How to describe any location on the human body
TEAS 7 outline: General orientation of human anatomy (terms, planes, cavities, organization)
Also covers HESI A2 Anatomy & Physiology (Terminology)
- Terms assume anatomical position: upright, facing forward, palms forward.
- Right and left always mean the subject's right and left.
- Proximal and distal are for limbs: closer to or farther from the trunk.
- Sagittal cuts right/left, frontal cuts front/back, transverse cuts upper/lower.
- The diaphragm separates the thoracic cavity from the abdominopelvic cavity.
Key facts
- In anatomical position the body stands upright, feet parallel, toes forward, upper limbs held out to each side with the palms facing forward; terms are always used as if the body were in this position.
- Proximal and distal describe positions on a limb: proximal is closer to where the limb attaches to the trunk, distal is farther from it.
- Medial means toward the midline and lateral means toward the side; in anatomical position the thumb is lateral to the other fingers.
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- A sagittal plane divides the body into right and left parts (midsagittal = equal halves), a frontal (coronal) plane into anterior and posterior parts, and a transverse plane into superior and inferior parts.
- The dorsal cavity holds the brain (cranial cavity) and spinal cord (spinal or vertebral cavity); the ventral cavity holds the thoracic and abdominopelvic cavities, which the diaphragm separates.
- Serous membranes have a parietal layer lining the cavity wall and a visceral layer covering the organ; the fluid between them reduces friction (pleura for the lungs, pericardium for the heart, peritoneum for abdominopelvic organs).
- Levels of organization, simplest to most complex: chemical, cellular, tissue, organ, organ system, organism.
Quick check1 question · 2 more at the end
A patient lies prone on an exam table with both hands resting palm-down beside the hips. A small scar is on the palm side of the right wrist. Which term correctly describes the location of the scar?
Correct answer: B.
Anatomical terms are always applied as if the body were in anatomical position, standing with the palms facing forward, no matter how the body is actually lying. In that position the palm side of the wrist faces the front, so it is anterior even when the person is prone with the palm down. The wrist is the carpal region; the forearm is antebrachial and the upper arm is brachial.
A This describes the wrist by its current orientation (facing the table) instead of by anatomical position, where the palm side faces forward.
B Correct: in anatomical position the palm side of the wrist faces forward, so the scar is in the anterior carpal region.
C Antebrachial refers to the forearm, between the elbow and the wrist, not the wrist itself.
D Brachial refers to the upper arm, between the shoulder and the elbow, not the wrist.
Full lesson
Each part starts with its main idea. Open a part when you want the details.
The short answer: Anatomists describe the body as if it stands in anatomical position: upright, facing forward, palms forward. Paired directional terms give relative locations, three planes (sagittal, frontal, transverse) describe cuts, and the dorsal and ventral cavities hold the organs. Structure builds from chemicals to cells, tissues, organs, organ systems, and the whole organism.
1 What is anatomical position, and why does it matter?Anatomy terms only work if everyone pictures the body the same way. 1 min
Anatomy terms only work if everyone pictures the body the same way. That shared starting pose is anatomical position. The body stands upright with feet about shoulder width apart and parallel, toes forward, upper limbs held out to each side, and palms facing forward.
Here is the key rule: terms are always used as if the body were in anatomical position, no matter how it is actually lying. A body lying face down is prone; face up is supine. Even if someone's hand is resting palm down on a table, the palm side of the wrist is still called anterior.
One more rule that trips people up: right and left always mean the subject's right and left, not yours as you face them.
2 Which directional terms come in pairs?Directional terms describe where one structure is relative to another, and they come in opposite pairs. 1 min
Directional terms describe where one structure is relative to another, and they come in opposite pairs.
| Term | Means | Opposite | Example |
|---|---|---|---|
| Superior (cranial) | Above, toward the head | Inferior (caudal) | The nose is superior to the mouth. |
| Anterior (ventral) | Front | Posterior (dorsal) | The breastbone is anterior to the heart. |
| Medial | Toward the midline | Lateral | The nose is medial to the eyes. |
| Proximal | On a limb, closer to the trunk | Distal | The knee is proximal to the ankle. |
| Superficial | Closer to the body surface | Deep | The ribs are deep to the skin of the chest. |
Use proximal and distal for limbs. The elbow is proximal to the wrist because it is closer to where the arm attaches to the trunk. Also note that the thumb is lateral to the other fingers only because the palms face forward in anatomical position.
3 How do the three body planes cut the body?A plane is an imaginary flat surface passing through the body, and a section is the surface you see after cutting along it. 1 min
A plane is an imaginary flat surface passing through the body, and a section is the surface you see after cutting along it. Medical scans are "virtual sections" along these same planes.
- Sagittal plane: a vertical cut into right and left parts. Right down the middle, with equal halves, it is the midsagittal (median) plane; off center, it is parasagittal.
- Frontal (coronal) plane: a vertical cut into anterior and posterior (front and back) parts.
- Transverse plane: a horizontal cut into superior and inferior (upper and lower) parts. The images are called cross sections.
4 Where are the body cavities, and what lines them?The body has two large cavities that hold and protect organs. 1 min
The body has two large cavities that hold and protect organs.
The dorsal (posterior) cavity contains the cranial cavity, which houses the brain, and the spinal (vertebral) cavity, which encloses the spinal cord. The two are continuous, and cerebrospinal fluid cushions what is inside.
The ventral (anterior) cavity has two main parts. The thoracic cavity, enclosed by the rib cage, holds the lungs and the heart; the heart sits in the central space called the mediastinum.
The diaphragm forms the floor of the thoracic cavity and separates it from the abdominopelvic cavity, the largest cavity in the body. Its upper abdominal part holds the digestive organs, and its lower pelvic part holds the reproductive organs.
Organs in the ventral cavity are wrapped in serous membranes. The parietal layer lines the cavity wall, the visceral layer covers the organ, and a thin film of serous fluid between them reduces friction as organs move. The pleura surrounds the lungs, the pericardium surrounds the heart, and the peritoneum surrounds several abdominopelvic organs.
5 How are body regions and abdominal quadrants named?To describe the abdomen more precisely, it is divided into four quadrants. 1 min
Regional terms name areas of the body surface:
- Head, neck and trunk: cephalic (head), cervical (neck), thoracic (chest), lumbar (lower back)
- Armpit and upper limb: axillary (armpit), brachial (upper arm), antecubital (front of the elbow), antebrachial (forearm), carpal (wrist)
- Lower limb: femoral (thigh), patellar (knee), crural (leg, knee to ankle), pedal (foot), plantar (sole)
To describe the abdomen more precisely, it is divided into four quadrants. A vertical and a horizontal line cross at the umbilicus (navel), giving right upper, left upper, right lower, and left lower. For example, the stomach lies mostly in the left upper quadrant. A more detailed map uses nine regions, such as the epigastric region in the upper center and the right and left hypochondriac regions beside it.
6 How is the body organized, from molecules to a whole person? 1 min
Body structure builds up in six levels of increasing complexity:
- Chemical: atoms join into molecules such as water and proteins.
- Cellular: the cell is the smallest independently functioning unit of life.
- Tissue: groups of similar cells working together. There are four basic types: epithelial, connective, muscle, and nervous.
- Organ: a distinct structure made of two or more tissue types, such as the urinary bladder.
- Organ system: organs that work together, such as the urinary system.
- Organism: the whole living person.
Common mistakes
The traps students fall into most. Read these before you practice.
Watch out: Right and left mean the subject's own right and left, not yours as you face them.
Watch out: A frontal (coronal) plane makes front and back parts, not left and right parts; left and right come from a sagittal plane.
Watch out: The visceral layer of a serous membrane covers the organ; the parietal layer lines the cavity wall, not the other way around.
Watch out: In anatomy the arm (brachium) is only shoulder to elbow and the leg (crus) is only knee to ankle; the forearm and the thigh have their own names.
Watch out: A body lying face down is prone and face up is supine, but the palm side of the wrist is still anterior either way.
How to remember it
Memory hook: Proximal means in close proximity to the trunk; distal means distant from it. And for planes, think of what you could see. A sagittal cut shows a profile, a frontal cut shows a face-on slice, and a transverse cut looks like a slice of bread.
Self-check:
- Stand in anatomical position and name one thing that is lateral, distal, and deep on your own body.
- Say which plane would separate the heart from the spine in a single cut, and why.
- Name the cavity, the subdivision, and the serous membrane for the lungs.