OF THE LOWER EXTREMITY. 325 



LEG. FOOT. 



Anterior tibio-fibular region. Dorsal region. 



Tibialis anticus. Extensor brevis digitorum. 



Extensor longus digitorum. Interossei dorsales. 

 Extensor proprius pollicis. Plantar region. 



Peroneus tertius. First layer. 



Posterior tibio-fibular region. Abductor pollicis. 



Superficial layer. Flexor brevis digitorum. 



Gastrocnemius Abductor minimi digiti. 

 Plantaris. Second layer. 



Musculus accessorius. 



Deep layer. Lumbricales. 



Popliteus. Third layer. 



Flexor longus pollicis. Flexor brevis pollicis. 



Flexor longus digitorum. Adductor pollicis. 



Tibialis posticus. Flexor brevis minimi digiti. 



Fibular region. Transversus pedis. 

 Peroneus longus. Fourth layer. 



Peroneus brevis. Interossei plantares. 



ILIAC REGION, 



Psoas Magnus. Psoas Parvus. Iliacus. 



Dissection. No detailed description is required for the dissection of these muscles. They are 

 exposed after the removal of the viscera from the abdomen, covered by the peritoneum and a 

 thin layer of fascia, the fascia iliaca. 



The iliac fascia is the aponeurotic layer which lines the back part of the 

 abdominal cavity, and incloses the Psoas and Iliacus muscles throughout their 

 whole extent. It is thin above; and becomes gradually thicker below, as it 

 approaches the femoral arch. 



The portion investing the Psoas is attached, above, to the ligamentum arcuatum 

 internum ; internally, to the sacrum ; and by a series of arched processes to the 

 intervertebral substances, and prominent margins of the bodies of the vertebrae ; 

 the intervals left opposite the constricted portions of the bodies transmitting the 

 lumbar arteries and sympathetic filaments of nerves. Externally, it is continuous 

 with the fascia lumborum. 



The portion investing the Iliacus is connected, externally, to the whole length 

 of the inner border of the crest of the ilium ; internally, to the brim of the true 

 pelvis, where it is continuous with the periosteum, and receives the tendon of 

 insertion of the Psoas parvus. External to the femoral vessels, this fascia is 

 intimately connected with Poupart's ligament, and is continuous with the fascia 

 transversalis ; but, corresponding to the point where the femoral vessels pass down 

 into the thigh, it is prolonged down behind them, forming the posterior wall of the 

 femoral sheath. Below this point, the iliac fascia surrounds the Psoas and Iliacus 

 muscles to their termination, and becomes continuous with the iliac portion of the 

 fascia lata. Internal to the femoral vessels the iliac fascia is connected to the ilio- 

 pectineal line, and is continuous with the pubic portion of the fascia lata. The 

 iliac vessels lie in front of the iliac fascia, but all the branches of the lumbar 

 plexus behind it; it is separated from the peritoneum by a quantity of loose areolar 

 tissue. In abscess accompanying caries of the lower part of the spine, the matter 

 makes its way to the femoral arch, distending the sheath of the Psoas ; and when 

 it accumulates in considerable quantity, this muscle becomes absorbed, and the 

 nervous cords contained in it are dissected out, and lie exposed in the cavity of 

 the abscess ; the femoral vessels, however, remain intact, and the peritoneum seldom 

 becomes implicated notwithstanding the extreme thinness of the membrane. 



