EXTRACTION OF THE BRAIN. 1049 



At the back of the neck the posterior and upper parts of the trapezius 

 arid steruo-niastoid muscles will be laid bare (pp. 200 and 193) ; and, be- 

 tween these, a part of the splenius muscle, and, when the trapezius is not 

 strongly developed, a small angle of the coniplexus muscle will be brought 

 into view. These muscles are to be left undivided at present. On the 

 posterior part of the cranium the structures to be examined are the occipital 

 artery and vein, and the great occipital nerve, which pierces the complexus 

 and trapezius muscles (pp. 351 and 634) ; the small occipital nerve, which 

 passes upwards along the posterior border of the sterno-mastoid muscle 

 (p. 638) ; and, beneath these, the occipital part of the occipito-frontalis 

 muscle (p. 169), which passes upwards from the superior curved line of the 

 occipital bone. Behiud the ear are the retrahens auriculam muscle and the 

 posterior auricular artery and nerve (pp. 353 and 612) ; above the ear 

 is the attolleus auriculam muscle ; and in front of the ear the attrahens 

 auriculam muscle connected with the attollens, the temporal artery and vein, 

 the small temporal branch of the third division of the fifth nerve, and the 

 superior branches of the facial nerve (pp. 170, 353, 612, and 606). Passing 

 upwards on the forehead, are the frontal part of the occipito-frontalis muscle, 

 the frontal vein, the supraorbital and frontal arteries, and the supraorbital 

 and supratrochlear nerves (pp. 360 and 597). 



2. Interior of the Cranium and Brain. During the third and fourth 

 days the brain and its membranes are to be removed and studied, and the 

 interior of the base of the skull dissected to show the sinuses, blood-vessels, 

 and nerves ; and, if there is time (as may be the case, should the head have 

 been previously opened), the orbit may be examined from above. To 

 remove the calvarium, the temporal aponeurosis and upper part of the 

 temporal muscle having been dissected, let the scalpel be carried round the 

 cranium from a point a little above the occipital protuberance, so as to pass 

 across the forehead at about an inch above the orbits ; and having cleared a 

 small portion of the bone on the circle so made, let the external table of 

 the skull be sawn through, leaving the inner table undivided. Let the 

 inner table be cracked completely round by a few smart strokes of the 

 chisel and mallet, and the calvarium may then be pulled away from the dura 

 mater which lines it. The superficial aspect of the dura mater having been ob- 

 served, and the superior longitudinal sinus laid open and inspected (p. 462), 

 the dura mater is to be divided on a level with the sawn edge of the skull, 

 excepting where it touches the middle line ; this will permit the arachnoid 

 membrane and pia mater to be examined, as well as the cerebral veins 

 entering the superior longitudinal sinus ; and when these veins are divided, 

 the falx cerebri will be seen dipping down between the cerebral hemispheres. 

 The falx cerebri is then to be separated from its attachment to the crista 

 galli and thrown backwards (p. 562). 



It will now be in the dissector's option to remove the brain at once from 

 the body, or to examine it in situ as far as the ventricles. If the latter 

 plan, which is generally to be preferred, be adopted, the dissectors ought 

 first to examine the convolutions of the upper aspect of the brain, noticing 

 the anterior and posteiior cerebral arteries arching respectively backward 

 and forwards ; they will then slice away the hemispheres to the level of the 

 corpus callosum, and observe the extent of that structure, its transverse 

 markings, the raphe and the longitudinal lines (p. 540). They will proceed 

 by incisions at the sides of the corpus callosum, to open the lateral ventricles 

 separately, so as to expose their cavities with the anterior and posterior 

 cornua and the parts lying on their floor : they must afterwards cut across 



