A single bone running along the whole length of the floor of the nasal cavities, where it occupies a central position. Its anterior border is deeply grooved, and gives lodgment to a flat piece of cartilage (septum nasi) by which the nasal passages are divided one from the other.

Fig. 290. - Lower Jaw.

1 Coronoid Process. - Condyle. 3 Molar Teeth. 4 Mental Foramen. 5 Incisor Teeth. 6 Surface for attachment of Masseter Muscle.