11.4
頭蓋骨：側面図
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Q1: What bones are visible in the lateral view of the skull?
The lateral view of the skull displays the temporal, sphenoid, and ethmoid bones along with other partially visible cranial bones. The temporal bone forms the lower lateral side, the sphenoid serves as a keystone bone joining with almost every other skull bone, and the ethmoid lies between the sphenoid and nasal bones. Together, these bones create the lateral skull structure visible from the side.
Q2: What is the zygomatic arch and which bones form it?
The zygomatic arch is a bony ridge formed by the zygomatic process of the temporal bone and the zygomatic bone. The temporal bone's zygomatic process projects anteriorly from the squamous portion, while the zygomatic bone extends posteriorly. Together, these structures create the prominent arch that forms the cheekbone.
Q3: Where is the mastoid process located and what is its function?
The mastoid process is a large prominence projecting inferiorly from the mastoid portion of the temporal bone, located just behind the earlobe on the side of the head. It serves as a muscle attachment site for neck muscles. The mastoid process can be easily felt on the surface of the skull due to its prominent position.
Q4: What structures does the petrous portion of the temporal bone contain?
The petrous portion of each temporal bone forms a diagonally oriented petrous ridge in the floor of the cranial cavity. Inside each petrous ridge are small cavities that house the structures of the middle and inner ears, including the auditory ossicles and vestibular apparatus. This region protects these delicate hearing and balance structures.
Q5: What is the sella turcica and what does it house?
The sella turcica, meaning Turkish saddle, is a saddle-shaped structure located at the midline of the middle cranial fossa on the superior surface of the sphenoid bone. Its rounded depression, called the hypophyseal fossa, houses the pea-sized pituitary gland. This protective bony structure is crucial for protecting the pituitary gland.
Q6: How do the pterygoid plates contribute to skull anatomy?
The pterygoid plates are thin, vertically oriented bony plates extending from the inferior aspect of the sphenoid bone. The medial pterygoid plates form the posterior lateral walls of the nasal cavity, while the larger lateral pterygoid plates serve as attachment sites for chewing muscles. These plates are essential for mastication and nasal structure.
Q7: What role does the ethmoid bone play in the cranial cavity?
The ethmoid bone is a single midline bone that forms the roof and lateral walls of the upper nasal cavity and contributes to the upper nasal septum. On the interior of the skull, it forms a portion of the floor of the anterior cranial cavity. The cribriform plate contains perforations for olfactory nerve filaments, while the crista galli secures the brain.