Fig. 90. Transverse Section through the Right Forearm at the 

 junction of the Upper and Middle Thirds. 



Frozen sec/ion. Vietv of a Kiglit Arm from beloiv, or a Left Arm from above. 



On the Flexor Aspect are to be noted : Position of the Palmar Branch of the 

 Radial Ner\e (too large in the figure) under cover of the Brachio-Radialis; position of 

 the Radial Artery between this muscle and the Pronator Radii Teres, about 2/5ths inch 

 from the fascia. INIedian nerve in the middle between the Radial and Ulnar Nerves, 

 both deeply embedded in the muscles. Between the Median and Ulnar Nerves is the 

 Ulnar Artery; the Anterior Interosseous Artery runs very near the Radius. Intermuscular 

 Septa are seen between the superficial and the deep flexors, and between the flexor and 

 the extensor muscles. 



Dorsal aspect ; Posterior Interosseous Nerve and Artery between the Supinator 

 Brevis and the Extensors. Near the condyles of the Humerus the special Fasciae blend 

 with the Deep Fascia of the forearm ; at the middle Y„rd they are separate, thus forming 

 the "Lymph spaces" in which inflammation — simple and suppurative — rapidly spreads. 



Fig. 91. Transverse Section through the Right Forearm at the 



lower end. 



Frozen section. I'ieiu of a Right Arm from beloiv, or nf a Left Arm from above. 



Note: Portion of the Radial Artery, where the pulse can be felt and where the 

 artery is generally ligatured, between the skin and the bone, separated from the latter 

 by fibres of the Pronator Quadratus. — Ulnar Artery usually covered by the Tendon 

 of the Flexor Carpi Ulnaris; at a deeper level, and more towards the inner (ulnar) side 

 lies the Ulnar Nerve — Median Nerve, between the Flexor Carpi Radialis and Flexor 

 Sublimis Digitonmi, usually somewhat covered by the Palmaris Longus (cf. Fig. 95), if 

 this muscle is present and normally developed. 



Fasciae and Septa are coloured blue in the figure which is a supplement to 

 Figs. 94, 97 and 98 in which the tendon sheaths at the wrist are shown. 



The separation of the special fasciae and the fascia of the forearm (cf. Fig. 90) 

 is also well carried out here, although there are no synovial sheaths. The fascia forms 

 on the flexor aspect special compartments for the Flexor Carpi Radialis, Flexor Carpi 

 Ulnaris and Palmaris Longus. This explains why there are 2 Fasciae in front of the 

 Ulnar Artery, whilst the Radial Artery lies immediately under the fascia of the forearm. 

 An incision for ligaturing the Ulnar Artery, carried along the border of the Flexor Carpi 

 Ulnaris, divides not only the fascia of the forearm, but a second fascia which becomes 

 thicker lower down. This fascia forms the posterior wall of the fascial canal, in which 

 the muscle runs. 



The Pronator Quadratus is covered by a fascia of its own. It is true that the 

 other Flexor Muscles and the Median Nerve also have their own fasciae, but they are 

 of no practical importance, and one should regard these muscles as lying in a common 

 "Lymph Space" which ends below at the upper limits of the Tendon Sheaths and is 

 bounded on either side by the Septa forming the canals for the 3 muscles mentioned 

 above. Above, this Lymph Space is continued into the arm, along the Vessels and 

 Nerves. This explains the danger (and also the necessity of making deep incisions) of 

 deep suppuration in the forearm. 



