28 ANATOMY OF THE HEAD AND NECK. 



best removed by a stream of water from a syringe or squeezed sponge. 

 In a fresh brain, or one which will harden well, they should be studied 

 in connection with the base of the brain ; in that connection they will 

 be described. 



The anterior lobes are to be carefully lifted by the fingers, together 

 with the olfactory bulbs from each side of the crista galli. The 

 carotid arteries, optic and motor oculi nerves are to be divided on 

 each side of the processus olivaris, and the pituitary gland lifted out 

 of the sella turcica ; this sometimes cannot be done, and then its pe- 

 dicle must be divided. The hemispheres being supported in the left 

 hand, and gradually allowed to roll out of the cranial cavity, the ten- 

 torium is brought into view, and, just in front of its anterior margin, 

 the fourth or trochlearis nerve ; this is to be divided, and the ten- 

 toriuin is to be detached from the petrous portion of the temporal 

 bone by cutting as close to its insertion thereto as possible. The fifth 

 nerve is next brought into view ; the sixth, small and slight, near the 

 median line of the clivus Blurnenbachii ; more externally the seventh 

 pair, composed of two parts, the facial and auditory ; below this the 

 three trunks of the eighth pair ; the upper being the glosso-phary ngeal , 

 the flat band next below, the pneumogastric ; and the one ascending 

 from the spinal canal, the spinal accessory. These being divided, as 

 well as the ninth, which is the remaining one, the vertebral arteries 

 are to be cut off close to the spinal cord. The spinal cord is to be cut 

 across, with the spinal nerves on each side, as far down the canal as 

 possible, and the brain will then roll out of the cranial cavity. 



The brain should be laid in a basin with the base uppermost ; it 

 should be immersed in alcohol to harden and preserve it, and covered 

 with a piece of doubled cotton cloth. The cloth will keep it wet by 

 imbibition, if there is not alcohol enough to cover it. 



It is. however, to be borne in mind that the brain softens very soon 

 after death, and that, unless early removed, it may be unfit for dissec- 

 tion. A portion of each hemisphere may be shaved off, in order to 

 give the spirit a better opportunity to penetrate ; but even this may 

 not prevent its decomposition in some of its deep-seated parts. The 

 autopsy-room is the best place for the study of the brain, as it can 

 always there be seen in its fresh and naturally firm condition. 



The dura mater at the base of the cranial cavity will be 

 found very adherent, on account of the sutures into which 

 it penetrates, and the foramina through which it is con- 

 tinued to form the sheath of the nerves ; it is also prolonged 

 downward into the spinal canal where it forms a loose 

 investment of the spinal cord. The tentorium, if replaced, 

 will be found to separate the spaces occupied by the cere- 

 brum and cerebellum, and to be attached along the trans- 

 verse groove of the occipital bone, the sharp edge of the 

 petrous portion of the temporal bone, and to the posterior 

 clinoid processes of the sphenoid. 



In the attachment of the tentorium to the occipital bone 

 will be seen the lateral sinuses; at the base of the petrous 



