Unit 2 Muscles of the Upper Arm

supraspinatus origin

supraspinous fossa of scapula

supraspinatus insertion

greater tubercle of humerus

supraspinatus function

initiation of abduction of the humerus to 15° at glenohumeral joint

supraspinatus innervation

suprascapular nerve

infraspinatus innervation

suprascapular nerve

infraspinatus origin

infraspinous fossa of scapula

infraspinatus insertion

greater tubercle of humerus

infraspinatus function

lateral rotation of arm at glenohumeral joint

teres minor origin

dorsal surface of scapula along lateral margin

superior to the origin of teres major

teres minor insertion

greater tubercle of humerus

teres minor function

lateral rotation of arm at glenohumeral joint (when arm adducted)

teres minor innervation

axillary nerve

subscapularis origin

subscapular fossa of the scapula

subscapularis insertion

lesser tubercle of the humerus

subscapularis innervation

upper and lower subscapular nerve

subscapularis function

medially rotates the arm at the glenohumeral joint

Rotator Cuff Muscles

anterior stabilization

• subscapularis

posterior stabilization

• infraspinatus

• teres minor

superior stabilization

• supraspinatus

inferior stabilization→no muscles or tendons

Deltoid origin

Anterior border of lateral 1/3 of clavicle

Spine of scapula

Acromion of scapula

Deltoid insertion

Deltoid tuberosity of humerus

Deltoid function

Clavicular

• abduction of glenohumeral joint beyond 15 degrees

• flexion of the arm at Glenohumeral joint

Posterior→extension of arm at glenohumeral joint

Deltoid innervation

Axillary nerve

Teres major origin

Inferior angle of scapula

inferior to the origin of teres minor

Teres major insertion

Medial border of Intertubercular sulcus of the humerus

Teres major function

Medial rotation of humerus at glenohumeral joint

Extension of humerus at glenohumeral joint

synergist muscle→works with latissimus dorsi

Teres major innervation

Lower subscapular nerve

Long head of biceps brachii origin

Supraglenoid tubercle of scapula

Long head of biceps brachii insertion

Radial/bicipital tuberosity of radius

Long head of biceps brachii function

Supination of forearm

Flexion of forearm at elbow joint

Aids flexion at glenohumeral joint

Long head of biceps brachii Innervation

Musculocutaneous nerve

Short head of biceps brachii origin

Coracoid process of scapula

Short head of biceps brachii insertion

Radial/bicipital tuberosity of radius

Short head of biceps brachii function

Supination of forearm

Flexion of forearm at elbow joint

Short head of biceps brachii innervation

Musculocutaneous nerve

Coracobrachialis origin

Tip of coracoid process of the scapula

Coracobrachialis insertion

Medial side of humerus mid-shaft

Coracobrachialis function

Adduction of arm at glenohumeral joint

Flexion of arm at glenohumeral joint

Coracobrachialis innervation

Musculocutaneous nerve

Brachialis origin

Anterior aspect of the humerus

Brachialis insertion

Tuberosity of ulna

Brachialis action

Flexion of forearm at elbow joint

Brachialis innervation

Musculocutaneous nerve

Long head triceps brachii origin

Infraglenoid tubercle of scapula

Long head triceps brachii insertion

Olecranon of ulna

Long head of the triceps brachii function

Extension of forearm at elbow joint

Extension of arm at glenohumeral joint

Adduction of arm at glenohumeral joint

Long head of the triceps brachii innervation

Radial nerve

Medial head of the triceps brachii origin

Posterior surface of humerus mid-shaft

Medial head of the triceps brachii Insertion

Olecranon of ulna

Medial head of the triceps brachii Innervation

Radial nerve

Medial head of the triceps brachii Function

Extension of forearm at elbow joint

Lateral head of the triceps brachii origin

Posterior surface of humerus

Lateral head of the triceps brachii insertion

Olecranon of ulna

Lateral head of the triceps brachii function

Extension of forearm at elbow joint

Lateral head of the triceps brachii innervation

Radial nerve

Pectoralis major origin

Clavicular head: anterior surface of clavicle at medial side

Sternocostal head

• anterior surface of sternum

• Costal cartilages 1-7

• Rib 6

Pectoralis major insertion

Lateral border of intertubercular sulcus of humerus

Pectoralis major innervation

Medial and lateral pectoral nerves

Pectoralis major function

Flexion of arm at glenohumeral joint

Extension of arm at glenohumeral joint

Adduction of arm at glenohumeral joint

Clavicular head: flexion of extended arm at glenohumeral joint

Sternocostal head: extension of flexed arm at glenohumeral joint

Pectoralis minor origin

Anterior surface of ribs 3-5

Pectoralis minor insertion

Coracoid process of scapula

Pectoralis minor innervation

Medial pectoral nerve

Pectoralis minor function

Protraction/abduction of scapula

Depression of lateral angle of scapula

Serratus anterior origin

Lateral surface of upper 8-9 ribs

Serratus anterior insertion

Medial border of scapula on anterior surface

Serratus Anterior Innervation

Long thoracic nerve

Serratus Anterior Function

Abduction/protraction of the scapula

Rotation of the scapula

Fix scapula

Latissimus dorsi origin

Spinous processes c7-sacrum

Iliac crest of os coxae

Ribs 10-12

Latissimus dorsi insertion

Floor of intertubercular surface of the humerus

Latissimus dorsi function

Extension of humerus of glenohumeral joint

Adduction of humerus of glenohumeral joint

Medial rotation of humerus of glenohumeral joint

Latissimus dorsi innervation

Thoracodorsal nerve

Muscle Function Hint

crosses over anterior side→flexion of the joint

crosses over posterior side→extension of the joint

crosses over lateral side→abduction of the joint

crosses over medial side→adduction of the joint

Long vs Short Head of Biceps Brachii

refers to the length of the tendon

long head→longer tendon

short head→shorter tendon

Rupture of the Tendon of Long Head of Biceps Brachii

proximal biceps brachii tendon ruptures→may hear “pop”

more common

• long head (96%)

• dominant arm

common cases

• weightlifters

• manual labor workers

no surgery→”popeye bicep”

• decrease in supination→50%

• decrease in flexion strength→20-30%