HAMSTRING MUSCLES ILIO-PSO AS. 271 



also from the external intermuscular septum between it and the vastus 

 extermis muscle, and terminates on the same aponeurosis as the long head. 

 The inferior tendon is inserted into the head of the fibula by two portions, 

 between which is attached the external lateral ligament of the knee-joiDt, 

 being separated from them by a synovial bursa. Some of the fibres of the 

 tendon, passing forwards and downwards, are inserted into the front of the 

 tibia, and others passing backwards strengthen the fascia of the leg. 



The semitendinosus muscle, arising from the tuberosity of the ischium by 

 the tendon common to it and the biceps, for a distance of about three 

 inches, descends on the back of the thigh, and terminates below the middle 

 in a long, rounded, and slender tendon, which passes along the inner side of 

 the popliteal space, resting on the semimembrauosus, and curves forwards to 

 be inserted in an expanded form into the upper part of the tibia at its 

 inner side. There the tendon is on the same plane, but below that of the 

 gracilis, both being under cover of the sartorius. A narrow oblique tendi- 

 nous intersection traverses the muscle about the middle. 



The semimembrauosus muscle arises from the tuberosity of the ischium, 

 above and to the outside of the origin of the biceps and semitendinosus, by a 

 strong flattened tendon, two or three inches long, which as it descends in 

 front of the common tendon of those two muscles, passes to their inner side. 

 It terminates inferiorly in a thick tendon, which is inserted in three parts : 

 the principal part turns forwards and is inserted into a well marked groove 

 on the inner tuberosity of the tibia, beneath the internal lateral ligament of 

 the knee-joint, some of its fibres joining that ligament ; a second part, passing 

 downwards and outwards, expands in the aponeurosis over the popliteus 

 muscle ; and the remaining fibres are directed upwards and outwards, and 

 blend with the posterior ligament of the knee-joint, of which they may be 

 said to form a considerable portion. The muscle consists of numerous short 

 fibres extending obliquely between two aponeurotic expansions, which are 

 continued upwards and downwards on the opposite sides of the muscle for 

 three fourths of its length from the superior and inferior tendons. 



The inferior tendon of the semimembranosus muscle is separated from the tendon 

 of the inner head of the gastrocnemius by a large bursa. The muscle rests on the 

 adductor magnus. 



The hamstring muscles descend in contact with one another, being bound down by 

 the fascia lata ; but inferiorly they diverge, the biceps passing to the outside, and the 

 semimembranosus and semitendinosus to the inner side of the knee, forming the supe- 

 rior borders of a diamond-shaped hollow at the back of the knee the popliteal space. 

 The great sciatic nerve is concealed by them while they are in contact, and its 

 principal division, the internal popliteal, lies in contact with the semimembranosus 

 muscle in the popliteal space, while the smaller or external popliteal division runs 

 along the edge of the biceps muscle. 



ILIAC REGION. 



The ilio-psoas muscle, the great flexor of the hip-joint, is divisible into two 

 parts, a broad outer part, the iliacus, and an elongated inner part, the psoas 

 magnus, which are inserted together into the small trochanter. 



The iliacus muscle arises from the iliac fossa of the innominate bone, and 

 from the anterior border of the same, likewise from the base of the sacrum, 

 the ilio-lumbar ligament, and the capsule of the hip-joint. Its fibres con- 

 verging, as they pass downwards and inwards, are inserted for the most part 

 into a tendon continuous with the psoas muscle ; while some are prolonged 

 to a special triangular impression on the upper part of the femur, in front of 

 and below the small trochanter. 



