The temporal bone: Anatomy and function

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The temporal bones are two major bones in the skull, or cranium. They help form the sides and base of the skull, where they protect the temporal lobe of the brain and surround the ear canal.

The other major bones in the skull are:

• the two parietal bones that make up the top of the skull
• the occipital bone at the back and base of the skull
• the frontal bone at the forehead
• the sphenoid bone at the temple
• the ethmoid bone behind the eye

Together, these bones fuse to create the neurocranium, which is the main cavity that surrounds and protects the brain and the brain stem.

Temporal comes from the Latin word tempus, which means time. This name reflects the fact that gray hairs, which mark the passage of time, often start appearing around the temporal area of the head.

The temporal bone surrounds the ears and protects nerves and structures that play a role in controlling hearing and balance.

Sound enters the ear canal and makes the tiny bones (ossicles) inside the ear vibrate. As they vibrate, they send sound signals into the oval window, a structure in the ear that leads to the cochlea. The cochlea contains hearing cells, which transmit sound information to the brain through cranial nerves. The brain then interprets these sounds.

Balance involves several areas of the inner ear, including the vestibule and semicircular canal.

The temporal bones comprise four regions:

• the squamous region, which is the largest
• the mastoid region
• the petrous region
• the tympanic region

Below is a 3D model of the temporal bone, which is fully interactive.

Explore the 3D model, using your mouse pad or touchscreen, to understand more about the temporal bone.

A range of injuries and medical conditions can affect the temporal bone, including those below.

Fractures

The temporal bones are the thickest bones of the skull, but a heavy impact to the head can fracture them.

Various cranial nerves pass through the temporal bones, so skull fractures that affect these bones can have serious consequences.

The brain receives oxygen-rich blood from the carotid artery, while the jugular vein carries blood out of the brain. These two structures also pass through the temporal bones.

Temporal bone fractures can occur due to motor vehicle accidents, assaults, or falls. About one-quarter of temporal bone fractures occur as a result of sports injuries, gunshot wounds, and cycling accidents, among other injuries.

Males are at least three times more likely than females to sustain a temporal bone fracture.

People with temporal bone fractures may present to the emergency department with the following signs and symptoms:

• bloody discharge from the ear
• blood in the middle ear
• dizziness
• altered eye movement
• paralysis of the facial muscles

Doctors treating a temporal bone fracture must first make sure that the injury is not life threatening. They will manage the bone fracture once they are confident that the person is in a stable condition.

Temporal bone fractures can involve damage to certain nerves or lead to bleeding in the brain. These issues may require surgery.

If a person has delayed paralysis of the facial muscles, they may have fluid buildup that is pressing on a nerve. If doctors believe inflammation to be the cause, they may treat this type of paralysis using a 1–3 week course of corticosteroids.

After a trauma, the fluid that surrounds the brain, called cerebrospinal fluid, can leak from the ears or nose. Treatments may involve:

• elevating the head
• bed rest
• avoiding strenuous activity
• surgery

Trauma around the temporal bone can cause hearing loss. In some situations, particularly those in which blood or swelling was responsible for this loss, the hearing may come back or improve over time. Sometimes, doctors can treat hearing loss with hearing aids, cochlear implants, or surgery to reconstruct the middle ear.

Infections

Temporal bone infections can sometimes be mild and unlikely to cause permanent damage. However, some infections can form abscesses in the tissues surrounding the temporal bones.

Abscesses in these tissues can grow and potentially cause a blood clot in the internal jugular vein. If the abscess becomes large enough, it can make a hole in the eardrum and affect the cranial nerves that pass through the temporal bones.

Tumors

Tumors at the temporal bones or base of the skull can be benign (noncancerous) or cancerous.

Symptoms usually affect the ear. Hearing loss and ringing in the ears, called tinnitus, are common symptoms. Tumors in this part of the body can also lead to pain, facial weakness, and problems with balance.

To detect these tumors, doctors examine the ear and often also use medical imaging methods. Different types of tumor have different treatment and management options.

The temporal bone is a thick, hard bone that forms part of the side and base of the skull. This bone protects nerves and structures in the ear that control hearing and balance.

Minor bumps are unlikely to cause this bone to fracture, but people who have been in car accidents or experienced significant head trauma may sustain a temporal bone fracture.

Many blood vessels and nerves pass through the temporal bone, so damage to it can have serious consequences involving blood loss and nerve damage.