What Is the Ethmoid Bone?

The ethmoid is located in front of the sphenoid bone and between the two orbits. It connects with the frontal nose and projects into the nasal cavity. The frontal view of the ethmoid bone is medium-shaped. The whole bone is divided into three parts: sieve plate, vertical plate and ethmoid labyrinth. The horizontal bone plate is the sieve plate, which divides the front of the cranial cavity and the nasal cavity in the horizontal direction. There is a chicken crown protruding upward in the middle of the plate, and there are many sieve holes on both sides. The median sagittal bone plate extending down the middle of the sieve plate is a vertical plate and participates in the formation of the bony nasal septum. The ethmoid labyrinth is located on both sides of the vertical plate, and is surrounded by a thin piece of bone. The upper and lower curved bone fragments on the inner wall of the labyrinth are the upper turbinate and the middle turbinate.

Chinese name: Ethmoid
Foreign name: ethmoid bone
Location: Between the orbits

Shape: "Towel" shape on the coronal plane
Make up: Sieve plate, vertical plate and ethmoid labyrinth
Pinyin: shi g

Ethmoid structure

Ethmoid, anatomy of the same name. The ethmoid is divided into three parts:

Ethmoid sieve plate

It is a porous horizontal bone plate that forms the top of the nasal cavity. The front part of the plate has a bone ridge protruding upwards and is called a chicken crown.

Ethmoidal vertical plate

It sags from the midline of the sieve plate and is in the middle sagittal position, forming the upper part of the bony nasal septum.

Ethmoid ethmoid labyrinth

It is located on both sides of the vertical plate, surrounded by Philippine thin bone slices into many small cavities, called the ethmoid sinus. The inner wall of the labyrinth has two curly small bone fragments, the upper turbinate and the middle turbinate. The outer wall of the labyrinth is extremely thin and constitutes the inner wall of the orbit, which is called the orbital plate.

Anterior ethmoidal sinus anatomy classification standard

According to whether the anterior ethmoid sinus invades into the ethmoid and is divided into: intraethmoidal type (Figure A), the anterior ethmoid sinus is limited to the ethmoid; extraethmoidal type, the anterior ethmoid sinus is invaded to the ethmoid, this type It is further subdivided into supraorbital type (Figure B, anterior ethmoidal sinus invades into the frontal orbital plate) and suborbital type (figure C, anterior ethmoidal sinus up to the suborbital bone) Plate invasion) and mixed type (Figure D, the anterior ethmoid sinus invades supraorbitally and suborbitally).

Anterior ethmoid sinus classification reflects anterior ethmoid sinus gasification

vanAlyea (1951) first described the ethmoid sinus gasification in detail. He believed that the ethmoid sinus continued to expand around until it stopped or turned around when it encountered hard and dense bone. iRtter believes that when the anterior ethmoid sinus is well vaporized, it can invade beyond the ethmoid bone and extend beyond the ethmoid. It has been reported in the literature that the anterior ethmoid sinus can be vaporized up to 44mm to the orbital apex. This study found that 70. 8% (85 sides) of the anterior ethmoid sinus of the intraethmoidal type, 17.5% (21 sides) of the anterior ethmoid sinus of the supraorbital type, 7.5% (9 sides) of anterior ethmoid sinus of the suborbital type, mixed Anterior ethmoid sinus 4.2% (5 sides). It conforms to the anterior ethmoidal sinus gasification law, that is, the anterior ethmoidal sinus is adjacent to the hard and dense bones such as the frontal bone and the upper collar bone, which is difficult to invade. Therefore, the intraethmoidal type is more common; The frontal bone, the upper collar bone, and the frontal bone are directly adjacent to the anterior ethmoid sinus. The upper collar bone is relatively far below the anterior ethmoid sinus, so the anterior ethmoid sinus invades the frontal bone more than the upper collar bone.

Clinical points of ethmoid bone

Anatomy and classification of anterior ethmoid sinus has important clinical significance. When anterior ethmoid sinus surgery is performed with micronasal endoscope, for patients belonging to intraethmoid ethmoid sinus, as long as the operation is limited to the ethmoid bone, the risk of surgery is relatively small. Patients who belong to the supraorbital ethmoid sinus, because of the need to open the frontal orbital ethmoid ethmoid surgery, it is likely to cause intracranial and intraorbital complications. For patients who belong to the suborbital ethmoid sinus, the orbital content is greatly increased; Patients with mixed ethmoid sinus have the greatest risk of intracranial and intraorbital complications. Therefore, the use of modern imaging methods such as coronary CT to check the anterior ethmoid sinus gasification range before surgery, and to fully understand the anterior ethmoid sinus classification, have important clinical practical value for selecting the intranasal ethmoid sinus surgery method and determining the surgical range.