Download Anatomical Directions

ANATOMICAL LOCATION
Anatomy is a difficult subject with a large component of memorization. There is just no
way around that, but we have made every effort to make this course diverse and fun.
The first and probably the most difficult component of the study of anatomy is
anatomical location. It is important for you to understand these terms thoroughly
regardless of which anatomy system (part(s) of the body) you are studying. It will also be
important for you to know these terms when you are learning about radiographs. As you
move through the other courses, it will be assumed that you know these terms. Take your
time and be sure these terms become like a second language in which you are fluent,
otherwise you will struggle needlessly in other courses as well as out in the field when
speaking with other professionals.
You will notice that these terms are used in both human bipeds, as well as in animal
quadrupeds. While there are general guidelines that some terms should not be used with
animals rather should be used only when referring to human anatomy- and visa versa,
you will find that many professionals use any and all terms regardless of whether they are
speaking of human or animal.
TERMS:
MORPHOLOGY –
1. a branch of biology that deals with the form and structure of an organism, in
whole or in part.)
ANTERIOR –
1. relating to or situated near or toward the head or toward the part most nearly
corresponding to the head
2. situated toward the front of the body : used in human anatomy because of the
upright posture of humans
POSTERIOR –
1. situated behind: situated at or toward the hind part of the body :
SUPERIOR –
1. situated toward the head and further away from the feet than another and
especially another similar part of an upright body especially of a human being
2. situated in a more anterior or dorsal position in the body of a quadruped
INFERIOR –
1. situated below and closer to the feet than another and especially another similar
part of an upright body especially of a human being
2. situated in a more posterior or ventral position in the body of a quadruped
Use in human anatomy
In human anatomy, the body and its parts are always described using the assumption that
the body is in anatomical position The anatomical position is a schematic convention for
describing the relative morphology of the human body. The person is oriented in an erect
standing position, with eyes and head facing forward, feet forward and perpendicular to
the body, arms close to the sides, and palms of the hands facing forward with fingers
extended. It should be noted that this is not the normal position for the arms, which in a
relaxed subject would be rotated more or less medially (with the palms of the hands
facing the body).
Portions of the body which are closer to the head end in the human are "superior"
("upper"); those which are farther away are "inferior" ("lower") – in the quadruped,
superior corresponds to dorsal, and inferior to ventral. If you imagine the quadruped
standing upright as a human, superior would correspond to cranial and inferior to
caudal. But “dorsal and ventral” are most commonly used.
In the human, objects near the front are "anterior"; those near the rear are "posterior" –
in the quadruped, these correspond respectively to "ventral" and "dorsal".
On the limbs, an object closer to the main body is "proximal"; an object farther away is
"distal".
The terms "anterior" and "posterior" should not be used when referring to most animals
however, and are particularly incorrect for quadrupeds. However, we mix these terms off
and on throughout the class because many professionals (vets, owners who work in the
medical field, etc.) use these terms interchangeably. You need to be able to translate in
your head so you can understand what they mean, even if they are using an incorrect term
relative to the horse.
TERMS:
DORSAL - 1 a : being or located near, on, or toward the upper surface of an animal (as a
quadruped) opposite the lower or ventral surface b : being or located near, on, or toward
the back or posterior part of the human body
VENTRAL - 1 : of or relating to the belly : ABDOMINAL 2 a : being or located near,
on, or toward the lower surface of an animal (as a quadruped) opposite the back or dorsal
surface b : being or located near, on, or toward the front or anterior part of the human
body
CRANIAL - of or relating to the skull or cranium; situated or directed toward the head
or front part of the body
CAUDAL - 1 : of, relating to, or being a tail 2 : situated in or directed toward the hind
part of the body
ROSTRAL - situated toward the oral or nasal region
Use in quadruped anatomy
Quadrupeds have one end with a head and mouth, with the opposite end with the anus
and tail. The head end is the cranial end; the tail end is the caudal end. Within the head
itself, rostral refers to the direction toward the end of the nose, and caudal is still used to
refer to the tail direction.
The surface or side of the body normally oriented upwards, away from the pull of gravity,
is the dorsal side; the opposite side, typically the one closest to the ground when walking
on all legs, swimming or flying, is the ventral side.
PLANES
Three basic reference planes are used in zoological anatomy. The sagittal plane divides
the body into left and right halves. A coronal plane divides the body into dorsal and
ventral halves. A transverse plane divides the body into cranial and caudal halves.
TERMS:
TRANSVERSE or AXIAL PLANE –
1. parallel to the ground in humans, it separates the superior from the inferior, or put
another way, the head from the feet. Perpendicular to the ground in the
quadruped, it separates the front end (cranial) from the back end (caudal).
CORONAL or FRONTAL PLANE –
1. perpendicular to the ground (in humans) and separates the anterior from the
posterior, the front from the back, the ventral from the dorsal.
2. For humans a coronal plane is vertical and a transverse plane is horizontal, but for
quadrupeds a coronal plane is horizontal and a transverse plane is vertical.
SAGITTAL PLANE –
1. perpendicular to the coronal plane, which separates left from right.
MID-SAGITTAL PLANE –
1. the specific sagittal plane that is exactly in the middle of the body.
2. the median vertical longitudinal plane that divides a bilaterally symmetrical
animal into right and left halves -- called also median plane.
OBLIQUE PLANE –
Oblique planes are planes of the body or any of its parts that are not cut along one of the
previously described anatomical planes.
RELATIVE DIRECTIONS
TERMS:
MEDIAL - lying or extending in the middle ; especially, of a body part : lying or
extending toward the median axis of the body
LATERAL - of or relating to the side ; especially, of a body part : lying at or extending
toward the right or left side : lying away from the median axis of the body - the lungs are
lateral to the heart
PROXIMAL or CENTRAL- situated next to or near the point of attachment or origin or
a central point : a) located toward the center of the body b) located toward the medial
plane of the body
DISTAL or PERIPHERAL - situated away from the point of attachment or origin or a
central point: as a) located away from the center of the body b) located away from the
medial plane of the body
MEDIAN – midline of the body
Structures near the midline are called medial and those near the sides of animals are
called lateral. Therefore, medial structures are closer to the midsagittal plane, lateral
structures are further from the midsagittal plane. Structures in the midline of the body are
median. For example, your cheeks are lateral to your nose and the tip of the nose is in the
median line.
Structures that are close to the center of the body are proximal or central, while ones far
removed are distal or peripheral. For example, the hands are at the distal end of the
arms, while the shoulders are at the proximal ends.
Structures on or closer to the body´s surface are superficial (or external) and those
further inside are profound or deep (or internal).
Relative directions in the limbs
In the limbs, the terms cranial and caudal are used in the regions proximal to the carpus
(the wrist in the forelimb) and the tarsus (the ankle in the hind limb). Objects and
surfaces closer to or facing towards the head are cranial; those facing away or further
from the head are caudal.
Distal to the carpal joint, the term dorsal replaces cranial and palmar replaces caudal.
Similarly, distal to the tarsal joint the term dorsal replaces cranial and plantar replaces
caudal. For example, the top of a For example, the top of a dog’s paw is its dorsal
surface; the underside, either the palmar (on the forelimb) or the plantar (on the
hindlimb) surface.
VOLAR - relating to the palm of the hand or the sole of the foot ; specifically : located
on the same side as the palm of the hand <the volar part of the forearm>
PALMAR - of, relating to, or involving the palm of the hand
AXIAL - Located on, around, or in the direction of an axis.
ABAXIAL - Located away from or on the opposite side of the axis.
AXIS - A line that passes through the center of the body or body part.
The terms axial/abaxial are available to indicate directions toward/away from the center
axis of the limb.
Relative motions
Muscles act by moving joints. Thus, the same terms apply to both muscle actions and
joint movements. All joint movements are described by opposing terms (directions). One
set of muscles moves a joint in one direction; another set of muscles moves the same joint
in the opposite direction. Most joints in the body function as "hinge" joints, meaning they
move (extend/flex) in one plane. Ball and socket joints (e.g., the hip joint) are capable of
circumduction (circular motion). Limbs as a whole are capable of rotation
(supination/pronation) and movement away from (abduction) and toward (adduction) the
body.
FLEXION means approximating adjacent parts of the body (usually at a joint). Flex =
decrease the angle formed by a hinge joint.
EXTENSION means separating them. For example, the legs are flexed at the knee joints
when sitting down, and extended when standing up. Extend = increase the angle formed
by a hinge joint.
ADDUCTION means moving a part of the body toward or past its median line or toward
the long axis of a limb. Adduct = move the limb toward the body.
ABDUCTION means moving a part of the body away from its median line or away from
the long axis of a limb. For example, adducting the thighs brings the legs together, and
abducting the thighs spreads the legs apart. Similarly, adducting the fingers brings them
into contact with one another, and abducting the fingers spreads them apart. Abduct =
move the limb away from the body.
ROTATION means moving a part about its long axis, for example, in turning the neck.
SUPINATION (a) rotation of the forearm such that the palm of the hand faces forward
or upward. Supinate = rotate the limb so the dorsum of the manus (or pes) is directed
laterally. (manus=front foot or “hand” pes=hind foot)
PRONATION (c) rotation of an anatomical part towards the midline: as a : rotation of
the hand and forearm so that the palm faces backwards or downwards b : rotation of the
medial bones in the mid tarsal region of the foot inward and downward so that in walking
the foot. Pronate -- rotate the limb so the dorsum of the manus (or pes) is directed
medially.