What Is the Sphenoid Bone?

The sphenoid bone, shaped like a butterfly, is the bone between the frontal, ethmoid, and temporal and occipital bones. It extends laterally at the base of the skull and is divided into four parts: body, winglet, large wing, and pterygoid.

The sphenoid bone, shaped like a butterfly, is the bone between the frontal, ethmoid, and temporal, occipital bones. It extends laterally at the base of the skull and is divided into four parts: body, winglet, large wing, and pterygoid.

Chinese name

Sphenoid

Foreign name

sphenoid bone

Pinyin

Die Gu

Location

Located between the frontal, ethmoid, temporal, and occipital bones

Sphenoid bone overview

The body part is centered, and the upper part of the middle part of the cranial fossa is saddle-shaped, called the saddle, and its central depression is called the pituitary fossa. There is a cavity in the body, called the sphenoid sinus, which opens in the nasal cavity. The winglets extend flat from left to right, and the trailing edge of the winglets is the boundary between the anterior cranial fossa and the middle cranial fossa. The optic nerve canal passes through the root of the winglet, and there is an optic cross groove connection between the inner mouths of the optic nerve canals. The large wing extends from the body to the sides, and then rises up. It can be divided into three faces: the brain face is located in the middle cranial fossa, the orbital face is facing the orbital, and the temporal face is facing downward. Round holes, oval holes and spinous holes can be seen from the front to the back of the large wing near the root. The middle meningeal artery that enters the skull from the spinous holes has arterial grooves on the bone surface. There is a shallow ditch on both sides of the body, which is called the carotid sulcus. There is a long and narrow supraorbital fissure between the winglet and the large wing to communicate the cranial cavity with the orbital cavity. The wing process is located below the sphenoid bone and extends downward from the root of the large wing. It consists of a medial plate and a lateral plate. There is a wedge-shaped deep socket between the two plates at the rear. .

Sphenoid sphenoid sinus

The sphenoid bone is divided into the anterior and middle cranial fossa, which is composed of sphenoid body, two wings (sphenoid wing, sphenoid winglet) and two plates (outer and inner wings). The sphenoid bone is composed of two vaporized sphenoid sinuses. The size of the two sphenoid sinuses is generally asymmetric, and the separation position is usually not centered. The separation may even be attached to the upper part of the outer side wall. The area of the festival. According to the degree of gasification, scholars have proposed the following classifications:

1) The incidence of sphenoid sinus was 0.7%.

2) It is only a small sinus in the anterior part of the sphenoid bone, the incidence is <5%.

3) The sphenoid sinus located in front of the saddle extends to the anterior wall of the pituitary fossa, accounting for 11% to 28%.

4) The rest is the sphenoid sinus, which extends to the posterior pituitary fossa.

The recent classification of the sphenoid sinus in the saddle area is based on the direction of gasification: sphenoid body, outer slope, sphenoid winglet, front of sphenoid mouth and attachment site.

Note during surgery: The surgical path should conform to the depressions and protrusions formed by sphenoid sinus gasification.

The anterior wall of the sphenoid sinus is usually thin and the posterior nasal artery (sphenoid diaphragmatic nasal septum branch) passes from below. The average distance between the sphenoid sinus and the superior lateral angle of the posterior nostril was (21 ± 6) mm (range 10 to 34 mm). The side of the sphenoid sinus can be higher than the optic nerve, maxillary nerve (V2), and internal carotid artery; the bottom wall is through the pterygoid nerve to form a dentate process. The degree of sphenoid sinus gasification will affect the significance of these structures, and the gasification can extend to the slope, sphenoid winglets and pterygium roots, very close to the middle skull fossa. When extremely vaporized, it can even reach the infratemporal fossa. The blood supply of the sphenoid sinus is mainly from the posterior ethmoid artery.

Note during operation: The nasal septum mucoperiosteal flap is supplied by the posterior nasal artery (the branch of the sphenoid diaphragm artery). This artery can be damaged when the sphenoid sinus is enlarged downward.