Where is the cranium in the body

It is a…. The skeletal system is the foundation of your body, giving it structure and allowing for movement. Health Conditions Discover Plan Connect. There are eight major bones and eight auxiliary bones of the cranium. Read this next.

Supraspinatus Medically reviewed by the Healthline Medical Network. Quadratus plantae Medically reviewed by the Healthline Medical Network. Depressor labii inferioris Medically reviewed by the Healthline Medical Network. Quadriceps femoris Medically reviewed by the Healthline Medical Network.

Palmaris brevis Medically reviewed by the Healthline Medical Network. The temporal bone is subdivided into several regions Figure 6. The flattened, upper portion is the squamous portion of the temporal bone. Below this area and projecting anteriorly is the zygomatic process of the temporal bone, which forms the posterior portion of the zygomatic arch.

Posteriorly is the mastoid portion of the temporal bone. Projecting inferiorly from this region is a large prominence, the mastoid process , which serves as a muscle attachment site. The mastoid process can easily be felt on the side of the head just behind your earlobe. Posterior to the mandibular fossa on the external base of the skull is an elongated, downward bony projection called the styloid process, so named because of its resemblance to a stylus a pen or writing tool.

This structure serves as an attachment site for several small muscles and for a ligament that supports the hyoid bone of the neck. See also Figure 6. The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella see Figure 6.

The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin, is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead.

The frontal bone is thickened just above each supraorbital margin, forming rounded brow ridges. These are located just behind your eyebrows and vary in size among individuals, although they are generally larger in males. Inside the cranial cavity, the frontal bone extends posteriorly. This flattened region forms both the roof of the orbit below and the floor of the anterior cranial cavity above see Figure 6. The occipital bone is the single bone that forms the posterior skull and posterior base of the cranial cavity Figure 6.

On the base of the skull, the occipital bone contains the large opening of the foramen magnum , which allows for passage of the spinal cord as it exits the skull. On either side of the foramen magnum is an oval-shaped occipital condyle.

These condyles form joints with the first cervical vertebra and thus support the skull on top of the vertebral column. The sphenoid bone is a single, complex bone of the central skull Figure 6. The sphenoid forms much of the base of the central skull and also extends laterally to contribute to the sides of the skull see Figure 6.

Inside the cranial cavity, the right and left lesser wings of the sphenoid bone , which resemble the wings of a flying bird, form the lip of a prominent ridge that marks the boundary between the anterior and middle cranial fossae. This bony region of the sphenoid bone is named for its resemblance to the horse saddles used by the Ottoman Turks, with a high back and a tall front.

The rounded depression in the floor of the sella turcica is the hypophyseal pituitary fossa , which houses the pea-sized pituitary hypophyseal gland. The greater wings of the sphenoid bone extend laterally to either side away from the sella turcica, where they form the anterior floor of the middle cranial fossa. The greater wing is best seen on the outside of the lateral skull, where it forms a rectangular area immediately anterior to the squamous portion of the temporal bone.

On the inferior aspect of the skull, each half of the sphenoid bone forms two thin, vertically oriented bony plates. The right and left medial pterygoid plates form the posterior, lateral walls of the nasal cavity. The somewhat larger lateral pterygoid plates serve as attachment sites for chewing muscles that fill the infratemporal space and act on the mandible.

The ethmoid bone is a single, midline bone that forms the roof and lateral walls of the upper nasal cavity, the upper portion of the nasal septum, and contributes to the medial wall of the orbit Figure 6. On the interior of the skull, the ethmoid also forms a portion of the floor of the anterior cranial cavity. Within the nasal cavity, the perpendicular plate of the ethmoid bone forms the upper portion of the nasal septum.

The ethmoid bone also forms the lateral walls of the upper nasal cavity. Extending from each lateral wall are the superior nasal concha and middle nasal concha, which are thin, curved projections that extend into the nasal cavity Figure 6. In the cranial cavity, the ethmoid bone forms a small area at the midline in the floor of the anterior cranial fossa.

This region also forms the narrow roof of the underlying nasal cavity. This portion of the ethmoid bone consists of two parts, the crista galli and cribriform plates. It functions as an anterior attachment point for one of the covering layers of the brain. Small nerve branches from the olfactory areas of the nasal cavity pass through these openings to enter the brain.

A suture is an immobile joint between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the bones of the brain case are not straight, but instead follow irregular, tightly twisting paths.

These twisting lines serve to tightly interlock the adjacent bones, thus adding strength to the skull for brain protection. The two suture lines seen on the top of the skull are the coronal and sagittal sutures. The coronal suture runs from side to side across the skull, within the coronal plane of section see Figure 6. It joins the frontal bone to the right and left parietal bones.

The sagittal suture extends posteriorly from the coronal suture, running along the midline at the top of the skull in the sagittal plane of section see Figure 6.

It unites the right and left parietal bones. On the posterior skull, the sagittal suture terminates by joining the lambdoid suture. The lambdoid suture extends downward and laterally to either side away from its junction with the sagittal suture.

The lambdoid suture joins the occipital bone to the right and left parietal and temporal bones. The squamous suture is located on the lateral skull. It unites the squamous portion of the temporal bone with the parietal bone see Figure 6. The facial bones of the skull form the upper and lower jaws, the nose, nasal cavity and nasal septum, and the orbit. The dens acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side.

Bones of the head : There are 29 bones in the human head. They consist of 8 cranial bones , 14 facial bones , the hyoid bone , and 6 auditory ear bones. The 8 cranial bones are the frontal, 2 parietal, occipital, 2 temporal, sphenoid, and ethmoid bones. Is the skull an organ? The skull or bones are not organs. The skull, in and of itself, is only an organ in the sense that the 22 bones that make up the skull are organs.

Why the skull is important? The skull is made up of several bones fused together. They form the world's most important natural helmet and protect the things underneath. Our body gave us a skull and spine to protect our brain and spinal cord. It's up to you to protect the skull and spine. Is there a hole in your skull for your ears? There are also three small bones in each ear. There is a large opening, called the foramen magnum, located in the back of the occipital bone.

This is where the medulla ends and projects out of the skull. Smaller holes in the skull, called foramina, allow nerves and blood vessels to enter and leave the cranium. Can you feel a fractured skull? A skull fracture is a break in a bone surrounding the brain. Skull fractures can occur with or without brain damage.

Symptoms may include pain, symptoms of brain damage, and, in certain fractures, fluid leaking from the nose or ears or bruises behind the ears or around the eyes.