In the inferior view of skull (with the mandible removed), the following components are prominent:
- Hard palate
- Parts of sphenoid bone
- Parts of temporal bone
- Occipital condyles
- Various foramina
Hard palate is formed by the palatine process of the maxillae and the horizontal plates of the palatine bone. Anteriorly, in the midline, is the incisive fossa and foramen. Posterolaterally are the greater and lesser palatine foramina.
Choanae are the posterior nasal apertures. They are present above the posterior edge of the hard palate and are separated from each other by the posterior margin of the vomer. They are bounded laterally by the medial pterygoid plates of the sphenoid bone.
The inferior end of the medial pterygoid plate is prolonged as a curved spike, called the pterygoid hamulus.
Parts of sphenoid bone:
Medial pterygoid plates:
The medial pterygoid plates of the sphenoid bone form the lateral boundaries of the Choanae.
Lateral pterygoid plates:
The lateral pterygoid plates of the sphenoid form part of medial wall of infratermporal fossa, and part of pterygoid fossa.
Greater wings of sphenoid:
These are two strong processes, arising from the side of the body of the sphenoid bone. Each is pierced by the large foramen ovale and the small foramen spinosum.
Spine of sphenoid:
At the apex of the greater wing, there is sharp downwardly directed process, called the spine of sphenoid bone.
Parts of temporal bone:
It is the depression in the temporal bone that forms the upper articular surface for the temporomandibular joint. Posteriorly, the mandibular fossa is separated from the tympanic plate by a fissure called the squamotympanic fissure. Through the medial end of this fissure, the chorda tympani nerve exits from the tympanic cavity.
The styloid process of the temporal bone projects downward and forward from its inferior aspect.
Petrous part of temporal bone:
It contains the auditory apparatus. It also helps in formation of the foramen lacerum.
It is formed in part by the temporal bone. It forms the bony part of the external auditory meatus.
Occipital condyles are the undersurface facets of the occipital bone that function in articulation with the superior facets of the atlas vertebra. Superior to the occipital condyle of each side is the hypoglossal canal for transmission of the hypoglossal nerve.
It is a funnel shaped opening immediately behind the incisor teeth. The nasopalatine nerves and the spenopalatine artery pass through it.
It is one of the larger foramina of the skull situated in the posterior part of the sphenoid bone. It transmits many nerves and vessels.
It is situated lateral to the foramen ovale. The middle meningeal artery and vein pass through it.
It is a triangular foramen located at the base of the medial pterygoid plate. It transmits many nerves and vessels.
It is situated between the styloid and mastoid processes of the temporal bone. It is in fact the termination of the facial canal and thus transmits the facial nerve and stylomastoid artery.
It is situated in front of the petrous part of temporal bone. It transmits many important structures including the vagus, glossopharangeal and accessory nerves as well as the sigmoid sinus.