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pachymeninx - Greek pachys = thick, and meninx = membrane; hence, the thick membrane covering the central nervous system, i.e., dura mater.

palaeo - Greek palaios = old; hence, palaeocerebellum, the earliest stage in the evolution of the cerebellum.

palate - Latin palatum = palate, adjective - palatal or palatine.

Palato- - (L. palatum, palate). Relating to the hard or soft palate.

paleo - Greek palaios = old; hence, paleocerebellum, the earliest stage in the evolution of the cerebellum.

Palliative - Palliative means "relief of symptoms." Most often, palliation is the relief of pain.

pallidus - adjective, Latin = pale.

pallium - Latin = cloak; hence, the cerebral cortex forming the outer covering of the cerebral hemisphere.

Pallor - Unnatural lack of color in the skin (as from bruising or sickness or emotional distress)

palma - Latin palma = palm; adjective, palmar - Latin palmaris.

Palmaris - (L. palma, palm of the hand). Pertaining to muscles of the forearm, wihich may insert into the palmar aponeurosis.

palpate - Latin palpare = to touch, and palpatus = touched; hence, to examine by feeling, and palpation, such an examination.

palpebra - Latin = eyelid, probably from palpitare = to flutter.

Palpebrae - (L. palpebra, eyelid). The eyelid.

pampiniform - adjective, Latin pampinus = tendril, and forma = shape.

pancreas - Greek = sweetbread, derived from Greek pan = all, and kreas = flesh; adjective - pancreatic.

Pancytopenia - An abnormal deficiency in all blood cells (red blood cells and white blood cells and platelets); usually associated with bone marrow tumor or with aplastic anemia

Panniculitis - Inflammation of subcutaneous fat.

Panniculus - (L. pannus, cloth). Pertaining to a thin sheet of dermal muscle. Diminutive of Latin pannus = cloth.

papilla - Latin = nipple or teat; adjective - papillary. Papilla (pl. papillae) - A hump or swelling.

paradidymis - Greek para = beside of near, and didymis = twinned or paired, refers to testes; hence the collection of convoluted tubules in the spermatic cord, above the head of the epididymis.

paraesthesia - Greek para = beside, and aisthesia = sensation; hence, abnormal sensation, usually burning or pricking.

paralysis - Greek para = beside, near, lyein = to loosen; hence loss or impairment of muscle function.

parametrium - Greek para = beside, and metra = womb; hence, connective tissue alongside the body of the uterus, within the broad ligament.

paraplegia - Greek para = beside, and plege = a stroke; hence, paralysis of the lower limbs.

pararenal - adjective, Greek para = beside, Latin ren = kidney; hence, beside the kidney, e.g., pararenal fat, the fatty capsule of the kidney.

parasternal - adjective, Greek para = beside, and sternon = chest; hence, the parasternal line is a vertical line about midway between the sternal edge and the midclavicular line.

parasympathetic - adjective, Greek para = beside, syn = with, and pathos = feeling; hence, the division of the autonomic nervous system complementary to the sympathetic system.

parasympathetic nervous system - activates tranquil functions, such as stimulating the secretion of saliva or digestive enzymes into the stomach.

parathyroid - adjective, Greek para = beside, and thyroid; hence, beside the thyroid gland.

Parenchyma - The essential elements of an organ, used in anatomical nomenclature as a general term to designate the functional elements of an organ, as distinguished from its framework or stroma. Greek para = beside or near, en = in, and chein = to pour; hence a general term to designate the functional elements of an organ, as opposed to the framework or stroma.

paresis - Greek = relaxation, but has come to mean partial paralysis.

parietal - adjective, Latin parietalis, pertaining to paries = wall.

Parietal Peritoneum - The peritoneum is a thin membrane that lines the abdominal and pelvic cavities, and covers most abdominal viscera. It is composed of layer of mesthelium supported by a thin layer of connective tissue. Parietal peritoneum is that portion that lines the abdominal and pelvic cavities.

parotid - adjective, Greek para = beside, and otos = of the ear; hence, beside the ear.

parous - adjective, Latin pario = I bear (children); hence, adjective, applied to woman who has borne one or more children (cf. nulliparous, multiparous).

pars - Latin = part.

passive transport - the movement of substances from regions of higher to lower concentration and do not require expenditure of energy.

patella - Latin a small pan; adjective - patellar.

Patency - The state of being freely open or exposed.

Pathogen - A specific causative agent (such as a bacterium or virus) of disease.

pecten - Latin = comb.

pectinate - adjective, from Latin pecten = a comb; applied to structures having the appearance of parallel teeth arising from a straight back (musculi pectinati), or the sellar appearance of the superior pubic ramus, which may have resembled the body of antique com

pectineal - adjective, from Latin pecten = a comb; applied to structures having the appearance of parallel teeth arising from a straight back (musculi pectinati), or the sellar appearance of the superior pubic ramus, which may have resembled the body of antique com

Pectineus - (L. pecten, a comb). Pertaining to the os pubis or any ridged structure. A muscle. Latin, pecten = a comb; hence the muscle attaching to the pecten (pectineal line) of the pubic bone.

pectoral - adjective, Latin pectoris = of the front of the chest.

pectoralis - adjective, Latin pectoris = of the front of the chest.

Pectoro- - (L.pectus, pector-, chest). Pertaining to the muscles of the chest wall.

pedicle - diminutive of Latin pedis = of the foot.

Pedis - (L. pes, foot). Refering to the foot. Latin = of the foot.

peduncle - variation of pedicle.

pellucidum - adjective, Latin per = through, and lucere - to shine; hence, translucent.

pelvis - Latin = basin, adjective - pelvic.

Penis - (L. penis, tail) The male reproductive organ. Latin = tail, the male organ of copulation (cf. appendix, appendage).

pennate - Latin penna = feather; hence, a muscle whose fibres approach the tendon from one direction is unipennate; from two, bipennate, and from more than two, multipennate.

pennatus - (pinnate) - adjective, Latin penna = feather; hence, a muscle whose fibres approach the tendon from one direction is unipennate; from two, bipennate, and from more than two, multipennate.

perianal - adjective, Greek peri = around, and Latin anus = lower opening of alimentary canal.

pericardium - Greek peri = around, and kardia = heart; hence, the membranes enclosing the heart.

Perichondrium - A membrane around the surface of cartilage.

pericranium - Greek peri = around, and kranion = skull; hence, the external periosteum of the skull.

perilymph - Greek peri = around, and lympha - Latin = clear water; hence, the fluid in the bony labyrinth surrounding the membranous labyrinth (and continuous with the cerebrospinal fluid).

perineum - Greek the caudal aspect of the trunk between the thighs, or, the region of the trunk below the pelvic diaphragm; adjective - perineal.

periodontal - adjective, Greek peri = around, and odont = tooth.

periosteum - Greek peri = around, and osteon = bone; hence, the membrane around a bone.

peripheral - adjective, Greek peri = around and phero = carry; hence, away from the centre (cf. periphery).

peripheral nervous system (PNS) - consists of nerves outside the central nervous system.

peristalsis - the major means of propulsion in moving food along the digestive tract. Consists of a series of alternating contractions and relaxations of smooth muscle that lines the walls of the digestive organs and that forces food to move forward. Greek peri = around, and stellein - to constrict; hence, a circular constriction passing as a wave along a tube; adjective - peristaltic.

Peritoneum - The smooth serous membrane which lines the cavity of the abdomen and covers most of the abdominal organs forming a closed, or nearly closed sac. Greek periteino = to stretch around; hence, the membrane stretched around the internal surface of the walls and the external aspect of some of the contents of the abdomen; adjective - peritoneal.

peroneal - adjective, Greek perone = clasp, brooch - see fibula.

Peroneus - (G. perone, brooch or fibula). Pertaining to several muscles on the lateral or fibular side of the leg.

pes - Latin = foot.

Petechiae - Pin-head-sized sites of bleeding in the skin. This type of bleeding results from a very low platelet count. The small punctate hemorrhages are frequently seen on the legs, feet, trunk and arms. They evolve from red to brown and are eventually disappear. They stop developing when the platelet count increases.

petrosal - adjective, Latin petrosus = rocky.

petrous - adjective, Latin petrosus = rocky.

Peyer's patch - These are quite large aggregates of lymphoid tissue found in the small intestine, part of the lymphatic system which help to fight infection.

pH - A measure of acidity and alkalinity of a solution. The measure is a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity. On the scale, each unit of change represents a tenfold change in acidity or alkalinity.

phagocytes - white blood cells that wander throughout the body attacking bacteria and other foreign invaders.

Phagocytic - Capable of functioning as a phagocyte. A phagocyte is a cell that is able to engulf and break down foreign particles, cell debris and disease producing micro-organisms in the body. Form an important part of the natural defence mechanism in most animals.

Phalangei - (F., G., L. phalanx, a formation of Roman soldiers). Pertaining to the bones of the fingers.

phalanx - Latin = row of soldiers; hence, one of the small bones of a digit, plural - phalanges, adjective - phalangeal.

phallus - Greek phallos = penis.

Pharyngeus - (G. pharynx, throat). Pertaining to the pharynx.

pharynx - Greek = throat; adjective - pharyngeal.

Phenotype - A set of observable physical characteristics of an individual organism. A single characteristic can be referred to as a "trait," although a single trait is sometimes also called a phenotype. For example, blond hair could be called a trait or a phenotype, as could obesity. A phenotype can be the result of many factors, including an individual's genotype, environment, and lifestyle, and the interactions among these factors. The observed manifestation of a genotype, a phenotype may be expressed physically, biochemically, or physiologically.

Pheochromocytoma - A tumor that is derived from chromaffin cells and is usually associated with paroxysmal or sustained hypertension.

Philadelphia Chromosome - Characteristic chromosomal abnormality in which a portion of chromosome 22 is translocated to chromosome 9. This abnormality is found in nearly all cases of chronic myeloid leukaemia and some cases of acute lymphoblastic leukaemia.

philtrum - Greek philtron - the median sulcus of the upper lip. Derivation doubtful.

phonation - Greek phone = sound or voice; hence, the production of either.

phrenic - Greek phren = diaphragm or mind; hence, diaphragmatic (cf. schizophrenic).

physiology - the study of the function of body parts and the body as a whole.

pia - Latin = faithful, hence, the membrane which faithfully follows the contour of the brain and spinal cord.

pilomotor - Latin pilus = a hair, and movere = to move; hence the action of the arrectores pilorum muscles.

pilus - Latin = a hair.

pineal - adjective, Latin pinea = a pine cone; hence, the pineal gland which is cone-shaped.

piriform - adjective, Latin pirum = a pear; hence, pear-shaped.

Piriformis - (L. pirum, pear + forma, shaped). Pear-shaped.

Pisiform - (L. pisum, pea + forma). Pea-shaped or pea sized.

pituitary - Latin pituita = mucous or phlegm, the gland was thought to produce mucous that discharged through the nose.

Placenta - The vascular organ in mammals, except monotremes and marsupials, that unites the fetus to the maternal uterus and mediates its metabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues.

placode - Greek plax = plate or flat, and eidos = shape or form.

plane - Latin planus = flat; hence, a real or imaginary flat surface.

planta - Latin the sole of the foot; adjective - plantar or plantaris.

plantar - adjective, Latin planta = the sole of the foot.

Plantaris - (L. plantaris, sole of the foot) Pertaining to a muscle of the foot, musculus plantaris.

Plasma - The fluid part of blood, lymph, or milk as distinguished from suspended material. Straw-colored, liquid portion of the blood, which consists of water, proteins, waste products, nutrients, electrolytes, and respiratory gases.

plasma (cell) membrane - separates internal metabolic events from the external environment and controls the movement of materials into and out of the cell. It bounds the cell and encloses the nucleus and cytoplasm.

Plasmacytoma - Any discrete, presumably solitary, mass of neoplastic plasma cells either in bone marrow or various extramedullary sites.

Platelets - A particle found in the bloodstream that binds at the site of a wound to begin the blood clotting process. Platelets are formed in bone marrow.

Platysma - (G. platys, flat or broad). A broad flat dermal muscle of the thorax and neck. Greek = flat object; hence, the flat subcutaneous muscle extending from below the clavicle to the mouth.

Pleomorphism - A hardening within the nervous system, especially of the brain and spinal cord, resulting from degeneration of nervous elements such as the myelin sheath.

Pleura - The delicate serous membrane that lines each half of the thorax of mammals and is folded back over the surface of the lung of the same side.

pleura - Greek = a rib. Later used to name the serous membrane lining the chest walls and the lung on each side.

Pleural Effusion - A collection of fluid (or blood) in the pleural space (in one side of the chest cavity around the lung). May be secondary to trauma, cancer, nephrotic syndrome, kidney disease, pancreatitis, congestive heart failure and cirrhosis.

plexus - Latin = a network or plait.

plica - Latin plicare = to fold; hence, a fold.

Plicae Circulares - Plicae circulares are macroscopically visible, crescent-shaped folds of the mucosa and submucosa. Plicae circulares extend around one-half to two-thirds of the circumference of the lumen of the small intestine.

pneumon - Greek pneuma = air.

pollex - Latin = thumb.

Pollicis - (L. pollex, thumb). Relating to the thumb. genitive (possessive case) of Latin pollex = thumb; hence of the thumb.

Polypectomy - Excision of a polyp.

polysaccharide - a carbohydrate that is a series of connected monosaccharides.

Polyvinylchloride - A carcinogenic polymer used in plastics and is commonly known as PVC.

pons - Latin = bridge; adjective - pontine; part of the brain stem.

Popliteus - (L. poples, the ham of the knee). Pertaining to a muscle of the popliteal space. Latin poples = the ham or thigh, and sometimes, the knee; adjective, popliteal, referring to the fossa behind the knee or its contents.

porta - Latin = a gate, also Latin portare = to carry; hence, the portal system carries venous blood from the alimentary tract to the porta hepatis; adjective - portal.

porus - Latin a pore or foramen; hence, the openings of the acoustic meatuses.

positive feedback - an action intensifies a condition so that it is driven farther beyond normal limits.

posterior - adjective, Latin post = behind (in place or time).

posture - Latin positus = placed; hence, the position of the body as a whole at a given moment, e.g. erect, recumbent, prone, supine, sitting, kneeling.

precuneus - Latin pre = before, and cuneus = wedge; hence, the parietal lobule anterior to the cuneus.

prepuce - Latin praeputium = foreskin (of penis or clitoris).

primary sex organs (gonads) - secrete hormones that produces gametes.

Primary Site - The anatomic site where the original tumor is located. Primary cancer is usually named after the organ in which it starts. For example, cancer that starts in the breast is always breast cancer even if it spreads (metastasizes) to other organs such as bones or lungs.

princeps - Latin primus = chief, and capere = to take; hence chief or principal.

Procerus - (L. procerus, long or stretched-out). A muscle of the nose.

procerus - Latin = slender, elongated; hence, the vertical slip of muscle between the medial part of frontalis and the root of the nose.

process - Latin = going forwards, used to indicate growing out, i.e., an outgrowth, usually of bone, e.g., the zygomatic process of the temporal.

process of sight - involves converting light energy into chemical energy.

processus - Latin going forwards, used to indicate growing out, i.e., an outgrowth, usually of bone, e.g., the zygomatic process of the temporal.

profundus - Latin pro = before, and fundus = bottom; hence profundus = deep.

Progesterone - A female steroid sex hormone C21H30O2 that is secreted by the corpus luteum to prepare the endometrium for implantation and later by the placenta during pregnancy to prevent rejection of the developing embryo or fetus.

Prognosis - The patient's potential clinical outlook based on the status and probable course of his disease.

Prolactin - Prolactin,produced from the anterior pituitary gland, it's found in the serum of normal females and males. Prolactin's principal physiological action is to initiate and sustain lactation.

Proliferation - The reproduction or multiplication of similar forms, especially of cells and morbid cysts.

prominens - Latin = projecting.

promontory - Latin promontorium = a headland, i.e., part of land jutting into the sea - used for a bony prominence.

pronate - Latin pronatus = bent forwards; hence to pronate = to turn the hand so that the palm faces posteriorly.

Pronator (L. pronare, to bend forward). A muscle that, on contraction, rotates the hand so that the palm of the hand faces backward when the arm is in the anatomical position. 

prone - Latin pronatus = bent forwards; hence, recumbent face-down posture.

proprioceptive - Latin proprius = one's own, and captum = taken; hence, sensory impulses received by the joints and muscles within one's own body.

Proptosis - Forward displacement (bulging) of an organ, typically the eyeball(s).

prosection - Latin pro = before, and sectum = cut. A dissection prepared for demonstration of anatomic structures.

prosector - Latin pro = before, and sectum = cut. One who prepares a dissection for demonstration.

prosencephalon - Latin pro = in front, and Greek enkephalos = brain; hence, the part of the brain rostral to the midbrain.

prostate - Greek pro = before, and Latin = statum = stood; hence, something which stands before - the prostate stands before the urinary bladder.

Protein - Any of numerous naturally occurring extremely complex substances that consist of amino-acid residues joined by peptide bonds, contain the elements carbon, hydrogen, nitrogen, oxygen, usually sulfur, and occasionally other elements (as phosphorus or iron), and include many essential biological compounds (as enzymes, hormones, or immunoglobulins). Represent a class of molecules that have varied functions. Eggs, muscles, antibodies, silk, fingernails, and many hormones are partially or entirely proteins. fragments of huge cells that adhere to damaged blood vessel walls and release enzymes that activate the stoppage of bleeding.

Proton - A proton is a subatomic particle found in the nucleus of every atom. The particle has a positive electrical charge, equal and opposite to that of the electron.

protract - Latin protractus = drawn out; hence, to put forwards (e.g., shoulder or mandible). Protraction - the act of protracting.

protrude - Latin protrudo = thrust forwards, e.g. the tongue; protrusion - the act of protruding.

protuberance - Latin protubero = I bulge out; hence, a bulging bony feature (see tuber).

proximal - adjective, Latin proxime = nearest; hence, nearer to the root of a limb.

Psoas - (G. psoa, muscle of the loin). Pertaining to muscles in the lumbosacral region, the "tenderloin".

psoas - Greek = loin.

Psoriasis - Psoriasis is a condition characterized by severe scaling and flakiness. Recent evidence indicates that the skin is rapidly reproducing cells creating an excess build-up because the skin cannot exfoliate normally.

pterion - Greek pteron = wing; hence, the region where the tip of the greater wing of the sphenoid meets or is close to the parietal, separating the frontal from the squamous temporal; alternatively the region where these 4 bones meet.

pterygoid - adjective, Greek pteryx = wing, and eidos = shape; hence, wing-shaped. transport oxygen and carbon dioxide in the blood.

Pterygoideus - (G. pteryx, or pteryg-, wing + eidos, resemblance). Wing-shaped. Applied to muscles associated with the pterygoid processes of the sphenoid bone.

ptosis - Greek = fall; hence, drooping of an eyelid, or descent of an internal organ.

Puberty - The condition of being or the period of becoming first capable of reproducing sexually marked by maturing of the genital organs, development of secondary sex characteristics, and in the human and in higher primates by the first occurrence of menstruation in the female. Latin puber = adult; hence, the time when hair appears in the pubic region - i.e., near the pubis - as a secondary sexual characteristic.

pubes - Latin = adult or signs of manhood, hence the lower abdominal secondary sexual hair.

Pubo- - (L. pubes, genitalis). Pertaing to muscles attaching to the os pubis.

pudendal - adjective, Latin pudendus = shameful; hence, pertaining to the external genitalia.

Puerperium - The period between childbirth and the return of the uterus to its normal size.

pulmonary - adjective, Latin pulmo = lung.

pulmonary circulation - deoxygenated blood travels from the right side of the heart to each of the two lungs. Within the lungs O2 enters and CO2 leaves so that oxygenated blood returns from the lungs to the left side of the heart.

pulp - Latin pulpa = a soft part of the body or tooth.

pulposus - Latin pulpa = a soft part of the body or tooth, hence pulpy or soft.

pulvinar - Latin pulvinus = rounded cushion; the posterior end of the thalamus.

punctum - Latin = a sharp point; hence a very small point or orifice.

pupil - the circular opening of the eye. The size of the pupil is controlled by the iris. The size of the pupil regulates the amount of light entering the eye and helps bring objects into focus. Latin pupilla = the central black orifice in the iris; adjective - pupillary.

Purpura - Hemorrhage under a surface that is about 1.0 cm. in diameter.

putamen - Latin = peel, husk or shell of fruit or seed (the external part of the lentiform nucleus).

Pyelogram - X-ray study of the kidney especially showing the pelvis (urine-collecting basin) of the kidney and the ureter. Greek pyelos = basin, and gramma = diagram; hence, radiograph of the renal pelvis (and usually of the ureter) after filling with contrast medium.

pylorus - Greek = gate-keeper; hence, the part of the pyloric canal containing the sphincter, which guards the opening into the duodenum; adjective - pyloric.

pyramid - Greek pyramis = a pyramid (solid with 3- or more-sided base, and flat sides meeting at the apex), adjective - pyramidal.

Pyramidalis - (G. pyramis, pyramid). Applied to muscles having, more or less, pyramidal shape.