1378 SUKFACE AND SUKGICAL ANATOMY. 



The tarsi are attached to the periosteum of the orbital margins by the superior 

 and inferior palpebral ligaments which shut off the communication between the sub- 

 cutaneous tissue of the eyelids and the fatty tissue of the orbital cavity. In fracture 

 of the anterior fossa of the base of the skull involving the orbital part, the blood 

 extends forwards between the periosteum and the musculo-fascial envelope of the 

 orbit and appears under the conjunctiva. 



To obtain free access to the cavity of the orbit, the surgeon first enlarges the 

 palpebral fissure by making a horizontal incision from the lateral palpebral com- 

 missure to the lateral margin of the orbit, and then, after everting the eyelid, 

 divides the conjunctiva along the fornix of the upper or lower lid, or of both, as 

 may be desired. 



Nose. To examine the anterior nares (anterior rhinoscopy} a strong light is 

 reflected into the nostril, which is dilated by means of a nasal speculum. The 

 anterior extremity of the inferior concha appears as a rounded body projecting 

 from the lateral wall of the nose ; in turgescence of its erectile tissue it is liable 

 to come in contact with the nasal septum and so occlude the nostril. The inferior 

 meatus, situated between the inferior concha and the floor of the nasal cavity, is 

 brought into view by tilting forwards the head. The inferior aperture of the naso- 

 lacrimal duct is concealed from view by the anterior part of the inferior concha. 

 The floor of the nose is horizontal and placed on a slightly lower level than the 

 anterior nares. The septum, generally more or less deviated to one or other side, 

 is seen when the head is slightly rotated away from the side to be examined. The 

 anterior extremity of the middle concha, which lies a little behind and medial to 

 the lower-medial angle of the orbital margin, is seen when the patient's head is 

 thrown well back ; between it and the septum is a slit-like interval (olfactory cleft}. 

 By rotating the patient's head towards the corresponding shoulder the anterior part 

 of the middle meatus is brought into view ; pus in that situation may originate from 

 the frontal, the anterior ethmoidal, or the maxillary sinuses, all of which open into 

 the hiatus semilunaris of the middle meatus. 



To make a satisfactory digital exploration of the anterior part of the nasal 

 cavities, it is necessary to divide the columella and the cartilaginous septum with 

 a strong pair of scissors, one blade being introduced into each nostril (Kocher) ; 

 blood spurts from the small arteries of the septum, but the bleeding soon ceases. 

 When these vessels, which are derived from the superior labial arteries, are the 

 source of the haemorrhage in epistaxis, the bleeding can be arrested either by com- 

 pressing the superior labial arteries, by plugging the anterior nares, or by grasp- 

 ing the cartilaginous part of the nose firmly between the finger and thumb. 



The maxillary sinus (O.T. antrum of Highmore), situated in the maxilla, is a 

 pyramidal cavity with its base formed by the lateral wall of the nose and its 

 apex directed towards the zygomatic bone. The cavity is lined by a thin rnuco- 

 periosteal membrane, easily separable from the bone ; in the mucous layer are 

 numerous mucous glands from which cysts may develop. The floor of the sinus, 

 which is at or a little below the level of the floor of the nose, is separated from 

 the roots of the premolar and molar teeth by a plate of bone of varying thickness. 

 When this plate is thin and devoid of spongy bone, the floor of the sinus sinks below 

 the level of the floor of the nose, and suppuration at the roots of one of the teeth 

 above mentioned is, in these circumstances, very liable to extend to the sinus. In 

 a sinus of average dimensions the line of union of the nasal and facial walls of 

 the cavity corresponds externally to the lateral edge of the canine ridge (Logan 

 Turner). The nasal orifice is situated at the highest part of the sinus, and 

 is therefore unfavourably placed for natural drainage ; it opens into the posterior 

 and lower part of the infundibulum, which in its turn communicates with the 

 middle meatus of the nose through the hiatus semilunaris. In old age there is 

 frequently a second communication between the sinus and middle meatus, the 

 opening being situated posterior to and below the normal orifice ; when this accessory 

 aperture exists, pus from the sinus may drain backwards into the nasal part of 

 the pharynx (Logan Turner). In empyema of the sinus the opening to evacuate 

 and drain the cavity may be made (1) through the alveolus of the second premolar 

 or of the first or second molar tooth, the first molar being the site of election; 



