Anatomy, Physiology, and Medical Terminology for the EMT

Why Anatomy and Terminology Matter in EMS

When you arrive on scene, you have seconds to communicate with your partner, the receiving hospital, and medical direction. Using precise anatomical language eliminates dangerous misunderstandings. Saying "pain in the upper-right belly" means something different to different listeners; saying "right upper quadrant pain" is unambiguous to every clinician on the radio. This lesson builds the vocabulary and structural knowledge that underpin every patient assessment you will ever perform.

Anatomical Position and Directional Terms

All descriptions of the human body assume anatomical position: the patient is standing upright, facing forward, arms at the sides with palms facing forward. Every directional term is anchored to this reference, regardless of how the patient is actually lying.

Key directional pairs:

• Superior / Inferior – toward the head vs. toward the feet. The chin is superior to the navel.
• Anterior / Posterior – toward the front vs. toward the back. The sternum is anterior to the spine.
• Medial / Lateral – toward the midline vs. away from it. The nose is medial to the ears.
• Proximal / Distal – closer to the trunk vs. farther from it. The elbow is proximal to the wrist.
• Bilateral / Unilateral – affecting both sides vs. one side.

The body is also described using planes: the midline divides the body into right and left halves (sagittal plane); a horizontal cut at the waist creates superior and inferior sections (transverse plane).

The abdomen is divided into four quadrants: right upper (RUQ), left upper (LUQ), right lower (RLQ), and left lower (LLQ). The liver sits mainly in the RUQ; the spleen is in the LUQ; the appendix is in the RLQ.

Safety note: When documenting injuries or patient complaints, always use the patient's anatomical right and left, not yours as you face them.

Medical Terminology: Building Blocks

Medical terms are built from three components: a root (the core meaning), a prefix (modifies meaning, placed before the root), and a suffix (modifies meaning, placed after the root). You do not need to memorize every medical word — you need to decode them.

Common EMS prefixes:

• tachy- = fast (tachycardia = fast heart rate)
• brady- = slow (bradypnea = slow breathing)
• hyper- = above normal (hypertension)
• hypo- = below normal (hypoglycemia)
• dys- = difficult or abnormal (dyspnea = difficulty breathing)

Common EMS suffixes:

• -emia = condition of the blood (hypoxemia = low oxygen in the blood)
• -pnea = breathing (apnea = absence of breathing)
• -cardia = heart rate condition
• -itis = inflammation (appendicitis)
• -plasty = surgical repair

Common roots: card/cardi = heart; pulm/pneum = lung; neur = nerve; cost = rib; cephal = head.

The Respiratory System

Air enters through the nose and mouth, passes through the pharynx and larynx (voice box), travels down the trachea, and splits at the carina into the left and right mainstem bronchi. The bronchi branch into smaller bronchioles that end in microscopic alveoli — tiny air sacs where gas exchange occurs. Oxygen crosses the alveolar membrane into capillaries; carbon dioxide moves in the opposite direction and is exhaled.

Normal adult respiratory rate is 12–20 breaths per minute. Rates outside this range (tachypnea or bradypnea) and inadequate tidal volume are critical findings requiring intervention.

Safety note: Always ensure your own airway protection (BSI/PPE — gloves and mask) before providing ventilatory assistance to any patient.

The Cardiovascular System

The heart is a four-chambered pump. Deoxygenated blood returns from the body through the vena cava into the right atrium, passes through the tricuspid valve into the right ventricle, and is pumped through the pulmonary valve into the pulmonary arteries toward the lungs. Oxygenated blood returns via pulmonary veins into the left atrium, passes through the mitral valve into the left ventricle — the strongest chamber — and is ejected through the aortic valve into the aorta.

Perfusion is the delivery of oxygenated blood to tissues. Failure of perfusion is shock. Normal adult pulse is 60–100 beats per minute.

The Musculoskeletal System

The skeleton provides structure, protects organs, and enables movement. Key EMT landmarks include the sternum (attachment for ribs, CPR landmark), clavicle, pelvis, femur (largest bone), and the vertebral column (cervical, thoracic, lumbar, sacral, coccygeal regions). Muscles attach to bones via tendons; bones connect to other bones via ligaments.

The Nervous System

The central nervous system (CNS) consists of the brain and spinal cord. The peripheral nervous system carries signals between the CNS and the body. The autonomic nervous system controls involuntary functions: the sympathetic division increases heart rate and respiratory rate in stress ("fight or flight"); the parasympathetic division promotes rest and digestion. Many cardiac and respiratory drugs — and many toxins — work by mimicking or blocking these pathways.