Information in this handbook is listed according to specific age or by age group. The following are definitions of age groups and age-related terminologies. These definitions should be used unless otherwise specified in the monograph.

Gestational age (GA)
The time from conception until birth. More specifically, gestational age is defined as the number of weeks from the first day of the mother's last menstrual period (LMP) until the birth of the baby. Gestational age at birth is assessed by the date of the LMP and by physical exam (Dubowitz score).
Postnatal age (PNA)
Chronological age since birth
Postconceptional age (PCA)
Age since conception. Postconceptional age is calculated as gestational age plus postnatal age (PCA = GA + PNA).
A full-term newborn 0-4 weeks postnatal age. This term may also be applied to a premature neonate whose postconceptional age (PCA) is 42-46 weeks.
Premature neonate
Neonate born at <38 weeks gestational age
Full-term neonate
Neonate born at 38-42 weeks (average ∼40 weeks) gestational age
1 month to 1 year of age
1-12 years of age
13-18 years of age
>18 years of age

Pediatric Cardiology

Nancy McDaniel M.D.

ABG (arterial blood gas): a test that tells how much oxygen is in the blood and how well the child is breathing.

Aneurysm: a bulging of the wall of an artery, vein, or wall of the heart.

Angiocardiography: a specialized x-ray of the heart. A fluid that shows up on xray is injected in to a vessel or chamber of the heart to make a detailed picture.

Anoxia: no oxygen.

Anticoagulant: a medication which delays the clotting of the blood. Also commonly called a blood thinner.

Aorta: the main artery that supplies the blood and oxygen to the body. It usually comes off the left ventricle (main pumping chamber).

Aortic valve: the valve between the aorta and the left ventricle (main pumping chamber). The aortic valve usually has three leaflets.

Arrhythmia: an abnormal pattern of the beating of the heart.

Atrial Septum: the muscular wall between the two collecting chambers of the heart (left atrium and right atrium).

Atrio-Ventricular Node (AV Node): part of the electrical (conduction) pathway of the heart that tells the ventricles when to beat (usually after the atria).

Atrium: one of the two upper chambers of the heart. The right atrium collects unoxygenated blood (blue blood) from the body. The left atrium collects oxygenated blood from the lungs.

Bacterial Endocarditis: an infection of the inner layer and/or valves of the heart, caused by bacteria.

Blood Pressure: the pressure of the blood in the arteries. Systolic blood pressure is the top number when the heart is contracted. Diastolic blood pressure is the bottom number when the heart is relaxed.

Bradycardia: abnormally slow heart rate.

Cardiac Output: the amount of blood pumped by the heart in one minute.

Cardiopulmonary Bypass: a machine that can perform the function of the heart and lung.

Catheter: a small tube used to collect fluid, measure blood pressure or give medication into a blood vessel or other body chamber.

Catheterization: a diagnostic test in which a catheter is inserted into the heart to measure pressure and oxygen, and to take pictures (angiography).

Congestive heart failure: a condition in which the heart cannot pump well enough, and there is backup of blood and congestion in the veins and lungs.

Cyanosis: blueness of the lips and fingernails, caused by a decreased amount of oxygen in the blood.

Diastole: when the heart muscle is relaxed and the ventricles fill with blood.

Heart Rate: how fast the heart is pumping.

Hemodynamics: the study of the flow of blood and the pressures in the heart, usually measured during a catheterization.

Hypertension: high blood pressure.

Hypoxia: less than normal oxygen content in the blood.

Ischemia: a local lack of oxygen in the blood.

Leads: the small wires connected to the child's chest by sticky pads which allow measurement of the electrocardiogram.

Mitral Valve: a valve of two leaflets, between the left atrium and left ventricle.

Murmur: an extra heart sound that may be heard between the normal heart sounds. Murmurs may be normal or abnormal.

Myocarditis: an inflammation of the heart muscle, usually caused by a virus or bacteria.

Myocardial Infarction: heart muscle which dies because of lack of oxygen, usually called a heart attack when it occurs in an adult.

Open Heart Surgery: surgery performed on the open heart while the blood flow is diverted through the heart lung machine.

Oxygen: a gas in the air we breath. Sometimes extra is needed due to illness or a heart defect.

Pericarditis: an inflammation of the sac which surrounds the heart.

Pulmonary valve: the valve between the right ventricle and the pulmonary artery.

Septum: dividing wall.

Shunt: an abnormal passage of blood between two blood vessels or between the two sides of the heart.

Stenosis: a narrowing of a heart valve or blood vessel.

Syncope: Fainting spell.

Systole: when the heart contracts and pumps the blood into the aorta and pulmonary artery.

Tachycardia: abnormally fast heart rate.

Ventricle: one of the two lower chambers of the heart. The left ventricle pumps to the aorta and supplies blood to the body. The right ventricle pumps to the pulmonary artery and supplies blood to the lungs.

Ventilator: a machine that breathes for a patient or helps his breathing.

Common terms and abbreviations that you are likely to see in a child's chart include:
  • AGE = acute gastroenteritis (stomach virus)
  • Allergic rhinitis = hay fever
  • AOM or OM = acute otitis media (ear infection)
  • ASD = atrial septal defect
  • BMI = body mass index
  • BOME = bilateral OME (fluid in both ears)
  • BPD = broncho-pulmonary dysplasia
  • CBC = complete blood count test
  • CP = cerebral palsy
  • FTT = failure to thrive
  • FUO = fever of unknown origin
  • FWLS = fever without localizing signs
  • GER = gastroesophageal reflux
  • HA = headache
  • HSM = hepatospenomegaly (enlarged liver and spleen)
  • IVH = intra-ventricular hemorrhage
  • LAD = lymphadenopathy (enlarged lymph glands)
  • LGA = large for gestational age
  • MR = mental retardation
  • Nocturnal enuresis = bedwetting
  • OME = otitis media with effusion (fluid in the ear)
  • Otitis externa = swimmer's ear
  • ROP = retinopathy of prematurity
  • SGA = small for gestational age
  • Tinea Capitis = ringworm on the scalp
  • Tinea Corporis = ringworm
  • VSD = ventricular septal defect
  • VUR = vesicoureteral reflux
A glossary of commonly used terms in pediatrics and parenting, such as NICU, thimerosal, AAP, SIDS, OSA, LATCH, VCUG, etc. so that you can understand what your pediatrician is talking about if he or she commonly uses medical terminology.
c. diff
C. diff is the short hand way of talking about the Clostridium difficile bacteria which can cause diarrhea and other gastrointestinal symptoms.
Munchausen Syndrome by Proxy
Munchausen syndrome by proxy is a rare form of child abuse in which a caregiver makes up symptoms and signs so as to make it appear that their child is sick.
Kawasaki Disease
Kawasaki disease is a complex childhood illness that mainly affects young children under age five. Although not well known by parents, it is actually one of the leading causes of acquired heart disease in children.
Erb's Palsy
Erb's Palsy is a form of Brachial Plexus injury, which is often caused by an injury to the nerves that controls the movement and feeling of the shoulder, arm, and hand.
Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy is a fairly common heart problem, occurring in 1 in every 500 people, and is a common cause of sudden death in young athletes.
Melamine is a chemical that is used in making many products that we use everyday, but can have devastating effects when it gets in food, as was seen in recent baby food and pet food recalls.
The AAP or American Academy of Pediatrics is a professional 'organization of 60,000 pediatricians committed to the attainment of optimal physical, mental, and social health and well-being for all infants, children, adolescents, and young adults.'
Adrenarche is the onset of androgen dependent signs of puberty in boys or girls, including pubic hair, axillary hair, acne, and adult body odor.
Apgar Score
The Apgar score is a standardized method for evaluating a newborn's health once they are born and was designed by Dr. Virginia Apgar in 1952.
BMI is an abbreviation for body mass index, and is calculated with a child's height and weight using a simple formula, and can be used to determine if a child is overweight, underweight, or at a healthy weight.
BPA and Baby Bottles
The use of BPA has become controversial, as there is a concern that BPA can leach out plastic and into baby formula, juice, food, and other substances inside plastic containers made with BPA.
Dyscalculia is a type of learning disability in which children have problems with math.
Dysgraphia is a type of learning disability in which children have problems with writing, including handwriting and spelling.
Dyspraxia is a type of learning disability in which children have problems with motor skill development, especially fine motor skills.
ECI or early childhood intervention programs are federally funded state programs that help infants, toddlers, and preschool aged children with developmental delays and disability get therapy.
According to the American Academy of Pediatrics, 'the FAAP designation after a pediatrician's name stands for Fellow of the American Academy of Pediatrics. Pediatricians who maintain their FAAP designation have obtained board certification in pediatrics and made an ongoing commitment to lifelong learning and advocacy for children.'
Flu Season
Flu season is when you are mostly to get infected with the influenza virus each year.
A fundoplication is a surgical procedure in which the upper part of the stomach is wrapped around the lower part of the esophagus. This prevents the reflux of stomach contents into the esophagus and out of a child's mouth.
GBS is an abbreviation for the Group B streptococcus bacteria, which according to the CDC 'is the most common cause of life-threatening infections in newborns.'
The GFCF diet (gluten-free casein-free diet) is advocated by some parents as an alternative treatment for children with autism.
An hemangioma, commonly called a strawberry or strawberry hemangioma by parents, is a type of vascular birthmark that typically appear in the first few weeks after a baby is born, can grow rapidly during an infant's first year of life, and then typically go away by the time the child is 5 to 8 years old.
Herd Immunity
Because of herd immunity, vaccines that children get can protect other people who aren't immune from vaccine preventable infections, either because they don't get vaccinated, their vaccine wasn't effective, or because they have become immunocompromised.
High Fructose Corn Syrup
High-fructose corn syrup is a common sweetener that is used in soft drinks, breakfast cereals, cookies, snacks and many other baked goods.
Irritable Bowel Syndrome (IBS)
IBS or irritable bowel syndrome is a common cause of chronic abdominal pain in children, especially older children and teens.
Juvenile rheumatoid arthritis (JRA) is arthritis that occurs in children and teens. Like arthritis in adults, common symptoms of JRA can include joint pain, swelling, stiffness, and swelling.
Ketogenic Diet
The ketogenic diet is a specialized diet that is sometimes used as a treatment for young children with epilepsy who continue to have seizures despite taking traditional or standard anticonvulsant medications.
LATCH refers to the Lower Anchors and Tethers for Children system, which according to the National Highway Traffic Safety Administration, 'is designed to make installation of child safety seats easier by requiring child safety seats to be installed without using the vehicle's seat belt system.'
An MDI (metered dose inhaler) is a pressured canister that contains a child's asthma medicine.
Menarche is the onset of menstruation or the first period in girls during puberty.
Mercuritol is a make-believe or fictional substance that the lawyer in the legal TV drama "Eli Stone" says has caused the title character's son to have autism. It may be confused with thimerosal by some parents.
MRSA is an abbreviation for Methicillin Resistant Staphylococcus aureus, a type of bacteria that has become resistant to many antibiotics, including methicillin, penicillin, amoxicillin, and cephalosporins.
A nebulizer, which is more commonly known as a "breathing machine" by parents, includes an air compressor to deliver an aerosolized breathing treatment to your child with asthma.
The NICU is also known as a neonatal intensive care unit and is the area of a hospital where sick babies, especially if they are premature, go once they are born.
Nutritional Rickets
Rickets is a condition that develops in children who do not have enough vitamin D in their diet, which leads to their having bones that don't mineralize properly — they have weak bones.
Occupational Therapy
Occupational therapy (OT) refers to therapy that helps children perform everyday skills and activities.
OSA is an acronym for obstructive sleep apnea, which is a common problem in children, and is increasing being recognized as a cause of daytime attentional and behavioral problems.
PANDAS is an acronym for pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections. It describes children who develop the sudden worsening of tics, obsessive/compulsive type behavior, or irritability following a strep infection, such as scarlet fever or strep throat.
Physical Therapy
Physical therapy (PT) refers to therapy that helps children that have problems with balance, coordination, muscle strength, and gross motor skills.
RAD is an acronym for reactive airway disease. It is term often used to describe younger children, especially infants and toddlers, who have recurrent episodes of coughing and wheezing.
Reye's Syndrome
Reye's syndrome is a rare condition that has been linked to viral infections and aspirin.
RSV is an acronym for the Respiratory Syncytial Virus, a common cause of colds and bronchiolitis for infants and children.
SIDS is an acronym for Sudden Infant Death Syndrome, which refers to the unexplained death of a child under one year of age.
Stomach Flu
The stomach flu is actually not related to the flu, but can be caused by other viruses including rotavirus, which often includes symptoms of diarrhea, vomiting, fever, and stomach cramps.
A T&A refers to a tonsillectomy and adenoidectomy, common pediatric surgical procedures in which a child's enlarged tonsils and adenoids are removed.
Thelarche is the onset of breast development in girls during puberty.
Thimerosal is a mercury containing preservative that was commonly found in vaccines since the 1930s. Although no link to autism or other conditions was ever found, because of concerns that thimerosal could be harmful and because alternatives to thimerosal were now available, according to the FDA, 'thimerosal has been removed from or reduced to trace amounts in all vaccines routinely recommended for children 6 years of age and younger, with the exception of inactivated influenza vaccine.'
Tucker Sling
The Tucker Sling is a medical device that helps keep babies and infants who have acid reflux positioned in an upright position, minimizing their chances of spitting up.
A Urinary Tract Infection (UTI) refers to an infection that involves the kidney (pyelonephritis), bladder (cystitis) or asymptomatic bacteriuria, when children have bacteria in their urine but no symptoms.
A VCUG or voiding cystourethrogram, along with a renal sonogram, is a test that is commonly done after a child has a urinary tract infection (UTI).
Walking Pneumonia
Walking pneumonia, a type of atypical pneumonia, is caused by the Mycoplasma pneumoniae bacteria.

Difficulty talking or understanding language

Weakening of the wall of an artery

Picture of the arteries supplying the brain that is generated by injecting dye through a blood vessel in the leg

Anterior Cerebral Artery (ACA)
The two blood vessels that supply part of the frontal lobe, one on each side of the brain

Medicine that prevent blood clots from forming; "blood thinner"

Medicine that makes platelets less sticky; aspirin is an example

Blood test that tells the doctors if your dose of LOVENOX is correct

Arterial Ischemic Stroke (AIS)
Brain injury caused by blockage of blood flow in an artery

An artery is the body's "pipeline" for carrying blood from the heart to other parts of the body including the brain. 

Arterial Dissection
A tearing in the wall of an artery

Arteriovenous Malformation (AVM) 
A tangled group of abnormally formed blood vessels that can sometimes burst and bleed into the brain

A medicine that prevents blood clots by making platelets less sticky

Trouble with balance or walking which often occurs with strokes affecting the cerebellum



Basilar Artery
The blood vessel that supplies the brain stem

Basal Ganglia
Part of the brain that is important for controlling movement

Blood is the fluid that carries oxygen and important nutrients to different parts of the body and carries away carbon dioxide and other waste materials not needed by the body. Blood travels to and from the heart by way of two different "pipelines," arteries and veins.

Brain Stem
The lower part of the brain that is important for movements of the eyes and body, alertness and breathing

(Blood) Clot
A blood clot occurs when blood changes from a liquid to a solid form. Some clotting is normal and not harmful. However, a blood clot can get stuck as it travels through an artery or a vein. This clot can cause different problems depending on where it is located.



Carotid Artery
Two blood vessels that travel in the front of the neck to the brain

Cerebral  Sinovenous Thrombosis (CSVT)
A condition that occurs when a blood clot gets stuck in a vein that carries blood from the brain to the heart. It may go away before permanent damage is done to the brain or it may cause an ischemic stroke.

Cerebral Vascular Accident (CVA)
Another term for stroke

Back part of the brain that is important for coordination

Congenital Heart Disease
Abnormalities in the structure of the heart that occur before a baby is born

A medicine that prevents blood clots, given as a pill

CT Scan (Computed Tomography)
A type of x-ray that can be used to diagnose stroke by taking a picture of the brain



Trouble talking or slurred speech that can happen with a stroke

Trouble eating or swallowing that can happen with a stroke



A test using sound waves to get a picture of the heart, used to look for blood clots that may have caused the stroke

A blood clot that moves through the bloodstream and may become stuck in a blood vessel

EEG (electro-encephalogram)
A test that looks for a tendency for seizures by measuring electrical activity in the brain



Frontal Lobe
The largest area of the brain that controls movement of the body's muscles, talking and is responsible for many parts of a person's personality



Hemorrhage or hemorrhagic

Weakness affecting one side of the body

Inability to see on one side

A medicine used to prevent blood clots, given through an IV



INR (International Normalized Ratio)
A blood test that tells the doctors if you are getting enough COUMADIN

Ischemia or ischemic
A term used to describe a blockage of blood flow to an area of the brain



A medicine used to prevent blood clots, given by injection

Lumbar Puncture (LP or "Spinal Tap")
A test used to test for brain infection or inflammation that is done by placing a small needle in the back to remove a small amount of spinal fluid



MRA (Magnetic Resonance Angiogram)
A test that takes a picture of the blood vessels in the brain using magnetic signals and a computer

MRI (Magnetic Resonance Imaging)
A test that takes a detailed picture of the brain using magnetic signals and a computer and shows if a stroke has occurred

MRV (Magnetic Resonance Venogram)
A test that takes a picture of the venous sinuses and other veins in the brain using magnetic signals and a computer and is used to look for CSVT

Middle Cerebral Artery (MCA)
The two blood vessels that supply part of the frontal lobe, parietal lobe and basal ganglia. There is one on each side of the brain.

A disease in which the ends of the carotid arteries get narrow and can lead to extra blood vessels growing; this can cause AIS and hemorrhage



Occipital Lobe
The back part of the brain that is important for vision



Parietal Lobe
The part of the brain that is important for feeling things and for being aware of your surroundings

Part of the blood that is important for forming blood clots

Posterior Cerebral Artery (PCA)
The two blood vessels that supply the occipital lobe and thalamus, one on each side of the brain

A tendency to form blood clots too easily

PTT (Partial Thromboplastin Time)
A blood test that tells your doctors if you are getting enough heparin



Uncontrolled movements or change in behavior caused by abnormal electrical activity in the brain

Sickle Cell Disease
A blood disease that runs in families and causes the red blood cells to get stuck in the arteries and can cause strokes

Brain damage caused by an interruption of blood flow to the brain, either by a blockage in an artery (AIS), in a vein (CSVT) or by rupture of a blood vessel in the brain (hemorrhagic stroke)



Temporal Lobe
Part of the brain that is important for understanding language and for hearing

Part of the brain that coordinates information from other parts of the brain.  Injury to the thalamus can cause problems with movement, sensation, seeing, hearing, memory or level of alertness.

Transcranial Doppler
A test using sound waves to help the doctors to get a closer look at the blood flowing through the arteries in the brain

Transient Ischemic Attack (TIA)
An episode of weakness or trouble speaking or seeing caused by a blockage in an artery that only last for a brief period of time.  This is often a warning of a stroke, sometimes called a "mini stroke."

A drug that breaks up or dissolves a thrombus (blood clot)

A blood clot that forms inside a blood vessel or inside the heart

A tendency to form blood clots easily



Abnormal narrowing of one or more arteries that supply the brain

A vein is the body's "pipeline" for carrying blood from other parts of the body (including the brain) back to the heart.

Visual Field Cut
A loss of vision on one side caused by brain injury

Language-symbolic behavior - The ability to use words to represent thoughts, feelings and ideas; the labeling of ideas with words.

Selective attention - Figure-ground discrimination; focus on relative versus distracting information.

Sustained attention - Maintaining attention of relevant stimuli over a period of time.

Auditory discrimination - Recognizing and distinguishing similarities and differences in sounds.

Sound localization - Identifying the source of sound - the area or direction from which the sound occurs.

Auditory memory skills
Sequencing - Remembering a series of unrelated information (digit, words) in the correct order.
Recall - Remembering related information (i.e., sentences) and supplying a verbal response.
Retention - Remembering a verbal or non-verbal task (i.e., directions) and supplying a gestural or motor response.

Auditory feedback - Evaluation or monitoring of the auditory message; the ability to detect errors and inconsistencies in intended messages.

Auditory-visual transduction - Linkage among auditory and other modalities such as visual, motor and tactile; ability to translate what is heard and seen into a written, spoken or gestural response.

Dysphasia - Partial loss of or reduced ability to process and formulate language due to brain damage or brain dysfunction; may affect auditory comprehension, oral language, reading and writing.

Dyslexia - A language disorder that prevents the child from acquiring meaning (translating) of the written word because of a deficient ability to deal with symbols (transduction). Auditory dyslexia is a condition in which the child cannot transduce the auditory component of the word. Visual dyslexia is a condition in which the child cannot transduce the visual image of the letter into its auditory equivalent.

Dysnomia - Partial loss of or reduced ability to name objects or recall and retrieve words.

Dysarthria - A peripheral disorder resulting in reduced function of the speech and/or voice musculature.

Dysgraphia - Impaired motor control for writing.

Dyspraxia - Reduced ability to plan out and execute volitional oral-motor movements. The peripheral musculature is intact, but there is difficulty in planning out and deciding how to perform the movements.

Debris behavior - Any behavior that diverts or prevents attention to a task or action leading to an acceptable response to a task. It can range from passive (withdrawal, tuning out, withholding speech) to active (kicking, screaming, crying without tears, biting, etc.). Frequently occurs in conjunction with receptive/expressive language disorders.

Tachyphemia (cluttering) - Disability of language formulation. This involves not only problems of temporal organization for speech (cluttering), but also problems of spatial organization for writing. It is important to distinguish this problem from that of stuttering, which means accounting for the source of dysfluency. Tachyphemia is characterized by a host of language disturbances, such as poor auditory skills, dysgraphia, dyspraxia, dyslexia and others.

Stuttering - Repetitions and/or prolongations of sounds and words, interjections of sounds or words, blocks, and/or prolonged pauses, which have as their basis tension/anxiety reactions. May be accompanied by secondary characteristics such as eye blinks, facial grimaces, etc.

Pediatric Epilepsy Surgery Glossary of Terms

The following are health and medical definitions of terms that appear in the Pediatric Epilepsy Surgery article.


Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer ).
See the entire definition of Abnormal


Absence seizure: A seizure that takes the form of a staring spell. The person suddenly seems to be "absent." An absence seizure involves a brief loss of awareness, which can be accompanied by blinking or mouth twitching. Absence seizures have a very characteristic appearance on an electroencephalogram ( EEG ).
See the entire definition of Absence seizure


Acquired: Anything that is not present at birth but develops some time later. In medicine, the word "acquired" implies "new" or "added." An acquired condition is "new" in the sense that it is not genetic (inherited) and "added" in the sense that was not present at birth.
See the entire definition of Acquired


Acute: Of abrupt onset, in reference to a disease. Acute often also connotes an illness that is of short duration, rapidly progressive, and in need of urgent care.
See the entire definition of Acute


Analysis: A psychology term for processes used to gain understanding of complex emotional or behavioral issues.
See the entire definition of Analysis

Anesthesia: Loss of feeling or awareness. A general anesthetic puts the person to sleep. A local anesthetic causes loss of feeling in a part of the body such as a tooth or an area of skin without affecting consciousness. Regional anesthesia numbs a larger part of the body such as a leg or arm, also without affecting consciousness. The term "conduction anesthesia" encompasses both local and regional anesthetic techniques. Many surgical procedures can be done with conduction anesthesia without significant pain. In many situations, such as a C-section, conduction anesthesia is safer and therefore preferable to general anesthesia. However, there are also many types of surgery in which general anesthesia is clearly appropriate.

Arms: An appendage in anatomy and in clinical trials. See: Arm.


Atonic: Without normal muscle tone or strength. An atonic seizure is one in which the person suddenly loses muscle tone and strength and cannot sit or stand upright and, unless supported, falls down.
See the entire definition of Atonic

Blood pressure: The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension".


Brain: That part of the central nervous system that is located within the cranium ( skull ). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."
See the entire definition of Brain


Cerebral: Pertaining to the brain, the cerebrum or the intellect.
See the entire definition of Cerebral


Cerebral cortex: A thin mantle of gray matter about the size of a formal dinner napkin covering the surface of each cerebral hemisphere. The cerebral cortex is crumpled and folded, forming numerous convolutions ( gyri ) and crevices ( sulci ). It is made up of six layers of nerve cells and the nerve pathways that connect them. The cerebral cortex is responsible for the processes of thought, perception and memory and serves as the seat of advanced motor function, social abilities, language, and problem solving.
See the entire definition of Cerebral cortex


Chest: The area of the body located between the neck and the abdomen . The chest contains the lungs , the heart and part of the aorta . The walls of the chest are supported by the dorsal vertebrae , the ribs , and the sternum .
See the entire definition of Chest

Clonic seizure: A seizure in which there are generalized clonic contractions with the entire body jerking, but without a preceding tonic phase.


Complication: In medicine, an additional problem that arises following a procedure, treatment or illness and is secondary to it. A complication complicates the situation.
See the entire definition of Complication back to top

Computed tomography: An x-ray procedure that uses the help of a computer to produce a detailed picture of a cross section of the body. Also called a CT scan or CAT scan.


Congenital: Present at birth. A condition that is congenital is one that is present at birth. There are numerous uses of "congenital" in medicine. There are, for example, congenital abnormalities. (For more examples, see below.)
See the entire definition of Congenital

Contraction: The tightening and shortening of a muscle.


Contraindication: A condition which makes a particular treatment or procedure inadvisable. A contraindication may be absolute or relative.

  • An absolute contraindication is a situation which makes a particular treatment or procedure absolutely inadvisable. In a baby, for example, aspirin is absolutely contraindicated because of the danger that aspirin will cause Reye syndrome .
  • A relative contraindication is a condition which makes a particular treatment or procedure somewhat inadvisable but does not rule it out. For example, X-rays in pregnancy are relatively contraindicated (because of concern for the developing fetus ) unless the X-rays are absolutely necessary.

See the entire definition of Contraindication

Contrast: Short for "contrast media." Contrast media are X-ray dyes used to provide contrast, for example, between blood vessels and other tissue.


Corpus: The body of the uterus (womb).
See the entire definition of Corpus


Corpus callosotomy: The corpus callosum is a band of nerve fibers connecting the two halves (hemispheres) of the brain . A corpus callosotomy is an operation in which all or part of this structure is cut, disabling communication between the hemispheres and preventing the spread of seizures from one side of the brain to the other. This procedure, sometimes called split-brain surgery, is for patients with extreme forms of uncontrollable epilepsy who have intense seizures that can lead to violent falls and potentially serious injury.
See the entire definition of Corpus callosotomy


Cortex: The outer portion of an organ.
See the entire definition of Cortex


Cortical: Having to do with the cortex, the outer portion of an organ.
See the entire definition of Cortical

Cranium: The upper portion of the skull, which protects the brain. The bones of the cranium include the frontal, parietal, occipital, temporal, sphenoid, ethmoid, lacrimal, and nasal bones; the concha nasalis; and the vomer.


CT scan: Computerized tomography scan. Pictures of structures within the body created by a computer that takes the data from multiple X-ray images and turns them into pictures on a screen. CT stands for computerized tomography.
See the entire definition of CT scan


Cyanosis: A bluish color of the skin and the mucous membranes due to insufficient oxygen in the blood. For example, the lips may show cyanosis. Cyanosis can be evident at birth, as in a "blue baby" who has a heart malformation that permits blood that is not fully oxygenated to enter the arterial circulation. Cyanosis can also appear at any time later in life.
See the entire definition of Cyanosis


Diagnosis: 1 The nature of a disease ; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies . 3 The identification of any problem. The diagnosis was a plugged IV.
See the entire definition of Diagnosis


Dilatation: The process of enlargement or expansion.
See the entire definition of Dilatation


EEG: Electroencephalogram, e technique for studying the electrical current within the brain. Electrodes are attached to the scalp. Wires attach these electrodes to a machine which records the electrical impulses. The results are either printed out or displayed on a computer screen. Electroencephalogram is abbreviated EEG.
See the entire definition of EEG back to top


Encephalitis: Inflammation of the brain. Encephalitis occurs, for example, in 1 in 1,000 cases of measles . It may start (up to 3 weeks) after onset of the measles rash and present with high fever , convulsions, and coma. It usually runs a blessedly short course with full recovery within a week. Or it may eventuate in central nervous system impairment or death.
See the entire definition of Encephalitis

Epilepsy (seizure disorder): When nerve cells in the brain fire electrical impulses at a rate of up to four times higher than normal, this causes a sort of electrical storm in the brain, known as a seizure. A pattern of repeated seizures is referred to as epilepsy. Known causes include head injuries, brain tumors, lead poisoning, maldevelopment of the brain, genetic and infectious illnesses. But in fully half of cases, no cause can be found. Medication controls seizures for the majority of patients.

fMRI: Functional magnetic resonance imaging.

Focal: Pertaining to a focus which in medicine may refer to:
1. The point at which rays converge as, for example, in the focal point.
2. A localized area of disease. A focal cancer is limited to one specific area.


Gene: The basic biological unit of heredity . A segment of deoxyribonucleic acid (DNA) needed to contribute to a function.
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Genetic: Having to do with genes and genetic information.

Gestation: Period of time from conception to birth.


Grand mal: A form of epilepsy characterized by tonic-clonic seizures. involving two phases -- the tonic phase in which the body becomes rigid, and clonic phase in which there is uncontrolled jerking. Tonic-clonic seizures may or may not be preceded by an aura , and are often followed by headache , confusion, and sleep . They may last for mere seconds, or continue for several minutes. If a tonic-clonic seizure does not resolve or if such seizures follow each other in rapid succession, seek emergency help. The person could be in a life-threatening state known as status epilepticus . Treatment is with antiseizure medications.
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Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest.
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Heart rate: The number of heart beats per unit time, usually per minute. The heart rate is based on the number of contractions of the ventricles (the lower chambers of the heart). The heart rate may be too fast ( tachycardia ) or too slow ( bradycardia ). The pulse is bulge of an artery from the wave of blood coursing through the blood vessel as a result of the heart beat. The pulse is often taken at the wrist to estimate the heart rate.
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Hoarseness: Hoarseness is a term referring to abnormal voice changes. Hoarseness may be manifested as a voice that sounds breathy, strained, rough, raspy, or a voice that has higher or lower pitch. There are many causes of hoarseness, including viral laryngitis, vocal cord nodules, laryngeal papillomas, gastroesophageal reflux-related laryngitis, and environmental irritants (such as tobacco smoking). An accumulation of fluid in the vocal cords associated with hoarseness has been termed Reinke's edema. Reinke's edema may occur as a result of cigarette smoking or voice abuse (prolonged or extended talking or shouting). Rarely, hoarseness results from serious conditions such as cancers of the head and neck region.


Hydrocephalus : Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain.
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Implant: 1. To embed; to set in firmly. In embryology, the fertilized egg implants in the uterine lining 6 or 7 days after conception (fertilization). In medicine today, many things may be implanted.
2. That which is embedded. For example: lens implants, breast implants, cochlear implants, defibrillator implants, pacemaker implants, etc.


Implantation: The act of setting in firmly.
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Indicate: In medicine, to make a treatment or procedure advisable because of a particular condition or circumstance. For example, certain medications are indicated for the treatment of hypertension during pregnancy while others are contraindicated.

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Indication: 1. In medicine, a condition which makes a particular treatment or procedure advisable. CML (chronic myeloid leukemia) is an indication for the use of Gleevec (imatinib mesylate). 2. A sign or a circumstance which points to or shows the cause, pathology, treatment, or outcome of an attack of disease. The presence of the Philadelphia chromosome in peripheral blood cells is an indication of a relapse in CML.


Infection: The growth of a parasitic organism within the body. (A parasitic organism is one that lives on or in another organism and draws its nourishment therefrom.) A person with an infection has another organism (a "germ") growing within him, drawing its nourishment from the person.
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Intracranial: Within the cranium , the bony dome that houses and protects the brain.
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Intractable: Unstoppable. For example, intractable diarrhea or intractable pain.


Labor: Childbirth, the aptly-named experience of delivering the baby and placenta from the uterus to the vagina to the outside world. There are two stages of labor. During the first stage (called the stage of dilatation), the cervix dilates fully to a diameter of about 10 cm. In the second stage (called the stage of expulsion), the baby moves out through the cervix and vagina to be born.
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Leg: In popular usage, the leg extends from the top of the thigh down to the foot. However, in medical terminology, the leg refers to the portion of the lower extremity from the knee to the ankle.
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Lesion: Pronounced "lee-sion" with the emphasis on the "lee," a lesion can be almost any abnormality involving any tissue or organ due to any disease or any injury.
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Lips: Aside from the lips of the mouth, there are two pairs of lips at the entrance to the vagina. They are the labia majora (the larger outside pair) and the labia minora (the smaller inside pair). Together they form part of the vulva (the female external genitalia).


Lobe: Part of an organ that appears to be separate in some way from the rest. A lobe may be demarcated from the rest of the organ by a fissure (crack), sulcus (groove), connective tissue or simply by its shape. For example, there are the frontal, parietal, temporal, and occipital lobes of the brain.
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Lobectomy: An operation done to remove a lobe of an organ such as the lobe of a lung or a lobe of the thyroid gland.
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Lungs: The lungs are a pair of breathing organs located with the chest which remove carbon dioxide from and bring oxygen to the blood. There is a right and left lung.


Memory: 1. The ability to recover information about past events or knowledge. 2. The process of recovering information about past events or knowledge. 3. Cognitive reconstruction. The brain engages in a remarkable reshuffling process in an attempt to extract what is general and what is particular about each passing moment.
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Meningitis: Inflammation of the meninges, usually due to a bacterial infection but sometimes from viral, protozoan, or other causes (in some cases the cause cannot be determined).
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Mesial: 1. Toward the middle. As, for example, a mesial temporal lobe structure.
2. In dentistry, toward the middle of the front of the jaw.
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Metabolic: Relating to metabolism, the whole range of biochemical processes that occur within us (or any living organism). Metabolism consists of anabolism (the buildup of substances) and catabolism (the breakdown of substances).
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Mortality: A fatal outcome or, in one word, death. The word "mortality" is derived from "mortal" which came from the Latin "mors" (death). The opposite of mortality is, of course, immortality. Mortality is also quite distinct from morbidity (illness).
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Motor: In medicine, having to do with the movement of a part of the body. Something that produces motion or refers to motion. For example, a motor neuron is a nerve cell that conveys an impulse to a muscle causing it to contract. The term "motor" today is also applied to a nerve that signals a gland to secrete. Motor is as opposed to sensory.

Mouth: 1. The upper opening of the digestive tract, beginning with the lips and containing the teeth, gums, and tongue. Foodstuffs are broken down mechanically in the mouth by chewing and saliva is added as a lubricant. Saliva contains amylase, an enzyme that digests starch. 2. Any opening or aperture in the body. The mouth in both senses of the word is also called the os, the Latin word for an opening, or mouth. The o in os is pronounced as in hope. The genitive form of os is oris from which comes the word oral.

MRI: Abbreviation and nickname for magnetic resonance imaging. For more information, see: Magnetic Resonance Imaging; Paul C. Lauterbur; Peter Mansfield.

Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."


Neck: The part of the body joining the head to the shoulders. Also, any narrow or constricted part of a bone or organ that joins its parts as, for example, the neck of the femur bone.
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Nerve: A bundle of fibers that uses chemical and electrical signals to transmit sensory and motor information from one body part to another. See: Nervous system.

Neurological: Having to do with the nerves or the nervous system.

Neurosurgeon: A physician trained in surgery of the nervous system and who specializes in surgery on the brain and other parts of the nervous system. Sometimes called a "brain surgeon."

Occipital: 1. Pertaining to the occiput, the back of head.
2. Located near the occipital bone as, for example, the occipital lobe of the brain.

Olfactory: Pertaining to olfaction, the sense of smell.


Operation: Although there are many meanings to the word "operation", in medicine it refers to a surgical procedure.
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Oxygen: A colorless, odorless and tasteless gas that makes up about 20% of the air we breathe (and at least half the weight of the entire solid crust of the earth) and which combines with most of the other elements to form oxides. Oxygen is essential to human, animal and plant life.
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Pain: An unpleasant sensation that can range from mild, localized discomfort to agony. Pain has both physical and emotional components. The physical part of pain results from nerve stimulation. Pain may be contained to a discrete area, as in an injury, or it can be more diffuse, as in disorders like fibromyalgia . Pain is mediated by specific nerve fibers that carry the pain impulses to the brain where their conscious appreciation may be modified by many factors.
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Paralysis: Loss of voluntary movement (motor function). Paralysis that affects only one muscle or limb is partial paralysis, also known as palsy; paralysis of all muscles is total paralysis, as may occur in cases of botulism.

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Pediatric: Pertaining to children.


Petit mal: A form of epilepsy with very brief, unannounced lapses in consciousness. A petit mal seizure involves a brief loss of awareness, which can be accompanied by blinking or mouth twitching. Petit mal seizures have a very characteristic appearance on an electroencephalogram (EEG).
See the entire definition of Petit mal


Positron emission tomography: PET. A highly specialized imaging technique that uses short-lived radioactive substances to produce three-dimensional colored images of those substances functioning within the body. These images are called PET scans and the technique is termed PET scanning.
See the entire definition of Positron emission tomography


Posterior: The back or behind, as opposed to the anterior.
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Recurrence: The return of a sign, symptom or disease after a remission. The reappearance of cancer cells at the same site or in another location is, unfortunately, a familiar form of recurrence.
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Referral: The recommendation of a medical or paramedical professional. If you get a referral to ophthalmology, for example, you are being sent to the eye doctor. In HMOs and other managed care schemes, a referral is usually necessary to see any practitioner or specialist other than your primary care physician (PCP), if you want the service to be covered. The referral is obtained from your PCP, who may require a telephone or office consultation first.
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Refractory: Not yielding (at least not yielding readily) to treatment.

Resection: Surgical removal of part of an organ.


Resistance: Opposition to something, or the ability to withstand it. For example, some forms of staphylococcus are resistant to treatment with antibiotics.
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Scan: As a noun, the data or image obtained from the examination of organs or regions of the body by gathering information with a sensing device.
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Sclerosis: Localized hardening of skin.


Seizure: Uncontrolled electrical activity in the brain, which may produce a physical convulsion, minor physical signs, thought disturbances, or a combination of symptoms.
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Seizure disorders: One of a great many medical conditions that are characterized by episodes of uncontrolled electrical activity in the brain (seizures). Some seizure disorders are hereditary, but others are caused by birth defects or environmental hazards, such as lead poisoning. Seizure disorders are more likely to develop in patients who have other neurological disorders, psychiatric conditions, or immune-system problems. In some cases, uncontrolled seizures can cause brain damage, lowered intelligence, and permanent mental and physical impairment. Diagnosis is by observation, neurological examination, electroencephalogram (EEG), and in some cases more advanced brain imaging techniques. Treatment is usually by medication, although in difficult cases a special diet or brain surgery may be tried.
See the entire definition of Seizure disorders


Skull: The skull is a collection of bones which encase the brain and give form to the head and face. The bones of the skull include the following: the frontal, parietal, occipital, temporal, sphenoid, ethmoid, zygomatic, maxilla, nasal, vomer, palatine, inferior concha, and mandible.
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SPECT: An acronym that stands for Single Photon Emission Computed Tomography, a nuclear medicine procedure in which a gamma camera rotates around the patient and takes pictures from many angles, which a computer then uses to form a tomographic (cross-sectional) image.
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Status epilepticus: An epileptic seizure that lasts more than 30 minutes; a constant or near-constant state of having seizures. Status epilepticus is a health crisis, and requires immediate treatment.
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Stomach: 1. The sac-shaped digestive organ that is located in the upper abdomen, under the ribs. The upper part of the stomach connects to the esophagus, and the lower part leads into the small intestine.
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Subdural: Below the dura, the outermost, toughest, and most fibrous of the three membranes (meninges) covering the brain and the spinal cord. An subdural hematoma is a collection of blood beneath the dura.


Surgery: The word "surgery" has multiple meanings. It is the branch of medicine concerned with diseases and conditions which require or are amenable to operative procedures. Surgery is the work done by a surgeon. By analogy, the work of an editor wielding his pen as a scalpel is s form of surgery. A surgery in England (and some other countries) is a physician's or dentist's office.
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Sweating: The act of secreting fluid from the skin by the sweat (sudoriferous) glands. These are small tubular glands situated within and under the skin (in the subcutaneous tissue). They discharge by tiny openings in the surface of the skin.
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Temporal: 1. Pertaining to time, limited in time, temporary, or transient.
2. Pertaining to the temple region of the head. The temporal lobe of the brain is located beneath the temple.
From the Latin tempus which means both time and the temple of the head.

Temporal lobe: The lobe of the cerebral hemisphere located down on the side just forward of the occipital lobe. The temporal lobe contains the auditory cortex which is responsible for hearing. It is also the site of the seizure activity characteristic of temporal-lobe epilepsy.


Tomography: The process for generating a tomogram , a two-dimensional image of a slice or section through a three-dimensional object. Tomography achieves this remarkable result by simply moving an x-ray source in one direction as the x-ray film is moved in the opposite direction during the exposure to sharpen structures in the focal plane, while structures in other planes appear blurred. The tomogram is the picture; the tomograph is the apparatus; and tomography is the process.
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Trauma: Any injury , whether physically or emotionally inflicted. "Trauma" has both a medical and a psychiatric definition. Medically, "trauma" refers to a serious or critical bodily injury, wound, or shock . This definition is often associated with trauma medicine practiced in emergency rooms and represents a popular view of the term. In psychiatry , "trauma" has assumed a different meaning and refers to an experience that is emotionally painful, distressful, or shocking, which often results in lasting mental and physical effects.
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Vagus nerve: A remarkable nerve that supplies nerve fibers to the pharynx (throat), larynx ( voice box ), trachea ( windpipe ), lungs , heart , esophagus , and the intestinal tract as far as the transverse portion of the colon . The vagus nerve also brings sensory information back to the brain from the ear , tongue , pharynx, and larynx.
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Vascular: Relating to the blood vessels of the body. The blood vessels of the body, as a group, are referred to as the vascular system.
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Viable: Capable of life. For example, a viable premature baby is one who is able to survive outside the womb.

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Radlex fetal development terms –not incorporated yet, 8-14-06



Amniotic fluid

amnion the fluid-filled sac initially above the embryonic disc (ectoderm and extaembryonic mesoderm), with embryonic disc folding this sac is drawn ventrally to enclose (cover) the embryo, then fetus


Chorionic villous sampling - In this technique, a small amount of tissue is removed from the chorion via a catheter inserted through the cervix or a needle inserted via the abdominal wall.


Cotyledons - During the fourth and fifth months, placental septa grow into the intervillous space, separating the villi into 15 to 25 groups called cotyledons.


Dizygotic (fraternal) twins


Erythroblastosis fetalis - If a mother who lacks Rh factors bears an Rh+ baby, and fetal blood leaks across the placenta into the maternal circulation (usually at birth), the mother may make antibodies against these factors. If she bears a second Rh+ fetus, the anti-Rh antibodies cross into the fetal circulation and destroy the fetuses red blood cells. The fetus overproduces red blood cells and so the number of immature nucleated erythroblasts increases within the fetal circulation resulting in the condition called erythroblastosis fetalis. 


First trimester - The first three months of gestation.


Fraternal (dizygotic) twins - These twins arise from two separate oocytes and therefore do not share any of the fetal membranes.


polyhydramnios  (preferred term for Hydramnios) - In this condition, the amount of amniotic fluid is excessive.


Monozygotic (identical) twins - These twins arise from the same oocyte, which may split at the two cell stage or at later stages of development. Therefore, these twins possess the same genetic makeup. Depending upon when the embryo splits, they may not share any fetal membranes or they may share the chorion alone or both the chorion and the amnion.


Intrauterine growth retardation (IUGR) - Effects of some toxins, teratogens, or disease states of the mother may lead to an inhibition of fetal growth.


Second trimester - The fourth through the sixth months of gestation.


Placenta - This organ is derived from the maternal decidua basalis and the fetal chorion. It provides a mechanism to exchange oxygen and nutrients and carbon dioxide and wastes between the fetal and the maternal circulations.


Third trimester - The seventh through the ninth month of gestation.

Cardinal system of veins - These veins drain the head and neck and body wall and extremities of the embryo. Anterior cardinals drain the head and neck and the trunk and lower extremities are drained by paired posterior cardinals. The posterior cardinal veins are replaced by subcardinal and supracardinal veins during the second month.


 Angiogenesis - This is the mechanism whereby preexisting vessels lengthen or branch by sprouting.


Branchial arches - These structures of humans are more appropriately named "pharyngeal" arches.


sclerotome - ventromedial half of each somite that forms the vertebral body and intervertebral disc.


surfactant a detergent secreted by Type 2 alveolar cells between alveolar epithelium. Functions to lower surface tension, allowing lungs to remain inflated. Note: In humans, these cells and their secretion develop towards the very end of the third trimester, just before birth. Hence the respiratory difficulties associated with premature births


abdominal circumference, used in clinical ultrasound measurements made in late pregnancy and reflects fetal growth in size and weight


alpha-fetoprotein test (AFP)


aneuploidy abnormal number of chromosomes.


BPD acronym for biparietal diameter, measurement between the 2 sides of the head, used in clinical ultrasound measurements after 13 weeks. [note that in pediatric radiology, this term BPD is more identified with Bronchial Pulmonary Dysplasia]


craniosynostosis premature closure of the skull sutures, or fusion of skull bones. May cause skull and brain abnormalities


ductus venosus vitelline blood vessel lying within the liver that connects (shunts) the portal and umbilical veins with the inferior vena cava and also acts to protect the fetus from placental overcirculation. Absence can cause hydrops fetalis and the umbilical vein then drains directly into the inferior vena cava or right atrium


ectoderm (Greek, ecto = outside + derma = skin) The layer (of the 3 germ cell layers) which form the nervous system from the neural tube and neural crest and also generates the epithelia covering the embryo; ditto mesoderm and endoderm


ectopic pregnancy; intra-abdominal pregnancy