Just anterior to the EAM is the mandibular fossa, the socket that articulates with the condyle of the mandible. The mastoid portion of the temporal bone contains many small air cells, and the mastoid process is palpable just posterior to the earlobe. Extending medially from the EAM area is a dense pyramid of bone called the petrous portion, which contains the middle and inner ear structures. The EAM is the opening to the ear canal and is an important positioning landmark. On the inferior lateral border is the external auditory meatus, also called the external acoustic meatus. They articulate with the sphenoid bone anteriorly and the occipital bone posteriorly. 17-3) also form portions of both the floor and the lateral outer surface of the cranium. The bilateral inferior projections are called the pterygoid processes. The rounded fossa in the center of its anterior superior surface, called the sella turcica, is the location of the pituitary gland. The sphenoid bone is posterior to the ethmoid bone and is shaped somewhat like a bat (Fig. The sphenoid bone is a complex bone that makes up part of the floor of the cranium and also portions of its lateral outer shell. The ethmoid bone also forms a portion of each orbit. It articulates with the underside of the frontal bone, extending inferiorly and posteriorly behind the nose. The ethmoid bone forms the anterior floor of the cranium. Between the frontal and the occipital bones are the two parietal bones. It is the passage for the spinal cord between the skull and the spine. The large round hole in the anterior portion of the occipital bone is called the foramen magnum. In the approximate center on the outer surface of the occipital bone is a palpable bony prominence called the external occipital protuberance. The occipital bone is at the lower part of the back of the skull and also forms the posterior portion of the cranial floor or base. On either side of the glabella, the frontal bone forms the superior portions of the orbits (eye sockets). The bony prominence on the frontal bone between the eyebrows is a palpable positioning landmark called the glabella. The frontal bone is the bone of the forehead and also constitutes the anterior portion of the top of the skull. C, Lateral aspect of interior of cranium. This bone is known as the sphenoid bone located in front of the basilar part of the occipital bone.FIG. In the middle of the skull, unpaired bone of the neurocranium is present. They are unpaired bones and can be located between the two orbits in the skull. The nasal cavity is separated from the brain through the ethmoid bone. Irregularly shaped, right and left halves of the maxilla fuse together, in the midline, this area is known as an intermaxillary suture (can be located below the nose). Note: The maxilla bone constructs the upper jaw of the skull. The neurovascular structures pass by the mental Foramen, which is located below the second premolar tooth on either side (present laterally to the mental protuberance). During developmental stages, a ridge-like structure develops due to the fusion of two halves of the mandibular known as Mandibular symphysis. The shape of the chin is formed by mental protuberance. Base –In the inferior area of the jaw and digastric muscle is attached to it. Alveolar process– superiorly located, lower teeth are held up by these 16 sockets. The structure of mandible bone is a curved shape depicting a horseshoe. With the help of the temporomandibular joint, it is connected to the temporal bone on either side of the skull. The strongest and largest bone of the face is the mandible. Mandible bone constructs the lower jaw of the skull and acts as a collecting cabin for the lower teeth, mandible can be located beneath the maxilla. Out of Mandible, Maxilla, Ethmoid, and Sphenoid the only movable bone in the skull is Mandible. Hint:It is a single bone forming a temporomandibular joint with the temporal bone and responsible for the chin shape.

Only movable bone in the skull