Bones are classified according to their shape. The four bone classifications and examples of each are as follows:
· Long bones-femur and humerus
· Flat bones-skull, sternum, and scapula
DIVISIONS OF SKELETON
Figure 1-13.-Human skeleton.
Figure 1-14.-Anatomy of a long bone.
The maxillary bones form the upper jaw, the anterior roof of the mouth, the floors of the orbits, and the sides and floor of the nasal cavity. The small holes on each side of the nasal opening are called the infraorbital foramina (sing. foramen). The maxillary bones contain large cavities called maxillary sinuses.
The palatine bones are L-shaped bones located behind the maxillary bones. They form the posterior section of the hard palate and the floor of the nasal cavity.
The zygomatic bones are responsible for the prominence of the cheeks. The zygomatic bones serve as part of the posterior section of the hard palate and the floor of the nasal cavity.
The lacrimal bones provide a pathway for a tube that carries tears from the eye to the nasal cavity. The lacrimal bone is a thin, scalelike structure located in the medial wall of each orbit.
The nasal bones have cartilaginous tissues attached to them. These tissues contribute significantly to the shape of the nose. The nasal bones are long, thin, and nearly rectangular in shape. They lie side by side and are fused together to form the bridge of the nose.
The vomer bone is connected to the ethmoid bone, and together they form the nasal septum (the wall separating the two nasal cavities).
The middle and inferior nasal conchae are fragile, scroll-shaped bones that are attached to the lateral wall of the nasal cavity. The inferior nasal concha provides support for mucous membranes within the nasal cavity.
The lower jawbone is called the mandible. The mandible is horseshoe-shaped with flat, bony projections on each end. The two small holes on the jawbone are called the mental foramina. The mandible's main function is mastication (chewing food).