The bridge is part of a highway-like structure between the brain and the body known as the brainstem. The brain stem has three parts and carries vital information to the body. The bridge conveys information about motor function, sensation, eye movement, hearing, taste, and more.
The bridge is located in the brain stem, which is the area where the brain connects to the spinal cord. The brain stem consists of three parts: the midbrain, the pons, and the medulla oblongata . Each element plays a role in the transmission of messages from the brain to the rest of the body .
The bridge is divided into two parts: the bridge on the inside and the basilar bridge on the outside. The basilar pons forms a bulbous bulge from the pons, which is a prominent feature of the brainstem. The basilar protuberance is located in the occipital bone and contains the basilar artery. The pons tectum makes up the lower part of the brain's fourth ventricle, and this is where the fibers called legs that connect the cerebellum to the midbrain originate.
Like other parts of the brain stem, the bridge plays an important role in the functioning of the autonomic nervous system . This system controls "automatic" body functions or things you don't think about, such as breathing and digestion. The main functions of the bridge are related to sensory and motor functions, especially of the head and neck. Four of the 12 cranial nerves of the body are located in the pons, as is the reticular activation system. The reticular activation system controls the sleep-wake cycle, alertness, responses to pain, and is part of the fight or flight system.
The cranial nerves that extend from the pons focus on motor responses, eye and face movements. Are:
Fifth cranial nerve : The trigeminal nerve is the largest cranial nerve that controls motor and sensory function. This nerve provides sensation in the face and head, controls the muscles used for chewing and biting, and transmits information about pain and temperature.
6th cranial nerve : The abducens nerve controls the movement of the eye. It activates the lateral rectus muscle, located on the outside of the eye, allowing the eye to move outward and away from the nose.
Cranial Nerve 7 : The facial nerve controls most of the muscles and sensation of the face. It causes tearing and salivation of the mouth, and promotes taste, hearing, facial sensations and control over them.
Cranial Nerve 8 : The vestibulocochlear nerve is responsible for hearing, but it also helps control balance and movement.
Bridge injury can be caused by trauma or other damage to the brainstem. Damage to the bridge will disrupt the functions of the cranial nerves associated with that part of the brain stem, and you may experience damage to facial sensations, eye movement, hearing, taste, and more.
An example of a bridge injury is a stroke . This can take the form of a stroke caused by a spotty clot or bleeding. In either case, these shocks cut off the oxygen supply to the affected area of the brain, causing damage to the areas where the clot or bleeding occurred.
Damage to the bridge can be detected by evaluating symptoms such as problems with eye movement, taste, and balance. The cranial nerve evaluation will test the function of the cranial nerves in the pons as well as other parts of the brain. Additionally, the images can help provide more specific information about the bridge injury and the extent of the damage. Here are some examples of tests that can be performed to determine the level of brainstem function.
- Cranial nerve evaluation: A physical exam that allows the doctor to see what functions may be affected, based on the tasks you are able to perform .
- Computed tomography (CT) or magnetic resonance imaging (MRI) : These can help the doctor visualize the damaged areas.
- Brain perfusion scan: This test allows the doctor to see which areas of the brain are receiving blood flow and is helpful in diagnosing brain death.