Medical Terminology
Glossary
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saccule - the lower and smaller of two chambers in the membranous labyrinth inside the vestibule of the inner ear; it contains a receptor organ for static equilibrium
sacral promontory - the superior surface of the body of the first sacral vertebra that projects anteriorly into the pelvic cavity; a line from the sacral promontory to the superior border of the pubic symphysis divides the abdominal and pelvic cavities
sagittal plane - vertical plane that divides the body or organs into left and right portions; such a plane may be midsagittal (median), with equal divisions, or parasagittal, with unequal divisions
saliva - a clear, alkaline, somewhat viscous secretion produced by the three pairs of salivary glands; contains various salts, mucin, lysozyme, and salivary amylase
salivary amylase - enzyme in saliva that initiates the chemical breakdown of starch, mostly in the mouth
salpingitis - inflammation of the uterine (Fallopian) or auditory (Eustachian) tube
sarcolemma - cell membrane of a muscle fiber (cell), especially, of a skeletal muscle fiber
sarcoma - a connective tissue tumor, often highly malignant
sarcomere - the contractile LETTER in a striated muscle fiber (cell) extending from one Z line to the next Z line
sarcoplasm - the cytoplasm of a muscle fiber (cell)
sarcoplasmic reticulum - a network of saccules and tubes surrounding the myofibrils of a muscle fiber (cell), comparable to endoplasmic reticulum; functions to reabsorb calcium ions during relaxation and to release them to cause contraction
satiety - fullness or gratification, as of hunger or thirst
scala tympani - lower spiral-shaped channel of the bony cochlea, filled with perilymph
scala vestibuli - upper spiral-shaped channel of the bony cochlea, filled with perilymph
sciatica - inflammation & pain along the sciatic nerve; felt at the back of the thigh, running down the inside of the leg
sclera - the white coat of fibrous tissue forming the outer protective covering over the eyeball, except in the most anterior portion; the posterior portion of the fibrous tunic
sclerosis - a hardening of tissues with loss of elasticity
scoliosis - abnormal lateral curvature compared with the normal vertical line of the backbone
scotoma - area of depressed or lost vision within the visual field
scotopsin - the protein portion of the visual pigment rhodopsin, found in rods of the retina
scrotum - a skin-covered pouch that contains the testes and their accessory structures
sebaceous - secreting oil
sebum - the secretion of sebaceous (oil) glands
secretion - production and release from a gland cell of a fluid, especially a functionally useful fluid as opposed to a waste product
sella turcica - depression on the superior surface of the sphenoid bone; houses the pituitary gland
semen - a fluid discharged at ejaculation by a male; consists of a mixture of spermatozoa and the secretions of the seminal vesicles, the prostate gland, and the bulbourethral (Cowper's) glands; also called seminal fluid
semilunar valve - valve guarding the entrance into the aorta or pulmonary trunk from a ventricle of the heart
seminal vesicle - one of a pair of convoluted pouchlike structures, lying posterior and inferior to the urinary bladder and anterior to the rectum in the male; they secrete a component of semen into the ejaculatory ducts
seminiferous tubule - tightly coiled duct, located in a lobule of the testis, in which spermatozoa are produced
senescence - the process of growing old; the period of old age
senile macular degeneration - a disease in which blood vessels grow over the macula lutea
senility - loss of mental or physical ability due to old age
sepsis - a morbid condition that results from the presence, in blood or body tissues, of pathogenic bacteria & their products
septicemia - presence of toxins or disease-causing bacteria in blood; also called blood poisoning
serosa - any serous membrane; the outermost layer of any organ, formed by a serous membrane; the membrane that lines pleural, pericardial, & peritoneal cavities
serous membrane - a membrane that lines a body cavity that does not open to the exterior; also called the serosa
sesamoid bones - small bones usually found in tendons
sigmoid colon - the S-shaped portion of the large intestine, beginning at the level of the left iliac crest, projecting inward toward the midline, and terminating at the rectum, at about the level of the third sacral vertebra
sigmoidoscopy - visualization of the anal canal, rectum, and colon to: screen for colorectal cancer, collect samples for biopsy, remove polyps, gather specimens for culture, and photograph the intestinal mucosa
sinoatrial (SA) node - a compact mass of cardiac muscle fibers (cells) that are specialized for conduction & located in the right atrium beneath the opening of the superior vena cava; also called the sinuatrial node or pacemaker
sinus - hollow in a bone (paranasal sinus) or other tissue; a channel for blood (vascular sinus); any cavity having a narrow opening
sinusitis - an inflammation of the mucous membrane of a paranasal sinus
sinusoid - microscopic space or passage for blood in certain organs, such as the liver or spleen
Snellen test - a test used to evaluate any problems or changes in vision by measuring visual acuity
somatic nervous system - a portion of the peripheral nervous system made up of the somatic efferent fibers that run between the central nervous system and the skeletal muscles and skin
somatomedin - a small protein produced by the liver in response to human growth hormone (hGH) stimulation; it mediates most of the effects of hGH
somesthetic - pertaining to sensations & sensory structures of the body
somite - block of mesodermal cells in a developing embryo; can be distinguished into a myotome (forms most of the skeletal muscles), a dermatome (forms connective tissues), and a sclerotome (forms the vertebrae)
spasm - a sudden, involuntary contraction of large groups of muscles
spastic - being characterized by an increase in muscle tone (stiffness), accompanying increased tendon reflexes and abnormal reflexes (Babinski sign)
spasticity - hypertonia, characterized by increased muscle tone, increased tendon reflexes, and pathological reflexes (Babinski sign)
spermatic cord - supporting structure of the male reproductive system, extending from the testis to the deep inguinal ring; it includes the ductus (vas) deferens, arteries, veins, lymphatics, nerves, a cremaster muscle, and connective tissue
spermatogenesis - formation and development of spermatozoa in the seminiferous tubules of the testis
spermatozoon - a mature sperm cell
spermicide - any agent that kills spermatozoa
spermiogenesis - the maturation of spermatids into spermatozoa
sphincter - circular muscle constricting an orifice
sphygmomanometer - instrument for measuring arterial blood pressure
spina bifida - a congenital defect of the vertebral column in which the halves of the neural arch of a vertebra fail to fuse in the midline
spinal cord - a mass of nerve tissue located in the vertebral canal from which 31 pairs of spinal nerves originate
spinous process - sharp or thornlike process or projection; also called a spine; the sharp ridge running diagonally across the posterior surface of the scapula
spirometer - apparatus used to measure air capacity of the lungs
splanchnic - pertaining to the viscera
spleen - a large mass of lymphatic tissue between the fundus of the stomach and the diaphragm; functions in phagocytosis, the production of lymphocytes, and blood storage
sputum - substance ejected from the mouth, containing saliva and mucus
squamous - scalelike
starvation - loss of energy stores in the form of glycogen, fats, and proteins, due to inadequate intake of nutrients or inability to digest, absorb, or metabolize ingested nutrients
stasis - a stagnation or halt of normal flow of fluids (as the blood or urine) or of the intestinal mechanism
static equilibrium - the maintenance of posture in response to changes in the orientation of the body, mainly the head, relative to the ground
stell. reticuloendothel. cell - phagocytic cell that lines a sinusoid of the liver; also called a Kupffer's cell
stenosis - an abnormal narrowing or constriction of a duct or opening
stereocilia - groups of extremely long, nonmotile microvilli, projecting from the epithelial cells lining the epididymis
stereognosis - an ability to recognize the size, shape, and texture of an object by touch
sterile - free from any living micro-organisms; unable to conceive or produce offspring
sterilization - an elimination of all living microorganisms; rendering an individual incapable of reproduction; e.g., castration, vasectomy, or hysterectomy
strabismus - a condition in which the visual axes of the two eyes differ, so that they do not fix on the same object; condition of being cross-eyed
stratum basalis - the outer layer of endometrium, next to the myometrium, that is maintained during menstruation and gestation; it produces a new functionalis following menstruation or parturition
stratum functionalis - the inner layer of the endometrium, adjacent to the uterine cavity, that is shed during menstruation; forms the maternal portion of the placenta during gestation
stricture - a local constriction of a tubular structure
stroma - the tissue that forms the ground substance, foundation, or framework of an organ, as opposed to its functional parts
stupor - state of unresponsiveness from which a patient can be aroused only briefly and by vigorous and repeated stimulation
subarachnoid space - space between the arachnoid and the pia mater; it surrounds the brain and the spinal cord; cerebrospinal fluid circulates through it
subcutaneous - underneath the skin; also called hypodermic
subdural space - a space between the dura mater and the arachnoid of the brain and spinal cord; it contains a small amount of fluid
sublingual gland - one of the pair of salivary glands situated in the floor of the mouth under the mucous membrane, to the side of the lingual frenulum; its duct (Rivinus's) opens into the floor of the mouth
submandibular gland - salivary gland beneath the base of the tongue under the mucous membrane in the posterior floor of the mouth (behind sublingual glands); duct (Wharton's) situated to the side of the lingual frenulum; also called the submaxillary gland
submucosa - layer of connective tissue located beneath a mucous membrane, as in the gastrointestinal tract or the urinary bladder; the submucosa connects the mucosa to the muscularis tunic
subserous fascia - layer of connective tissue internal to the deep fascia, lying between deep fascia and the serous membrane lining the body cavities
sudoriferous gland - an apocrine or exocrine gland in the dermis or subcutaneous layer; produces perspiration; also called a sweat gland
sulcus - groove or depression between parts, especially between the convolutions of the brain; plural, sulci
summation - algebraic addition of the excitatory and inhibitory effects of all stimuli applied simultaneously to a nerve cell body (spatial); increased strength of muscle contraction resulting when stimuli occur in rapid succession (temporal)
superficial - located on or near the surface of the body
superior - toward the head of upper part of a structure; also called cephalad or craniad
supination - movement of the forearm in which the palm of the hand is turned anteriorly or superiorly
suppuration - pus formation & discharge
surfactant - a phospholipid substance produced by the lungs; it decreases surface tension
susceptibility - a lack of resistance of a body to the deleterious or other effects of agents such as pathogenic micro-organisms
suspensory ligament - fold of peritoneum extending laterally from the surface of the ovary to the pelvic wall
sustentacular cell - a supporting cell of seminiferous tubules; produces a hormone (inhibin) as well as secretions supplying nutrients to spermatozoa; also called a Sertoli cell
sutural bone - small bone located within a suture between certain cranial bones; also called Wormian bone
suture - an immovable fibrous joint in the skull where bone surfaces are closely LETTERed
sympathetic division - autonomic nervous system subdivision; preganglionic neuron cell bodies are in thoracic and upper lumbar segments of the spinal cord; primarily concerned with processes involving energy expenditure; also called the thoracolumbar division
sympathomimetic - producing effects mimicking those brought about by the sympathetic division of the autonomic nervous system
symphysis - a line of union; a slightly movable cartilaginous joint, e.g., the symphysis pubis between the anterior surfaces of the coxal (hip) bones
symptom - a subjective change in body function not apparent to an observer, such as fever or nausea, that indicates the presence of a disease or disorder of the body
synapse - the junction between the processes of two adjacent neurons; the place where the activity of one neuron affects the activity of another; may be electrical or chemical
synapsis - the pairing of homologous chromosomes during prophase I of meiosis
synaptic cleft - the narrow gap that separates the axon terminal of one nerve cell from another nerve cell or muscle fiber (cell) and across which a neurotransmitter diffuses to affect the postsynaptic cell
synarthrosis - an immovable joint
synchondrosis - a cartilaginous joint in which connecting material is hyaline cartilage
syncope - a faint; sudden temporary loss of conciousness associated with loss of postural tone and followed by a spontaneous recovery; most commonly caused by cerebral ischemia
syndesmosis - a fibrous joint in which articulating bones are LETTERed by dense fibrous tissue
syndrome - a group of signs and symptoms that occur together in a pattern that is characteristic of a particular disease or abnormal condition
syneresis - process of clot retraction
synergist - a muscle that assists the prime mover by reducing undesired action or unnecessary movement
synergistic effect - a hormonal interaction in which the effects of two or more hormones complement each other so that the target cell responds to the sum of the hormones; an example is the combined actions of estrogens, progesterone, prolactin, and oxytocin in lactation
synostosis - a joint in which the dense fibrous connective tissue that LETTERes bones at a suture has been replaced by bone, resulting in a complete fusion across the suture line
synovial cavity - the space between the articulating bones of a synovial (diarthrotic) joint filled with synovial fluid; also called a joint cavity
syphilis - a sexually transmitted disease caused by the bacterium Treponema pallidum
systemic lupus erythematosus - autoimmune inflammatory disease that may affect every tissue of the body; characterized by weakness, fever, fatigability, joint pain or arthritis, reddish skin lesions, lymphadenopathy, and malfunctions of many organ systems; also called SLE
systole - a part of the cardiac cycle; the phase of contraction of the heart muscle, especially the ventricles
systolic blood pressure - force exerted by blood on the arterial walls during ventricular contraction; highest pressure measured in the large arteries, about 120 mm Hg under normal conditions for young, adult males