Fig. I. Median Section through the Head. 



Right half of a frozen-section through the Head and Neck of a girl aged 15. 

 In front the plane of section is carried accurately through the middle line, but posteriorly 

 it deviates about ^/sths inch to the left. The bones are left intact, as is shewn by the 

 bisected Odontoid Process ; the soft parts (particularly brain-substance) have been carefully 

 cleared away as far as the middle line. 



A median section gives the best general idea of the relations and positions of 

 the structures of the head, and in particular of the topographical relations of the brain 

 to the face ; it clearly shows how the brain extends further down posteriorly than in front. 

 That portion of the skull cap under which the Cerebrum lies is only covered by a thin 

 la}er of soft parts — skin and epicranial aponeurosis (the latter is blue in the figure). 



The Hemispheres, therefore, are easily injured in fracture of the vault of the 

 skull. The Cerebellum is better protected. The thickness of the skull cap varies con- 

 siderably at different points, and in different people — it is normally at the vertex Vio^^ 

 inch. On either side of the middle line the bone may be very thin, because for a 

 distance of ^^ths inch from the middle line Pacchionian bodies may be present, and only 

 covered by a very thin lamina of bone. 



The Superior Longitudinal Sinus is exhibited throughout its whole length (the 

 oYlier Venous Sinuses are shewn in Figs. 15 and 16), beginning at the Foramen Caecum 

 and increasing in width as it extends backwards and receives more blood it finally forms 

 by junction with the Straight Sinus the Torcular Herophyli at the level of the External 

 Occipital Protuberance (or somewhat higher up) and unites with each lateral Sinus, 

 especially with the right. 



Its position is very exposed ; as it can be easily injured it demands consideration 

 during trephining. 



The Nasal Septum is usually asymmetrical, being bent to one side (left in this 

 case). Dense connective-tissue is found at the anterior surface of the base of the skull 

 and is continued downwards as the Anterior Common Spinous Ligament which covers 

 the anterior surfaces of the bodies of the vertebrae. A thick mass of lymphoid tissue 

 lies under the mucous membrane of the posterior wall of the pharynx (i. e. the Pharyngeal 

 Tonsil) ; lower down between the Oesophagus and the Vertebral Column there is only a 

 thin layer of connective tissue in which pus may easily spread downwards (Retropharyn- 

 geal Abscess). 



When the mouth is closed, the Tongue lies against the Palate (in this figure, 

 depending upon the form of death, suicide by drowning, the tongue is seen pushed be- 

 tween the Canine teeth). 



On the posterior surface of the Hyoid Bone the Hyoid Bursa is seen lying be- 

 tween the Hyoid Bone and the Thyreohyoid Membrane which is attached to the upper 

 border of the bone. 



The Larynx is here seen at a higher level than usual; the Glottis, as a rule, is 

 situated at the level of the 5th Cervical Vertebra or of the disc between the 5 th and 

 6th Cervical Vertebrae. 



The Pyramidal Process of the Thyreoid Gland (Pyramid of Lalouette), in this 

 figure extends almost up to the Hyoid Bone whereas the usual height to which the 

 Isthmus of the Gland reaches is the ist Tracheal ring. 



