Brain And The Twelve Cranial Nerves example essay topic

The Brain and Cranial Nerves One of the most complex and fascinating things in the human body is the brain. The body is "capable of almost everything, but it would not be possible, without the brain receiving information, and analyzing the information". The brain is aware of its surroundings, via input from the spinal cord and cranial nerves. Cranial nerves with sensory functions allow us to smell and see. Nerves with both motor and sensory functions are responsible for everything from tasting and chewing, to breathing and the heating of your heart. Many of the little things we take for granted are also made possible by cranial nerves.

Solving problems, feeling hungry, laughing. Each of these activities occurs in a different region of the brain. The portion of the central nervous system is contained in the cranium. About one hundred billion neurons and ten to fifty trillion neuralgia make up the brain.

In adults, the brain has a mass of about three pounds. The four major parts of the brain are the Brain Stem, Cerebellum, Diencephalons, and the Cerebrum. The brain stem is continuous with the Spinal Cord and consists of the Meclulla Oblongata, Pons, and the Mid Brain. Posterior to the Brain Stem is the Cerebellum. Superior to the Brain Stem is the Diencephalon. The Diencephalons consists mainly of the Thalamus and Hypothalamus.

Supported on the Diencephalon of the Brain Stem, the Cerebrum which is the largest part of the brain. Since the brain does not store oxygen, it needs a constant flow to prevent it shutting down. Blood flows to the brain mainly via, the internal Caroticl and Vertebral Arteries. The internal Tubular Veins return blood from the head to the heart. In adults, the brain is only two percent of the total body weight, but it consumes about two percent of the oxygen and glucose used at rest. When activity of neurons and neuralgia increases in a region of the brain, blood flow to that area also increases.

Even a brief slowing of brain blood flow may cause unconsciousness. Typically an interruption in blood flow for one or two minutes impairs neuronal function. Should total deprivation of oxygen incur for about four minutes, damage can occur. Because virtually no glucose is stored in the brain, the supply of glucose also must be continuous.

If the blood entering the brain has a low level of glucose, mental confusion, dizziness, convulsions, and loss of consciousness may occur. The blood brain barrier protects brain cells from harmful substances, as well as, pathogens, by preventing passage of many substances from blood into brain tissue. Tight junctions seal together the cells of brain capillaries, which also are surrounded by a thick basement membra in. The process of many pressing up against the capillaries is known as the Astrocytes Process. This process selectively passes some substances from the blood to the neurons, at the same time, inhibiting the passage of others. A few water soluble substances, like glucose, cross the brain blood barrier by active transport.

Other substances like creatinine, vres, and most ions, cross very slowly. Other substances and potions, including most antibiotic drugs, do not pass at all from the blood into brain tissue. Trauma, certain toxins, and inflammation, can all cause a breakdown of the Brain blood barrier. The cranium and the Cranial Meninges surround and protect the brain. The Cranial meninges are continuous with the Spinal meninges. Both have the same basic structure.

Cerebrospinal fluid is a clear, colorless, liquid that protects the brain and spinal cord against chemical and physical injuries. It also carries oxygen, glucose, and other needed chemicals from the flood to neurons, and neuroglia. The brain stem is the part of the brain between the spinal cord and the Diencephalon. The brain stem is made up of three structurally and functionally connected regions. These regions are the Medulla Oblongata, the Pons, and the Midbrain.

The Medulla Oblongata is a continuation of the Spinal cord. The Medulla contains white matter that is sensory and motor tracts. These tracts extend between the spinal cord and other parts of the brain. The Pons lies directly superior to the Medulla.

Like the Medulla, the Pons is a bridge that connects parts of the brain with one another. The midbrain extends fro the Pons to the Diencephalon. The Midbrain contains both tracts and nuclei. The interior art of the midbrain contains a pair of tracts called Cerebral Pedunctis.

They contain axons of and motor neurons. These conduct nerve impulses from the cerebrum to the spinal cord, medulla, and pons. The posterior part of the midbrain is called the tetum. The Tetum contains four rounded elections, two superior, and two inferior.

The two superior elevations are known as the superior. They serve as reflex centers for certain visual activities. The two inferior elevations, the inferior, are art of the auditory pathway, relaxing impulses from the receptors for hearing in the ear to the thalamus. The Cerebellum is the second largest part of the brain.

The cerebellum occupies the inferior and posterior aspects of the cranial cavity. The Diencephalon extends from the brain stem to the cerebrum. It includes the thalamus, , epi thalamus, and. The twelve cranial nerves are responsible for a variety of things. Some of these nerves bring information from the sense organ to the brain, other cranial nerves control muscles.

Then we have cranial nerves that are connected to glands or internal organs such as the heart and lungs. Cranial Nerve I - The Olfactory Nerve. This nerve has only a special sensory component. Special sensory is the sense of smell or olfaction.

Cranial Nerve II - The Optic Nerve. The optic nerve has only a social sensory component, this special sensory conveys visual information from the retina. Cranial Nerve - The Oculomotor Nerve. This nerve consists of two components with distinct functions. The somatic motor supplies four of the six extra ocular muscles of the eye and the levator superior is muscle of the upper eyelid. The visceral motor thru the parasympathetic innervation's of the constrictor pupil and ciliary's muscles.

The visceral motor component is in the papillary light so by reflex your pupil will dilate or not. Cranial Nerve IV - The Trochlear Nerve. The trochlear nerve has only a somatic motor component. The somatic motor signal the superior oblique muscle of the contra lateral orbit.

The superior oblique muscle is one of the six extra ocular muscles responsible for the precise movement of the eye for visual tracking or fixation on an object. Cranial Nerve V - The Trigeminal Nerve. This cranial nerve has three components. The nerve has three branches - the nerve that is sensory for your face and mouth. The maxillary nerve for chewing and the mandibular nerve for sensation of pain and the jaw. Cranial Nerve VI - The Abduces Nerve.

This nerve has only a somatic motor component. The somatic motor innervates the late rial rectus muscle of the orbit. Cranial Nerve VII - The Facial Nerve. The facial nerve has four components. The Branchial motor supplies the muscles of facial expressions. The Visceral motor parasympathetic innervation of the, sub mandibular, and glands, as well as mucus membranes of nasopharynx, hard and soft palate.

The Special sensory is a taste sensation from the anterior two-thirds of tongue; hard and soft pa lets. The General sensory sends general sensation from the skin of the concha of the auricle and from a small area behind the ear. Cranial Nerve V - The Vestibulocochler Nerve. The nerve has two components. The vestibular nerve carries impulses for equilibrium where as the cochlear nerve comes impulse for learning. Cranial Nerve IX - The Glossopharyngeal Nerve.

The nerve consist of five components with distinct functions. The branchial motor nerve supplies the muscle. The visceral motor controls a smooth muscle and gland of the pharynx, larynx, and viscera of the thorax and abdomen. The next visceral is sensory and carries visceral sensory information from the carotid sinus and body. The general sensory provides general sensory information from the skin of the external ear, internal surface of the tympanic membrane, upper pharynx, and the posterior, with is one-third of the tongue. The special sensory provides taste sensation from the posterior one-third of the tongue.

Cranial Nerve X - The Vagus Nerve. The word "vagus" comes from the latin meaning wandering. This is a good name as the nerve wanders from the brain stem to the splenic flexure of the colon. The vagus nerve consists of five components.

The branchial motor supplies the voluntary muscles of the pharynx and most of the larynx, as well as, the tongue. The visceral motor innervates the smooth muscle and glands of the pharynx, larynx, and also the viscera of the thorax and abdomen. The visceral sensory provides visceral sensory information from the larynx, esophagus, trachea, and abdominal and thoracic viscera. Also the str each receptors of the aortic arch and chemoreceptors of the aortic bodies.

The general sensory provides general sensory information from the skin of the back of the ear and external auditory meatus parts of the external surface of the thy panic member and the pharynx. The special sensory provides task sensation from the epiglottis region. Cranial Nerve XI - the Accessory Nerve. The accessory nerve has a cranial root and a spinal root, both of which consist of branchial motor fibers. The Branchial motor cranial root supplies muscles of the larynx and pharynx. The Branchial motor spinal root supplies the trapezius and muscles, helping to move the head.

Cranial Nerve XII - The Hypoglossal Nerve. This nerve has two components. The sensory portion controls muscles in the tongue. The somatic motor is responsible for supplying muscles in the tongue to help with speech and swallowing.

As you can tell from reading this report, this information just scratches the surface of how in depth and complex we are. I hope you now have a better understanding of the brain and the twelve cranial nerves, as well as, an understanding of all the things we take for granted..