Important land marks on the back like external occipital protuberance, nuchal furrow, spine of 7th cervical vertebra, spines of all the 12th thoracic vertebrae, iliac crest, posterior superior iliac spine, spine of scapula are mentioned. The superior angle of the scapula lies on the second rib, while the inferior angle of it lies on the 7th intercostal space. Muscles of the back are divided into two groups the superficial and the deep. Trapezius and the latissimus dorsi are the members of the superficial group. Muscles subscapularis, supra-spinatus, infra-spinatus and teres minor form the musculo-tendinus cuff called as the rotator cuff of the shoulder. Intermuscular spaces, i.e. quadrangular and triangular are described. Quadrangular space is bounded by the shoulder joint, subscapularis and the teres minor above, long head of the triceps medially, shaft of the humerus laterally and the teres major below. The space contains axillary nerve and the posterior hemeral circumflex artery. Axillary nerve is one of the two terminal branches of the posterior cord of the brachial plexus other being the radial. It supplies the shoulder joint, deltoid and the teres minor muscles and upper part of the skin over the deltoid. (Regiment batch anesthesia) Anastomosis around the scapula is affected by the branches of the first part of the subclavian and the third part of the axillary arteries.