817 



SKELETON. 



SKELETON. 



819 



appended ; they may be regarded as mere prolongations of the ribs, 

 the purpose of their being cartilaginous instead of bony being that 

 of giving more elasticity to the walls of the chest. Each of them, 

 except the first, is articulated with a slight capacity of motion to a 

 depression on the border of the sternum-. 



The Sternum, or Breast-Bone, is single only in the adult ; in youth 

 it is composed of at least two pieces (of which the upper, jig. 8, A, is 

 named Manubrium), and in the foetus of many more. Considered as 

 one bone, its form is elongated, broader and thicker aboye than below, 

 where it terminates in a long narrow process, which is generally carti- 



lagiuous, and is named the Ensiform or Xiphoid Cartilage (B). Tin 

 anterior surface of the sternum is marked by four transverse lines 

 (3, 4, 5, 6), which indicate the divisions between the five principal 

 parta of which it is composed. These marks are repeated on the 

 posterior surface. Along its borders, there are (proceeding from above 

 downwards), first, at each of the angles between its upper and lateral 

 edges, a shallow depression (1), into which the extremity of the 

 clavicle is received ; then immediately below this an oval depressed 

 surface (2), to which the cartilage of the first rib is fixed ; and lastly, 



along encli aid* six other nimil ir Huii.ices MpAnttd by notches, with 

 which the cartilages of the six following ribs articulate. Of these six, 

 KAI. HIST. DIV. VOL. IV. 



the upper four are placed at the ends of the transverse lines ; so that 

 each of these ribs articulates at its sternal end with two pieces of the 

 sternum, just as, at its other extremity, it articulates with two 

 vertebrae. [RESPIRATION ; LUNGS.] 



The Bones of the Skull are divided into two chief sets those of 

 the Cranium, or case for the brain, and those of the Face. They are 

 represented in the annexed sketches separated, yet in their natural 

 relative positions, in three different aspects : in fig. 9, as seen from 

 the front; in fig. 10, as seen in profile ; in fig. 11, as seen when, after 

 removing the top of the skull, one looks from above upon the bottom 

 of its interior. 



The Bones of the Cranium are the Frontal (a), the two Parietal 

 (i), the two Temporal (c), the Occipital (d), the Sphenoid (e), and the 

 Ethmoid (/) ; those of the face are the two Nasal (g), the two 

 Superior Maxillary, or Upper Jaw-bones (A), the two Palate, the two 

 Malar (), the two Lachrymal (j), the two Inferior Turbinated, the 

 Vomer (k), and the Inferior Maxillary (I). 



Fig. 10. 



PI-, n 



The Kioutal Cone (fiy. 12, a, I) forms tha Forehead and the roof of 

 the Orbit. The front or frontal portion is the larger. Its anterior 

 mrface, which is represented in fig. a, is convex and smooth; it is 

 bounded below by two arched, thick, and rounded borders, separated 

 by rough notch in the middlo line. The borders (1,1) are called 



3d 



