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1/5/2014 Anatomical Terminology
http://cnx.org/content/m45990/latest/ 1/12
OpenStax_CNXY ou are here: Home » Content » Anatomical Terminology
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Anatomical Terminology
Module by : OpenStax College.
Sum m ary : By the end of this section, y ou will be able to:
Demonstrate the anatomical position
Describe the human body using directional and regional terms
Identify three planes most commonly used in the study of anatomy
Distinguish between the posterior (dorsal) and the anterior (ventral) body cav ities, identify ing theirsubdiv isions and representative organs found in each
Describe serous membrane and explain its function
Anatomists and health care prov iders use terminology that can be bewildering to the uninitiated.
However, the purpose of this language is not to confuse, but rather to increase precision and reduce
medical errors. For example, is a scar “above the wrist” located on the forearm two or three inches away
from the hand? Or is it at the base of the hand? Is it on the palm-side or back-side? By using precise
anatomical terminology , we eliminate ambiguity . Anatomical terms derive from ancient Greek and Latin
words. Because these languages are no longer used in every day conversation, the meaning of their words
does not change.
Anatomical terms are made up of roots, prefixes, and suffixes. The root of a term often refers to an organ,
tissue, or condition, whereas the prefix or suffix often describes the root. For example, in the disorder
hy pertension, the prefix “hy per-” means “high” or “over,” and the root word “tension” refers to pressure,
so the word “hy pertension” refers to abnormally high blood pressure.
Anatomical Position
To further increase precision, anatomists standardize the way in which they v iew the body . Just as maps
are normally oriented with north at the top, the standard body “map,” or anatom ical position, is that
of the body standing upright, with the feet at shoulder width and parallel, toes forward. The upper limbs
are held out to each side, and the palms of the hands face forward as illustrated in Figure 1 (#fig -
ch 01 _06 _01 ) . Using this standard position reduces confusion. It does not matter how the body being
described is oriented, the terms are used as if it is in anatomical position. For example, a scar in the
“anterior (front) carpal (wrist) region” would be present on the palm side of the wrist. The term “anterior”
would be used even if the hand were palm down on a table.
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Figu re 1: Th e h u m a n body is sh ow n in a n a tom ica l posit ion in a n (a ) a n ter ior v iew a n d a (b)
poster ior v iew . Th e r eg ion s of th e body a r e la beled in boldfa ce.
Regions of the Hum an Body
A body that is ly ing down is described as either prone or supine. Prone describes a face-down
orientation, and supine describes a face up orientation. These terms are sometimes used in describing
the position of the body during specific phy sical examinations or surgical procedures.
Regional Terms
The human body ’s numerous regions have specific terms to help increase precision (see Figure 1 (#fig -
ch 01 _06 _01 ) ). Notice that the term “brachium” or “arm” is reserved for the “upper arm” and
“antebrachium” or “forearm” is used rather than “lower arm.” Similarly , “femur” or “thigh” is correct, and
“leg” or “crus” is reserved for the portion of the lower limb between the knee and the ankle. Y ou will be
able to describe the body ’s regions using the terms from the figure.
Directional Terms
Certain directional anatomical terms appear throughout this and any other anatomy textbook (Figure 2
(#fig -ch 01 _06 _02 ) ). These terms are essential for describing the relative locations of different body
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structures. For instance, an anatomist might describe one band of tissue as “inferior to” another or a
phy sician might describe a tumor as “superficial to” a deeper body structure. Commit these terms to
memory to avoid confusion when y ou are study ing or describing the locations of particular body parts.
Anterior (or ventral) Describes the front or direction toward the front of the body . The toes are
anterior to the foot.
Posterior (or dorsal) Describes the back or direction toward the back of the body . The popliteus is
posterior to the patella.
Superior (or cranial) describes a position above or higher than another part of the body proper.
The orbits are superior to the oris.
Inferior (or caudal) describes a position below or lower than another part of the body proper;
near or toward the tail (in humans, the coccy x, or lowest part of the spinal column). The pelv is is
inferior to the abdomen.
Lateral describes the side or direction toward the side of the body . The thumb (pollex) is lateral to
the digits.
Medial describes the middle or direction toward the middle of the body . The hallux is the medial
toe.
Proxim al describes a position in a limb that is nearer to the point of attachment or the trunk of the
body . The brachium is proximal to the antebrachium.
Distal describes a position in a limb that is farther from the point of attachment or the trunk of the
body . The crus is distal to the femur.
Superficial describes a position closer to the surface of the body . The skin is superficial to the
bones.
Deep describes a position farther from the surface of the body . The brain is deep to the skull.
Directional T erm s Applied to the Hum an Body
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Figu re 2: Pa ir ed dir ect ion a l ter m s a r e sh ow n a s a pplied to th e h u m a n body .
Body Planes
A section is a two-dimensional surface of a three-dimensional structure that has been cut. Modern
medical imaging dev ices enable clinicians to obtain “v irtual sections” of liv ing bodies. We call these scans.
Body sections and scans can be correctly interpreted, however, only if the v iewer understands the plane
along which the section was made. A plane is an imaginary two-dimensional surface that passes through
the body . There are three planes commonly referred to in anatomy and medicine, as illustrated in Figure
3 (#fig -ch 01 _06 _03 ) .
The sagittal plane is the plane that div ides the body or an organ vertically into right and left sides.
If this vertical plane runs directly down the middle of the body , it is called the midsagittal or median
plane. If it div ides the body into unequal right and left sides, it is called a parasagittal plane or less
commonly a longitudinal section.
The frontal plane is the plane that div ides the body or an organ into an anterior (front) portion
and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. (“Corona” is
Latin for “crown.”)
The transverse plane is the plane that div ides the body or organ horizontally into upper and
lower portions. Transverse planes produce images referred to as cross sections.
Planes of the Body
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Figu re 3: Th e th r ee pla n es m ost com m on ly u sed in
a n a tom ica l a n d m edica l im a g in g a r e th e sa g it ta l, fr on ta l (or
cor on a l), a n d tr a n sv er se pla n e.
Body Cavities and Serous Membranes
The body maintains its internal organization by means of membranes, sheaths, and other structures that
separate compartments. The dorsal (posterior) cavity and the ventral (anterior) cavity are the
largest body compartments (Figure 4 (#fig -ch 01 _06 _04 ) ). These cav ities contain and protect delicate
internal organs, and the ventral cav ity allows for significant changes in the size and shape of the organs as
they perform their functions. The lungs, heart, stomach, and intestines, for example, can expand and
contract without distorting other tissues or disrupting the activ ity of nearby organs.
Dorsal and Ventral Body Cavities
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Figu re 4: Th e v en tr a l ca v ity in clu des th e th or a cic a n d a bdom in opelv ic ca v it ies a n d th eir
su bdiv ision s. Th e dor sa l ca v ity in clu des th e cr a n ia l a n d spin a l ca v it ies.
Subdivisions of the Posterior (Dorsal) and Anterior (Ventral) Cavities
The posterior (dorsal) and anterior (ventral) cav ities are each subdiv ided into smaller cav ities. In
the posterior (dorsal) cav ity , the cranial cavity houses the brain, and the spinal cavity (or
vertebral cav ity ) encloses the spinal cord. Just as the brain and spinal cord make up a continuous,
uninterrupted structure, the cranial and spinal cav ities that house them are also continuous. The
brain and spinal cord are protected by the bones of the skull and vertebral column and by
cerebrospinal fluid, a colorless fluid produced by the brain, which cushions the brain and spinal
cord within the posterior (dorsal) cav ity .
The anterior (ventral) cav ity has two main subdiv isions: the thoracic cav ity and the
abdominopelv ic cav ity (see Figure 4 (#fig -ch 01 _06 _04 ) ). The thoracic cavity is the more
superior subdiv ision of the anterior cav ity , and it is enclosed by the rib cage. The thoracic cav ity
contains the lungs and the heart, which is located in the mediastinum. The diaphragm forms the
floor of the thoracic cav ity and separates it from the more inferior abdominopelv ic cav ity . The
abdom inopelvic cavity is the largest cav ity in the body . Although no membrane phy sically
div ides the abdominopelv ic cav ity , it can be useful to distinguish between the abdominal cav ity ,
the div ision that houses the digestive organs, and the pelv ic cav ity , the div ision that houses the
organs of reproduction.
Abdominal Regions and Quadrants
To promote clear communication, for instance about the location of a patient’s abdominal pain or
a suspicious mass, health care prov iders ty pically div ide up the cav ity into either nine regions or
four quadrants (Figure 5 (#fig -ch 01 _06 _05 ) ).
Regions and Quadrants of the Peritoneal Cavity
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Figu re 5: Th er e a r e (a ) n in e a bdom in a l r eg ion s a n d (b) fou r a bdom in a l qu a dr a n ts in th e
per iton ea l ca v ity .
The more detailed regional approach subdiv ides the cav ity with one horizontal line immediately
inferior to the ribs and one immediately superior to the pelv is, and two vertical lines drawn as if
dropped from the midpoint of each clav icle (collarbone). There are nine resulting regions. The
simpler quadrants approach, which is more commonly used in medicine, subdiv ides the cav ity
with one horizontal and one vertical line that intersect at the patient’s umbilicus (navel).
Membranes of the Anterior (Ventral) Body Cavity
A serous m em brane (also referred to a serosa) is one of the thin membranes that cover the
walls and organs in the thoracic and abdominopelv ic cav ities. The parietal lay ers of the
membranes line the walls of the body cav ity (pariet- refers to a cav ity wall). The v isceral lay er of
the membrane covers the organs (the v iscera). Between the parietal and v isceral lay ers is a very
thin, fluid-filled serous space, or cav ity (Figure 6 (#fig -ch 01 _06 _06 ) ).
Figu re 6: Ser ou s m em br a n e lin es th e per ica r dia l ca v ity a n d r eflects
ba ck to cov er th e h ea r t—m u ch th e sa m e w a y th a t a n u n der in fla ted
Serous Mem brane
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ba ck to cov er th e h ea r t—m u ch th e sa m e w a y th a t a n u n der in fla ted
ba lloon w ou ld for m tw o la y er s su r r ou n din g a fist .
There are three serous cav ities and their associated membranes. The pleura is the serous
membrane that surrounds the lungs in the pleural cav ity ; the pericardium is the serous
membrane that surrounds the heart in the pericardial cav ity ; and the peritoneum is the serous
membrane that surrounds several organs in the abdominopelv ic cav ity . The serous fluid
produced by the serous membranes reduces friction between the walls of the cav ities and the
internal organs when they move, such as when the lungs inflate or the heart beats. Both the
parietal and v isceral serosa secrete the thin, slippery serous fluid that prevents friction when an
organ slides past the walls of a cav ity . In the pleural cav ities, pleural fluid prevents friction
between the lungs and the walls of the cav ity . In the pericardial sac, pericardial fluid prevents
friction between the heart and the walls of the pericardial sac. And in the peritoneal cav ity ,
peritoneal fluid prevents friction between abdominal and pelv ic organs and the wall of the cav ity .
The serous membranes therefore prov ide additional protection to the v iscera they enclose by
reducing friction that could lead to inflammation of the organs.
Chapter Review
Ancient Greek and Latin words are used to build anatomical terms. A standard reference position for
mapping the body ’s structures is the normal anatomical position. Regions of the body are identified using
terms such as “occipital” that are more precise than common words and phrases such as “the back of the
head.” Directional terms such as anterior and posterior are essential for accurately describing the relative
locations of body structures. Images of the body ’s interior commonly align along one of three planes: the
sagittal, frontal, or transverse. The body ’s organs are organized in one of two main cav ities—dorsal (also
referred to posterior) and ventral (also referred to anterior)—which are further sub-div ided according to
the structures present in each area. The serous membranes have two lay ers—parietal and v isceral—
surrounding a fluid filled space. Serous membranes cover the lungs (pleural serosa), heart (pericardial
serosa), and some abdominopelv ic organs (peritoneal serosa).
Review Chapter
EXERCISE 1
What is the position of the body when it is in the “normal anatomical position?”
a. The person is prone with upper limbs, including palms, touching sides and lower limbs touching at
sides.
b. The person is standing facing the observer, with upper limbs extended out at a ninety -degree angle
from the torso and lower limbs in a wide stance with feet pointing laterally
c. The person is supine with upper limbs, including palms, touching sides and lower limbs touching at
sides.
d. None of the above
D
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EXERCISE 2
To make a banana split, y ou halve a banana into two long, thin, right and left sides along the ________.
a. coronal plane
b. longitudinal plane
c. midsagittal plane
d. transverse plane
C
EXERCISE 3
The lumbar region is ________.
a. inferior to the gluteal region
b. inferior to the umbilical region
c. superior to the cerv ical region
d. superior to the popliteal region
D
EXERCISE 4
The heart is within the ________.
a. cranial cav ity
b. mediastinum
c. posterior (dorsal) cav ity
d. All of the above
B
Critical Thinking Question
EXERCISE 5
In which direction would an MRI scanner move to produce sequential images of the body in the frontal
plane, and in which direction would an MRI scanner move to produce sequential images of the body in the
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sagittal plane?
If the body were supine or prone, the MRI scanner would move from top to bottom to produce
frontal sections, which would div ide the body into anterior and posterior portions, as in “cutting”
a deck of cards. Again, if the body were supine or prone, to produce sagittal sections, the scanner
would move from left to right or from right to left to div ide the body lengthwise into left and right
portions.
EXERCISE 6
If a bullet were to penetrate a lung, which three anterior thoracic body cav ities would it enter, and which
lay er of the serous membrane would it encounter first?
The bullet would enter the ventral, thoracic, and pleural cav ities, and it would encounter the
parietal lay er of serous membrane first.
GLOSSARY
abdom inopelvic cavity :div ision of the anterior (ventral) cav ity that houses the abdominal and
pelv ic v iscera
anatom ical position:standard reference position used for describing locations and directions
on the human body
anterior:describes the front or direction toward the front of the body ; also referred to as ventral
anterior cavity :larger body cav ity located anterior to the posterior (dorsal) body cav ity ;
includes the serous membrane-lined pleural cav ities for the lungs, pericardial cav ity for the heart,
and peritoneal cav ity for the abdominal and pelv ic organs; also referred to as ventral cav ity
caudal:describes a position below or lower than another part of the body proper; near or toward
the tail (in humans, the coccy x, or lowest part of the spinal column); also referred to as inferior
cranial:describes a position above or higher than another part of the body proper; also referred
to as superior
cranial cavity :div ision of the posterior (dorsal) cav ity that houses the brain
deep:describes a position farther from the surface of the body
distal:describes a position farther from the point of attachment or the trunk of the body
dorsal:describes the back or direction toward the back of the body ; also referred to as posterior
dorsal cavity :posterior body cav ity that houses the brain and spinal cord; also referred to the
posterior body cav ity
frontal plane:two-dimensional, vertical plane that div ides the body or organ into anterior and
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posterior portions
inferior:describes a position below or lower than another part of the body proper; near or
toward the tail (in humans, the coccy x, or lowest part of the spinal column); also referred to as
caudal
lateral:describes the side or direction toward the side of the body
m edial:describes the middle or direction toward the middle of the body
pericardium :sac that encloses the heart
peritoneum :serous membrane that lines the abdominopelv ic cav ity and covers the organs
found there
plane:imaginary two-dimensional surface that passes through the body
pleura:serous membrane that lines the pleural cav ity and covers the lungs
posterior:describes the back or direction toward the back of the body ; also referred to as dorsal
posterior cavity :posterior body cav ity that houses the brain and spinal cord; also referred to as
dorsal cav ity
prone:face down
proxim al:describes a position nearer to the point of attachment or the trunk of the body
sagittal plane:two-dimensional, vertical plane that div ides the body or organ into right and left
sides
section:in anatomy , a single flat surface of a three-dimensional structure that has been cut
through
serous m em brane:membrane that covers organs and reduces friction; also referred to as
serosa
serosa:membrane that covers organs and reduces friction; also referred to as serous membrane
spinal cavity :div ision of the dorsal cav ity that houses the spinal cord; also referred to as
vertebral cav ity
superficial:describes a position nearer to the surface of the body
superior:describes a position above or higher than another part of the body proper; also
referred to as cranial
supine:face up
thoracic cavity :div ision of the anterior (ventral) cav ity that houses the heart, lungs, esophagus,
and trachea
transverse plane:two-dimensional, horizontal plane that div ides the body or organ into
superior and inferior portions
ventral:describes the front or direction toward the front of the body ; also referred to as anterior
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ventral cavity :larger body cav ity located anterior to the posterior (dorsal) body cav ity ;
includes the serous membrane-lined pleural cav ities for the lungs, pericardial cav ity for the heart,
and peritoneal cav ity for the abdominal and pelv ic organs; also referred to as anterior body
cav ity
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Last edited by CNX Anatom y and Physiology on Jun 3, 2013 2:46 pm -0500.