The parietal bone is one of the bones of the skull, located on the sides and top of the head. It is a flat bone that plays a vital role in the protection of the brain and the support of the face.
Structure
The parietal bone is a flat bone with a roughly quadrilateral shape. It has two surfaces – an outer surface and an inner surface – and four edges.
- The outer surface of the parietal bone is convex and rough, with numerous grooves and ridges for the attachment of muscles and ligaments. The temporal, occipital, and sphenoid bones articulate with the parietal bone at the sagittal suture, the squamous suture, and the lambdoid suture, respectively. The parietal bone also articulates with the frontal bone at the coronal suture.
- The inner surface of the parietal bone is smooth and concave. It forms part of the cranial cavity and surrounds the brain. The inner surface also has several important landmarks, including the parietal eminence, the parietal foramen, and the parietal tubercle.
The parietal eminence is a prominent bump on the inner surface of the parietal bone, located near the coronal suture. It is an attachment site for the falx cerebri, a fold of dura mater that separates the cerebral hemispheres.
The parietal foramen is a small hole located near the sagittal suture on the inner surface of the parietal bone. It is the point of exit for the parietal branch of the trigeminal nerve, which supplies sensory innervation to the scalp.
The parietal tubercle is a small protrusion on the inner surface of the parietal bone, located near the lambdoid suture. It is an attachment site for the falx cerebelli, a fold of dura mater that separates the cerebellar hemispheres.
Location
The parietal bones are located on the sides and top of the head, forming the top and sides of the cranial cavity. There are two parietal bones in the human body, one on the left side of the head and one on the right side. The parietal bones are separated by the sagittal suture, a fibrous joint that allows for some movement during birth.
Function
The parietal bone has several important functions in the human body.
- Protection of the brain: The parietal bone, along with the other bones of the skull, forms a protective casing around the brain. It helps to protect the brain from external impacts and injuries.
- Support of the face: The parietal bone helps to support the structure of the face, particularly the cheeks and the orbits.
- Attachment site for muscles and ligaments: The outer surface of the parietal bone has numerous grooves and ridges for the attachment of muscles and ligaments. These muscles and ligaments help to move the head and neck, and maintain the structural integrity of the head and face.
Clinical Significance
There are several conditions that can affect the parietal bone, including fractures, infections, and tumors.
- Fractures: Fractures of the parietal bone can occur due to trauma, such as a blow to the head. These fractures can range from simple to complex, depending on the severity of the injury. Treatment for parietal bone fractures may include rest and pain management, as well as the use of protective headgear. In severe cases, surgery may be necessary to repair the fracture.
- Infections: Infections of the parietal bone, known as osteomyelitis, can occur due to bacterial or fungal infections. These infections can be serious and may require intravenous antibiotics and surgery to remove infected tissue.
- Tumors: Tumors can also occur in the parietal bone, either as primary tumors (originating in the bone) or secondary tumors (spread from elsewhere in the body). Treatment for parietal bone tumors may include surgery, radiation therapy, and chemotherapy, depending on the type and stage of the tumor.
In addition to these conditions, the parietal bone may also be involved in certain medical procedures, such as brain surgery or the insertion of a shunt to treat hydrocephalus.
