Medulla. Anatomy. Structure and function of the medulla oblongata
The brain performs the most important functions in the human body and is the main organ of the central nervous system. At the termination of his activity, even if breathing is maintained by means of artificial ventilation of the lungs, doctors state a clinical death.
The medulla oblongata is located in the posterior cranial cavity and looks like an inverted bulb. From below, through the occipital foramen, it connects to the spinal cord, from above has a common border with the variolium bridge. Where is the medulla oblongata in the skull, is clearly shown in the picture, which is placed further in the article.
In an adult, the organ in its widest part is approximately 15 mm in diameter, the full length reaches no more than 25 mm. Outside, the oblong brain encircles the white matter, but inside it is filled with a gray matter. In its lower part there are separate clusters - nuclei. Through them, reflexes are carried out, covering all the systems of the body. Let's take a closer look at the structure of the medulla oblongata.
The ventral surface is the outer anterior part of the medulla oblongata. It consists of paired cone-shaped lateral lobes widening upward. Departments are formed by pyramidal tracts and have a median slit.
The dorsal surface is the posterior outer part of the medulla oblongata. It looks like two cylindrical thickenings, separated by a median groove, consists of fibrous bundles that connect to the spinal cord.
Consider the anatomy of the medulla oblongata, responsible for the motor functions of skeletal muscles and the formation of reflexes. The core of the olive is a plate of gray matter with jagged edges and resembles the shape of a horseshoe. It is located on the sides of the pyramid parts and has the form of an oval elevation. Below is the reticular formation, consisting of plexuses of nerve fibers. The medulla oblongata includes nuclei of the cranial nerves, centers of respiration and blood supply.
The glossopharyngeal nerve contains 4 cores and affects the following organs:
- pharynx muscles;
- palatine tonsils;
- receptors taste the back of the tongue;
- salivary glands;
- drum cavities;
- auditory tubes.
The wandering nerve includes 4 cores of the medulla oblongata and is responsible for the work:
- of the abdominal and breast organs;
- of the larynx muscles;
- of skin receptors of the auricle;
- internal glands of the abdominal cavity;
- of the neck.
The accessory nerve has 1 nucleus, controls the sternocleidus and trapezius muscles. The sublingual nerve contains 1 nucleus and affects the muscles of the tongue.
What are the functions of the medulla oblongata?
The reflex function acts as a barrier when harmful pathogens and external stimuli enter, regulates muscle tone.
- When a large amount of food, poisonous substances or irritation of the vestibular apparatus enters the stomach, the vomiting center in the medulla oblongum commands the body to empty it. When the emetic reflex triggers, the contents of the stomach exit through the esophagus.
- Sneezing is an unconditioned reflex, removing dust and other irritating agents from the nasopharynx by accelerated exhalation.
- Isolation of mucus from the nose performs the function of protecting the body against the penetration of pathogenic bacteria.
- Cough is a forced exhalation caused by contraction of the muscles of the upper respiratory tract. Cleans the bronchi from phlegm and mucus, protects the trachea from foreign objects entering it.
- Blinking and lacrimation are protective eye reflexes caused by contact with foreign agents and protecting the cornea from drying out.
The centers of the medulla oblongata are responsible for the tonic reflexes:
- static: body position in space, rotation;
- statokinetic: adjusting and rectifying reflexes.
- secretion of gastric juice;
What are the functions of the medulla oblongata in other cases?
- cardiovascular reflexes regulate the functioning of the heart muscle and blood circulation;
- respiratory function ensures ventilation of the lungs;
- conductor - is responsible for the tone of the skeletal musculature and acts as an analyzer of sensory stimuli.
lesions The first descriptions of the anatomy of the medulla oblongata occur in the 17th century after the invention of the microscope. The organ has a complex structure and includes the main centers of the nervous system, when the work of the whole body suffers from a malfunction.
- Hemiplegia( crossover paralysis) - paralysis of the right arm and left lower half of the trunk or vice versa.
- Dysarthria - restriction of the mobility of the organs of speech( lips, palate, tongue).
- Gemianesthesia - reduced sensitivity of the muscles of one half of the face and numbness of the lower opposite part of the trunk( limbs).
Other signs of dysfunction of the medulla oblongata:
- Mental development stop;
- unilateral paralysis of the body;
- sweating disorder;
- memory loss;
- paresis of facial muscles;
- decreased ventilation of the lungs;
- eyelid gland overgrowth;
- pupillary narrowing;
- inhibition of the formation of reflexes.
The study of the anatomy of the medulla oblongata showed that when the left or right side of the organ is affected, alternating syndromes occur. Diseases are caused by a violation of the conductor functions of the cranial nerves on the one hand.
Develops with dysfunction of the nuclei of the sublingual nerve, the formation of thrombi in the branches of the subclavian and vertebral arteries.
- paralysis of the larynx muscles;
- motor reaction disorder;
- language paresis on one side;
Diagnosed with lesions of the pyramidal parts of the brain.
- soft palate paralysis;
- swallowing disorder;
Occurs with dysfunction of the motor centers of the medulla oblongata.
- trapezius muscle paralysis;
- paresis of the vocal cords;
- incoherent speech.
Develops when the conductivity of the fibers of the eye muscles and the dysfunction of the sublingual nerve deteriorate.
- vestibular-cerebellar changes;
- paresis of soft palate;
- decreased sensitivity to facial skin;
- hypertonic skeletal muscle.
Diagnosed with extensive lesions of the brain stem and nuclei of the medulla oblongata.
- decreased vision;
- spasm of facial muscles;
- violation of the swallowing function;
- pain of the bones under the eyes.
The histological structure of the medulla oblongata is similar to that of the dorsal brain, when the nuclei are damaged, the formation of conditioned reflexes and motor functions of the organism is disrupted. To determine the exact diagnosis, instrumental-laboratory studies are carried out: tomography of the brain, collection of cerebrospinal fluid, radiography of the skull.