Muscles of the Back, Shoulder, and Arm

Deep Back Muscles

erector spinae muscles (lateral to medial)

• iliocostalis m

• longissimus m

• spinalis m

erector spine muscles (A, Inn)

A: acting bilaterally, extend head and vertebral column; Acting unilaterally, lateral flexion of head and vertebral column.

Inn: dorsal rami of spinal nn

Muscles from axial skeleton to pectoral girdle POSTERIOR

• Produce actions of the scapula

• All innervated by dorsal scapular nerve EXCEPT trapezius

• Trapezius m

• levator scapulae m

• Rhomboid Major m

• Rhomboid minor m

Trapezius muscles (A and Inn)

A: elevates, retracts, and depresses scapula

Inn: Accessory nerve

Levator Scapulae M (A and Inn)

A: Elevates scapula

Inn: Dorsal scapular n

Rhomboid Minor and Major m (A and Inn)

A: retracts scapula

Inn: Dorsal scapular n

Muscles from Axial Skeleton to Pectoral Girdle ANTERIOR

• produce actions on the scapula

• serratus anterior m

• perctoralis minor m

Serratus Anterior m (A and Inn)

A: protracts scapula and holds scapula against thoracic wall

inn: long thoracic n

Winging of the scapula

damage to the long thoracic nerve, causing paralysis of the serratus anterior muscle

Pectoralis Minor m (I, A, and Inn)

I: Coracoid process of Scapula

A: protracts scapula, and elevates ribs when scapula is stationary to assist in inhalation.

Inn: medial pectoral n

Muscles from Axial Skeleton to Humerus

• produce actions on the humerus

• Pectoralis Major m

• Latissimus Dorsi m

Pectoralis Major m (A and Inn)

A: adducts arm (shoulder) and Medially rotates arm (shoulder)

Inn: medial pectoral n and lateral pectoral n

Latissimus dorsi m (A and inn)

A: adduct, extend and medially rotates arm

inn: thoracodorsal n

Muscles from Pectoral girdle to humerus

• Produce actions on the humerus

• subscapularis m

• supraspinatus m

• infraspinatus m

• teres minor m

• teres major m

• deltoid m

what muscles make up the “rotator cuff”

SITS

• subscapularis m

• supraspinatus m

• infraspinatus m

• teres minor m.

subscapularis m (O, I, A, and Inn)

O: subscapular fossa

I: lesser tubercle of humerus

A: medially rotates arm

Inn: upper and lower subscapular n

supraspinatus m (O, I, A, Inn)

O: Supraspinous fossa of scapula

I: Greater tubercle of humerus

A: Abducts arm

Inn: suprascapular n

infraspinatus m (O, I, A, and Inn)

O: Infraspinous fossa of scapula

I: Greater tubercle of humerus

A: laterally rotates arm

Inn: suprascapular n

Teres minor (I, A, and Inn)

I: Greater tubercle of humerus

A: Laterally rotates arm

Inn: axillary n

Teres Major m (A and Inn)

A: adducts, extends, and medially rotates arm

Inn: lower subscapular n

Deltoid m (I, A, Inn)

I: deltoid tuberosity of humerus

A: Everything but adduction

• Anterior part: Flex arm and medially rotates arm

• middle part: abducts arm

• posterior part: extend arm and laterally rotates arm

Inn: axillary nerve

Muscles of the Anterior Compartment of the arm

• Major flexors

• ALL INNERVATED BY MUSCULOCUTANEOUS N

• Coracobrachialis m

• Bicepts brachii m (long and short head)

• brachialis m

Bicpes Brachii m (O, I, A, and Inn)

• long head is lateral, short head is medial

O: short head: coracoid process of scapula; long head: supralenoid tubercle of scapula

I: radial tuberosity

A: Flexes and supinates forarm

Inn: Musculocutaneous n

Coracobrachialis m (O, A, and inn)

O: coracoid process of scapula

A: flex arm and adducts arm (does not flex forearm)

Inn: Musculocutaneous n

brachialis m (A and Inn)

A: Flex forearm

inn: musculocutaneous nerve

Muscles of the posterior arm compartment

• major extensors

• ALL INNERVATED BY RADIAL N

triceps brachii m [O(only of long head), I, A, Inn]

O: infraglenoid tubercle of scapula

I: Olecranon Process of ulna

A: extend forearm

Inn: radial n

What three muscles orginate from the Coracoid process of the scapula?

• Pectoralis minor

• Biceps brachii short head

• Coracobrachialis