The rest of the skull is composed of the fourteen facial bones. These are the two nasal, the two lacrimal, the two maxillae, the two zygomatic, the vomer, the two inferior nasal conchae, the two palatine, and the only movable bone of the skull, the mandible. One way to learn these bones is to consider how they form the nose and orbits of the eyes.
The nasal bones make up the bridge of the nose. They are best seen in a frontal view of the skull.
Lateral to the nasal are processes extending upwards from the maxillae (sing. - maxilla). The maxillae form the upper jaw and a portion of the inferior surfaces of the orbits. They have sockets called alveoli for the teeth. The bony projections which form the alveoli are called alveolar processes.
The palatine processes of the maxillae form the anterior hard palate or roof of the mouth. The incisive foramen can be seen on the base of the skull in the suture between the two palatine processes.
Between the maxillae and the temporal bones, forming the lateral walls of the orbits, are the two zygomatic bones. The zygomatic bones also form the remainder of the inferior surfaces of the orbits as well as the prominent ridges of the cheeks. You have already noted the temporal process of the zygomatic which joins with the zygomatic process of the temporal to form the zygomatic arch.
Lateral to the nasal and maxillae bones within the orbits of the eyes can be seen the small lacrimal Qacrima » L. tear) bones.
The remainder of the orbits is composed of a portion of the ethmoid lateral to each lacrimal, the sphenoid on the posterior surface, and the frontal forming the superior surfaces. Note that though there are two orbits there is only one ethmoid, one sphenoid, and one frontal. These three bones form part of each orbit. The two fissures seen in each orbit are the superior orbital fissure and the inferior orbital fissure.
Figure 9.5 Skull, Frontal View
Alveolar process of maxilla Alveolar process of mandible Coronal suture Frontal Inferior nasal concha Inferior orbital fissure Lacrimal Mandible Maxilla Mental foramen Nasal Parietal Perpendicular plate of ethmoid Sphenoid Superior orbital fissure Supraorbital foramen Temporal Vomer Zygomatic
The nasal cavity contains the vomer and the two inferior nasal conchae. The vomer lies on the midline of the nasal cavity and forms the inferior portion of the nasal septum. The inferior nasal conchae are situated to form part of the lateral walls of the nasal cavity.
Typically, these three fragile bones are broken in the laboratory skulls, though you should be able to find at least a portion of each of them.
The two palatine bones can be seen on the inferior surface of the skull. They form the posterior portion of the hard palate. The anterior hard palate is formed by the palatine processes of the maxillae.
The final facial bone is the mandible. This is the only movable bone of the skull and the only skull bone which is not joined by a suture. The mandible forms a joint with the temporal bones at the mandibular fossae. The processes of the mandible which join the temporals are the mandibular condyles. The vertical parts of the mandible are the rami (sing. - ramus). The horizontal portion is the body. The rami and the body are joined at the angles of the mandible. The body has alveolar processes to hold the inferior teeth. On either side of the chin can be seen the mental foramina (rnentum = L. chin). The notch at the top of each ramus is a mandibular notch. On the medial surface of each ramus is a mandibular foramen where the nerve enters to innervate the teeth.
Alveolus Angle of mandible Body Mandibular condyle Mandibular foramen Mandibular notch Mental foramen Ramus
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