of intertubercular groove

Teres Major Innervation

lower subscapular nerve

Teres Major Action

Adduction, extension, and internal rotation of arm

Lattissumus Dorsi

Lattissumus Dorsi Origin

1. Spinous processes of lower 6 thoracic and all lumbar vertebrae

2. Thoracolumbar fascia

3. Sacrum

4. Iliac crest

5. Portions of lower 3 ribs

6. Inferior angle of scapula

Lattissumus Dorsi Insertion

Floor of intertubercular groove

Lattissumus Dorsi Innervation

Thoracodorsal nerve

Lattissumus Dorsi Action

Adduction, externsion, and internal rotation of arm

Rotator Cuff Muscles (S.I.T.S)

S = supraspinatus

I = infraspinatus

t = teres minor

S = subscapularis

Supraspinatus

Supraspinatus Origin

supraspinous fossa of scapula

Supraspinatus Insertion

Superior facet of greater tubercle of humerus

Supraspinatus Innervation

suprascapular nerve

Supraspinatus Action

abduction of arm

Infraspinatus

Infraspinatus Origin

infraspinous fossa of scapula

Infraspinatus Insertion

Middle facet of greater tubercle

Infraspinatus Innervation

suprascapular nerve

Infraspinatus Action

External rotation of arm

Teres Minor

Teres Minor Origin

Upper 2/3 of axillary boreder of scapula

Teres Minor Insertion

Inferior facet of greater tubercle

Teres Minor Innervation

Axillary Nerve

Teres Minor Action

External rotation of arm

Subscapularis

Subscapularis Origin

Subscapular fossa

Subscapularis Insertion

Lesser tubercle

Subscapularis Innervation

Upper and lower subscapular nerves

Subscapularis Action

Internal rotation of arm

anterior arm muscles

biceps brachii, brachialis, coracobrachialis

Biceps Brachii

Biceps Brachii Origin

Long head: supraglenoid tubercle and labrum

Short head: coracoid process

Biceps Brachii Insertion

Radial tuberosity and biceptial aponeurosis

Biceps Brachii Innervation

Musculocutaneous nerve

Biceps Brachii Action

Flexion and supination of forearm

Long head: flexion of arm

Short head: adduction of arm

Brachilis

Brachilis Origin

Anterior surface of distal humerus

Brachilis Insertion

Coronoid process and tuberosity of ulna

Brachilis Innervation

Musculocutaneous nerve

Brachilis Action

Flexion of forearm

Coracobrachialis

Coracobrachialis Origin

Coracoid process

Coracobrachialis Insertion

Middle third of medial side of humerus

Coracobrachialis Innervation

Musculocutaneous nerve

Coracobrachialis Action

Flexion and adduction of arm

Posterior arm muscles

triceps brachii, anconeus

Triceps Bracii

Triceps Bracii Origin

Long head : infraglenoid tubercle of scapula

Lateral head : proximal half of humerus

Medial head : distal half of humerus

Triceps Bracii Insertion

Olecranon process

Triceps Bracii Innervation

Radial nerve

Triceps Bracii Action

Extension of forearm

Long head: extends arm

Anconeus

Anconeus Origin

Lateral epicondyle of the humerus

Anconeus Insertion

Olecranon process and posterior surface of proximal ulna

Anconeus Innervation

Radial nerve

Anconeus Action

Extension of forearm