The nervous system controls the various functions of the body, for this it needs to collect information both from the outside and from the internal environment, process it and then send signals that will result in movements, hormonal secretion, changes in the activity of the viscera or even motivational manifestations and learning. Cranial Pairs
These functions are performed in the central nervous system , located within the skull and in the spinal duct of the spine. The transport of information and effector signals from the brain and higher centers to the different organs and systems occurs thanks to the processes that form the nerves and constitute the peripheral nervous system.
This system is made up of the nerves that emerge from the vertebral column originating from the spinal cord, which are the spinal nerves, as well as those originating from the brain and brainstem that are exteriorized when passing through the various orifices of the skull, known as cranial pairs.
Cranial nerves or pairs
The cranial pairs are paired nerves as the name implies, as there is one for each side of the body, there are 12 nerves in total and named with roman numbers : Cranial Pairs
III: Ordinary ocular motor or Oculomotor
VI: External eye motor or Abducens
VIII: Vestibulocochlear (auditory)
XI: Spinal or Accessory
Cranial Pair Functions
Olfactory . It originates in nerve cells related to the sense of smell located in the roof of the nasal cavities, from there it moves to the higher centers to allow for smell. Cranial Pairs
Optical . Visual impulses originate in retinal cells (cones and rods) and pass through a system of 4 neurons that end in the optic nerve, responsible for carrying information to the visual cortex located in the occipital lobe of the brain.
Ordinary eye motor or eye-motor . Controls most of the eye muscles, which allows you to move the eye up, down, and inward; it also performs the control of pupil diameter and lens accommodation essential for near vision.
Trochlear . It works by bringing the eye up and down.
Triplet. It is the nerve responsible for the sensitivity of the face and the mobility of the masticatory muscles. It has three branches, upper or ophthalmic, upper and lower jaw. Cranial Pairs
External eye motor . It is dedicated exclusively to movements that allow the eye to be taken out.
Facial . It is the nerve that allows the mobility of the face and ear muscles , it also provides the sensitivity of the anterior two thirds of the tongue and controls the functions of the lacrimal and salivary glands.
Vestibulocochlear . It originates in the inner ear, it allows to carry the electrical signals originated by the vibrations of the eardrum to the cerebral auditory centers so that hearing can occur. It consists of a vestibular branch that transmits information about the head’s position in space, as well as its movements, which is fundamental for balance control.
Glossopharyngeal . Provides sensitivity to the throat and the back of the palate, also controlling its mobility.
Vacant . It is the longest cranial nerve. It emerges from the skull and descends to the chest and abdomen to provide sensory and autonomic (parasympathetic) innervation to the organs of the cardiovascular, respiratory and digestive systems, as it is an important regulator of functions such as blood pressure control, heart rate, breathing , movements intestinal and digestion . Cranial Pairs
Spinal or accessory . It is a nerve that provides motor control to the sternocleidomastoid muscle and the upper part of the trapezius muscle, both located at the level of the neck.
Greater Hypoglossus . It is responsible for the motor control of the muscles that make up the tongue.