Insertion: the deltoid tuberosity on the lateral surface of the humerus

Actions: The main action of the deltoid is to abduct the humerus (an action initiated with supraspinatus). The clavicular portion adducts the humerus towards the midline and medially rotates the humerus to aid flexion of the humerus by pectoralis major. The spinous portion aids extension of the humerus by latissimus dorsi by laterally rotating the humerus.

Nerve supply: the axillary nerve C5, C6

Pronunciation: dehl-toyed

Insertion: The medial, anterior border of the scapula

Actions: Protracts the scapula and laterally rotates the scapula

Nerve supply: Long thoracic nerve C5, C6, C7.

C5 supplies the slips attaching to ribs 1 and 2

C6 supplies the slips attaching to ribs 3 and 4

C7 supplies the slips attaching to ribs 5 to 8

Pronunciation: seh-rate-us an-tea-ree-uhr

Insertion: The lesser tubercle of the humerus and the anterior shoulder capsule

Actions: Adducts the arm, medially rotates the humerus. It also stabilises the shoulder joint by preventing anterior dislacement of the humerus – this is part of its role as one of the rotator cuff muscles.

Nerve supply: The upper and lower subscapular nerves C5, C6

Pronunciation: suhb-skap-you-lah-rihs

Insertion: The posterior portion of the proximal olecranon process of the ulna

Action: Extends the forearm at the elbow and extends the arm at the shoulder joint

Nerve supply: The radial nerve C7, C8

Pronunciation: try-seps brak-ee-eye

Insertion: The radial tuberosity of the radius, forming an aponeurosis which blends with the deep fascia of the forearm

Actions: Supinates a partially flexed forearm and flexes a supinated forearm

Nerve supply: The musculocutaneous nerve C5,C6

Pronunciation: by-seps brak-ee-eye