The head consists of the cranium and the face. The former of these partscon slats of 1 or 2 ossa frontis ; 2 ossa parieta lia ; 1 as splienobasilare ; 2 ossa tempo rum ; 2 mallei ; 2 ineudes; 2 orhicubtria; 2 stapedes ; and 1 as athmoideum: on the whole, of 15 or 16 bones.
The face has 2 ossa maxillaria superi ora ; 2 ossa palati ; 2 ossa maim ; 2 ossa nasi ; 2 ossa lacrymalia or uncuis ; 2 ossa turbinate inferiore ; 1 os vomer ; 1 max illa inferior ; 32 teeth ; on the whole, 46 bones.
The os hyoides consists of a body, 2 la teral portions called cornea, and 2 sural processes called appendices.
The bones of the head are therefore 61 or 62; with the os hyoides 66 or 67.
In the neck there are 7 cervical verte brx; in the chest 12 dorsal vertebra ; 24 ribs ; 2 or 3 bones of the sternum; in the loins 5 lumbar vertebra; in the pelvis 1 sacrum, 4 ossa coccygis, '2 ossa innomi nata.
Therefore the whole trunk has 57 or 58 bones.
The shoulders have two clavicles, and 2 scapula; the arms 2 humeri ; the fore arms 2 ulna and 2 radii ; the wrists 2 os sa seaphoidea ; 2 ossa 'merle; 2 ossa euneiformia; 2 ossa pisiformia; 2 ossa tra pezia; 2 ossa trapezioidea ; 2 ossa magna; 2 ossa unciformia; the metacarpi lOmete carpal bones ; the fingers 10 posterior phalanges, 8 middle phalanges, 10 ante rior phalanges, and 8 sesamoid bones.
The hones of the upper extremities are in the whole 72.
The thighs have 2 femora ; the legs 2 tibix,'2 patella, and 2 fibulz ; the tarsi 2 astragftli, 2 ossa calcis, 2 asset navicularia, 6 cuneiform bones, 2 ossa cuboidea ; the metatarsi 10 metatarsal bones ; the toes 10 posterior phalanges, 8 middle phalan ges,10 anterior phalanges, and 6 sesamoid bones.
The bones of the lower extremities are 66.
The whole skeleton contains 259 or 261 bones.
Of the bones just enumerated, the os frontis, spheno-oecipitale, ethmoideum, vomer, inferior maxilla, the vertebra, sa crum, and os coccygis, the bones of the sternum, and the os linguale medium, or body of the os hyoides, are single bones; and being placed in the middle of the bo dy, are consequently symmetrical. Of all the other bones, there is a pair, consisting of a bone for the right, and another for the left side.
The structure of the whole skeleton is therefore symmetrical ; since an imagina ry perpenaicular line drawn through the whole would divide even the single bones into a right and a left half. exactly resem
bling each other. This observation must however be taken with some allowance ; since the corresponding bones of one side are not always perfectly similar to those of the opposite ; nor do the two halves of the single bones always exactly agree in form, &c.
The entire natural skeleton of a man of middle stature, in a dried state, weighs from 150 to 200 ounces ; that of a woman from 100 to 160 ounces.
Bones of the head.—The cranium is the oval bony cavity containing the brain ; the face is placed at the anterior and low er part of this cavity, and holds some of the organs of sense, and the instruments of mastication.
The bones of the head are joined by sutures, a mode of union nearly peculiar to themselves ; hence, when all the soft parts are destroyed by maceration, they still remain most firmly connected to each other, excepting the front teeth and the lower jaw. The sutures are formed by numerous sharp and ramified processes of the opposed edges of the different bones, shooting into corresponding vacui ties of each other. In some instances, however, the bones seem to be joined by the opposition of plane surfaces, and here the union appears externally like a mere line, instead of the irregular zigzag course which it takes in the former case The last mentioned junction is called har in On ia.
In the foetal state, the bones of the cra nium do not touch each other, but are separated by considerable intervals of membrane, and have thin extenuated margins, which allow them to ride over each other when subjected to pressure. The larger and more conspicuous of these intervals are called fontanelles, and allow of the pulsation of the brain being felt in a young subject. The importance of title structure, in allowing the head to accotn.
modate itself to the varying figure of the parts through which it passes, in the act of parturition, and to sustain the violent pressure which it experiencesin the same act, is sufficiently obvious. In the pro gress of ossification the edges of the bones meet each other, and become mu ted by the sutures. The use of these in the adult cranium cannot be satisfactorily assigned, nor do we see any difference that would arise, if the head had been composed of one piece only, without any suture. In old persons the sutures often become more or less generally obliterated.