Final answer:
The ethmoid bone forms the floor of the anterior cranial fossa and the roof of the nasal cavity, consisting of the crista galli and cribriform plates. It articulates with the frontal bone and has olfactory foramina for nerve branches. The nasal bone also articulates with the frontal bone and supports the structure of the nose.
Step-by-step explanation:
The bone being described is the ethmoid bone, which is a key structure in both the cranial cavity and the nasal cavity. In the anterior cranial fossa, it forms the floor at the midline, and it also provides the narrow roof of the nasal cavity beneath it. The ethmoid bone is comprised of the crista galli and cribriform plates. The crista galli serves as an anterior attachment point for the brain's covering layers, while the cribriform plate, flanking the crista galli, contains olfactory foramina. These allow nerve branches from the olfactory areas to enter the brain.
The ethmoid bone also articulates with the frontal bone at the top of the nasal cavity. Additionally, the nasal bone lays under the root and bridge of the nose and articulates with both the frontal bone and maxillary bones, while the septal and alar cartilage form other structural components of the nose.