Dictionary Definition
laterally adv
1 to or by or from the side; "such women carry in
their heads kinship knowledge of six generations depth and
extending laterally among consanguineal kin as far as the
grandchildren of second cousin"
2 in a lateral direction or location; "the body
is spindle-shaped and only slightly compressed laterally"
User Contributed Dictionary
Extensive Definition
Human anatomical terms make up a distinct
nomenclature to describe areas of the body, to provide
orientation when describing parts of human
anatomy, and to distinguish different movements of the body. An
understanding of these terms is necessary to study the human body
in depth. Many of these terms are also applicable in animal anatomy
(zootomy).
Anatomical body position
The anatomical position is the position that
provides a reference point for describing the structures of the
body. In this position, the body is erect and the face forward. The
feet are together, flat on the floor and the toes pointing forward.
The arms are down at the sides with the palms turned forward with
the thumb side of the hand away from the body. When the body lying
face down in the anatomical position, this is the prone position.
When the body is lying face up, this is the supine position.
Body landmarks
Anatomists use specific terms to indicate visible
areas of the body. The cephalon or cephalic region refers to the
head. This area is further differentiated into the cranium (skull),
facies (face), frons (forehead), oculus (eye area), auris (ear),
bucca (cheek), nausus (nose), oris (mouth), and mentis (chin). The
neck area is called the cervicis or cervical region.
On the trunk of the body, the chest is referred
to as the thoracic area. The shoulder in general is the acromial,
while the curve of the shoulder is the deltoid. The back as a
general area is the dorsum or dorsal area, and the lower back as
the lumbus or lumbar region. The shoulderblades are the scapular
area and the breastbone is the sternal region. The abdominal area
is the region between the chest and the pelvis. The breast is
called the mamma or mammary, the armpit as the axilla and axillary,
and the navel as the umbilicus and umbilical. The pelvis is the
lower torso, between the abdomen and the thighs. The groins, where
the thigh joins the trunk, are the inguen and inguinal area.
The entire arm is referred to as the brachium and
brachial, the front of the elbow as the antecubitis and
antecubital, the back of the elbow as the olecranon or olecranal,
the forearm as the antebrachium and antebrachial, the wrist as the
carpus and carpal area, the hand as the manus and manual, the palm
as the palma and palmar, the thumb as the pollex, and the fingers
as the digits, phalanges, and phalangeal. The buttocks are the
gluteus or gluteal region and the pubic area is the pubis.
Anatomists divide the lower limb into the thigh,
the part of the limb between the hip and the knee, and the leg,
which refers only to the area of the limb between the knee and the
ankle. The thigh is the femur and the femoral region. The kneecap
is the patella and patellar while the back of the knee is the
popliteus and popliteal area. The leg (between the knee and the
ankle) is the crus and crural area, the outside of the leg is the
peroneal area, and the calf is the sura and sural region. The ankle
is the tarsus and tarsal, and the heel is the calcaneus or
calcaneal. The foot is the pes and pedal region, and the sole of
the foot the planta and plantar. As with the fingers, the toes are
also called the digits, phalanges, and phalangeal area. The big toe
is referred to as the hallux.
Use of the terms right and left
When anatomists refer to the right and left of
the body, it is in reference to the right and left of the subject,
not the right and left of the observer. When observing a body in
the anatomical position, the left body is on the observer’s left
and vice versa.
Regions of the abdomen and pelvis
Anatomists and medical personnel divide the
'Abdomen Proper' into smaller regions to facilitate study and
discussion. The two most common schemes are division into four
quadrants and also into nine areas.
The abdominopelvic quadrants evenly divide the
space of the torso below the diaphragm into four. They are referred
to simply by location: the right upper quadrant, right lower
quadrant, left upper quadrant, and left lower quadrant. The right
upper quadrant contains the right portion of the liver, the
gallbladder, right kidney, a small portion of the stomach, portions
of the ascending and transverse colon and parts of small intestine.
The left upper quadrant is the location of the left portion of the
liver, the larger portion of the stomach, the pancreas, left
kidney, spleen, portions of the transverse and descending colon and
parts of the small intestine. In the right lower quadrant sits the
cecum, appendix, part of the small intestines, the right
reproductive organs, and the right ureter. The left lower quadrant
houses the majority of the small intestine, some of the large
intestine, the left reproductive organs and the left ureter.
The nine divisions (sometimes also called nine
quadrants, though the word 'quadrant' itself means division into
four equal parts) of the abdominopelvic region are smaller than the
four abdominopelvic quadrants and allow more detailed discussion of
the area. These are the right hypochondriac, right lumbar, right
inguinal (or right iliac), epigastric, umbilical, hypogastric (or
pubic), left hypochondriac, left lumbar, and left inguinal (or left
iliac). The right and left hypochondriac regions are the outer and
uppermost segments. The epigastric lies between these two. The
outer middle sections are the right lumbar and left lumbar regions,
with the umbilical region between them. The lowest portions are the
right and left iliac region with the hypogastric between
these.
The Perineum is considered to be the 10th
division.
Anatomical directions
Anatomists use specific directional terms to
describe structures of the body. These terms always use anatomical
position as a point of reference, even if the structure or body
described is in another position. Some terms have different
connotations in veterinary anatomy.
Anterior and ventral both mean toward the front
of the body, while posterior and dorsal mean the back of the body.
These terms are almost always used in pairs, with anterior pairing
with posterior and ventral pairing with dorsal. The nose is on the
anterior (ventral) surface of the head. The spine is on the
posterior (dorsal) side of the body. (In veterinary anatomy,
ventral is abdominal side of the animal and dorsal is the backside,
while anterior means toward the head while posterior means toward
the tail.)
The terms superior, cranial, and cephalic all
mean toward the head or the upper part of a structure while
inferior and caudal refer to the lower part of a structure or away
from the head. For example, the shoulder is superior (cranial) to
the elbow and the elbow is inferior (caudal) to the shoulder. These
terms are also used in their respective pairs: superior with
inferior and cranial or cephalic with caudal. (The terms superior
and inferior are not used in veterinary anatomy.)
Proximal means closer to the trunk (torso) while
distal is away from the trunk. The statement “the knee is proximal
to the foot” means the knee is closer to the torso than the foot.
Conversely, the foot is distal to the knee.
Medial describes a structure toward the midline
of the body and lateral away from that median plane (the median
plane is often referred to as the "midline", however this is
wrong). Intermediate describes a structure between a medial and a
lateral structure. The nose is medial to the ears while the ears
are lateral to the nose. The cheeks are intermediate between the
nose and the ears.
Superficial means close to the surface of the
body while deep means away from the surface. The brain is deep to
the skull while the skull is superficial to the brain.
Planes of the body
Anatomists also divide the body into planes to
facilitate discussion. These are the coronal or
frontal plane, the sagittal,
midsagittal or median sagittal, and the transverse
or horizontal plane. These planes are defined using the
anatomical position as a reference point. The coronal or frontal
section divides the body lengthwise from anterior to posterior and
side to side. When the body is divided into the coronal plane, the
anterior of the face, trunk and legs would be separated from the
posterior. The sagittal plane bisects the left and right sides of
the body longitudinally. This plane runs down the center of the
head, torso, and between the legs and feet. A midsagittal or median
sagittal section evenly divides the body along the median plane,
while a parasagittal division is parallel to a midsagittal
division. The transverse or horizontal plane runs perpendicularly
to the longitudinal axis of the body, dividing it into upper and
lower sections.
Body cavities
The body contains two main cavities, dorsal and
ventral, that house and protect the internal organs. These cavities
are subdivided to further distinguish location.
The dorsal body cavity is the space within the
cranium (skull) and the spinal canal, which is surrounded by the
vertebrae. The fluid filled space inside the cranium is called is
the cranial cavity, and it contains the brain. The spinal cavity is
the space that encloses the spinal cord and extends from the
cranial cavity to the base of the spine.
The ventral body cavity contains the organs in
the chest and abdomen. It is further divided by the diaphragm into
the superior thoracic cavity and the inferior abdominopelvic
cavity.
The thoracic cavity contains the lungs, heart,
the lower esophagus, the thymus gland, and other organs of the
cardiovascular, respiratory, and lymphatic systems. This cavity is
subdivided into the right pleural cavity of the right lung, the
left pleural cavity of the left lung, and the mediastinum, between
the pleural cavities, which houses the trachea, esophagus, thymus,
heart, and vessels connected to the heart. The medistinum contains
the pericardial cavity, which is the area surrounding the
heart.
The abdominopelvic cavity is often divided into
the superior abdominal and inferior pelvic cavities. The abdominal
cavity contains the digestive organs and glands, namely the liver,
gallbladder, spleen, kidneys, pancreas, stomach, small intestine
and the majority of the large intestine. The pelvic cavity is
surrounded by the pelvis and contains the inferior portion of the
large intestine, bladder, uterine tubes, and reproductive
organs.
Types of movement
The body has a wide variety of movements
available to it, depending on the joint where the movement occurs.
Movement occurs when a muscle or muscles contract over joints and
is dependent on the joint’s mobility and the location of the muscle
in relation to the joint. The different types of movement have
specific terms, often in pairs to describe opposite
movements.
Flexion occurs in the sagittal plane, when the
angle of a joint decreased. It occurs in hinge joints and
ball-and-socket joints. When the knee is bent, this is a form of
flexion. Conversely, extension occurs when the angle is increased
along the same plane. Straightening of the leg is extension.
Hyperextension occurs when the extension is beyond 180°. The neck
is hyperextended when the chin tilts up toward the ceiling. Some
people with flexible ligaments and tendons can hyperextend the
elbows and knees, which can cause injury in these joints. Flexion
and extension of the ankle are dorsiflexion and plantar flexion,
respectively.
Abduction is the movement of a limb away from the
median
plane of the body. This occurs when someone jumps the arms legs
apart, as in jumping jacks, and also when fanning the fingers and
toes. Adduction is the reversal of this movement, bringing the limb
back to the median plane.
Circumduction is a circular movement of the
joint, such as drawing a circle with the arm and wrist straight. It
is a combination of abduction, adduction, flexion and extension in
a ball-and-socket joint.
A movement of the vertebrae in the coronal plane
away from the midline is lateral flexion. The cervical and thoracic
regions of the spine are most capable of this movement. It occurs
when one moves the ear toward the shoulder with the nose facing
forward.
Rotation is movement of a bone around the
longitudinal axis of that bone. Lateral (or external) rotation
occurs when the anterior aspect rotates outward and medial rotation
occurs when it rotates inward. Turning the head to look to the side
is lateral rotation, and bringing it back to the center is medial
rotation. These movements occur across all ball-and-socket joints.
Pronation and supination occur at the wrist to rotate the palm.
Pronation is the turning of the palm from the anatomical position
to face backward. Turning the palm forward is supination.
Inversion is a movement of the foot to turn the
sole medially while eversion turns it laterally.
Gliding is the motion in any direction of two
articulating surfaces sliding past one another. This minimum
movement occurs in the carpal bones of the hands and tarsal bones
of the feet and also between the clavicles and sternum.
Protraction is movement anteriorly in the
transverse plane. Biting the upper lip with the lower teeth is
protraction of the jaw, and moving the jaw back to its normal
position is retraction.
Elevation is the motion of a limb superiorly,
such as lifting the shoulders toward the ears. Depression is the
opposite, inferior movement as in opening the mouth.
Opposition is a movement unique to the thumb when
it moves toward a finger or the palm to grasp something
Systematic and regional approaches to anatomy
In the systematic approach to the study of
anatomy, each system of the body, such as the digestive system, is
studied in its continuity until every system has been examined. The
regional approach observes all aspects of a particular region at
one time. For example, each muscle, organ, bone, nerve and any
other structure in the abdomen is studied together, then the
student continues in this fashion with each region. The regional
approach better facilitates study with dissection, while the
systematic approach is appreciated for its comprehensive look at
each system throughout the body.
References
- Calais-Germain, Blandine. "Anatomy of Movement", Eastland Press, 1993. ISBN 0-939616-17-3
- Drake, Richard; Vogl, Wayne; Mitchell, Adam. “Gray’s Anatomy for Students”, Churchill Livingstone, 2004. ISBN 0-443-06612-4
- Martini, Frederic; Timmons, Michael; McKinnley, Michael. "Human Anatomy", 3rd Edition, Prentice-Hall, 2000. ISBN 0-13-010011-0
- Marieb, Elaine. "Essentials of Human Anatomy and Physiology", 6th Edition. Addison Wesley Longman, 2000. ISBN 0-8053-4940-5
- Muscolino, Joseph E. “The Muscular System Manual: The Skeletal Muscles of the Human Body”, 2nd Edition, C.V. Mosby, 2005. ISBN 0-323-02523-4
See also
laterally in Hebrew: אנטומיה - מונחים
laterally in Turkish: İnsan Anatomik
Terimleri