Nasal and Lacrimal Bones
These two paired bones participate in the formation of vital anatomical spaces of the facial skull.
Nasal bone (Os nasale) is a thin plate. It has no distinct anatomical parts. Located in the area of the nasal bridge, it articulates extensively with neighboring structures:
- Superiorly — with the frontal bone (os frontale).
- Laterally — with the maxilla (maxilla).
- In the midline — with the contralateral nasal bone.
- Posteriorly — with the ethmoid bone (os ethmoidale).
Lacrimal bone (Os lacrimale) is the smallest bone contributing to the orbital walls. Like the nasal bone, it has no separate anatomical parts, but its orbital surface features important landmarks. Here lies the posterior lacrimal crest (Crista lacrimalis posterior), anterior to which runs the lacrimal groove (Sulcus lacrimalis). This groove unites with the lacrimal groove of the frontal process of the maxilla (sulcus lacrimalis maxillae) and the inferior nasal concha to form the nasolacrimal canal (Canalis nasolacrimalis).
Zygomatic Bone (Os zygomaticum)
This is a paired bone with no distinct parts described, but it features three surfaces and two processes. It plays a key role in forming the lateral facial contour and the orbital walls.
Surfaces of the zygomatic bone:
- Lateral surface (Facies lateralis) — faces outward.
- Temporal surface (Facies temporalis) — faces toward the temporal fossa.
- Orbital surface (Facies orbitalis) — contributes to the orbit. It may feature the orbital tubercle (Tuberculum orbitale), and near the posterior margin of the frontal process — the marginal tubercle (Tuberculum marginale).
Processes of the zygomatic bone:
- Temporal process (Processus temporalis) — articulates with the zygomatic process of the temporal bone (processus zygomaticus ossis temporalis), completing the zygomatic arch.
- Frontal process (Processus frontalis) — participates in forming the lateral orbital wall.
On the orbital surface is the zygomaticoorbital foramen (Foramen zygomaticoorbitale). From here, a canal begins within the bone and subsequently bifurcates, resulting in two exit foramina: the zygomaticofacial foramen (Foramen zygomaticofaciale) on the lateral surface and the zygomaticotemporal foramen (Foramen zygomaticotemporale) on the temporal surface.
Bones of the Nasal Cavity: Inferior Nasal Concha and Vomer
Two independent minor bones participate in forming the nasal cavity: one is paired, and the other is unpaired.
Inferior nasal concha (Concha nasalis inferior) is a paired and completely independent bone of the nasal cavity. Its primary functional role is forming the lateral wall of the nasal cavity. Additionally, it closes off the nasolacrimal canal with its own lacrimal process.
Vomer (Vomer) is an unpaired, vertically oriented bony plate. In basic anatomical study, no minor subdivisions are distinguished. The main function of the vomer is forming the posteroinferior part of the nasal septum.