418 THE MUSCLES AND FASCIJE. 



into the thigh, to the outer side of the femoral vessels. It thus follows that a Psoas abscess may 

 be described as consisting of four parts : (1) a somewhat narrow channel at its upper part, in the 

 Psoas sheath ; (2) a dilated sac in the iliac fossa ; (3) a constricted neck under Poupart's liga- 

 ment ; and (4) a dilated sac in the upper part of the thigh. When the lumbar vertebrae are 

 the seat of the disease, the matter finds its way directly into the substance of the muscle. The 

 muscular fibres are destroyed, and the nervous cords contained in the abscess are isolated and 

 exposed in its interior; the femoral vessels which lie in front of the fascia, remain intact, and the 

 peritoneum seldom becomes implicated. All Psoas abscesses do not, however, pursue this 

 course : the matter may leave the muscle above the crest of the ilium, and, tracking backward, 

 may point in the loin (lumbar abscess) ; or it may point above Poupart's ligament in the inguinal 

 region; or it may follow the course of the iliac vessels into the pelvis, and, passing through the 

 great sacro-sciatic notch, discharge itself on the back of the thigh ; or it may open into the 

 bladder or find its way into the perinaeum. 



II. MUSCLES AND FASCIA OF THE THIGH. 

 1. Anterior Femoral Region. 



| Rectus. 



Tensor fasciae femoris. Quadriceps] Vastus externus. 

 Sartorius. extensor | Vastus internus. 



I Crureus. 



Subcrureus. 



Dissection. To expose the muscles and fasciae in this region, make an incision along 

 Poupart's ligament, from the anterior superior spine of the ilium to the spine of the os pubis; 

 a vertical incision from the centre of this, along the middle of the thigh to below the knee-joint; 

 and a transverse incision from the inner to the outer side of the leg, at the lower end of the ver- 

 tical incision. The flaps of integument having been removed, the superficial and deep fasciae 

 should be examined. The more advanced student should commence the study of this region by 

 an examination of the anatomy of femoral hernia and Scarpa's triangle, the incisions for the 

 dissection of which are marked out in the figure 252. 



The superficial fascia forms a continuous layer over the whole of the thigh, 

 consisting of areolar tissue, containing in its meshes much fat, and capable of 

 being separated into two or more layers, between which are found the superficial 

 vessels and nerves. It varies in thickness in different parts of the limb : in the 

 groin it is thick, and the two layers are separated from one another by the super- 

 ficial inguinal lymphatic glands, the internal saphenous vein, and several smaller 

 vessels. One of these two layers, the superficial, is continuous above with the 

 superficial fascia of the abdomen. The deep layer of the superficial fascia is a 

 very thin, fibrous layer, best marked on the inner side of the long saphenous vein 

 and below Poupart's ligament. It is placed beneath the subcutaneous vessels and 

 nerves and upon the surface of the fascia lata. It is intimately adherent to the 

 fascia lata a little below Poupart's ligament. It covers the saphenous opening in 

 the fascia lata, being closely united to its circumference, and is connected to the 

 sheath of the femoral vessels, corresponding to its under surface. The portion of 

 fascia covering this aperture is perforated by the internal saphenous vein and by 

 numerous blood- and lymphatic vessels ; hence it has been termed the cribriform 

 fascia, the openings for these vessels having been likened to the holes in a sieve. 

 The cribriform fascia adheres closely both to the superficial fascia and to the fascia 

 lata, so that it is described by some anatomists as part of the fascia lata, but is 

 usually considered (as in this work) as belonging to the superficial fascia. It is not 

 until the cribriform fascia has been cleared away that the. saphenous opening is 

 seen, so that this opening does riot in ordinary cases exist naturally, but is the 

 result of dissection. Mr. Callender, however, speaks of cases in which, probably 

 as the result of pressure from enlarged inguinal lymphatic glands, the fascia lias 

 become atrophied, and a saphenous opening exists independent of dissection. A 

 femoral hernia in passing through the saphenous opening receives the cribriform 

 fascia as one of its coverings. A large subcutaneous bursa is found in the super- 

 ficial fascia over the patella. 



The deep fascia of the thigh is exposed on the removal of the superficial fascia, 



