NERVOUS SYSTEM

The nervous system consists of highly specialized cells designed to transmit information rapidly between various parts of the body. Topographically it can be divided into two major parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The brain and spinal cord constitute the CNS, which lies within the skull and vertebral canal, while nerves in the PNS connect the CNS with all other parts of the body.

The CNS is a massive collection of nerve cells connected in an intricate and complex fashion to subserve the higher order functions of the nervous system, such as: thought, language, emotion, control of movement and the analysis of sensation. It is isolated from the rest of the body; its cardinal characteristic is that it is located wholly within the skull and vertebral canal.

READ:   CEREBRAL CONCUSSION

The PNS consists of cells that connect the CNS with the other tissues of the body. These cells are aggregated into a large number of cable-like structures called nerves, which are threaded like wires throughout the tissues of the body.

HEAD TRAUMA Head trauma usually results from an accident, a blow to the head, or a serious fall. Recovery may be rapid or extended, depending on the severity of the trauma. It is important to watch an individual who has suffered head trauma for any signs of dizziness, nausea, severe headache, and loss of consciousness. The forms of head trauma considered here are concussions, hematomas, contusions, and traumatic brain injuries.
CEREBRAL CONCUSSION ICD-9: 850.xx Description A cerebral concussion may result in a temporary loss of consciousness, typically lasting from a few seconds to a few minutes, followed by a short period of amnesia. The reaction of a boxer who has just been “knocked out” is a classic example of cerebral concussion. It is the most common head injury in sports. Etiology This condition is usually caused by a blunt impact to the head of sufficient force to cause the brain to strike and rebound from the skull. The loss of consciousness, subsequent amnesia, and other bodily symptoms of cerebral concussion are due to disruption of normal electrical activity in the brain. The brain tissue itself is usually not injured. Signs and Symptoms Primary symptoms are temporary loss of consciousness with shallow respirations, depressed pulse rate, and flaccid muscle tone. After the individual regains consciousness, there is usually a variable period of amnesia that may be accompanied by bradycardia, faintness, pallor, hyp...
Neurons The nervous system contains billions of neurons, or nerve cells, that make up nerves. The cell body of each neuron contains deoxyribonucleic acid (DNA) in its nucleus, endoplasmic reticulum and ribosomes for building proteins, and mitochondria for making energy. The neuron is a cell specialized to initiate or conduct electrochemical impulses and to react to physical and chemical changes in its surroundings. Each neuron has a long axon that may be sheathed in myelin and many tiny branches called dendrites. The dendrites of the neuron carry messages to the cell body coming from other neurons; the axon of the neuron carries impulses away from the cell body to other neurons, sometimes at a great distance. For example, the neurons making up the nerves going from the spinal cord to the toes may be as long as 3 feet. The neuron cell bodies and all their dendrites appear gray to the naked eye—thus the reference to gray matter. The neuron axons and their myelin sheathes appear white in color...
Peripheral Nervous System Together the CNS and the PNS provide three general functions: sensory, integrative, and motor. The sensory function consists of receptors that monitor the body both externally and internally. The sensory receptors convert their information into nerve impulses, which are then transmitted via the PNS to the CNS, and the signals are integrated. They are brought together, creating sensations and helping to produce thoughts and perceptions. As a result, we make decisions and use motor functions to act on them. The PNS includes the cranial and spinal nerves as well as the ANS. Cranial Nerves Twelve pairs of cranial nerves come from the brain. They are named both by Roman numeral and name. The Roman numeral partially identifies the cranial nerves’ location in the brain. Refer to Table for a summary of the cranial nerves and their function. Table. Cranial Nerves NUMBER AND NAME FUNCTION(S) I Olfactory • Sense of smell II Optic • Sense of sight III Oculomo...
COMMON SYMPTOMS OF NERVOUS SYSTEM DISEASES AND DISORDERS Individuals may present with the following common symptoms, which deserve attention from health-care professionals: Headache Weakness Nausea and vomiting Motor disturbances, such as stiff neck or back, rigid muscles, seizures, convulsions, or paralysis Sensory disturbances of any kind, especially vision or speech Drowsiness, stupor, unconsciousness, or coma Mood swings Fever Pain