Rotator cuff

muscles

Subscapularis

Origin

· costal surface of scapula (medial 4/5)

· intermuscular septa raise ridges from surface

· to axillary border of scapula

· up to infraglenoid tubercle

Path

· covered by dense fascia

· runs edge-to-edge with offspring teres major

· teres major has moved origin to dorsal scapula

· fibres converge over glenoid angle of scapula

· separated from bare area of bone by subscapular bursa

· bursa communicates with shoulder joint

· forms tendon laterally

· tendon fuses with capsule of shoulder joint

Insertion

· lesser tuberosity of humerus

· medial lip of bicipital groove for 1 cm below

Nerve supply

· upper and lower subscapular nerves (C6,7) from posterior cord

Supraspinatus

Origin

· supraspinous fossa of scapula (medial 3/4)

· upper border of spine of scapula

Path

· separated from lateral 1/4 of scapula by bursa

· crosses superior shoulder joint

· tendon blends with capsule

Insertion

· upper facet of greater tuberosity

Nerve supply

· suprascapular nerve (C5,6) from upper trunk

Infraspinatus

Origin

· infraspinous fossa (medial 3/4)

Path

· separated from lateral 1/4 of bone by bursa

· covered by infraspinatus fascia

· dense fascia covering both infraspinatus and teres minor

· attached to lower border of scapular spine, vertebral border of scapula and axillary border of scapula

Insertion

· central facet of greater tuberosity

Nerve supply

· suprascapular nerve (C5,6) from upper trunk

Teres minor

Origin

· oval area at axillary border of scapula

· lateral to teres major

Path

· hidden beneath deltoid

· covered by infraspinatus fascia

· at lower border medially

· lies edge-to-edge with teres major

· form triangular and quadrilateral spaces with long head of triceps

· at upper border laterally

· lies edge-to-edge with lower border of infraspinatus

Insertion

· lower facet of greater tuberosity

· 2 cm of bone below this

Nerve supply

· posterior branch of axillary nerve (C5,6) from posterior cord

Other muscles

Deltoid

Origin

· anterior fibres

· anterior border of lateral third of clavicle

· intermediate fibres

· lateral border of acromion

· posterior fibres

· inferior lip of crest of spine of scapula to deltoid tubercle

Path

· covers shoulder like cape

· 4 septae pass down from acromion

· 3 septae pass up from deltoid tuberosity

· one from each limb

· one from central ridge

Insertion

· into deltoid tuberosity

· U-shaped with central ridge

· anterior and posterior fibres

· limbs of tuberosity

· intermediate fibres

· central ridge

Nerve supply

· axillary nerve (C5,6) from posterior cord

Teres major

· offspring of subscapularis

· origin migrated dorsally

Origin

· oval area on lateral side of inferior angle

· along axillary border

· medial to teres minor

Path

· not covered by infraspinatus fascia

· separates it from teres minor

· runs edge-to-edge with subscapularis

· tendon of latissimus dorsi winds around it

· lies in front of it at insertion

Insertion

· medial lip of bicipital groove

· in continuity with subscapularis

Nerve supply

· lower subscapular nerve (C6,7) from posterior cord

vessels

Scapular anastomosis

· consists of scapular vessels

· dorsal and supra from sub-1

· circumflex from ax-3

Dorsal scapular artery

· branch of transverse scapular artery

· from 1st part of subclavian artery (occas. 3rd)

· from thyrocervical trunk

· passes along verebral border of scapula to inferior angle

· accompanies dorsal scapular nerve

Suprascapular artery

· branch of thyrocervical trunk

· from 1st part of subclavian artery (occ. 3rd)

· crosses over transverse ligament of scapular notch

· passes through supraspinous fossa

· turns around lateral border of spine of scapula

· ends in infraspinous fossa

Circumflex scapular

· branch of subscapular artery

· from 3rd part of axillary artery

· enters infraspinous fossa

· through medial triangular space

spaces

Quadrilateral space

· lateral - humerus

· medial - long head of triceps

· superior - subscapularis (teres minor from front)

· inferior - teres major

· transmits - axillary nerve and posterior circumflex humeral vessels

Inferior triangular space

· lateral - humerus

· medial - long head of triceps

· superior - teres major

· transmits - radial nerve and profunda brachii vessels

Medial triangular space

· lateral - long head of triceps

· superior - subscapularis (teres minor from front)

· inferior - teres major

· transmits - circumflex scapular vessels