How many skull bones

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Cranial Bones Overview. Medically reviewed by Seunggu Han, M. Anatomy and function Diagram of cranial bones Cranial bone conditions Health tips What are cranial bones?

There are several types of bones within your body, including: long bones short bones flat bones irregular bones sesamoid bones There are two types in your cranium: Flat bones. As their name suggests, these bones are thin and flat, though some of them have a slight curve. Irregular bones. Anatomy and function. Diagram of cranial bones. Cranial bone conditions. The skull is formed of several bones which, with the exception of the mandible, are joined together by sutures—synarthrodial immovable joints.

The adult human skull is comprised of twenty-two bones which are divided into two parts of differing embryological origin: the neurocranium and the viscerocranium. The neurocranium forms the cranial cavity that surrounds and protects the brain and brainstem.

The neurocranium is formed from the occipital bone, two temporal bones, two parietal bones, the sphenoid, ethmoid and frontal bones; they are all joined together with sutures.

Components of neurocranium : Neurocranium consists of 8 parts: frontal, sphenoid, ethmoid, occipital, 2 temporal, and 2 parietal bones. The viscerocranium bones form the anterior and lower regions of the skull and include the mandible, which attaches through the only truly motile joint found in the skull. The facial skeleton contains the vomer, two nasal conchae, two nasal bones, two maxilla, the mandible, two palatine bones, two zygomatic bones, and two lacrimal bones.

Components of viscerocranium : The face is made of 2 nasal, 2 lacrimal, 2 palantine, 2 inferior nasal concha, 2 zygomatic, 2 maxilla, 1 mandible, and 1 vomer.

The skull also contains the sinuses. These are air-filled cavities that contribute to lessening the weight of the skull with a minimal reduction in strength. They contribute to resonance of the voice and assist in the warming and moistening of air inhaled via the nose. The neurocranium is comprised of eight bones: occipital, two temporal bones, two parietal bones, sphenoid, ethmoid, and the frontal bone. The neurocranium consists of the occipital bone, two temporal bones, two parietal bones, the sphenoid, ethmoid, and frontal bones—all are joined together with sutures.

Evolutionary,it is the expansion of the neurocranium that has facilitated the expansion of the brain and its associated developments. Neurocranium : A lateral view showing the bones that structure the neurocranium. The occipital bone forms the base of the skull at the rear of the cranium. It articulates with the first vertebra of the spinal cord and also contains the foramen magnum, the large opening of the skill through which the spinal cord passes as it enters the vertebral column.

The occipital bone borders the parietal bones through the heavily serrated lambdoidal suture, and also the temporal bones through occipitomastoid suture. The temporal bones are situated at the base and sides of the skull, lateral to the temporal lobes of the brain. The temporal bones consist of four regions the squamous, mastoid, petrous and tympanic regions.

The squamous region is the largest and most superior region. Inferior to the squamous is the mastoid region, and fused between the squamous and mastoid regions is the petrous region.

Finally, the small and inferior tympanic region lies anteriorly to the mastoid. The two large parietal bones are connected and make up part of the roof and sides of the human skull. The two bones articulate to form the sagittal suture. In the front, the parietal bones form the coronal suture with the frontal bone, and in the rear, the lambdoid suture is formed by the occipital bone. Finally, the squamosal suture separates the parietal and temporal bones.

The sphenoid bone is situated in the middle of the skull towards the front and forms the rear of the orbit. It has been described as resembling a butterfly due to its wing-like processes. The sphenoid bone is divided into several parts: the body of the bone, two greater wings, two lesser wings, and the pterygoid processes. The sphenoid bone is one of the most complex in the body due to its interactions with numerous facial bones, ligaments, and muscles.

The body that forms the middle of the sphenoid bone articulates with the ethmoid and occipital bone and forms a key part of the nasal cavity; it also contains the sphenoidal sinuses.

The greater wings form the floor of the middle cranial fossa that houses the frontal lobes and pituitary gland, and also the posterior wall of the orbit. The lesser wings project laterally and form the floor of the anterior cranial fossa and the superior orbital fissure through which several key optical nerves pass.

The ethmoid bone is a small bone in the skull that separates the nasal cavity from the brain. It is lightweight due to its spongy, air-filled construction and is located at the roof of the nose and between the two orbits. The ethmoid bone forms the medial wall of the orbit, the roof of the nasal cavity, and due to its central location it articulates with numerous bones of the viscerocranium.

Inside the neurocranium it articulates with the frontal and sphenoid bones. The frontal bone borders two other neurocranial bones—the parietal bones through the coronal sutures and the sphenoid bone through the sphenofrontal suture.

It also articulates with the zygomatic and nasal bones and the maxilla. The viscerocranium face includes these bones: vomer, 2 inferior nasal conchae, 2 nasals, maxilla, mandible, palatine, 2 zygomatics, and 2 lacrimals.

The viscerocranium or facial bones supports the soft tissue of the face. The viscerocranium consists of 14 individual bones that fuse together. However, the hyoid bone, ethmoid bone, and sphenoid bones are sometimes included in the viscerocranium.

The two zygomatic bones form the cheeks and contribute to the orbits. They articulate with the frontal, temporal, maxilla, and sphenoid bones. The two lacrimal bones form the medial wall of the orbit and articulate with the frontal, ethmoid, maxilla, and inferior nasal conchae. The lacrimal bones are the two smallest bones located in the face. The two slender nasal bones located in the midline of the face fuse to form the bridge of the noise and also articulate with the frontal, ethmoid and maxilla bones.

The inferior nasal conchae are located within the nasal cavity. They are spongy and curled in shape; their primary function is to increase the surface area of the nasal cavity, which also increases the amount of air that contacts the mucous membranes and cilia of the nose, thus filtering, warming, and humidifying the air before it enters the lungs. At the base of the nasal cavity is the small vomer bone which forms the nasal septum.

The maxilla bones fuse in the midline and form the upper jaw. They provide the bed for the upper teeth, the floor of the nose, and the base of the orbits. The maxilla articulates with the zygomatic, nasal, lacrimal, and palatine bones.

The palatine bones fuse in the midline to form the palatine, located at the back of the nasal cavity that forms the roof of the mouth and the floor of the orbit. Finally, the mandible forms the lower jaw of the skull. The joint between the mandible and the temporal bones of the neurocranium, known as the temporomandibular joint, forms the only non-sutured joint in the skull.

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