![]() Each side of the nasal cavity is triangular in shape, with a broad inferior space that narrows superiorly. The upper portion of the nasal septum is formed by the perpendicular plate of the ethmoid bone and the lower portion is the vomer bone. ![]() Inside the nasal area of the skull, the nasal cavity is divided into halves by the nasal septum. An anterior view of the skull shows the bones that form the forehead, orbits (eye sockets), nasal cavity, nasal septum, and upper and lower jaws. The 22nd bone is the mandible (lower jaw), which is the only moveable bone of the skull.įigure 2. Anterior View of Skull. In the adult, the skull consists of 22 individual bones, 21 of which are immobile and united into a single unit. The rounded brain case surrounds and protects the brain and houses the middle and inner ear structures. The facial bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the teeth of the upper and lower jaws. It is subdivided into the facial bones and the brain case, or cranial vault (Figure 1). The cranium (skull) is the skeletal structure of the head that supports the face and protects the brain. Identify the bony openings of the skull.Identify the bones and structures that form the nasal septum and nasal conchae, and locate the hyoid bone.Name the bones that make up the walls of the orbit and identify the openings associated with the orbit.Define the paranasal sinuses and identify the location of each.Locate and define the boundaries of the anterior, middle, and posterior cranial fossae, the temporal fossa, and infratemporal fossa.Locate the major suture lines of the skull and name the bones associated with each.List and identify the bones of the brain case and face.The posterior fontanelle usually closes first, before the anterior fontanelle, during the first several months of an infant's life. This is the junction of the 2 parietal bones and the occipital bone. Doctors can assess if there is increased intracranial pressure by feeling the anterior fontanelle. The anterior fontanelle remains soft until about 18 months to 2 years of age. This is the junction where the 2 frontal and 2 parietal bones meet. There are 2 fontanelles (the space between the bones of an infant's skull where the sutures intersect) that are covered by tough membranes that protect the underlying soft tissues and brain. The fontanelles include:Īnterior fontanelle (also called soft spot). This results in an abnormal head shape (craniosynostosis). This may force growth to happen in another area or direction. If any of the sutures close too early (fuse prematurely), there may be no growth in that area. Each parietal bone plate meets the occipital bone plate at the lambdoid suture. This extends across the back of the head. The 2 parietal bone plates meet at the sagittal suture. This extends from the front of the head to the back, down the middle of the top of the head. Each frontal bone plate meets with a parietal bone plate at the coronal suture. The 2 frontal bone plates meet at the metopic suture.Ĭoronal suture. This extends from the top of the head down the middle of the forehead, toward the nose. The major sutures of the skull include the following: One suture in the middle of the skull extends from the front of the head to the back. Some sutures extend to the forehead, while others extend to the sides and back of the skull. The result is a symmetrically shaped head. ![]() This allows the bone to enlarge evenly as the brain grows and the skull expands. Sutures allow the bones to move during the birth process. These bony plates cover the brain and are held together by fibrous material called sutures. The major bones that compose the skull of a newborn include the following: Although the skull appears to be 1 large bone, there are actually several major bones that are connected together. ![]()
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