The extremities or tingles are formed by the union of the two borders ; the posterior extre mity is more pointed than the anterior.
Connexions.— Eaeh inferior turbinated is united with four other bone, viz. the upper maxillary, the lachrymal, the ethntoid, and the palate. It is covered with the pituitary mem brane; it contributes to enlarge the surface of the nasal cavity, and to form a part of the nasal canal and middle and lower meatus.
Its structure is compact.
Its development commences at the fifth month by a single point of ossification.
The vomer (Germ. dos Pflugscharbein ) is of a quadrilateral figure, and resembles a ploughshare ; it is a single and symmetrical bone, situated in the median plane, and forming the posterior and inferior part of the septum nasi. It has two lateral surfaces and four borders. The surfaces, which are right and left, are smooth, flat, and lined by the pitui tary membrane ; sometimes, when the bone inclines much to either side of the nose, one of these surfaces is convex and the other concave ; they present an oblique groove or grooves for the naso-palatine nerves and vessels.
The superior border (or surface) is broad, and may be termed the base of the bone ; it presents a deep groove in the middle, which receives the rostrum of the sphenoid, and on each side of this are two plates or laminae (sometimes called the ahe) which are received into fissures of the sphenoid on each side of the rostrum, and which contribute to form a longitudinal canal for the ethmoidal vessels.
The anterior border is oblique from above downwards and forwards; above it presents a deep groove, which is a continuation of that on the upper border, and which receives the perpendicular plate of the ethmoid : below, this border is nearly flat, where it is united to the middle cartilage of the nose.
The inferior border is the longest, and is received into the grooved crest formed by the united palatine plates of the superior maxillary and palate bones; in front this border extends as far as the anterior nasal spine.
The posterior border, thick above, thin be low, is oblique, slightly curved, and forms the partition between the two posterior openings of the nose.
Conncrions.—The vomer is connected with four bones, viz, the sphenoid and ethmoid above, the superior maxillary and palate below: it is covered with the pituitary membrane, and forms, with the perpendicular plate of the ethmoid and the middle cartilage, the septum of the nose.
Its structure is compact, and it is formed of two thin lateralplates, which are distinct above, but united ioferiorly.
Its development occurs by a single ossific point about the third month, and at birth it is completely ossified.
The os maxillare iVerius (Germ. das 'acre oder der Unterkiefer). This single bone, which alone forms the lower jaw, occupies the lower and lateral parts of the face ; it is a flat, symmetrical bone, and bears some resemblance in shape to a horse-shoe. It con sists of a middle or horizontal portion (the body), and of two lateral ascending branches (the ram), which are connected with the body nearly at right angles.
The body is curved, nearly horizontal, in clining from before backwards, and a little upwards, and presents two surf/aces and two borders.
The anterior surface is convex, and has in the centre a vertical line (erista menials ex tuna), which marks the union of the two halves of which the bone consists in the young subject : this line terminates below in a tri angular eminence (the mental process). The vertical dircetion of the lower jaw at the sym physis, and its curved figure anteriorly, form ing what is termed the chin, are both charac teristic of the human race. From the angles of the mental process arises on each side the external oblique line, faintly marked in front, but becoming distinct as it ascends diagonally along this surface of the bone to terminate at the anterior border of the ramus of the jaw; it gives attachment to muscles and separates the external surface of the bone into two parts, viz. an anterior superior, which presents, ex ternal to the symphysis, 1. a depression (the Assa mentalis) for the attachment of a muscle; 2. to the outer side of this the mental foramen, which is directed obliquely upwards and out wards; it is the lower orifice of the inferior dental canal, which conveys nerves and vessels to the teeth of the lower jaw; 3. a number of ridges and grooves near the alveolar border of the jaw, which correspond to the sockets of the teeth and to the septa which divide them : this part of the hone is covered by the gums. The surface below and behind the oblique line is smooth, or only faintly marked with irre gular lines for the attachment of the platysma myoides.