AND PHYSIOLOGY. 



47 



Fig, 52. 



ragged edges called Sutures. These are small and rough 

 projections of bone which are largest at their extremities. 

 They are made to fit into the edges of the opposite bone with 

 great firmness, thus joining the bones together, by essentially 

 the same process which in cabinet work is known as dovetail- 

 ing. The name Suture is applied, since when these edges 

 are perfectly joined by this articulation, they resemble the 

 seam made by sewing together two pieces of cloth by the 

 4 'over and over" stitch. Situated directly within these sut- 

 ures are frequently found 

 small bones, uncertain as to 

 number, sometimes two inches 

 in diameter, called Ossa Tri- 

 quetra. No special use for 

 them has been discovered as 

 yet. 



109. The Lower Surface 

 of the Skull.— The whole of 

 the lower surface of the skull 

 is extremely uneven for the 

 attachment of a great number 

 of muscles, and the protection 

 of delicate nerves and blood- 

 vessels which pass to and 

 from the brain and face. 



110. Bones in the Face, — 

 The Face is that portion of 

 the head situated below a line 

 drawn from the orbit of the 

 eye to the passage of the in- 

 ternal ear. Its framework con- 

 tains fourteen bones. 2 Nasal ; 



A Front View of che Skull, showing the 

 Bones composing the Face. 1, Os Frontis. 

 2, Nasal Tuberosity. 3, Supra-Orbital Ridge. 

 4, Optic Foramen. 5, Sphenoidal Fissure. 

 6, Spheno-Maxillary Fissure. 7, Lachrymal 

 Fossa, and commencement of the Nasal Duct. 

 8, Opening of the Anterior Nares, and the 

 Vomer. 9, Infra-Orbital Foramen. 10, Ma- 

 lar Bone. 11, Symphysis of the Lower Jaw. 

 12, Anterior Mental Foramen. 13, Ramus of 

 the lower Jawbone. 14, Parietal Bone. 15, 

 Coronal Suture. 16, Temporal Bone. 17, 

 Squamous Suture. 18, Great Wing of the 

 Sphenoid. 19, Commencement of the Tem- 

 poral Ridge. 20, Zygomatic Process. 21, Mas- 

 toid Process. 



How do the bones of the skull join with each other ? What process in cabinet making 

 does it correspond to ? What are often found in these sutures? 109. W T hat is the sur- 

 face of the lower part of the skull ? 110. Give the boundaries of the face. 



3 



