SURFACE FORM OF THE LOWER EXTREMITY 545 



and the thigh on the pelvis, and rotating the thigh outward, presents a well-marked surface 

 form. At its upper part, where it constitutes the outer boundary of Scarpa's triangle, it forms 

 a prominent oblique ridge, which becomes changed into a flattened plane below, and this grad- 

 ually merges in a general fulness on the inner side of the knee-joint. When the Sartorius is 

 not in action, a depression exists between the Quadriceps extensor and the Adductor muscles, 

 running obliquely downward and inward from the apex of Scarpa's triangle to the inner side 

 of the knee, which depression corresponds to this muscle. In the depressed angle formed bv 

 the divergence of the Sartorius and Tensor fasciae femoris muscles, just below the anterior 

 superior spinous process of the ilium, the Rectus femoris muscle appears, and, below this, deter- 

 mines to a great extent the convex form of the front of the thigh. In a well-developed subject 

 the borders of the muscle, when in action, are clearly to be defined. The Vastus externus 

 forms a long flattened plane on the outer side of the thigh, traversed by the longitudinal groove 

 formed by the iliotibial band. The Vastus interims, on the inner side of the lower half of the 

 thigh, gives rise to a considerable prominence, which increases toward the knee and terminates 

 somewhat abruptly in this situation with a full, curved outline. The Crureus and Subcrureus 

 are completely hidden, and do not directly influence surface form. The Adductor muscles, 

 constituting the internal femoral group, are not to be individually distinguished from each 

 other, with the exception of the upper tendon of the Adductor longus and the lower tendon of 

 the Adductor magnus. The upper tendon of the Adductor longus, when the muscle is in action, 

 stands out as a prominent ridge, which runs obliquely downward and outward from the neigh- 

 borhood of the pubic spine, and forms the inner boundary of a flattened triangular space on 

 the upper part of the front of the thigh, known as Scarpa's triangle. The lower tendon of the 

 Adductor magnus can be distinctly felt as a short ridge extending down to the Adductor tubercle 

 on the internal condyle, between the Sartorius and Vastus internus. The Adductor group 

 of muscles fills in the triangular space at the upper part of the thigh, formed between the oblique 

 femur and the pelvic wall, and to them is due the contour of the inner border of the thigh, the 

 Gracilis largely contributing to the smoothness of the outline. These muscles are not marked 

 off on the surface from those of the posterior femoral region by any intermuscular marking, but 

 on the outer side of the thigh these latter muscles are defined from the Vastus externus by a 

 distinct marking, corresponding to the external intermuscular septum. The Gluteus maximus 

 and a part of the Gluteus medius are the only muscles of the buttock which influence surface 

 form. The other part of the Gluteus medius, the Gluteus minimus, and the external Rotators 

 are completely hidden. The Gluteus maximus forms the full rounded outline of the buttock; 

 it is more prominent behind, compressed in front, and terminates at its tendinous insertion in 

 a depression immediately behind the great trochanter. Its lower border does not correspond 

 to the gluteal fold, but is much more oblique, being marked by a line drawn from the side of 

 the coccyx to the junction of the upper with the lower two-thirds of the thigh on the outer side. 

 From beneath the lower margin of this muscle the Hamstring muscles appear, at first narrow 

 and not well marked, but as they descend becoming more prominent and widened out, and 

 eventually dividing into two well-marked ridges, which constitute the upper boundaries of the 

 popliteal space, and are formed by the tendons of the inner and outer Hamstring muscles, 

 respectively. In the upper part of the thigh these muscles are not to be individually distin- 

 guished from each other, but lower down the separation between the Semitendinosus and Semi- 

 membranosus is denoted by a slight intermuscular marking. The external hamstring tendon, 

 formed by the Biceps is seen as a thick cord running down to the head of the fibula. The inner 

 Hamstring tendons comprise the Semitendinosus, the Semimembranosus, and the Gracilis. 

 The Semitendinosus is the most internal of these, and can be felt, in certain positions of the 

 limb, as a sharp cord; the Semimembranosus is thick, and the Gracilis is situated a little farther 

 forward than the other two. All the muscles on the front of the leg appear to a certain extent 

 somewhere on the surface, but the form of this region is mainly dependent upon the Tibialis 

 anticus and the Extensor longus digitorum. The Tibialis anticus is well marked, and presents 

 a fusiform enlargement at the outer side of the tibia, and projects beyond the crest of the shin 

 bone. From the muscular mass its tendons may be traced downward, standing out boldly, 

 when the muscle is in action, on the front of the tibia and ankle-joint, and coursing down to its 

 insertion along the inner border of the foot. A well-marked groove separates this muscle exter- 

 nally from the Extensor longus digitorum, which fills up the rest of the space between the upper 

 part of the shaft of the tibia and fibula. It does not present so bold an outline as the Tibialis 

 anticus, and its tendon below, diverging from the tendon of the Tibialis anticus, forms with the 

 latter a sort of plane, in which may be seen the tendon of the Extensor proprius hallucis. A 

 groove on the outer side of the Extensor longus digitorum, seen most plainly when the muscle 

 is in action, separates the tendon from a slight eminence corresponding to the Peroneus tertius. 

 The fleshy fibres of the Peroneus longus are strongly marked at the upper part of the outer 

 side of the leg, especially when the muscle is in action. It forms a bold swelling, separated by 

 furrows from the Extensor longus digitorum in front and the Soleus behind. Below, the fleshy 

 fibres terminate abruptly in a tendon Avhich overlaps the more flattened form of the Peroneus 

 brevis. At the external malleolus the tendon of the Peroneus brevis is more marked than that 



