ANATOMY IN A NUTSHELL. 



The internal border articulates with its fellow, and with the nasal spine of 

 the frontal bone above and the perpendicular plate of the ethmoid below. 



Ossification. — It ossifies from one center. 



Articulation. — It articulates with four bones. The frontal and ethmoid 

 of the cranium, and its fellow and the superior maxillary of the fare. 



An \< iiMi.vr of Muscles. — A few fibers of the Occipito-frontalis of the 

 cranial region may he attached to this hone 



Blood Supply. Nasal branch of the ophthalmic artery, frontal, the 

 angular and the anterior tehmoidal arteries. 



For ORIGIN and ensertion of the Occipito-frontalis muscle see page 

 Lachrymal Bonk. (Plate CCLI.) 



The lachrymal bone lies on the anterior part of the inner wall of the orbit. 

 It resembles a finger nail, and has the following points for consideration: 



The external surface has upon it a vertical ridge called the lachrymal 

 cresl which passes in its mid-line and ends below in the hamular process. This 

 process is sometimes separated from the bone and then is called the lesser 

 lachrymal bone. It helps to form the lachrymal groove above by articula- 

 ble with the lachrymal tubercle of tin' superior maxillary bone. The portion 

 of this surface behind the lachrymal crest helps to form the inner wall of the 

 orbit, while the part in front of the lachrymal crest forms part of the lachrymal 

 groove. 



The internal surface, or nasal surface, forms part of the middle meatus by 

 its anterior portion, while its posterior portion by its articulation with the 

 ethmoid bone completes the anterior ethmoidal canals. This surface has a 

 furrow upon it corresponding to the position of the crest of the external surface. 



The anterior border articulates with tin 1 nasal process of the superior 

 maxillary bone and is the longest. 



The posterior border articulates with the os planum of the ethmoid. 



The superior border, which is the shortest and thickest, articulates with 

 the internal angular process of the frontal bone. 



The inferior border articulates with the lachrymal process of the inferior 

 turbinated bone, and posteriorly with the orbital plate of the superior maxil- 

 lary bone These two portions of this border are separated by thecrest. 



Ossification. — It ossifies from one center. 



Articulation. It articulates with four bones. The frontal and ethmoid 

 of the cranium, and the superior maxillary and inferior turbinated of the face. 



Attachment of Muscles. — It has one muscle attached to it. namely, the 

 Tensor tarsi i f the palpebral region. 



Blood Supplj . Inferior orbital, nasal branch of ophthalmic, and anterior 

 ethmoii lal artei ies. 



Tensor tarsi. Descr iption.— This muscle is the deep part of the Orbi- 

 cularis palpebral urn. 



Origin. — It arises from the crest of the lachrymal bone and passes across 

 the lachrymal sac and divides into two portions. 



Insertion. Into the upper and lower tarsal cartilages. 



