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 subcutaneous 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 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 commissure 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 speculumn. 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 nasolacrimal 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.

Hare-lip is du

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 then of the fro source of the hæmorrhage in epistaxis, the bleeding can be arrested either by com-poken of as co pressing the superior labial arteries, by plugging the anterior nares, or by grasp the cleft ing the cartilaginous part of the nose firmly between the finger and thumb. erely involves are may invo 2atter case t ciated with a hare-lip may

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 mucoperiosteal 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

as the defic sally the left) Fig. 1080, ta

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

I through the ine tooth; or In an antero

thesents a pyram
e rounded ape
us extends
f the maxilla
the sinus ar
S and the
matic bone

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.

the supe ocld be place the orbits.

the maxillary Lon of the ve In a profile tine of the horizontal

e molar teeth. floor of the coidal-cell a the pterygoid The anterior pa scared by the e gomatic b Lips. In co der cover of t lips are abu eath the mu ads are a fr genitally, giv

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 ds from the

enth week, sh from the nas

cess of two cesses) which other and septum of ops as a de Es cranii, is C Tmedial nas marilla and per lip. The due to the sch other and aft palate, wh

the canine fossa, lateral to the prominence caused by the root of the ; or (3) through the lateral wall of the inferior meatus of the nose. tero-posterior skiagram of the skull, the shadow of the maxillary sinus yramidal outline, the base corresponding to the floor of the orbit and apex to the alveolar recess of the sinus. Sometimes the floor of the Is medially, below the floor of the nose, into the palatine process lla so as to form a distinct palatine recess. The medial outline area is formed by the foreshortened shadow of the nasal wall of the he lateral pterygoid lamina, while laterally it is outlined by the one. The petrous portion of the temporal bone throws a deep shadow uperior half of the sinus. In taking the skiagram, therefore, the head laced in such a position that this shadow is raised as much as possible its. In the living subject the inferior and medial portion of the outline xillary sinus is considerably obscured by that caused by the cervical the vertebral column (Killian).

profile skiagram of the facial region of the dried skull, the shadow of the f the maxillary sinus is well defined. It is represented below by the rizontal shadow of the hard palate which crosses the tips of the roots of ar teeth. Above it is limited anteriorly by the dark curved shadow of r of the orbit, while above and posteriorly is the shadow of the posterior dal-cell area. Behind the maxillary area are the vertical linear shadows pterygoid laminæ overlapped by that of the coronoid process of the mandible. nterior part of the sinus area is overlapped and, to a considerable extent, red by the shadow caused by the denser and somewhat triangular shadow of ygomatic bone.

ips.-In compressing the labial arteries, it must be remembered that they run er cover of the mucous surface, a short distance from the free margins of the lips. lips are abundantly supplied with mucous glands which can be felt immediately neath the mucous membrane nearer their attached than their free borders; the ands are a frequent source of mucous cysts; occasionally they are enlarged ngenitally, giving rise to one form of hypertrophy of the lip.

Globular process

Hare-lip is due to failure of the union of the superficial parts of the median nasal subdivision of the fronto-nasal process with the maxillary process (Fig. 1079). The deformity is spoken of as complete or incomplete according as the cleft extends into the nostril or merely involves a portion of the lip. The fissure may involve the lip only, or it may include the alveolar process of the maxilla; in the latter case the cleft may or may not be associated with a cleft of the palate. Lastly, the hare-lip may be single or double, according as the deficiency has occurred on one (usually the left) or both sides.

Fig. 1080, taken from a coronal section through the head of a human embryo at the seventh week, shows how the mouth is shut off from the nasal cavities by the growth inwards from the deep aspect of the maxillary process of two horizontal plates (palatine processes) which unite in the median line with

each other and with the inferior border of FIG. 1079.-HEAD OF HUMAN EMBRYO ABOUT 29

the septum of the nose; the latter, which
develops as a downgrowth from the primitive
basis cranii, is continuous anteriorly with the
two medial nasal processes which form the
premaxilla and the median portion of the
upper lip. The various degrees of cleft palate
are due to the more or less complete failure of union of the palatine processes with
each other and with the premaxillary part of the median nasal processes. The cleft in the
soft palate, which is always median, may be either partial or complete, and may or may

DAYS OLD, showing the division of the lower part
of the median nasal process into the two globular
processes, the intervention of the olfactory pits
between the median and lateral nasal processes,
and the approximation of the maxillary and
lateral nasal processes, which, however, are
separated by the oculo-nasal sulcus (from His).

Prosencephalon

Olfactory pit

Lateral nasal

process

Maxillary process

not extend forwards into the hard palate. The cleft in the latter is spoken of as single or double according to whether the palatal processes have failed to unite with the lower edge of the nasal septum on one, or on both, sides. When the cleft extends forwards

Nasal septum

Inferior concha

through the alveolar process to become continuous with a cleft of the lip, the medial (premaxillary) edge of the cleft is usually projected forwards in advance of the lateral (maxillary) edge. Before proceeding to repair the cleft in the lip, the projecting premaxillary edge is forced back into line with the maxillary edge.

on

In what is known as a complete double cleft palate, the palatine processes fail to join the nasal septum and the premaxillæ on both sides; the result is a wide median cleft which communicates with both nasal cavities. The free inferior border of the vomer extends along the middle of the cleft to be continuous anteriorly with the rounded premaxillary mass; the latter, along with the central portion of the upper lip, is projected forwards between the two labial clefts, often to such an extent that it appears to spring from the tip of the nose (Fig. 1081). In operating such a double harelip the first step is to get rid of the premaxillary projection. This is done, not by removing it altogether, but by removing a triangular portion of the septum of the nose behind it, so as to allow of its being bent back into line with the alveolar processes of the maxillæ. The base of the triangular piece of bone should not be taken from the constricted portion of neck of the premaxillary projection, but should consist of the oliveshaped thickening situated immediately behind the neck. This thickening is crossed by the transverse suture uniting the premaxilla with the anterior extremity of the

Nasal cavity

Buccal cavity

Ala nasi Anterior extremity of inferior concha Central portion of upper lip

Crystalline lens
of the eyeball

Premaxilla

Left nasal cavity
Lateral edge of left
labial cleft
Right nasal cavity-
Nasal septum
Palatine process
of right maxilla

Tongue-
Lower lip-1

FIG. 1080.-FRONTAL SECTION THROUGH THE FACE OF A HUMAN EMBRYO
AT THE SEVENTH WEEK.

FIG. 1081.-FROM A PHOTOGRAPH SHOWING DOUBLE COMPLETE HARE-LIP
AND CLEFT PALATE.

082).

If the premaxillary projection be removed altogether, there is nothing t the upper lip, and the result is an ugly deformity, due to the comparative d redundancy

p.

milk

- The o appear from o the eighth rst to emerge ower central he first dentipleted about ieth month. entition is gento rickets. Of ment set the first

Palatine process of maxilla

Horizontal plate of palate bone

are the first which appear at of the sixth or year; the third

the last to appear, FIG. 1082.-SHOWS ARRANGEMENT OF BONES IN DOUBLE CLEFT PALATE upt any time be(Handbook of Practical Surgery, Bergmann, Bruns, and Mikulicz).

the eighteenth and wenty-fifth year, or even later. As the permanent teeth push their way As the surface, absorption of the roots of the first set takes place, and the first ther fall out of their own accord or are easily removed. Loss of the permanent is followed by absorption of the alveolar margin of the jaw. The tooth ets are lined by a thin periosteum, which is anatomically continuous with pulp tissue of the teeth on the one hand and the dense fibrous tissue of the p layer of the gum on the other.

The upper incisors and canines and the lower premolars have cylindrical roots, nce in extracting those teeth they should be first loosened by a slight rotatory Ovement; the roots of the lower incisors and canines and of the upper premolars e flattened, so that they must be loosened by a lateral movement. The roots of he third molars are convergent, generally welded together and curved backwards, especially in the mandible. The first and second upper molars have three roots which are often divergent.

Tongue. For practical purposes, as well as on developmental and structural grounds, it is convenient to divide the tongue into an anterior two-thirds-the oral part, and a posterior third-the pharyngeal part (Fig. 1085). At the junction of the two portions, immediately behind the median vallate papilla, is the foramen cæcum, which represents the remains of the upper or pharyngeal extremity of the thyreo-glossal duct. Congenital cysts and fistula which develop from persistent remains of this tract are always median; those arising from the upper or lingual portion of the tract are situated above the hyoid bone, whereas those developed from the lower or thyreoid portion are situated below the hyoid bone. The liability of these cysts and fistula to recur after operation is due to the fact that part of the epithelial tract lies in the substance of the hyoid bone.

The mucous membrane covering the pharyngeal part is much more sensitive than that covering the oral, hence in using a tongue depressor the instrument should, except under special circumstances, rest only upon the latter region, otherwise a reflex arching of the tongue will be set up, which prevents the operator from obtaining a satisfactory view of the throat. Scattered over the pharyngeal part are clusters of lymph follicles (lingual tonsils), which appear on the surface as a number of nodular umbilicated elevations provided with little crypts into which mucous glands open (Fig. 1085). The lingual tonsils are liable to chronic inflammation and hypertrophy, conditions which are often accompanied by a varicose condition of the veins which lie immediately beneath the mucous membrane containing the palatoglossus muscle. To obtain a satisfactory view

of the lingual tonsils in the living subject the laryngoscopic mirror must be account of th

employed.

the tongue, sce