The bridge or get brainstem it is a region of Brain stem which in humans is found in the lower part of the midbrain, in front of cerebellum and directly above spinal bulb. He was the Italian anatomist Varolio who called this structure as such, that is why it is also known as “Varolio Bridge”. This scientist perceived this region as such due to its prominence and the similarity it had with a bridge that connected the two hemispheres of the cerebellum.
- 1 Bridge location
- 2 Anatomy of the brainstem bridge
- 3 Functions of the brainstem bridge
- 4 Problems in the brain bridge
The brain stem bridge It is the most prominent area of the brain stem. The shape of the brainstem bridge resembles the middle of a ring that connects the left and right cerebellum from its sides, as well as the cerebellum with the midbrain. Despite this, the bridge is not a direct connection between these two hemispheres. In this structure, two zones are distinguished, one posterior and the other anterior.
The back area from the bridge directly leads to the cerebellum and connects to the cerebellar peduncles mediales, large bundles of fibers that connect to the bridge with the cerebellum, being one of the main routes of connection of the brain with this structure. In addition, from this area the bridge forms the base of the room ventricle.
The anterior or rostral part contains transverse fibers and is crossed by the basilar artery, one of the sources of the highest proportion of oxygenated blood in the brain.
Anatomy of the brainstem bridge
From the bridge arise different cranial nerves very important that connect with other areas of the brain. These are the nerve trigeminal, which has sensory and motor functions, the nerve abducens, which is involved in eye movements, the nerve facial, which manages to control the muscles of the face by creating facial expressions and the nerve lobbyr, which relates to auditory information. Thus, the nuclei that make up the brainstem bridge are associated with these nerves being: the somatic motor core abductor, the special motor nucleus of the trigeminal, the special motor nucleus of the facial and the superior salivatory nucleus.
Internally, the bridge is made up of the ventral zone, in which the pontino core That is responsible for coordinating the movement. In the tegmentum, the oldest part of the bridge, which is part of the freticular formation, are a set and nuclei responsible for arousal system and attention.
The bridge contains groups of neurons essential for nervous system neurotransmitter systems. For example, him locus coeruleus that is in the dorsal part of the bridge and that is involved in stress processes, gives rise to the largest collection of noradrenergic neurons of the nervous system that project to the rest of it. The Rafe cores, also located on the bridge are groups of neurons that contain high levels of serotonin.
Functions of the brainstem bridge
As we have seen, the brainstem bridge is a structure composed of several nuclei and tracts that have very diverse functions and are involved in numerous actions, from facial expressions to aspects related to sleep, especially with the REM phase of it. The brainstem bridge becomes a connection zone between different areas of the brain that cross messages from the cortex or cerebellum, connecting the upper and lower areas of the brain.
So the bridge works like a center connector which intervenes in the general functioning of the nervous system and whose functions address different abilities, both motor and regulatory, that address from balance, through breathing, to emotions.
Brain Bridge Problems
When injuries occur in the brainstem bridge, the consequences affect multiple very basic functional capacities for human survival. The lesions that can occur in this area are normally caused by vascular problems, as well as tumors or traumas, although different diseases can also affect its functioning, such as the disease of Parkinson or the Alzheimer's.
The Millard-Gübler syndrome It is a disease caused by a lesion in the lower bridge and can cause facial paralysis ipsilateral to the lesion, as well as contralateral brachiocrural paralysis. This lesion is usually caused by vascular causes, although it may also be due to a tumor or trauma. Thus, paralysis occurs on the side opposite to the lesion that affects the face or body of the affected person.
The lower foville syndrome It is also due to an injury to this region of the brain, usually caused by problems such as tumors or heart attacks. In this case, the affected fibers are the VI and VII of the cranial nerves and ocular paralysis occurs, as well as contralateral pyramidal hemiplegia and ipsilateral facial paralysis. This can also lead to deafness or dizziness, as well as loss of taste since as we see, the implications of the bridge are so wide that your injuries can affect very different abilities.