The brain performs the most important functions in the human body and is the main organ of the central nervous system. Upon termination of its activity, even if breathing is maintained by means of mechanical ventilation, doctors report clinical death.
Anatomy
The medulla oblongata is located in the posterior cranial notch and looks like an inverted bulb. From below, through the occipital foramen, it connects to the spinal cord; from above, it shares a common border with the warolium bridge. Where the medulla oblongata is located in the cranium is clearly depicted in the picture below in the article.
In an adult, the organ in its widest part is approximately 15 mm in diameter, in full length reaches no more than 25 mm. Outside, the medulla oblongata envelops the white matter, and inside it is filled with gray matter. In its lower part there are separate clumps - nuclei. Through them, reflexes are carried out, covering all body systems. Let's take a closer look at the structure of the medulla oblongata.
Outer part
The ventral surface is the outer front part of the medulla oblongata. It consists of paired conical lateral lobes, expanding upward. Departments are formed by pyramidal tracts and have a median gap.
The dorsal surface is the posterior external part of the medulla oblongata. It looks like two cylindrical thickenings, separated by a median groove, consists of fibrous bundles connected to the spinal cord.
Inside
Consider the anatomy of the medulla oblongata, which is responsible for the motor functions of skeletal muscles and the formation of reflexes. The olive kernel is a plate of gray matter with jagged edges and resembles the shape of a horseshoe. It is located on the sides of the pyramidal parts and has the appearance of an oval elevation. Below is the reticular formation, consisting of plexuses of nerve fibers. The medulla oblongata includes the nuclei of the cranial nerves, the centers of respiration and blood supply.
Kernels
The glossopharyngeal nerve contains 4 nuclei and affects the following organs:
- throat muscles;
- palatine tonsils;
- taste receptors in the back of the tongue;
- salivary glands;
- drum cavities;
- auditory tubes.
The vagus nerve includes 4 nuclei of the medulla oblongata and is responsible for the work:
- abdominal and breast organs;
- larynx muscles;
- cutaneous receptors of the auricle;
- internal glands of the abdominal cavity;
- organs of the neck.
The accessory nerve has 1 core, controls the sternoclavicular and trapezius muscles. The hyoid nerve contains 1 core and affects the muscles of the tongue.
What are the functions of the medulla oblongata?
Reflex function acts as a barrier when pathogenic microbes and external irritants get in, regulates muscle tone.
Protective reflexes:
- If too much food or toxic substances enter the stomach or if the vestibular apparatus is irritated, the vomiting center in the medulla oblongata gives the body an order to empty it. When the gag reflex is triggered, the contents of the stomach exit through the esophagus.
- Sneezing is an unconditioned reflex that removes dust and other irritating agents from the nasopharynx by accelerated expiration.
- The secretion of mucus from the nose performs the function of protecting the body from the penetration of pathogenic bacteria.
- A cough is a forced expiration caused by a contraction of the muscles of the upper respiratory tract. Cleans the bronchi from sputum and mucus, protects the trachea from foreign objects getting into it.
- Blinking and tearing are protective reflexes of the eyes that occur when in contact with extraneous agents and protect the cornea from drying out.
Tonic reflexes
The centers of the medulla oblongata are responsible for tonic reflexes:
- static: body position in space, rotation;
- statokinetic: installation and rectification reflexes.
Food reflexes:
- secretion of gastric juice;
- sucking;
- swallowing.
What are the functions of the medulla oblongata in other cases?
- cardiovascular reflexes regulate the work of the heart muscle and blood circulation;
- respiratory function provides ventilation of the lungs;
- conduction - is responsible for the tone of skeletal muscles and acts as an analyzer of sensory stimuli.
Symptoms of defeat
The first descriptions of the anatomy of the medulla oblongata are found 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, in violation of which the whole body suffers.
- Hemiplegia (cross paralysis) - paralysis of the right arm and left lower half of the trunk or vice versa.
- Dysarthria is a limitation of the mobility of speech organs (lips, palate, tongue).
- Hemianesthesia - a decrease in the sensitivity of the muscles of one half of the face and numbness of the lower opposite part of the trunk (limbs).
Other signs of medulla dysfunction:
- mental retardation;
- unilateral body paralysis;
- sweating disorder;
- memory loss;
- paresis of the muscles of the face;
- tachycardia;
- decreased lung ventilation;
- retraction of the eyeball;
- narrowing of the pupil;
- inhibition of the formation of reflexes.
Alternating Syndromes
A study of the anatomy of the medulla oblongata showed that with damage to the left or right side of the organ, alternating (alternating) syndromes occur. Diseases are caused by a violation of the conduction functions of the cranial nerves on the one hand.
Jackson's Syndrome
It develops with dysfunction of the nuclei of the hyoid nerve, the formation of blood clots in the branches of the subclavian and vertebral arteries.
Symptoms
- paralysis of the muscles of the larynx;
- impaired motor reaction;
- paresis of the tongue on one side;
- hemiplegia;
- dysarthria.
Avellis Syndrome
Diagnosed with damage to the pyramidal parts of the brain.
Symptoms
- soft palate paralysis;
- violation of swallowing;
- dysarthria.
Schmidt syndrome
It occurs with dysfunction of the motor centers of the medulla oblongata.
Symptoms
- trapezius muscle paralysis;
- paresis of the vocal cords ;
- incoherent speech.
Wallenberg-Zakharchenko Syndrome
It develops with a violation of the conductive ability of the muscle fibers of the eye and dysfunction of the hyoid nerve.
Symptoms
- vestibular cerebellar changes;
- paresis of the soft palate;
- decreased sensitivity of the skin of the face;
- hypertonicity of skeletal muscles.
Glick syndrome
It is diagnosed with extensive damage to the parts of the brain stem and nuclei of the medulla oblongata.
Symptoms
- decreased vision;
- facial muscle spasm;
- violation of swallowing function;
- hemiparesis;
- bone pain under the eyes.
The histological structure of the medulla oblongata is similar to the dorsal, with damage to the nuclei, formation of conditioned reflexes and motor functions of the body is disturbed. To determine the exact diagnosis, instrumental and laboratory studies are performed: brain tomography, cerebrospinal fluid sampling, skull x-ray.