Nervous System Terms

Nervous System Diseases

Multiple Sclerosis – Literally, “many hardenings”, MS is a disease of unknown cause that manifests as multiple hard plaques of degeneration of the insulating layer of nerve fibers in the central nervous system. The loss of insulation allows “short circuiting” of nerve impulses. Depending upon where the degeneration occurs, patients may suffer paralysis, sensory disturbances or blindness.

Cerebrovascular accident (CVA) - the fancy name for a “stroke”. A blood vessel in the brain may burst causing internal bleeding. Or, a clot may arise in a brain blood vessel (a thrombus), or arise elsewhere (embolus) and travel to get stuck in a brain vessel which then deprives brain tissue of oxygen. Depending upon the area of the brain involved, the patient may suffer paralysis, loss of speech or loss of vision.

Transient Ischemic Attack (TIA) - “Ischemia” was introduced previously in the circulatory diseases module referring to the heart. It literally means “not quite enough blood”. A short period of insufficient blood supply to the brain can have the same signs and symptoms as a stroke such as weakness in an arm, a partial loss of vision, but the problem lasts less than 24 hours. People who get TIA’s are at increased risk of having a stroke in the future.

Epilepsy - a Greek word for “seizure”. Convulsions is another term used. Seizures may have many causes and not all seizures are epilepsy. High fevers in young children may trigger seizures which are short in duration, easily controlled and, typically, have no permanent aftereffects. Epilepsy is a specific condition which may occur at any age, seizures are more intense, longer lasting in duration, and recur with some frequency. The condition may be controlled with medication, or if unresponsive to drugs, may require surgery.

Aphasia - loss of speech. The speech centers are located on the left side of the brain in a majority of people. If someone suffers a “stroke” (cerebrovascular accident-CVA), or traumatic brain injury, and it involves the left side of the brain, they may suffer speech impediments that vary over a spectrum of problems from difficulty in finding the right word, speaking slowly and with difficulty, or complete loss of speech. Actually, there are two speech centers. Injury described above involves the motor speech area, the area of the brain that produces language by integrating thoughts of speech with the movements of the larynx, lips and tongue. There is a second speech area, the receptive or sensory area, that enables us to understand speech. Injury to the latter results in still fluent speech, but the individual does not understand what they are hearing.

Nervous System Procedures

Neurologist - a physician specializing in diseases of the brain, spinal cord and nerves. He/she may refer a patient to a neurosurgeon. Neurologists do not do surgery.

Lumbar (spinal) puncture or tap (LP) - introducing a needle between the lower bony vertebrae of our spinal column allows a physician to sample the fluid, cerebrospinal fluid (CSF), surrounding the brain and spinal cord. Lab tests on the fluid are used for diagnostic purposes such as presence of bacteria in meningitis, special proteins in multiple sclerosis, or blood cells.

Brain scan - introducing a radioactive element into the blood can image possible tumors in the brain. The radioactive dose is very low and detectable only with special, very sensitive instruments that are much more sophisticated than the old Geiger counters.

Electroencephalography (EEG) - Wow, what a mouthful, but take it apart. Starting at the end of the word: an image (in this case a written recording) of the brain’s electrical activity. EEG’s are used to diagnose different types of seizure disorders such as epilepsy, brain tumors, and are used in sleep research to identify stages of sleep.

Computed tomography (CT) - a specialized X-ray machine that takes multiple images of a body area from different angles and has a computer that integrates the multiple images into “slices” of the body. The resolution is much better than standard X-rays, lower X-ray doses are used, and there is better differentiation of types of tissue (bone, air, solid organ).

Magnetic Resonance Imaging (MRI) – Although the image produces the “slices” through the body seen by CT (see above), no X-rays are involved. The patient’s body is placed in a strong magnetic field. Radio pulses affect the resonance or “spin” of atoms in the tissues. A computer analyzes this information to show subtle differences in tissue molecular structure producing very high resolution and better differentiation of soft tissue, such as a tumor within the liver.

Roots, suffixes, and prefixes

fat -        adip/o
fat -         lip/o
fat-         steat/o
skin -        cutane/o
skin-         dermat/o
skin-         derm/o
sweat-         hidr/o
sweat-         sudor/o
dry, scaly-         ichthy/o
horny tissue; hard; cornea-         kerat/o
fungus (plural, fungi) -        myc/o
nail -        onych/o
nail-         ungu/o
hair -        pil/o
hair -        trich/o
hardening; sclera (white of eye) -        scler/o
sebum, sebaceous-         seb/o
scale -        squam/o
foreign, strange -        xen/o
skin –        derma
treatment -        -therapy
same -        homo-

Clavicle – clavicul/o  – Collar bone

Functions of the skeletal system

There are about 206 bones in the human body, they have the function of protecting and preserving the shape of soft tissues. The skeleton provides a framework for the muscles, it controls and directs internal pressure and provides stability anchoring points for other soft tissues. There are a wide variety of bones/bony tissues adapted for specific functions to aid locomotion and support, bones are moved by the skeletal muscles. In addition the skeletal system stores and produces blood cells in the bone marrow.

The skeleton

It is not the aim of this guide to catalogue each bone, but the following may be useful:

Thorax

the bones of the thorax (ribs, sternum and thoracic vertebrae) form a cage which protects many of the body’s vital organs.

The Axial skeleton

This is the main body including the pelvis, thorax, and skull (excluding the arms and legs).

The Proximal skeleton

The femur and humerus (ie the bones proximal to the Axial skeleton)

The Distal skeleton

The lower legs (tibia, fibula, and feet bones) and lower arm (radius, ulna, and bones of the hand). The Proximal and Distal skeleton are sometimes collectively referred to as bones of the extremities.

The spine The spine is divided into 5 main areas and each bone (verebrae) has a letter and number.

Cervical vetebrae C1 – C7

the neck region. C1 is the upper most vertebrae.

Thoracic vertabrae T1 – T12

vertebrae of the upper body (thorax)

Lumbar vertebrae L1 – L5

vertebrae of the lower back

Bones of the sacrum S1 – S5

vertebra within the pelvic girdle. These bones fuse together between ages 16 and 18.

The coccyx Co1 – Co4

The lower tip of the spine. These bones fuse together between ages 20 to 30.

Parts of a bone

Diaphysis - The long shaft of the bone.
Epiphysis - The knob like end of the bone, often contains red marrow (blood cells).
Metaphysis - Region where the diaphysis joins the epiphysis, important in bone growth.
Medullary - Marrow cavity inside the bone. Contains yellow marrow (fat cells).
Foramina - Tiny canals in the bone through which blood and lymph vessels connect to the medullary.
Cartilage - Tough connective tissue covering the ends of the bone. The cartilage reduce friction and acts as a shock absorber.
Ligament - Fibrous tissue that connects bones or cartilage to strengthen and support joints.The end of the bones are often refered to by the Proximal end (towards the main body) or the Distal end (away from the main body), e.g. the proximal femur is the top end of the thigh bone..

Types of bone

Compact bone - Compact bone is dense and hard, especially the outer layer of the bone.
Spongy bone - Made up of a lattice work of bone, the spaces are filled with red marrow which produce blood cells.Classification of bones by shape:
Long bones - Slightly curved for STRENGTH with long narrow shafts with knobbly ends (especially found in arms and legs e.g. femur).
Short bones - Tend to be spongy e.g. wrists, fingers, toes and ankles.
Flat bones - Plate like and highly PROTECTIVE e.g. bones of the skull protect the brain.
Irregular bones e.g. vertebrae (spine)

Bones and growth

Ossification is the gradual conversion of cartilage or other tissue into bone. At birth ossification is not complete, there are still may membrane filled spaces in the skull, these are called fontanels or “soft spots”. Most bone growth occurs during childhood, and ossification of most bones is usually complete by age 25. The 5 bones of the sacrum fuse together from ages 18 to 25. When all bone growth is complete the body is said to be skeletally mature.

Roots, suffixes, and prefixes