What Is the Cranium?

The cranium is located above the head and occupies about one-half of the head. It is vaulted and protects the bone layer of the brain.

[tóu gài g]

Skull position for head

Pinyin: tou gai gu

The cranium is composed of the front bone, temporal bone, parietal bone, occipital bone, sphenoid bone, and ethmoid bone.

Cranium frontal

Cranium ^[1]

A pair of membranous bones in the upper front of the skull, followed by the parietal bone in front, form a single bone on the human head.

Cranial temporal bone

The temporal (pronounced: niè) bone, the temporal bone, is one of the 29 bones that make up the human skull. There are two pieces. One on each side. It is located on both sides of the skull and extends to the base of the skull. It can be divided into three parts: the temporal scales, the drum, and the rock. Temporal scales are scale-like, with inner meningeal sulcus on the inside and smooth on the outside. There is a condyle below the anterior part. The condyle extends horizontally forward and meets the temporal process of the sacrum to form the condylar arch. Under the rear of the condylar process there is an oval shallow fossa called the mandibular fossa. The anterior edge of the fossa is raised and called the joint nodule. The drum is a bone plate that surrounds the front of the external ear canal and behind the lower part. The rock part is also known as the temporal bone cone. The cone has three faces, the tip faces the anterior medial side, the front part of the rock part is located in the middle cranial fossa, and the middle part has an arch-shaped bulge. There are slightly concave finger indentations called trigeminal nerve indentations. The posterior upper part of the rock part is located in the posterior cranial fossa, and there is an inner ear portal near the central part, which connects the inner ear canal. The upper edge of the rock is where the upper back meets the upper front. The lower part of the rock part faces the outside of the skull base, and the shape is rough. The carotid arterial canal has an outer mouth near the center. The carotid arterial canal passes through the inner side of the rock part and forms the inner carotid canal orifice at the tip of the cone. Fossa, which forms a jugular foramen with a jugular vein notch on the posterior occipital bone. There is a thin and long styloid process on the outer side of the fossa, and the stem milky hole can be seen outside the root, located between the styloid process and the mastoid process. The mastoid is approximately conical and pointed downward. The mastoid containing the honeycomb-like cavity is called the mastoid small chamber, and the larger one above it is called the drum (mastoid) sinus, which communicates with the middle ear.

Skull structure diagram (9 photos)

Cranium and parietal bone

One of the skulls, which is slightly flat and square, on the top of the head, one on each side.

The parietal bone is also called the cranial parietal bone. The parietal bone is an intramembranous bone during embryonic development. It has not been fully ossified at birth. Therefore, some membrane structures, such as the anterior and posterior condyles, remain. The bones at the top of the skull are flat bones. The front is the front bone and the back is the occipital bone. Between the frontal and occipital bones are the left and right parietal bones. The small part of the anterior part on both sides is the sphenoid wing; the posterior part is mostly the temporal bone scale. The bones at the top of the skull are joined by cranial sutures. When intracranial pressure increases, the sutures in children can be slightly separated. The thickness of the skull in adults is about 0.5cm, the thickest part can reach 1cm, and the thinnest part is only 0.2cm in the temporal region. Due to the varying thickness of the skull and parietal bone, care should be taken when craniotomy. The parietal bone is domed and has some elasticity. When hit by external forces, they are often concentrated in one point. Adult fracture lines are mostly radiated around the stress point, and the cranial parietal bone is more elastic, so depression fractures often occur after trauma. The parietal skull is divided into three layers: the outer plate, the plate barrier and the inner plate. The outer plate is thicker and has greater resistance to tension, while the arc is smaller than the inner plate. The inner plate is thin and the texture is fragile. Therefore, the outer pole can remain intact during trauma, but the inner plate is fractured. At the same time, the fracture plate can puncture local blood vessels, meninges, and brain tissue. Obstacles are cancellous bones between the inner and outer plates, containing bone marrow, and there are obstruction veins located in the obstruction duct. The obstruction tube is cracked on the X-ray film, which can sometimes be mistaken for the fracture line, and attention should be paid to identification. Because the plate vein is located in the bone, it cannot be ligated during surgery, and bone wax is often used to stop bleeding.

Cranium occipital bone

One of the skulls. Also known as posterior mountain bone, jaw occipital bone, occipital bone, posterior occipital bone.

Cranium sphenoid

One of the skulls, shaped like a butterfly, is at the bottom of the skull, before the occipital bone.

Cranial ethmoid

One of the craniums is in front of the base of the cranial cavity, between the two eye sockets, and on the top of the nasal cavity, is the disintegrated bone between the cranial cavity and the nasal cavity. Ethmoid, anatomy of the same name. Located between the frontal bone and sphenoid bone, this bone has vacuole holes and is a gas-containing bone.