The dissection of the arm:
First, extend the incision in the skin from the upper part of the arm inferiorly. Continue to separate the skin and fascia and try to identify the medial and lateral cutaneous nerves of the forearm and the superficially located basilic and cephalic veins. At the middle of the arm the basilic pierces the fascia. Notice that the medial and lateral intermuscular septa divides the arm into anterior and posterior compartments that extends bilaterally from the medial and lateral supracondylar ridges. After removing the fascia the most superficial muscle is biceps brachii, biceps superiorly is recognisable by its short and long heads. Coracobrachialis is attached together with the short head to the coracoid process of the scapula. In the lower part of the arm, brachialis lies directly on the bone under cover of biceps. The brachial artery runs in an oblique course on the medial side of biceps. It has three main branches, the profunda brachii, and the superior and inferior ulnar collateral arteries. The median nerve is closely related to the brachial artery first laterally, then it crosses it to lie medially along the remainder of the arm. The ulnar nerve also runs on the medial side of the brachial artery. Try to follow its course when it pierces the medial intermuscular septum and passes behind the medial epicondyle of the humerus. The radial nerve passes from the posterior surface of the brachial artery to the radial groove on the posterior surface of the humerus. The musculocutaneous nerve passes laterally and pierces coracobrachialis in the upper part of the arm, after which it leaves the arm to become the lateral cutaneous nerve of the forearm. In the posterior compartment of the arm, triceps is the only muscle. Attempt to identify the three heads and the insertion of the muscle. Separate the long and lateral head of triceps to expose the radial nerve and profunda brachii artery running in the radial groove. The radial nerve gives three cutaneous branches in the arm as follows: the posterior cutaneous nerve of the arm, the inferior lateral cutaneous nerve of the arm, and the posterior cutaneous nerve of the forearm. Follow the course of the radial nerve after it leaves the radial groove, piercing the lateral intermuscular septum, to the anterior compartment between brachialis and brachioradialis. At the level of the lateral epicondyle the radial nerve divides into deep and superficial branches.
First, extend the incision in the skin from the upper part of the arm inferiorly. Continue to separate the skin and fascia and try to identify the medial and lateral cutaneous nerves of the forearm and the superficially located basilic and cephalic veins. At the middle of the arm the basilic pierces the fascia. Notice that the medial and lateral intermuscular septa divides the arm into anterior and posterior compartments that extends bilaterally from the medial and lateral supracondylar ridges. After removing the fascia the most superficial muscle is biceps brachii, biceps superiorly is recognisable by its short and long heads. Coracobrachialis is attached together with the short head to the coracoid process of the scapula. In the lower part of the arm, brachialis lies directly on the bone under cover of biceps. The brachial artery runs in an oblique course on the medial side of biceps. It has three main branches, the profunda brachii, and the superior and inferior ulnar collateral arteries. The median nerve is closely related to the brachial artery first laterally, then it crosses it to lie medially along the remainder of the arm. The ulnar nerve also runs on the medial side of the brachial artery. Try to follow its course when it pierces the medial intermuscular septum and passes behind the medial epicondyle of the humerus. The radial nerve passes from the posterior surface of the brachial artery to the radial groove on the posterior surface of the humerus. The musculocutaneous nerve passes laterally and pierces coracobrachialis in the upper part of the arm, after which it leaves the arm to become the lateral cutaneous nerve of the forearm. In the posterior compartment of the arm, triceps is the only muscle. Attempt to identify the three heads and the insertion of the muscle. Separate the long and lateral head of triceps to expose the radial nerve and profunda brachii artery running in the radial groove. The radial nerve gives three cutaneous branches in the arm as follows: the posterior cutaneous nerve of the arm, the inferior lateral cutaneous nerve of the arm, and the posterior cutaneous nerve of the forearm. Follow the course of the radial nerve after it leaves the radial groove, piercing the lateral intermuscular septum, to the anterior compartment between brachialis and brachioradialis. At the level of the lateral epicondyle the radial nerve divides into deep and superficial branches.