Fig. 2. Frontal Section of the Head through the Orbits. 



Frozen section through the middle of the eye-halls. The slender nerves and 

 vessels as well as the articulations of the bones have been determined by careful 



dissection. 



The frontal bones are very thick owing to the obliquit}' of the section. 



The Superior Longitudinal Sinus bulges to the right, owing to one of the 

 "Lacunae Lateral es" — accessory dilatations of the Sinus which are of frequent 

 occurrence at the Vertex, and may extend Vs^hs inch from the middle line. 



The Temporal Muscle is observed to be covered by the Temporal Fascia, 

 which extends from the Superior Temporal Ridge to the Zygoma. At the upper 

 border of the Zygoma it splits into 2 laminae (which may reunite), between which 

 some fatty tissue becomes collected. 



The Cavit}' of the Orbit (into the inner and upper portion of its roof the 

 posterior extremit}" of the Frontal Sinus protrudes) is only partialh' filled b}' the 

 eye-ball; the greater space is taken up bj- fat in which the eye muscles rim. 



Closely applied to the outer wall of the orbit is the Lacrimal Gland. The 

 point at which the Optic Nerve enters the e}'e-ball is marked in y e 1 1 o w. 



The figure shews the very large space occupied by the Nasal Cavity and 

 its Accessory Cavities. The Nasal Cavity which is only separated from the Cranial 

 Cavity by the thin cribriform plate of the Ethmoid Bone, presents 3 turbinated 

 bones. On the left side the Sphenoidal Turbinated Bone was so short as to nearly 

 escape the section. 



Between the Middle and Inferior Turbinated Bones, the communication 

 between the Nasal Cavity and the Frontal Sinus — the Infundibulum — is visible. 



Directly below this orifice lies the aperture of the Antrum of HiGHMORE. 

 This aperture situated almost at the top of the Antrum, is necessarily most un- 

 favourable to drainage. The Nasal Septum is deviated from the middle Une 

 (cf. Fig. i). 



The Antrum is separated from the Orbit by the thin floor of the Orbit 

 in which along the Infra-Orbital Canal the nerve and vessels of the same name 

 pass. For the relations of the Alveoli of the Teeth to the Antrum vide Fig. 40. 

 The wall between the Antrum and the Nasal Cavity is thin so that perforation 

 can be easily carried out from the nasal cavity (if better drainage be sought by 



this route). 



The Buccal Cavity is closed below by the Mylohyoid Muscle, which ex- 

 tends from the inner surface of the lower jaw downwards and inwards to meet 

 its fellow in the middle line (Diaphragma Oris). 



At the junction of the mucous membrane of the Cheek and the Gums, 

 groups of mucous glands are found — buccal glands. 



