Cavities and fossae of the skull and cranial communications
Cavities of the skull are present inside and outside of the cranium. There are three intracranial fossae and six extracranial fossae and cavities.
Axial Skeleton
Cranial walls
The external surface of the skull presents the anterior and posterior wall, the paired lateral wall, the calvaria and the external cranial base. Inside the skull there is the internal cranial base.
Paranasal sinuses
The air spaces located inside the bone are called the paranasal sinuses (sinuses paranasales). They are lined with the respiratory epitheliums which usually consist of pseudostratified columnar ciliated epithelium. The direction of flow created by the ciliary beat is toward the ostium. During inspiration negative pressure is created which helps to facilitate drainage of the: Maxillary sinus (sinus maxillaris) …
Temporomandibular joint
The temporomandibular joint (articulatio temporomandibularis) or TMJ is an articulation between the mandible and the temporal bone. The TMJ is a paired, modified, combined, bicondylar joint which is capable of a range of motions under the control and restraint of a number of muscles and ligaments. It is formed by the: Articular surfaces of the mandibular fossa (the anterior part of mandibular fossa) which …
Zygomatic bone
The zygomatic bone (os zygomaticum) is considered the strongest paired bone of the skull. The zygomatic bone is important in the articulation of the face. It connects the: Frontal bone Temporal bones Maxilla, by the following articulating processes: Frontal process (processus frontalis), which articulates with the zygomatic process of the frontal bone and with t he greater wing of the sphenoid bone. Temporal process (processus …
Vomer
The vomer is a single bone located vertically at the back of nasal cavity forming part of the nasal septum. Its superior border is split into two ala or wings of vomer (alae vomeris), which fit over the rostrum of the sphenoid bone. The vomer articulates with the: Perpendicular plate of the ethmoid bone. Cartilaginous nasal septum. Nasal crests of the maxilla. …
Lacrimal bone
The lacrimal bone (os lacrimale)is a paired bone with a thin plate found in the medial wall of the orbit im- mediately behind the frontal process of the maxilla. It’s lateral surface carries the: Posterior crest of the lacrimal bone (crista lacrimalis posterior). Lacrimal groove (sulcus lacrimalis), which meets the sulcus of the frontal process of the maxilla to form the …
Nasal bone
The nasal bone (os nasale)joins the frontal spine and perpendicular plate of the ethmoid bone. It appears as the ethmoidal groove (sulcus ethmoidalis) which is created by the external nasal branch of the anterior ethmoidal nerve.
Inferior nasal concha (inferior turbinate bone)
The inferior nasal conchaor inferior turbinate bone (concha nasalis inferior)is a paired bone. Each inferior nasal concha presents two surfaces, two borders, two extremities and three processes (maxillary, lacrimal, and ethmoidal). Its inferior edge is free, while the upper edge articulates with the conchal crests of the maxilla and the palatine bone.
Palatine bone
The palatine bone (os palatinum)is a paired bone. It is a thin bone consisting of two plates (horizontal, and perpendicular) and three processes (pyramidal, orbital, and sphenoidal).