The maxillary bones form the upper jaw, theanterior roof of the mouth, the floors of the orbits, andthe sides and floor of the nasal cavity. The small holeson each side of the nasal opening are called theinfraorbital foramina (sing. foramen). The maxillarybones contain large cavities called maxillary sinuses.The palatine bones are L-shaped bones locatedbehind the maxillary bones. They form the posteriorsection of the hard palate and the floor of the nasalcavity.The zygomatic bones are responsible for theprominence of the cheeks. The zygomatic bones serveas part of the posterior section of the hard palate and thefloor of the nasal cavity.The lacrimal bones provide a pathway for a tubethat carries tears from the eye to the nasal cavity. Thelacrimal bone is a thin, scalelike structure located inthe medial wall of each orbit.The nasal bones have cartilaginous tissuesa t t a c h e d t o t h e m . T h e s e t i s s u e s c o n t r i b u t esignificantly to the shape of the nose. The nasal bonesare long, thin, and nearly rectangular in shape. They lieside by side and are fused together to form the bridge ofthe nose.The vomer bone is connected to the ethmoid bone,and together they form the nasal septum (the wallseparating the two nasal cavities).The middle and inferior nasal conchae arefragile, scroll-shaped bones that are attached to thelateral wall of the nasal cavity. The inferior nasalconcha provides support for mucous membraneswithin the nasal cavity.The lower jawbone is called the mandible. Themandible is horseshoe-shaped with flat, bonyprojections on each end. The two small holes on thejawbone are called the mental foramina. Themandible's main function is mastication (chewingfood).VERTEBRAL (SPINAL) COLUMN.—Thevertebral column consists of 24 movable or truevertebrae; the sacrum; and the coccyx, or tail bone (fig.1-17). The vertebrae protect the spinal cord and thenerves that branch out from the spinal cord. Eachvertebra has an anterior portion, called the body, whichis the large solid segment of the bone (fig. 1-18). Thisvertebral body supports not only the spinal cord butother structures of the body as well. At the bottom ofthe spinal column is the sacrum and the coccyx. Manyof the main muscles are attached to the vertebrae.The vertebral foramen is a hole directly behindthe body of the vertebrae that forms the passage for thespinal cord. The vertebral projections are for theattachments of muscles and ligaments and forfacilitating movement of one vertebra over another.The spinal column is divided into five regions in thefollowing order: cervical (neck), thoracic (chest),1-9HM3F0116PARIENTALBONEFRONTALBONELACRIMALBONEETHMOIDBONESQUAMOSALSUTURETEMPORALBONESPHENOIDBONEPERPENDICULAR PLATEOF THE ETHMOID BONEINFRAORBITALFORAMENVOMERBONEMANDIBLEMENTALFORAMENMAXILLAINFERIOR NASALCONCHAZYGOMATICBONEMIDDLE NASALCONCHASPHENOIDBONENASALBONEFigure 1-16.—Facial bones.
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