Surfaces The
medial surface is
convex, perforated by numerous apertures, and traversed by longitudinal grooves for the lodgement of vessels. The
lateral surface is
concave, and forms part of the
inferior meatus.
Borders Its
upper border is thin, irregular, and connected to various bones along the lateral wall of the nasal cavity. It may be divided into three portions: of these, • the
anterior articulates with the conchal crest of the
maxilla; • the
posterior with the conchal crest of the
palatine; • the
middle portion presents three well-marked
processes, which vary much in their size and form. • Of these, the anterior or
lacrimal process is small and pointed and is situated at the junction of the anterior fourth with the posterior three-fourths of the bone: it articulates, by its apex, with the descending process of the
lacrimal bone, and, by its margins, with the groove on the back of the frontal process of the maxilla, and thus assists in forming the canal for the
nasolacrimal duct. • Behind this process a broad, thin plate, the
ethmoidal process, ascends to join the uncinate process of the ethmoid; from its lower border a thin lamina, the
maxillary process, curves downward and lateralward; it articulates with the maxilla and forms a part of the medial wall of the
maxillary sinus. The
inferior border is free, thick, and cellular in structure, more especially in the middle of the bone.
Extremities Both extremities are more or less pointed, the posterior being the more tapering.
Development The inferior nasal concha is ossified from a single center, which appears about the fifth month of fetal life in the lateral wall of the cartilaginous nasal capsule. The entire inferior concha may be absent in some people. This is a consequence of embryologic
agenesis and is a normal anatomic variant. == Clinical significance ==