20 



EXPERIMENTAL PHYSIOLOGY 



adductor brevis, adductor magnus and sartorius, s. The semimembranosus, 

 s///, is seen on the posterior surface with its outer border in relation with the 

 |i\ i iioiniis above and the biceps, b, below. Both muscles arise above from 

 the symphysis pubis, and below are inserted by tendinous aponeuroses into 

 the tibio-fiimla. Cut through the aponeurosis at the outer border of each 

 muscle, and then separate each from the subjacent muscles, viz. the 

 adductors and semitendinosus. Isolate the muscles right down to their lower 

 insertion ami cut through the tibio-fibula just below this, and then 

 divide the femur a little above the knee-joint. By holding the piece of bone 

 thus isolated the two muscles can now be easily separated right up to the 

 symphysis. The semitendinosus usually tends to separate with them, and 

 may he removed later by cutting through its lower attachment, then dissect- 

 ing it away from the gracilis, or finally dividing its two heads of attachment 

 to the pelvis. The other muscles attached to the symphysis are now cut 

 through, and the head of the femur disarticulated from the acetabulum. In 

 many cases it is convenient to make a second preparation in a similar 

 manner from the opposite leg ; but if this be not required, the whole leg may 

 he removed, disarticulating at the acetabulum. The great advantage of this 

 preparation is that we have a mass of muscle in which the fibres are very 

 nearly straight, and are of a good length. With a double preparation the 

 muscles can hang side by side, and so the tranverse section is doubled. The 

 upper end can be conveniently fixed by passing a strong needle through the 

 acetabula. With the two preparations dissected out they can also be hung one 

 below the other, being united by a piece of the symphysis, and thus a muscle 

 of double length is obtained. 



MAKE A HYOGLOSSUS PREPARATION.— One of the simplest 



and most convenient muscle prepara- 

 tions that can be obtained from a frog 

 is the hyoglossus muscle. Fig. 26 

 shows the general course and arrange- 

 ment of the muscle. It is attached to 

 the anterior edge of the body of the 

 hyoid cartilage, and from this the 

 fibres run forwards to meet in the 

 mid line with the muscle of the oppo- 

 site side. The two then run forward 

 as two bands to the apex of the lower 

 jaw, and thence into the substance of 

 the tongue. In the tongue the fibres 

 run towards the tip and the muscle 

 gradually ends by becoming inserted 

 into the submucous connective tissue 

 of that organ. It is supplied by the 

 hypoglossal nerve (h, fig. 26). To 

 utilise the muscle when we wish to 

 stimulate directly, all that is necessary 

 is to lift up the lower jaw and cut 

 through the joint between the two jaws on either side, extending the in- 



Fig. 26. — The Relations of the 

 Hyoglossus, h g, in the Fkog. 



