Bma Illustrated Medical Dictionary

tomographyAn imaging technique that

produces a cross-sectional image (“slice”)

of an organ or part of the body. Most

tomography today is performed using

CT scanningand MRI, which produce

accurate and detailed images.

-tomyA suffix denoting the operation

of cutting or making an incision.

tone, muscleThe natural tension in the

musclefibres. At rest, all muscle fibres

are kept in a state of partial contraction

by nerve impulses from the spinal cord.

Abnormally high muscle tone causes an

increased resistance to movement, spas-

ticity, and rigidity. Abnormally low

muscle tone causes floppiness (see

hypotonia; hypotonia in infants).

tongue A muscular, flexible organ in the

floor of the mouththat is composed of a

mass of muscles covered by a mucous

membrane. The muscles are attached to

the mandible(lower jaw) and hyoidbone

above the larynx. Tiny nodules called

papillae stick out from the tongue’s

upper surface, giving it a rough texture.

Between the papillae at the sides and

base of the tongue are the taste buds.

Taste signals are picked up by nerve

fibres from 1 of 4 cranial nerves, and

impulses then travel to the brain. The

tongue plays an essential part in masti-

cation, swallowing, and speech.

tongue cancerThe most serious type of

mouth cancerdue to its rapid spread. It

mainly affects people over 40 and is as-

sociated with smoking, heavy alcohol

consumption, and poor oral hygiene. The

edge of the tongue is most commonly

affected. The first sign may be a small

ulcer with a raised margin, a leukoplakia,

a fissure, or a raised, hard mass.

Diagnosis of tongue cancer is made by

a biopsy. Small tumours, especially

those occurring at the tip of the tongue,

are usually removed surgically. Larger

tumours or those that have spread

often require radiotherapy.

tongue depressorA flat wooden or

metal instrument used to hold the

tongue on the floor of the mouth to

allow examination of the throat.

tongue-tieA minor mouthdefect, also

known as ankyloglossia, in which the

frenulum (the band of tissue attaching

the underside of the tongue to the floor

of the mouth) is too short and extends

forwards to the tip of the tongue. There

are usually no symptoms apart from lim-

ited movement of the tongue. Rarely,

the condition causes a speech defect,

and a minor operation is required to

divide the frenulum.

tonicOne of a diverse group of reme-

dies intended to relieve symptoms such

as malaise, lethargy, and loss of ap-

petite. Evidence suggests that tonics

mainly have a placeboeffect. The term

tonic is also used adjectivally to relate

to muscle tone (see tone, muscle), as in

the tonic neck reflex, one of the primi-

tive reflexesfound in newborn infants.

tonometryThe procedure for measur-

ing the pressure of the fluid within the

eye, usually performed by an ophthal-

mologist during an eye examination (see

eye, examination of). Tonometry is use-

ful in diagnosing glaucoma.

tonsilOne of a pair of oval tissue masses

at the back of the throat on either side.

The tonsils are made up of lymphoid

tissue and form part of the lymphatic

system. Along with the adenoids, at the

base of the tongue, the tonsils protect

against upper respiratory tract infec-

tions. The tonsils gradually enlarge

TOMOGRAPHY TONSIL

T

10th and

9th cranial

nerves

Epiglottis

Sweet

Tonsil

TONGUE

5th and

7th cranial

nerves

Sectioned

tongue

Bitter

taste

receptor

Sour

Salty