Muscles Of Shoulder And Arm

Front 1

Deltoid

Back 1

(named by triangle shape)

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

I: deltoid tuberosity

A: all: abduct; post: extend and laterally rotate; ant: flex and medially rotate

N: axillary

Front 2

Trapezius

Back 2

O: external occipital protuberance, medial portion of superior nuchal line of occiput, ligamentum nuchae and SP of C7-T12

I: lateral 1/3 of clavicle, acromion, spine of scapula

A: Upper: extends head and neck, contralaterally extends and laterally flexes head and neck, elevate and upwardly rotate the scapula; Middle: adduct scapula (retraction), stabilizes the scapula; Lower: depress and upwardly rotate the scapula

N: Spinal Accessory Nerve Cranial Nerve 11

Front 3

Latissimus Dorsi

Back 3

(broadest muscle of back, strong adductor, handcuff muscle, between two majors)

O: Spinous Process of T7-L5, last 3 or 4 ribs, thoracolumbar aponeurosis, posterior iliac crest, inferior angle of scapula

I: crest of lesser tubercle of the humerus (lower edge of the intertubercular groove)

A: extend the GH joint, adduct the GH joint, medially rotate the GH joint

N: Thoracodorsal Nerve

Front 4

Teres Major

Back 4

(Handcuff muscle, round, major trouble, synergist to lats, lats little brother)

O: Dorsal surfaces of inferior angle and lower half of the lateral border of the scapula

I: crest of the lesser tubercle of the humerus, medial aspect

A: extend, adduct, and medially rotate the humerus

N: Lower Subscapular C5, 6, 7

Front 5

Supraspinatus

Back 5

(Rotator cuff, deltoid synergist, most commonly injured, gets the ball rolling)

O: Supraspinous fossa of the scapula

I: greater tubercle (superior aspect)

A: abducts the humerus the first 15-20 degrees, stabilizes the head of the humerus in the glenoid cavity

N: suprascapular nerve

Front 6

Infraspinatus

Back 6

(Rotator cuff, thick up top then thins out)

O: infraspinous fossa of the scapula

I: posterior superior greater tubercle of the humerus

A: laterally rotates, abducts, and extends the shoulder joint and stabilizes the head of the humerus in the glenoid cavity

N: Suprascapular Nerve

Front 7

Teres Minor

Back 7

(Rotator cuff)

O: superior half of the lateral (axillary) border of the scapula

I: Greater tubercle of the humerus posterior inferior

A: laterally rotate, adduct, and extend the shoulder and stabilizes the head of the humerus in the glenoid cavity

N: Axillary C5, 6

Front 8

Subscapularis

Back 8

(Rotator cuff, lies underneath scapula)

O: Subscapular fossa of the scapula

I: lesser tubercle

A: medially rotates the shoulder joint, stabilies the head of the humerus in the glenoid cavity

N: Subscapular Nerve

Front 9

Rhomboid Major and Minor

Back 9

(deep to trapezius, sometimes can be 1 muscle, can cause flaring of the scapula)

O: Major: SP of T2-T5 Minor: SP of C7-T1

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

A: adduct, elevate, and downwardly rotate the scapula

N: Dorsal Scapular C 4,5

Front 10

Levator Scapula

Back 10

(round, cord-like)

O: TP of C1-C4

I: Superior Angle of the scapula (kinda medial border)

A: Uni- elevate and downwardly rotate the scapula, laterally flex the head and neck

Bi- extend the head and neck

N: dorsal scapular nerve

Front 11

Serratus Anterior

Back 11

(if attached to secondary ribs then its a muscle of respiration, Boxer's muscle, could cause winging of scapula, SALTY BOXER)

O: Surfaces of upper 8 or 9 ribs

I: Ventral surface of the medial border of the scapula

A: With origin fixed- abduct the scapula, holds medial border of scap against rib cage; If scap is stabilized- may act in forced inspiration

N: Long Thoracic C5, 6, 7, 8

Front 12

Pectoralis Major

Back 12

(fibers twist at insertion, strong rotator)

O: medial half of the clavicle, sternum, cartilage of ribs 1-6

I: crest of the greater tubercle

A: whole- adduct, medially rotate shouder joint and may assist in forced inspiration; upper- flex, medially rotate, and horizontally adduct the shoulder; lower- extend and adduct the shoulder

N: Pectoral Nerves (medial and lateral)

Front 13

Pectoralis Minor

Back 13

(underneath major, major is 2x, doesn't cross joint)

O: 3rd, 4th, 5th ribs

I: Coracoid process

A: protractor, depress, abduct, tilt the scapula anteriorly and assist in forced inspiration

N: medial pectoral nerve

Front 14

Subclavius

Back 14

(underneath clavicle, small, secondary muscle)

O: first rib and cartilage

I: inferior, medial aspect of the clavicle

A: draws the clavicle down and forward, elevates the 1st rib, stabilizes the sternoclavicular joint

N: 5th and 6th Cervical Nerves

Front 15

Biceps Brachii

Back 15

(only lies in front of the humerus, two heads)

O: Short Head- coracoid process of the scapula; Long Head- supraglenoid tubercle of the scapula

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

A: flex the elbow, supinate the forearm, flex the shoulder joint

N: Musculocutaneous (C5, C6)

Front 16

Triceps Brachii

Back 16

(three heads, could also help stabilize GH, only muscle in post part of upper extremity is radial nerve)

O: Long- infraglenoid tubercle of the scap; Lat- posterior surface of proximal half of humerus; Med- posterior surface of distal half of humerus

I: Olecranon process of the ulna

A: All- extend the elbow; Long- extend and adduct the shoulder joint

N: Radial (C6,7,8 T1)

Front 17

Coracobrachialis

Back 17

O: Coracoid process of the scapula

I: Medial surface of the middle shaft of the humerus

A: Flex and adduct the shoulder joint

N: Musculocutaneous (C6, 7)