Compartments
Extrinsic - superficial + deep
Intrinsic - rotator cuff + other
Extrinsic = originate from torso and attach to bones of the shoulder Intrinsic = originate from scapula/clavicle and attach to humerus
Extrinsic superficial muscles
Trapezius
Latissimus dorsi
Trapezius
Origin
Skull, nuchal ligament + spinal processes of C3-4
Trapezius
Insertion
Clavicle, acromion and scapula spine
Trapezius
Innervation
Motor = accessory nerve Sensory = C3/4 spinal nerves
Trapezius
Function
Upper fibres = elevate/rotate scapula during abduction
Middle fibres = retract scapula
Lower fibres = pull scapula inferiorally
Latissimus dorsi
Origin
Spinous processes T6-12 and inferior 3 ribs
Latissimus dorsi
Insertion
Intertubercular sulcus of humerus
Latissimus dorsi
Innervation
Thoracodorsal nerve
Latissimus dorsi
Function
Extends, adducts and medially rotates upper limb
Extrinsic deep muscles
Levator scapulae
Rhomboid major
Rhomboid minor
All innervates by dorsal scapular nerve
All insert on the medial border of the scapula
Levator scapulae
Origin
Transverse processes of C1-4 vertebrae
Levator scapulae
Insertion
Medial border of scapula
Levator scapulae
Innervation
Dorsal scapular nerve
Levator scapulae
Function
Elevates scapula
Rhomboid major
Origin
Spinous processes of T2-5
Rhomboid major
Insertion
Medial border of scapula
Rhomboid major
Innervation
Dorsal scapular nerve
Rhomboid major
Function
Retracts and rotates the scapula
Rhomboid minor
Origin
Spinous processes of C7-T1 vertebrae
Rhomboid minor
Insertion
Medial border of scapula
Rhomboid minor
Innervation
Dorsal scapular nerve
Rhomboid minor
Function
Retracts and rotates scapula
Intrinsic muscles (non-rotator cuff)
Deltoid
Teres major
Deltoid
Origin
Scapula + clavicle
Deltoid
Insertion
Deltoid tuberosity on lateral surface of humerus
Deltoid
Innervation
Axillary nerve
Deltoid
Function
Anterior = flex Middle = abductor (0-15 degrees) Posterior = extend
Teres major
Origin
Posterior surface of inferior angle of scapula
Teres major
Insertion
Intertubercular groove of humerus
Teres major
Innervation
Lower subscapular nerve
Teres major
Function
Adducts
Medially rotates
Intrinsic rotator cuff muscles
Supraspinatus
Infraspinatus
Subscapularis
Teres minor
Originate from the scapula and attach to humeral head
Act to pull the humeral head into the glenoid fossa
Supraspinatus
Origin
Supraspinous fossa of the scapula
Supraspinatus
Insertion
Greater tubercle of the humerus
Supraspinatus
Innervation
Suprascapular nerve
Supraspinatus
Function
Abducts the arm 0-15 degrees
Infraspinatus
Origin
Infraspinatous fossa of scapula
Infraspinatus
Insertion
Less tubercule of the humerus
Infraspinatus
Innervation
Suprascapular nerve
Infraspinatus
Function
Laterally rotates
Subscapularis
Origin
Subscapular fossa of scapula
Subscapularis
Insertion
Greater tubercle of the humerus
Subscapularis
Innervation
Upper/lower subscapular nerves
Subscapularis
Function
Medially rotates
Teres minor
Origin
Posterior surface of scapula
Teres minor
Insertion
Greater tubercle of the humerus
Teres minor
Innervation
Axillary nerve
Teres minor
Function
Laterally rotates