Part of the anterior surface of the bend of the elbow.
7. The Palmar Cutaneous branch of the Median nerve is seen piercing the fascia about the centre of the forearm just above the wrist.
8. The Palmar Cutaneous branch of the Ulnar nerve lies over the line of the Ulnar artery, and pierces the fascia lata just above the wrist. Sometimes a second branch is cutaneous higher up, and joins the anterior branch of the Internal Cutaneous nerve. Behind—
9. The lower portions of the Radial and Posterior Ulnar veins, as mentioned above.
10. The posterior branch of the Internal Cutaneous nerve, supplying about the upper half of the internal portion of the forearm.
11. The posterior branch of the External Cutaneous nerve supplying about the lower third of the outer border of the forearm.
12. Twigs of the lesser Internal Cutaneous nerve, between the internal Condyle and the Olecranon process, and a junction with the posterior branch of the Internal Cutaneous nerve.
13. The lower External Cutaneous branch of the Musculospiral nerve, supplying the skin of the back of the forearm, between the Internal and External Cutaneous nerves as far as the wrist, and communicating with the latter.
14. The Radial nerve, cutaneous between from two to three inches above the wrist, and its points of division into branches for the thumb, the next two, and half the ring fingers.
15. The Dorsal branch of the Ulnar nerve, perforating on the inner side at a lower point than the Radial, and its points of division into branches for the remaining finger and a half.
a. Remove the preceding, and expose the fascia lata, joined above in front of the bend of the elbow, by the semilunar process from the tendon of the Biceps muscle. Behind the wrist it is seen to be strengthened by transverse fibres, and to constitute the Posterior Annular ligament.
b. Clear away the deep and Bicipital fascia, and expose— In Front—
1. Above, the lower part of the triangular space of the bend of the elbow, bounded: externally, by the Supinator longus muscle; internally, by the Pronator radii teres muscle; and having the floor formed by the lower part of the Brachialis anticus muscle and a small portion of the Supinator brevis muscle. It contains—
2. The tendon of the Biceps muscle running down to the Tuberosity of the Radius, most externally.
3. The Brachial artery, surrounded by its venae comites, placed internal to the Biceps tendon. The division of the artery into Radial and Ulnar branches is seen, and the commencement of the Radial Recurrent branch.
4. The Median nerve is exposed inside the artery, and its branch to the Pronator radii teres muscle may be traced.
5. Internal to the Pronator radii teres muscle is seen the Flexor carpi radialis muscle, as far as the wrist.
6. The Palmaris longus muscle, next internally, and:
7. The Plexor carpi ulnaris muscle, innermost of all.
8. At the wrist between the tendons of the two preceding muscles, those of the Flexor sublimis digitorum muscle come into view.
9. Small portions of the Pronator quadratus muscle are seen below on the Radius and Ulna.
10. The Radial artery and its venae comites are exposed farther than has been indicated above,—viz., as low down as the wrist. At first it lies in the triangular space, then crosses over the insertion of the Pronator teres muscle, and finally lies between the Supinator longus and Plexor carpi radialis tendons.
11. The Ulnar artery with its veins is seen for. about its lower third, below and internally, passing from beneath the fleshy portion of the Flexor carpi ulnaris muscle, and running on the outer side of its tendon as far as the wrist.
12. The Radial nerve is seen external to its artery, as far as about three inches above the wrist. It is overlapped above by the fleshy part of the Supinator longus muscle.
13. The Ulnar nerve lies on the inner side of the lower exposed portion of the corresponding artery, as far as the wrist.
14 A further small portion of the Median nerve is seen just above the wrist, between the Flexor carp radialis and outermost tendon of the Flexor sublimis digitorum. Behind—
15. The Anconeus muscle, passing between the external Condyle, and the outer surfaces of the Olecranon process and the upper part of the shaft of the Ulna.
The following muscles from without inwards—
16. The Supinator longus.
17. The Extensor carpi radialis longior.
18. The Extensor carpi radialis brevior.
19. The Extensor communis digitorum.
20. The Extensor minimi digiti.
21. The Extensor carpi ulnaris.
At the lower part, passing out between the Extensor communis digitorum and Extensor carpi radialis brevior tendons, are—
22. The Extensor ossis metacarpi and primi internodii pollicis muscles.
23. The Posterior Interosseous artery is seen on the outer side of the Extensor carpi ulnaris tendon for about the lower third of the forearm, accompanied by its vein.
In Front— a. Divide the Pronator radii teres muscle at its insertion, and at its origin from the Coronoid process, and pull it upwards, cutting through at the same time the Anterior Ulnar Recurrent artery and the Median nerve.
b. Cut through the tendons of the Palmaris longus and Flexor carpi radialis muscles at the wrist, and pull these muscles upwards. Their nerves from the Median will be divided, and arterial twigs from the Radial and Ulnar. There will now be exposed— 1. The Flexor sublimis digitorum muscle, its origin above from the internal Condyle, the inner side of the I
Olecranon, the oblique line and upper three fourths of the anterior border of the Radius; and its tendons below as far as the wrist. 2. A small portion of the tendon of the Flexor longus pollicis muscle below, lying upon the lower part of the Radius.