Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary
Category: Health and Medicine > Medical Dictionary
Date & country: 31/12/2010, USA
Words: 39128


objective
(ob-jek´tiv) perceptible by the external senses. the lens or system of lenses of a microscope nearest the object that is being examined. achromatic objective one in which the chromatic aberration is corrected for two colors and the spherical aberration for one color. ...

objective sign
one that can be seen, heard, or felt by the diagnostician; called also physical sign.

objective symptom
one perceptible to others than the patient, such as pallor, rapid pulse, rapid respiration, or restlessness.

obligate
(ob´lĭ-gāt) not facultative; necessary; compulsory; pertaining to or characterized by the ability to survive only in a particular environment or to assume only a particular role, as an obligate anaerobe.

obligate parasite
obligatory parasite one that is entirely dependent upon a host for its survival.

obligatory
(әb-lig´ә-tor″e) obligate.

oblique
(o-blēk´) slanting; inclined.

oblique arytenoid muscle
one of the intrinsic muscles of the larynx; origin, muscular process of arytenoid cartilage; insertion, apex of opposite arytenoid cartilage; innervation, recurrent laryngeal nerve; action, closes inlet of larynx.

oblique auricular muscle
origin, cranial surface of concha; insertion, cranial surface of auricle above concha; innervation, temporal and posterior auricular nerves.

oblique fracture
one in which the break is in an oblique direction.

oblique hernia
oblique inguinal hernia indirect inguinal hernia.

oblique muscle of auricle
origin, cranial surface of concha; insertion, cranial surface of auricle above concha; innervation, temporal and posterior auricular nerves (branches of facial nerve).

oblique ridge
a variable linear elevation obliquely crossing the occlusive surface of a maxillary molar.

oblique vein of left atrium
a small vein from the left atrium that opens into the coronary sinus.

obliquity
(o-blik´wĭ-te) the state of being oblique or slanting, such as a fetus in utero.

obliquus capitis inferior muscle
origin, spinous process of axis; insertion, transverse process of atlas; innervation, posterior rami of spinal nerves; action, rotates atlas and head.

obliquus capitis superior muscle
origin, transverse process of atlas; insertion, occipital bone; innervation, posterior rami of spinal nerves; action, extends and moves head laterally.

obliquus reflex
stimulation of the skin below Poupart ligament contracts a part of the external oblique muscle.

obliterating pericarditis
pericarditis obliterans.

obliterating phlebitis
obliterative phlebitisobstructive phlebitis phlebitis that obstructs a vein.

obliteration
(ob-lit″әr-a´shәn) complete removal, as by disease, degeneration, surgical procedure, or irradiation, or by the filling up of a space with fibrous tissue or inflammation.

oblongata
(ob″long-gah´tә) oblong; see medulla oblongata.

obsession
(ob-sesh´әn) a recurrent, persistent thought, image, or impulse that is unwanted and distressing (ego-dystonic) and comes involuntarily to mind despite attempts to ignore or suppress it. Common obsessions involve violence, contamination, and doubts. See also obsessive-compulsive disorder and obsessive-compul...

obsessive-compulsive disorder
(OCD) an anxiety disorder characterized by recurrent obsessions and compulsions that are severe enough to interfere significantly with personal or social functioning. Performing compulsive rituals may release tension temporarily, and resisting them causes increased tension. This disorder is not the same as obsessi...

obstetric forceps
forceps for extracting the fetal head from the maternal passages.

obstetric paralysis
that due to injury received at birth; called also birth paralysis.

obstetrician
(ob″stә-trĭ´shәn) a physician who specializes in obstetrics.

obstetrician's hand
the contraction of the hand in tetany; the hand is flexed at the wrist, the fingers are flexed at the metacarpophalangeal joints but extended at the interphalangeal joints, and the thumb is strongly flexed into the palm.

obstetrics
(ob-stet´riks) the branch of health science dealing with pregnancy, labor, and the puerperium. adj., obstet´ric, obstet´rical., adj.

obstipation
(ob″stĭ-pa´shәn) intractable constipation.

obstructed testis
an ectopic testis whose descent was prevented by a fascial sheet at the entrance to the scrotum.

obstruction
(ob-struk´shәn) the act of blocking or clogging. the state or condition of being clogged; see also atresia. Called also blockade, closure, and occlusion. chronic airflow obstruction , chronic airway obstruction name given to a group of disorders in whi...

obstructive apnea
obstructive sleep apnea.

obstructive atelectasis
absorption atelectasis.

obstructive dysmenorrhea
that due to mechanical obstruction to the discharge of menstrual fluid.

obstructive emphysema
overinflation of the lungs associated with partial bronchial obstruction which interferes with exhalation.

obstructive jaundice
that due to blockage of the flow of bile; called also mechanical jaundice.

obstructive nephropathy
nephropathy caused by obstruction of the urinary tract (usually the ureter), with hydronephrosis, slowing of the glomerular filtration rate, and tubular abnormalities.

obstructive pneumonia
that due to obstruction of the air passages, as by bronchogenic carcinoma.

obstructive sleep apnea
obstructive sleep apnea syndrome(OSAS) sleep apnea resulting from collapse or obstruction of the airway with the inhibition of muscle tone that occurs during REM sleep. In adults it is seen primarily in middle-aged obese individuals, with a male predominance; in children it is often seen accompanying conditions su...

obstructive small airways disease
chronic bronchitis with irreversible narrowing of the bronchioles and small bronchi with hypoxia and often hypercapnia.

obstruent
(ob´stroo-әnt) causing obstruction or blocking. an agent that so acts.

obtund
(ob-tund´) to render dull, blunt, or less acute, or to reduce alertness.

obtundation
(ob″tәn-da´shәn) mental blunting with mild to moderate reduction in alertness and a diminished sensation of pain.

obturation
(ob″tә-ra´shәn) obstruction. canal obturation filling of a root canal completely and densely with a nonirritating hermetic sealing agent.

obturator
(ob´tә-ra´tәr) a disk or plate that closes an opening. a prosthesis for closing an acquired or congenital opening of the palate (cleft palate).

obturator artery
origin, internal iliac artery; branches, pubic, acetabular, anterior, and posterior branches; distribution, pelvic muscles, hip joint.

obturator externus muscle
origin, pubis, ischium, and external surface of obturator membrane; insertion, trochanteric fossa of femur; innervation, obturator nerve; action, rotates thigh laterally.

obturator foramen
the large opening between the pubic bone and the ischium.

obturator hernia
herniation of intestine or other abdominal organs through the obturator foramen.

obturator internus muscle
origin, pelvic surface of hip bone and obturator membrane, margin of obturator foramen, ramus of ischium, inferior ramus of pubis; insertion, greater trochanter of femur; innervation, fifth lumbar nerve, first and second sacral nerves; action, rotates thigh laterally.

obturator nerve
origin, lumbar plexus—L3–L4; branches, anterior, posterior, and muscular branches; distribution, adductor muscles and gracilis muscle, skin of medial part of thigh, and hip and knee joints; modality, general sensory and motor.

obturator sign
a sign of appendicitis: hypogastric or adductor pain elicited by passive internal rotation of the flexed thigh, due to contact between an inflammatory process and the internal obturator muscle.

obturator veins
veins that drain the hip joint and the regional muscles, enter the pelvis through the obturator canal, and empty into the internal iliac or the inferior epigastric vein, or both.

obtusion
(ob-too´zhәn) blunting of sensation and perception.

occipital
(ok-sip´ĭ-tәl) pertaining to the occiput; see occipital bone and occipital lobe.

occipital artery
origin, external carotid artery; branches, auricular, meningeal, mastoid, descending, occipital, and sternocleidomastoid branches; distribution, muscles of neck and scalp, meninges, mastoid cells.

occipital bone
the bone constituting the back and part of the base of the skull. It joins with the two parietal and two temporal bones, the sphenoid bone, and the atlas. It contains a large opening, the foramen magnum.

occipital diploic vein
the largest of the diploic veins, which drains blood from the occipital bone and empties into the occipital vein or the transverse sinus.

occipital emissary vein
an occasional small vein running through a minute foramen in the occipital protuberance of the skull and connecting the junction of the sinuses with the occipital vein.

occipital fontanelle
posterior fontanelle.

occipital gyrus
any of the three (superior, middle, and inferior) gyri of the occipital lobe.

occipital horn syndrome
the X-linked recessive form of cutis laxa.

occipital lobe
the most posterior portion of each cerebral hemisphere, forming a small part of its posterolateral surface.

occipital point
the posterior point on the occipital bone.

occipital pole
the posterior end of the occipital lobe of the brain.

occipital sinus
a venous sinus of the dura mater, passing upward along the midline of the cerebellum.

occipital triangle
the area bounded by the sternocleidomastoid muscle in front, the trapezius muscle behind, and the omohyoid muscle below.

occipital vein
a vein in the scalp that follows the distribution of the occipital artery and opens under the trapezius muscle into the suboccipital venous plexus; it may continue with the occipital artery and end in the internal jugular vein. any of the group of superficial superior cerebral veins that drain the cortex of the oc...

occipitalization
(ok-sip″ĭ-tәl-ĭ-za´shәn) synostosis of the atlas with the occipital bone.

occipitoanterior position
a position of the fetus in cephalic presentation in labor, with its occiput directed toward the right (ROA) or left (LOA) anterior quadrant of the maternal pelvis.

occipitocervical
(ok-sip″ĭ-to-sur´vĭ-kәl) pertaining to the occiput and neck.

occipitofrontal
(ok-sip″ĭ-to-fron´tәl) pertaining to the occiput and the face.

occipitofrontalis muscle
occipitofrontal muscle: origin,FRONTAL BELLY—galea aponeurotica, OCCIPITAL BELLY—highest nuchal line of occipital bone; insertion,FRONTAL BELLY—skin of eyebrows and root of nose, OCCIPITAL BELLY—galea aponeurotica; innervation,FRONTAL BELLY—temporal branch of facial nerve, OCCIPITAL BELLY—posterior...

occipitomastoid
(ok-sip″ĭ-to-mas´toid) masto-occipital.

occipitomental
(ok-sip″ĭ-to-men´tәl) pertaining to the occiput and chin.

occipitoparietal
(ok-sip″ĭ-to-pә-ri´ә-tәl) pertaining to the occipital and parietal bones or lobes of the brain.

occipitoposterior position
a position of the fetus in cephalic presentation in labor, with its occiput directed toward the right (ROP) or left (LOP) posterior quadrant of the maternal pelvis.

occipitosacral position
a position of the fetus in cephalic presentation in labor, with the occiput presenting directly behind, or rotated squarely into the hollow of the sacrum.

occipitotemporal
(ok-sip″ĭ-to-tem´pә-rәl) pertaining to the occipital and temporal bones.

occipitothalamic
(ok-sip″ĭ-to-thә-lam´ik) pertaining to the occipital lobe and thalamus.

occipitotransverse position
a position of the fetus in cephalic presentation in labor, with its occiput directed toward the right (ROT) or left (LOT) iliac fossa of the maternal pelvis.

occiput
(ok´sĭ-pәt) the posterior part of the head.

occlude
(ә-klldbomacd´) to fit close together. to close tight, as to bring the mandibular teeth into contact with the teeth in the maxilla. to cause an obstruction.

occluding ligature
a ligature that occludes the blood supply to distal tissue. (A), Occluding ligature; (B), terminal ligature.

occlusal
(ә-kloo´zәl) occlusive. pertaining to the masticating surfaces of the premolar and molar teeth, or to the contacting surfaces of opposing occlusion rims. designating a position toward the hypothetical plane passing between the mandibular and maxillary teeth when the jaws are ...

occlusal plane
the hypothetical horizontal plane formed by the contacting surfaces of the upper and lower teeth when the jaws are closed.

occlusal position
occlusal relation a functional position of the jaws in which contact between some or all of the upper and lower teeth occurs when the mandible is closed, which may or may not coincide with centric occlusion.

occlusal surface
the surface of the teeth that comes in contact with those of the opposite jaw during occlusion; called also masticatory surface.

occlusal zone
that third of the coronal zone of the teeth which is nearest the occlusal plane.

occlusion
(ә-kloo´zhәn) obstruction. the trapping of a liquid or gas within cavities in a solid or on its surface. the relation of the teeth of the upper and lower jaws when in functional contact during activity of the mandible. momentary complete closure of some area in the vocal t...

occlusive
(ә-kloo´siv) pertaining to or causing occlusion; called also occlusal.

occult
(ә-kult´) obscure or hidden from view.

occult bleeding
escape of blood in such small quantity that it can be detected only by chemical tests or by microscopic or spectroscopic examination. See also occult blood.

occult blood
that present in such small amounts as to be detectable only by chemical tests or by spectroscopic or microscopic examination.

occult blood test
examination by microscope or chemical test of a specimen (such as feces, urine, or gastric juice) for presence of blood that is not otherwise detectable. Feces are tested when intestinal bleeding is suspected but there is no visible evidence of blood.

occupational
(ok″u-pa´shun-al) pertaining to a vocation or source of livelihood. pertaining to the skills a person needs to live independently and carry on a desired lifestyle.

occupational acne
contact acne caused by exposure to industrial chemicals, such as oils, tars, waxes, or chlorinated hydrocarbons (see chloracne).

occupational asthma
extrinsic asthma due to an allergen present in the workplace.

occupational dermatitis
contact dermatitis caused by substances found in the work place. Called also industrial dermatitis and industrial or occupational dermatosis.