Terms Used to Describe Direction and Surface
Term
Meaning
Ventral
Refers to the belly or
underside of a body or body
part
Dorsal
Refers to the back – also
refers to the cranial surface
of the manus (front of paw)
and pes (rear of paw)
Cranial
Front of the body
Posterior
Rear of the body
Rostral
Nose end of the head
Cephalic
Pertaining to the head
Caudal
Toward the tail
Medial
Toward the midline
Lateral
Away from the midline
Term
Meaning
Superior
Uppermost, above, or toward
the head
Inferior
Lowermost, below or toward
the tail
Proximal
Nearest the midline or
nearest to the beginning of a
structure
Distal
Farthest from the midline or
farthest from the beginning
of the structure
Superficial (also called
external)
Means near the surface
Deep (also called internal)
Away from the surface
Palmar
The caudal surface of the
manus(front paw) including
the carpus
Plantar
The caudal surface of the pe
(rear paw) including the
tarsus
Planes
Imaginary lines that are used descriptively to divide the body into sections
Plane
Midsagittal (median and
midline)
Description
Divides the body into equal
right and left halves
Sagittal (frontal and coronal) Divides the body into dorsal
(back) and ventral (belly)
parts
Transverse (horizontal
and/or cross-section 0plan)
Divides the body into cranial
and caudal parts
Planes are imaginary lines that are used descriptively to
divide the body into sections.
Midsagittal: the plane that divides the body into equal right
and left halves .
* median
* midline
Sagittal: the plane that divides the body into unequal right
and left parts
Dorsal: the plane that divides the body into dorsal (back) and
ventral (belly) parts
* frontal
* coronal
Transverse: the plane that divides the body into cranial and
caudal parts
* horizontal plan
* cross-sectional plan
The terms anterior, posterior, superior and
inferior can be confusing when used with
quadrupeds.
In quadrupeds, ventral is a better term for
anterior and dorsal is a better term than
posterior
Study . . . .
-ology: study of
physiology: then study of body function
pathology: the study of the nature, causes and development of
abnormal conditions
pathophysiology: the study of changes in function caused by disease
etiology: the study of the cause of disease
The Mouth
Term
Meaning
Arcade
Describes how teeth are
arranged in the mouth
Lingual surface
Aspect of the tooth that
faces the tongue
Maxilla
Upper jaw
Mandible
Lower jaw
Palatal surface
Tooth surface of the maxilla
that faces the tongue
Lingual surface
The tooth surface of the
mandible that faces the
tongue
Term
Meaning
Buccal surface (vestibular
surface)
Aspect of the tooth that
faces the cheek
Occlusal surface
The aspects of the teeth that
meet where you chew
Labial surface
The tooth surface facing the
lips
Contact surface
The aspects of the tooth that
touch other teeth
Mesial contact
Contact surface is the one
closest to the midline of the
dental arcade or arch
Distal contact
The surface furthest from the
midline of the dental arcade
The dental arcade is the term used to describe
how teeth are arranged in the mouth.
Teeth Surfaces
The lingual surface is the aspect of the tooth that faces the
tongue.
The palatal surface is the tooth surface of the maxilla that
faces the tongue and the lingual surface is the tooth surface
of the mandible surface that faces the tongue.
The buccal surface is the aspect of the tooth that faces the
cheek (Bucca means cheek).
* sometimes called the vestibular surface
(Vestibule means cavity or entrance)
The occlusal surfaces are the aspects of the teeth that meet
when you chew.
Hint: think of the teeth occluding, or stopping, things
from passing between them when you clench the
them.
The labial surface is the tooth surface facing the lips.
(labia means lip)
Contact surfaces are divided into
* mesial : the one closest to the midline of the dental
arcade
* distal: furthest from the midline of the dental arcade
HOLES = CAVITIES
A body cavity is a hole or hollow space in the body that contains
and protects organs.
The cranial (crani = skull) cavity is the hollow space that
contains the brain and skull.
The spinal cavity is the hollow space that contains the spinal
cord within the spinal column.
The thoracic cavity (thorac = chest) is the hollow space that
contains the heart and lungs with the ribs between the neck
and diaphragm.
The abdominal cavity is the hollow space that contains the
major organs of digestion located between the diaphragm and
pelvic cavity.
The peritoneal cavity is the hollow space within the abdominal
cavity between the parietal peritoneum and the visceral
peritoneum.
The pelvic cavity is the hollow space that contains the
reproductive and some excretory systems organs bounded by
the pelvic bones.
TERMS YOU NEED TO KNOW . . .
REGIONS
Abdomen – the portion of the body between the thorax and
the pelvis containing the abdominal cavity.
Thorax – is the chest region located between the neck and
the diaphragm.
Groin – the lower region of the abdomen adjacent to the
thigh (also known as inguinal area)
MEMBRANES . . .
Membranes – are thin layers of tissue that cover a surface, line
a cavity or divide a space or an organ.
Peritoneum – the membrane lining the walls of the
abdominal and pelvic cavities and covers some of the organs
in this area.
(the peritoneum maybe further divided in reference to its
location)
* parietal (side) peritoneum – outer layer of the
peritoneum that lines the abdominal and pelvic
cavities
* visceral (organ) peritoneum – the inner layer of the
peritoneum that surrounds the abdominal
organs.
Peritonitis – inflammation of the peritoneum
ABDOMEN . . .
Umbilicus (navel) – the pit in the abdominal wall marking the
point where the umbilical cord entered the fetus.
Mesentery – the layer of the peritoneum that suspends parts of
the intestine in the abdominal cavity.
Retroperitoneal – superficial to the peritoneum.
LYING AROUND . . .
Recumbent – lying down
Dorsal recumbency – lying on the back – also known as
supine
Ventral recumbency (sternal recumbency) – lying on
the belly – also known as pron
Left lateral recumbency – lying on the left side
Right lateral recumbency – lying on the right side
Dorsal or supine
Sternal or ventral
Right lateral
Left lateral
MOVING ALONG . . .
Adduction – movement toward the midline
Abduction – movement away from the midline
Flexion – closure of a joint angle or reduction of the angle.
Extension – straightening of a joint or an increase in the angle
between two bones
* hyperflexion and hyperextension occur when the
joint is flexed or extended too far.
CELLS . . .
Cyte = cell
Ology = study of
* cytology = involves studying cell origin, structure,
function and pathology
Prot = first
Plasm = formative material of cells
* protoplasm = the cell membrane, cytoplasm, and
nucleus
GENES . . .
Genetic – term used to denote something that pertains to genes
or heredity.
Genetic Disorder – any inherited disease or condition caused by
defective genes
Congenital – denotes something that is present at birth
Anomaly – deviation from what is regarded as normal (used
instead of defect)
Tissue . . .
Hist/o = tissue
Ology = study of
* histology = the study of structure, composition and
function of tissue
Tissue – a group of specialized cells that are similar in
structure and function
Four types of tissue:
1. epithelial (epithelium) – covers internal and external
body surfaces and is made up of tightly packed cells
a. Endothelium – lining of the internal organs
b. Mesothelium – covering that forms the lining
of serous membranes such as the peritoneum
2. Connective - adds support and structure to the body
by holding the organs in place and binding body parts
together
Examples: bone, cartilage, tendons, ligaments
a. Adipose – fat (connective)
3. Muscle – contains cell material with the specialized
ability to contract and relax
a. Skeletal
b. Smooth
c. cardiac
4. Nervous - contains cells with the specialized ability
to react to stimuli and conduct electrical impulses
-plasia = formation, development, growth and cell numbers
-Trophy = formation, development, and increase in size of
tissue and cells
Anaplasia – a change in the structure of cells and their
orientation to each other
Aplasia – lack of development of an organ or tissue or a cell
Dysplasia – abnormal growth or development of an organ or a
tissue or a cell.
Hyperplasia – abnormal increase in the number of normal cells
in normal arrangement in an organ or a tissue or a cell
Hypoplasia – incomplete or less than normal development of an
organ or a tissue or a cell.
Neoplasm – any abnormal new growth of tissue in which
multiplication of cells is uncontrolled, more rapid than normal,
and progressive
* usually form a distinct mass of tissue called a
tumor
* benign – not cancerous or not recurring
* malignant – tending to spread and be life
threatening (cancerous)
-oma = tumor or neoplasm
Atrophy – decrease in size or complete wasting of an organ or
tissue or cell
Dystrophy – defective growth in the size of an organ or tissue
or cell
Hypertrophy – increase in the size of an organ or tissue or cell
Reminder:
a – without
dys – bad
hypo – less than normal
hyper – more than normal
ana – without
neo – new
5. Glands: groups of specialized cells that secrete material
used elsewhere in the body
Aden/o = gland
Exocrine gland: groups of cells that secrete their chemical
substances into ducts that lead out of the body or to
another organ. (sweat glands, sebaceous glands)
Endocrine gland: groups of cells that secrete their
chemical substances directly into the bloodstream,
which transports them throughout the body.
They are ductless (thyroid glands, pituitary and the
portion of the pancreas that secretes insulin.
6. Organ: part of the body that performs a special function or
functions.
NUMBERS
Medical terms can be further modified by the use of prefixes to
assign number value, numerical order, or proportions.