Download understanding anatomy: a primer for lawyers

31-FEB Pa. Law. 32
Pennsylvania Lawyer
January/February, 2009
Feature
UNDERSTANDING ANATOMY: A PRIMER FOR LAWYERS
Samuel D. Hodge Jr.a1
Copyright © 2009 by the Pennsylvania Bar Association; Samuel D. Hodge Jr.
Lawyers are trained to recognize theories of liability. That, however, is only a part of a
personal injury claim. Causation and damages play an equally important role in a case, but
most attorneys are not well versed in medical matters. This places them at a distinct
disadvantage when reading a medical report, cross-examining a health care professional or
trying to explain an injury to the jury. This article will provide an overview of anatomy in order
to assist counsel in understanding the human body and in deciphering medical reports.
The human form is a complex mechanism whose many parts work together as a single unit.
Learning the names and functions of more than 200 bones and a variety of soft-tissue structures
seems like a daunting task. The study of anatomy has existed for thousands of years, however, and
basic principles have emerged that simplify this learning process. By becoming familiar with these
building blocks, a lawyer's job in handling medical issues will become a lot easier.
As first-year medical students learn, anatomy may be analyzed in three ways: systemic, regional and
surface. Systemic anatomy examines the body by breaking it down into different functions ranging
from respiration to digestion. Regional anatomy focuses on the body by sections, such as the hand,
abdomen or back. This is the approach followed by first-year medical students during the dissection
of a cadaver. Only one region of the body is analyzed at a time. Diagnostic testing follows a similar
logic by imaging the body based upon the area in question.
For instance, pain in the back will be the subject of an MRI of that portion of the spine in question.
Surface anatomy involves the shapes and structures of the body that can be observed by inspection
and palpation. Physicians routinely use this concept by visually examining and touching the body
part at issue. For example, bruising, swelling, pain on palpation and anatomical alignment of the
structure provide diagnostic clues as to the source of the problem.
Systems of the Body
The body is like a successful business that has an important job to do on a very tight schedule. To
ensure that everything is done properly and on time, a well-run business has divisions that work
independently but in concert with each other. The human body works in the same organized fashion
through the process known as homeostasis. Its many parts must complete their individual tasks in a
proper and timely fashion so the body can function as a whole.
For instance, the body needs nourishment to survive. This simple task requires a number of body
systems to work in concert. The brain arranges the coordinated movements necessary for eating.
The gastrointestinal system breaks down the food so it can be absorbed into the blood. The
circulatory system then distributes the nutrients to the various parts of the body. Finally, the urinary
tract disposes of the liquid waste and the bowel eliminates the remaining solid material.
Overall, there are 10 major divisions of the body that account for many of the specialty practices in
medicine.
Integumentary System
The skin is the largest organ in the body and forms the external covering of the human form. Its job
is to act as a protective barrier to the outside environment. Other functions include maintaining the
body at a constant temperature through perspiration, blocking harmful ultraviolet radiation and
transmitting sensory information to the brain.
The prefix for integumentary is derma. A dermatologist is the medical specialist who treats disorders
of the skin.
*34 Gastrointestinal System
The digestive process involves a series of interconnecting tubes in the middle of the body. Each tube
performs a different function, but their collective purpose is to break down food into a liquid state so
it can be absorbed into the blood and then to reassemble the leftover materials into a solid so that it
can be discarded by the bottom tube.
The prefix for this system is gastro. A gastroenterologist is the medical specialist who treats
disorders of the digestive tract.
Skeletal System
The skeleton provides structure for the body and protects the internal organs. For instance, the skull
protects the brain, and the vertebrae encase the spinal cord. At birth, the body has more than 300
bones that are held together by cartilage. Eventually some of the bones fuse together so that 206
remain as we mature.
Bone has a variety of compositions. The outside layer is very dense so it is called compact bone.
The inside layer consists of spongy bone that is light in composition and resembles a honeycomb.
Some bones also have a middle part that contains bone marrow where new blood cells are
produced.
Many bones articulate with each other to provide for movement by creating a joint.
In turn, there are a variety of joints in the body that are classified according to their structure and
ability to move. For instance, a fixed joint is one that does not move, such as the bones in the skull.
A ball and socket joint is the most mobile in the body and includes the shoulder and hip.
The prefix for skeletal is osteo. An orthopedic surgeon is the medical specialist who treats disorders
of the bones.
The Muscular System
Muscles are responsible for movement of the body and these structures constitute 40 percent of the
body's weight. Since muscles can only contract, they frequently work in pairs so that a person can
raise and lower an arm or leg.
There are three types of muscle tissue: skeletal, smooth and cardiac. Skeletal muscles produce
movement through voluntary signals originating from the *35 nervous system. For instance, when
the brain forms the intent to move an arm, it transmits a signal along the nerve that goes to that body
part in order to stimulate the muscle into movement.
Smooth muscles are involuntary, so they cannot be actively controlled. These tissues are found in
the walls of most hollow organs, such as the digestive tract and blood vessels. Their contractions
reduce the size of the organs, thereby regulating the flow of blood in the arteries or by moving food
through the digestive system.
Cardiac muscle is found in the heart and makes up the walls of the heart's chambers. This type of
muscle is not under conscious control; the autonomic nervous system signals the muscle to beat
about 70 times a minute.
The bones of the body must be held together in order to provide the body with structure. This task is
accomplished by ligaments, which are disbursed throughout the body. This tough band of
connection tissue has a degree of elasticity and its ends are embedded into bone to secure the
structure in place.
Muscle has to be anchored into bone so is has the necessary tension in order to facilitate
movement. This is accomplished by a tendon, a fibrous cord that originates at the end of the muscle
that anchors that soft tissue structure into bone on the other side of a joint. When a muscle
contracts, this shortening pulls the tendon, causing the bone to move.
The body has one other layer of soft tissue that is not well known outside of medical circles. Fascia
is a band of fibrous tissue that attaches the skin to the underlying soft tissue structures, especially
muscle.
Sprain and strain are the words used to explain injuries to these soft tissue structures, and the terms
are often misunderstood by lawyers. A sprain refers to one thing: a stretching or tearing of a
ligament that occurs when the cord is forced beyond its normal anatomical position. On the other
hand, a strain identifies an injury to a muscle or tendon.
The prefix for muscle is myo. Any number of medical specialists can treat muscular problems.
Respiratory System
The cells in the body require a constant supply of oxygen to function. Respiration starts by inhaling
air through the nose or mouth. This air proceeds down the trachea until the tube divides into two
branches called bronchi that force the air directly into the lungs. The lungs contain millions of tiny airfilled sacs dubbed alveoli. Very small blood vessels surround these tiny sacs, allowing oxygen to be
absorbed into the capillaries. In turn, these small vessels transfer the oxygenated blood to the heart
for distribution to the body.
Breathing occurs about 20 times a minute, during which period a person takes in roughly 13 pints of
air. Respiration can only be done in concert with the environment, however. After air is used, carbon
dioxide is expelled from the body. This used gas is then absorbed by plants, which turn it into
oxygen.
Circulatory System
The heart and blood vessels are the body's delivery system for oxygen and nutrients.
The heart is responsible for pumping blood throughout the vessels of the circulatory system. As this
fist-sized *36 muscle contracts, it forces the blood to course through the body.
The body's transportation highway is made up of hollow tubes known as the arteries, veins and
capillaries. An artery carries oxygenated blood away from the heart while a vein returns oxygendepleted blood back to this important muscle. A capillary is the smallest of the blood vessels and
acts as a bridge between the arteries and veins.
The prefix for the circulatory system is angio. Cardiologists or hematologists are the medical
specialists who deal with disorders of the heart and blood.
Nervous System
It was originally thought that the heart was the control center of the body; however, movement,
breathing, speech and even the beating of the heart are regulated by the nervous system. This
complex structure is made up of a constellation of parts that include the brain, spinal cord, nerves
and ganglia. The nervous system itself has two parts. The first is the central nervous system, and it
consists of the brain and spinal cord. The brain weighs about three pounds and is the computer
center for the body. It is responsible for all voluntary and involuntary actions and has more than 100
billion cells called neurons that send and receive electrical signals from the brain.
The spinal cord is a bundle of nerves whose length provides a cable for the brain to send and
receive signals from areas outside of the central nervous system. In turn, the spinal cord is encased
in bone called vertebrae. Thirty-one pairs of nerves exit from these bones through holes called
foramen.
The second part of this complex unit is the peripheral nervous system, which is made up of the
neurons that can be found outside of the central nervous system, such as the spinal nerves. These
nerve fibers control the muscles in the body.
The prefix for the nervous system is neuro. Neurologists or neurosurgeons are the medical
specialists who treat this body system.
Urinary System
The primary responsibility of the urinary tract is to produce and eliminate liquid waste called urine.
This waste originates in the blood after food is broken down in the body. The byproduct of this waste
is “urea,” which travels from the bloodstream to the kidneys. This bean-shaped organ then removes
the undesirable urea through tiny filters called nephrons.
In turn, urine trickles down two long tubes called ureters on its journey to the bladder. The ureters
empty into the top part of the bladder, which is a balloon-shaped organ that can comfortably store up
to 16 ounces of fluid. Urine, however, must travel down one more tube called the urethra as it is
expelled from the body through the penis or vulva, depending upon the person's sex.
Urology is the study of this body system and uro is the operative prefix. Urinary problems are treated
by urologists or nephrologists.
Endocrine System
This is the most misunderstood system in the body. The ovaries, thyroid, adrenal, testicles, pancreas
and thymus glands are some of the components of the endocrine system. Their job is to
manufacture hormones such as estrogen, testosterone, cortisone and insulin that are released into
the blood to affect growth, metabolism, tissue function and reproduction.
The word “hormone” is Greek for “to urge on.” These substances act as chemical messengers. Their
task is to transfer information from one set of cells to another to facilitate the function of different
parts of the body.
Endocrinology is the study of this body system. An endocrinologist is a physician who specializes in
diseases of the glands.
*37 Reproductive System
The need to reproduce is critical to the survival of the human race. The main reproductive organs
are the testes and ovaries. These body parts produce sperm and eggs, which are united in the
fallopian tube through intercourse or artificial insemination. After the egg has been fertilized, it travels
from the fallopian tube to the uterus where it develops over a nine-month period.
The medical field devoted to the female reproductive system is gynecology and that devoted to the
male reproductive system is andrology.
Understanding Medical Terminology
A uniform language has been developed to describe the body and its positions. It is also helpful to
realize that many medical terms are merely combinations of smaller words. These divisions are
classified as a prefix, root and suffix.
The root is the focal point or primary meaning of the word. The prefix is the modifier at the beginning
of the root word. The suffix is a letter or series of letters added to the end to change the word's
meaning. For example, the term “polyneuropathy” contains three parts. The base or root word
is neuro, which refers to the nervous system. The suffix pathy refers to a diseased process. The
prefix poly is Greek for “many.” When these words are combined, polyneuropathy refers to a
diseased process involving a number of the peripheral nerves.
Anatomists have designed a uniform reference system for describing the relative position of the body
or in distinguishing the relationship of one body part to another. This system is called the anatomic
position and identifies the body standing erect while facing frontward. The feet are together and the
palms of the hands are pointed forward. The following terms are grouped according to their opposite
parts based upon the anatomic position:
1. Anterior refers to the front of a structure. Posterior means the back of a structure.
2. Medial means toward the midline. Lateral refers to something away from the center.
3. Proximal identifies a point closer to a reference point. Distal means a location away from a
reference point.
4. Superior indicates a position above a reference point. Inferior identifies a point below a reference
point.
5. Ipsilateral refers to a body part on the same side. Contralateral refers to a body part on the
opposite side.
6. Cranial means toward the head. Caudial refers to something toward the buttocks.
7. Dorsal references a point toward the back. Ventral denotes a point toward the front or abdomen.
Medical professionals also refer to the body in planes that represent imaginary lines that pass
through the body while it is in anatomic position. These planes are particularly useful in providing a
description of the diagnostic images created by a CT scan or an MRI.
“Transverse” or “axial” refers to horizontal slices of the body from the top to the bottom similar to
when one slices a loaf of bread.
“Sagittal” represents a vertical slice in the body that runs from one side to the other, such as in a left
to right fashion.
*38 “Coronal” references a slice of the body that runs from the front to the back.
“Oblique” is a view of the body from an angle.
“Longitudinal” denotes a slice that runs up and down the long axis of the body.
Conclusion
Understanding medical terms and how the body works is not as difficult as it may seem. The body is
analyzed according to its systems, regions and surface areas. Anatomic terms also have been
developed to provide an international language in describing these parts and their functions. The key
to understanding medical terms is to realize that most multi-syllable words are mere combinations of
smaller words. By understanding the root word, it is frequently possible to decipher the meaning of a
much longer medical term or phrase. With a little practice, a basic understanding of anatomy and a
good reference book, counsel will discover that medical jargon is not difficult to master.
Footnotes
a1
Samuel D. Hodge Jr., a skilled litigator, is a professor at Temple University, where he chairs the
Legal Studies Department. He has taught law at all university levels and teaches anatomy at
Temple's James E. Beasley School of Law in both the J.D. and master's degree programs. He has
received many teaching awards, has authored more than 80 articles and trial manuals, and has
written several law texts. His most recent book, Anatomy for Litigators, was published by ALI-ABA,
the educational arm of the American Bar Association.
To comment on this article for publication in our next issue, please e-mail us at [email protected].