Shoulder And Rotator Cuff

Front 1

Trapezius

Back 1

Origin:
- Superior nuchal line
- External occipital protuberance
- C1-C7: ligamentum nuchae
- Spinous processes of C7-T12

Insertion:
- Superior edge of scapular spine
- Acromion process
- Posterior border of lateral 1/3 of clavicle

Innervation:
- Accessory Nerve (CN 11)
- Sensory: anterior rami of C3-C4

Blood Supply:
- Occipital artery
- Superficial cervical
- Dorsal scapular artery

Function:
- Prime mover of scapular elevation
- During overhead abduction, raises and laterally rotates the scapula
- Middle Fibers: retracts the scapula
- Lower Fibers: depress scapula

Front 2

Deltoid

Back 2

Origin
- Inferior edge of scapular spine
- Lateral acromion margin
- Anterior border of lateral 1/3 of clavicle

Insertion
- Deltoid tuberosity on the humerus

Innervation
- Axillary Nerve (C5), C6

Blood Supply
- Anterior and posterior circumflex humeral arteries
- Acromial and deltoid branches of thoracoacromial artery

Function
- Prime mover of arm abduction
Anterior Fibers:
- Arm Flexion
- Medial rotation of arm
Posterior Fibers:
- Arm Extension
- Lateral rotation of arm

Front 3

Levator Scapulae

Back 3

Origin
- Transverse processes of C1-C4

Insertion
- Posterior surface of medial scapular border

Innervation
- Dorsal scapular nerve (C5)
- Anterior Rami of (C3-C4)

Blood Supply
- Transverse cervical artery

Function
- Scapular elevation
- Scapular Retraction
- Medially rotate scapula

Front 4

Rhomboid Major

Back 4

Origin
- Spinous processes of T2-T5
- Intervening supraspinous ligament

Insertion
- Posterior surface of medial scapular border

Innervation
- Dorsal Scapular Nerve (C4-C5)

Blood Supply
- Deep branch of transverse cervical artery
- or Dorsal scapular artery

Function
- Scapular Elevation
- Scapular Retraction

Front 5

Rhomboid Minor

Back 5

Origin
- Spinous processes of C7-T1

Insertion
- Posterior surface of medial scapular border

Innervation
- Dorsal scapular Nerve: C4-C5 (no primary)

Blood Supply
- Deep branch of transverse cervical artery
- or dorsal scapular artery

Function
- Scapular elevation
- Scapular retraction

Front 6

Supraspinatus

Back 6

Origin
- Supraspinatus fossa

Insertion
- Most superior facet on greater tubercle of humerus

Innervation
- Suprascapular Nerve (C5), C6

Blood Supply
- Suprascapular and dorsal scapular arteries

Function
- Maintain integrity of shoulder joint
- Initiate abduction up to 15 degrees
- Assist deltoid in abduction post 15 degrees

Front 7

Infraspinatus

Back 7

Origin
- Infraspinatus fossa
- Overlying deep fascia

Insertion
- Middle posterior facet on greater tubercle of humerus

Innervation
- Suprascapular Nerve (C5), C6

Blood Supply
- Suprascapular and circumflex scapular arteries

Function
- Maintain integrity of shoulder joint
- Laterally rotate humerus in glenoid cavity

Front 8

Teres Minor

Back 8

Origin
- Middle lateral scapular border

Insertion
- Inferior posterior facet on greater tubercle of humerus

Innervation
- Axillary Nerve (C5), C6

Blood Supply
- Posterior circumflex humeral and circumflex scapular arteries

Function
- Maintain integrity of the shoulder joint
- Laterally rotate humerus in glenoid cavity
- Weak humeral adductor

Front 9

Subscapularis

Back 9

Origin
- Subscapular fossa

Insertion
- Lesser tubercle of the humerus

Innervation
- Upper and lower subscapular nerves C5, (C6), C7

Blood Supply
- axillary, subscapular and suprascapular branches

Function
- Maintain integrity of the shoulder joint
- Medially rotate humerus in glenoid cavity