The midbrain is a structure of the brainstem, located in the cranial box.

Position. Directly connected to the brain, the midbrain constitutes the upper part of the brainstem. The latter originates under the brain within the cranium and passes through the occipital foramen. The brainstem then moves to the top of the spinal canal where it is extended by the spinal cord (1).

Structure. The brainstem is made up of three structures, the midbrain, the bridge and the medulla oblongata (2). The midbrain itself is made up of three structures: the cerebral peduncles, forming two bulges, the tegmentum, and the tectum.

Control center. The midbrain is involved in various functions essential to the body, such as:

• involuntary motor control
• control of respiratory centers
• control of cardiovascular centers
• control of the state of consciousness
• the control of the exchange pathways, in particular with the cerebellum, impacting on muscle tone and locomotion
• relaying the visual and auditory pathways.

Of degenerative, vascular or tumor origin, certain pathologies can develop in the mesencephalon and affect the central nervous system.

Stroke. Cerebrovascular accident, or stroke, is manifested by obstruction, such as the formation of blood clots or the rupture of a blood vessel in the brain. (3) This pathology can impact the functions of the midbrain.

Head trauma. It corresponds to a shock to the skull which can cause brain damage. (4)

Parkinson disease. It corresponds to a neurodegenerative disease, the symptoms of which are in particular a tremor at rest, or a slowing down and reduction in the range of motion. (5)

Multiple sclerosis. This pathology is an autoimmune disease of the central nervous system. The immune system attacks the myelin, the sheath surrounding nerve fibers, causing inflammatory reactions. (6)

Tumors of the brainstem. Benign or malignant tumors can develop in the midbrain. (7)

Drug treatments. Depending on the pathology diagnosed, certain treatments may be prescribed such as anti-inflammatory drugs.

Thrombolyse. Used during strokes, this treatment consists of breaking up the thrombi, or blood clots, with the help of drugs. (3)

Surgical treatment. Depending on the type of pathology diagnosed, surgery may be performed.

Chemotherapy, radiotherapy. Depending on the stage and evolution of the tumor, these treatments can be implemented.

Physical examination. First, a clinical examination is performed in order to observe and assess the symptoms perceived by the patient.

Medical imaging examination. In order to assess damage to the midbrain, a brain and spinal CT scan or a brain MRI may be performed.

Biopsy. This examination consists of a sample of cells.

Lumbar puncture. This exam allows the cerebrospinal fluid to be analyzed.

Neurological description of the brain. Thomas Willis is an English doctor considered one of the pioneers of neurology. He was one of the first to present a concrete description of the brain through his treatise cerebral anatome. (8)