156 OSTEOLOGY. 
THE VOMER. 
The vomer, a bone of irregular quadrilateral shape, is placed mesially in the 
hinder part of the nasal septum. It has four borders and two surfaces. The 
superior border, which can readily be distinguished by the presence on either side 
of an everted lip or ala, slopes from behind upwards and forwards, and articulates 
with the under surface of the body of the sphenoid, the poimted rostrum of which 
it receives in the groove formed by the projecting ale. Laterally these ale are 
wedged in between the sphenoidal processes of the palate bone in front, and the 
vaginal processes at the root of the im- 
For rostrum Le eth, af aroONS Ter ternal pterygoid plates behind. The 
of sphenoid Oig naso-palatine ! ah to, Saas 6G : ee wae 
y aaa Groove posterior border, which slopes from behind 
ee en downwards and forwards, is free, and 
* forms a sharp, shghtly-curved edge ; this 
constitutes the posterior margin of the 
nasal septum, and serves to separate the 
openings of the posterior nares. The 
inferior border, more or less horizontal 
in direction, articulates with the nasal 
crest formed by the superior maxillary 
and palate bones. The anterior edge is the longest; it slopes obliquely from above 
downwards and forwards. In its upper half it is ankylosed to the perpendicular 
plate of the ethmoid; in its lower half this margin is grooved for the reception of 
the septal cartilage of the nose. The anterior extremity of the bone forms a 
truncated angle, which articulates with the hinder border of the incisor crest of 
the superior maxilla, and sends downwards a pointed process which passes between 
the incisor foramina. The right and left surfaces of the bone are smooth, and 
covered by mucous membrane. It is not uncommon to find them deflected to one 
or other side. A few vascular grooves may be noticed scattered over these 
surfaces, and one, usually more distinct than the others, running obliquely down- 
wards and forwards, indicates the course of the nasopalatine nerve. 
Free 
border a 
Palate Superior maxilla 
Kia. 107. —VOMER AS SEEN FROM THE RIGHT SIDE. 
Connexions.—The vomer articulates with the sphenoid, the ethmoid, the palates, and the 
superior maxille. In front it supports the septal cartilage. 
Architecture.—The bone is composed of two compact layers fused below, but separated above 
by the groove for the lodgment of the rostrum of the sphenoid behind, and the septal cartilage in 
front. ‘The lamelle are also separated from each other by a canal which runs horizontally ‘trom 
behind forwards in the substance of the bone, and which transmits the nutrient vessel of 
the bone. 
Variations.—Owing to imperfect ossification there may be a deficiency in the bone, filled up 
during life by cartilage. The separation of the two lamellz along the anterior border varies 
considerably, and instances are recorded where they were separated by a considerable cavity 
within the substance of the bone. The spheno-vomerine canal is a minute opening behind 
the rostrum of the sphenoid, and between it and the al of the vomer, by which the nutrient 
artery enters the bone. 
Ossification.—The vomer, primitively double, begins to ossify about the end of the 
second month of foetal life. A nucleus appears on either side in the membrane overlying 
the back and lower part of the vomerine cartilage; these form the primitive lamelle 
developed on either side of, and not from, the cartilage. About the third month these 
laminze become fused behind and below, thus forming a deep groove in which the cartilage 
is lodged. As growth goes on the groove becomes reduced by the further fusion of the 
lateral plates, and the absorption of the cartilage, until the age of puberty, by which 
time the lateral laminee have united to form a mesial plate, Thal primitively divided con- 
dition of which is now only represented by the eversion of the ale, and the grooving 
along the anterior border. 
THE PALATE BONES, 
The palate bone (os palatinui), of irregular shape, assists in the formation of 
the outer wall of the back part of the nasal fossee, the posterior portion of the hard 
palate, the orbit, the spheno-maxillary, zygomatic, and the pterygoid fosse. It 
a 
