The nasal surface presents a large, irregular opening leading into the maxillary sinus. At the upper border of this aperture are some broken air cells, which, in the articulated skull, are closed in by the ethmoid

Ethmoid bone

The ethmoid bone is a bone in the skull that separates the nasal cavity from the brain. As such, it is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that makes up the orbit of the eye...

 and lacrimal bone

Lacrimal bone

The lacrimal bone, the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders.-Lateral or orbital surface:...

s.

Below the aperture is a smooth concavity which forms part of the inferior meatus

Inferior meatus

The inferior meatus, the largest of the three meatuses of the nose, is the space between the inferior concha and the floor of the nasal cavity....

 of the nasal cavity

Nasal cavity

The nasal cavity is a large air filled space above and behind the nose in the middle of the face.- Function :The nasal cavity conditions the air to be received by the other areas of the respiratory tract...

, and behind it is a rough surface for articulation with the perpendicular part of the palatine bone

Perpendicular plate of palatine bone

The vertical part of the palatine bone is thin, of an oblong form, and presents two surfaces and four borders.- Surfaces :...

; this surface is traversed by a groove, commencing near the middle of the posterior border and running obliquely downward and forward; the groove is converted into a canal, the pterygopalatine canal

Pterygopalatine canal

Pterygopalatine canal can refer to:* Greater palatine canal* Palatovaginal canal...

, by the palatine bone

Palatine bone

The palatine bone is a bone in many species of the animal kingdom, commonly termed the palatum .-Human anatomy:...

.

In front of the opening of the sinus is a deep groove, the lacrimal groove

Lacrimal groove

On the nasal surface of the body of the maxilla, in front of the opening of the sinus is a deep groove, the lacrimal groove , which is converted into the nasolacrimal canal, by the lacrimal bone and inferior nasal concha; this canal opens into the inferior meatus of the nose and transmits the...

, which is converted into the nasolacrimal canal

Nasolacrimal canal

The canal containing the nasolacrimal duct is called the nasolacrimal canal.It is formed by indentations in the inferior nasal conchae, maxilla and lacrimal bone...

, by the lacrimal bone and inferior nasal concha; this canal opens into the inferior meatus of the nose and transmits the nasolacrimal duct

Nasolacrimal duct

The nasolacrimal duct carries tears from the lacrimal sac into the nasal cavity. Excess tears flow through nasolacrimal duct which drains into the inferior nasal meatus...

. More anteriorly is an oblique ridge, the conchal crest, for articulation with the inferior nasal concha.

The shallow concavity above this ridge forms part of the atrium of the middle meatus of the nose, and that below it, part of the inferior meatus.