Radial nerve in the radial groove
This specimen shows the muscles of the shoulder, the extensors of the arm along with the radial nerve in the spiral groove.
The deltoid is a muscle of the shoulder region. The back of the arm has one muscle, the triceps brachii, which is made up of three heads. The radial nerve passing through the spiral nerve can be visualized in the specimen.
The deltoid is a muscle of the shoulder. It takes origin from the clavicle, the spine of the scapula and the acromion process. It insertion lies at the deltoid tuberosity of the humerus. It is supplied by the axillary nerve. It mainly brings about flexion, extension and abduction of the shoulder joint. It is mainly used to give intramuscular injections.
The back of the arm has one large muscle, known as, the triceps brachii. It consists of the long head, the lateral head and the medial head. All these heads converge to form a tick tendon and insert into the dorsal surface of the olecranon process of the ulna. It is supplied by the radian nerve. It acts as the extensor of the arm.
The radial nerve is a branch of the posterior cord of the brachial plexus. It passes through the spiral groove in the humerus along with the profunda brachii artery, which is a branch of the brachial artery. It mainly supplies the muscles of the back of the upper limb. Its damage in the radial groove leads to wrist drop. In this condition, the extension of the wrist is not possible.