Premaxilla

Definition:

Premaxilla is the embryologic unit of bone lying anterior to the incisive foramen of hard palate. It contains all four upper incisors as well as the nasal spine and maxillary crest. Some authors consider it to be a subsection of the paired alveolar process of maxilla. The word premaxilla often used by rhinologists to mean maxillary crests.

Contents of premaxilla:

1. Upper four incisors

2. Nasal spine

3. Maxillary crest

Nasal spine:

Also known as anterior nasal spine. It is a prominent midline projection from the lower margin of pyriform aperture. It has three sides and three margins. It supports the septal cartilage above. Its right and left sides are concave and curves downwards and laterally to blend with the incisive fossae.

Maxillary crest: The two laminae of nasal spine raise ridges low on the anterior portion of nasal septum. These are known as maxillary crests. These crests encompass a midline groove on the superior margin of vomer. The size and symmetry of these maxillary crests are highly variable.

Tumors involving the floor of the nasal cavity can spread through this premaxillary fused structures with little regard to the side of origin.

When tumor is absent in the premaxillary region, but surgical resection is necessary there, a detailed knowledge of the bony and adhesional anatomy is necessary if function and cosmesis is to be preserved.

Maxilla premaxilla approach of cottle has been used to approach the nasal cavity to remove bilateral nasal tumors and in transeptal sphenoid surgeries.

Soft tissues in the region of premaxilla could be systematically elevated by detaching the soft tissue and mucosa that could be easily detached from this area. The more difficult to detach areas should be attempted only towards the end.

It is difficult to elevate septal perichondrium from the maxillary crest.

The subcutaneous tissue of upper lip that lie immediately anterior to the sides of nasal spine can be stretched over the spine when a nasal speculum is inserted through the lower end of a septal hemitransfixation incision. The soft tissues can then be incised and pushed aside using a septal elevator.