Anatomy Terms

Anatomic terms describe the directions within the body as well as the body’s reference planes, cavities and regions.

There are many times in medicine that a doctor has to record in a medical record or tell another doctor the exact body part or location of disorders or damage to the body or an organ. To do that, the are standard terms for describing human anatomy including the body and it’s organs. The terms used to describe positions reference the person in the standard anatomical position. The standard anatomical position for humans is standing upright as in the image above. By using this as a standard for descriptions, we avoid confusion even when the person is in some other position. For example, suppose the doctor was describing someone lying down? The doctor’s description would be as if the person were standing up in the standard position.

Anatomy is the study of the structure of the human body.

The standard anatomical position for humans has its feet together (or slightly separated), and the arms are rotated outward so that the palms are forward, and the thumbs are pointed away from the body (forearms supine). As well, the arms are usually moved slightly out from the body, so that the hands do not touch the sides. The positions of the limbs (and the arms in particular) have important implications for directional terms in those appendages. The penis in men is also erect in the anatomical position, hence the dorsal surface of the penis is actually anterior in the flaccid state. The head is upright and facing forward so that certain parts of the eyes and ears are in the same horizontal plane.

For "normal" human bodies, the right and left sides are mirror images if divided right down the center as shown by the sagittal plane in the image. The dotted line represents an axis or dividing line.

Directional Terms

In general, directional terms are grouped in pairs of opposites.

• Superior and inferior. Superior means above, inferior means below. The elbow is superior to the hand. The foot is inferior to the knee.
• Anterior and posterior. Anterior means toward the front of the body, posterior means toward the back.
• Medial and Lateral. Medial means toward the midline of the body, lateral means away from the midline. Ipsilateral means on the same side—the left arm is ipsilateral to the left leg.
• Proximal and distal. Proximal means closest to the point of origin or trunk of the body, distal means farthest. Often used when describing arms and legs.
• Superficial and deep. Superficial means toward the body surface, deep means farthest from the body surface.

Other directional terms:

• Intermediate – means between—your heart is intermediate to your lungs.
• Caudal – at or near the tail or posterior end of the body.
• Visceral – may be used instead of deep.

There are also terms that are used for describing specific body parts. Palmar is used to describe the palm side of the hand, Dorsal describes the back side of the hand. Plantar describes the bottom of the foot.

Anatomical Reference Planes

The body reference planes are used to locate structures in the body. These terms are most often used to describe medica imaging such as CAT scans, PET scans and MRIs where the scans take pictures of the body in slices. Brain scans are often of sagittal plane slices from ear to ear. Abdominal CAT scans are often transverse plane slices.

Main Reference Planes

• Median sagittal plane – this plane divides the body into left and right sides.
• Frontal (or coronal) plane – divides the body into front (anterior) and back (posterior)
• Transverse plane – this plane is parallel to the ground and divides the body into up (cranial or head) and down (tail or caudal)
• Oblique plane is not shown and is a slanted plane that lies between the horizontal and vertical planes.

Body Cavities

Body cavities are the areas in the body that contain our internal organs. The dorsal and ventral cavities are the two main cavities. The dorsal cavity is on the posterior (back side) of the body and contains the cranial cavity and vertebral cavity. In human anatomy, dorsal, caudal and posterior mean the same thing. The ventral cavity is on the front (anterior) of the body and is divided into the thoracic cavity and abdominopelvic cavity.

Dorsal Cavity

The dorsal cavity is further divided into subcavities:

• cranial cavity (also called the calvaria) which surrounds the brain
• vertebral cavity (also called the spinal cavity) which includes the vertebrae and spinal cord.

Ventral Cavity

The ventral cavity is on the front of the trunk and is divided into subcavities:

• thoracic cavity which is surrounded by the ribs and chest muscles is superior (above) the diaphragm and abdominopelvic cavity. It is further divided into the pleural cavities (left and right) which contain the lungs, bronchi, and the mediastinum which contains the heart, pericardial membranes, large vessels of the heart, trachea (windpipe), upper esophagus, thymus gland, lymph nodes, and other blood vessels and nerves.
• abdominopelvic cavity is divided into the abdominal cavity and pelvic cavity. The abdominal cavity is between the diaphragm and the pelvis. It is lined with a membrane and contains the stomach, lower part of the esophagus, small and large intestines (except sigmoid and rectum), spleen, liver, gallbladder, pancreas, adrenal glands, kidneys and ureters. The pelvic cavity contains the bladder, some reproductive organs and the rectum.

Other Cavities

• oral cavity – the space in the mouth inside the teeth and gums and is filled with the tongue when it is relaxed.
• nasal cavity – in the nose
• orbital cavities (left and right) – hold the eyes
• middle ear cavities (left and right) – hold the small bones of the middle ear
• synovial cavities – are inside the joint capsules that surround freely moving joints (such as the hip, knee, elbow, and shoulder)

Body Quadrants

Quadrants are another way our bodies are divided into regions for diagnostic and descriptive purposes.

Body Regions

Body regions are used to describe areas of the body that have a special function or are supplied by specific blood vessels or nerves. The terms most widely used terms are those that describe the 9 abdominal regions shown in the image to the right. The regions are named below and the corresponding regions are labeled.

Abdominal Regions

• right (1) and left (3) hypochondriac regions – on either side of the epigastric region. Contains the diaphragm, some of the kidneys, right side of the liver, the spleen and part of the pancreas.
• epigastric region (2) – superior (above) the umbilical region and contains most of the pancreas, part of the stomach, liver, inferior vena cava, abdominal aorta and duodenum
• right (4) and left (6) lumbar (lateral) regions – on either side of the umbilical region. They contain portions of the large and small intestines and kidneys.
• umbilical region (5) – area around the umbilicus (belly button). Includes sections of the large and small intestines, inferior vena cava and abdominal aorta
• right (7) and left (9) iliac (inguinal) regions – are on either side of the hypogastric region and include portions of the large and small intestines.
• hypogastric (pubic) (8) region – inferior (below) the umbilical region. Contains parts of the sigmoid colon, the urinary bladder and ureters, the uterus and ovaries (women), and portions of the small intestines.

Abdominal Quadrants

Quadrants are another way our bodies are divided into regions for diagnostic and descriptive purposes. The quadrants are defined by drawing an imaginary line vertically and horizontally though the umbilicus (belly button). This following is a list of the organs located in each of the four quadrants.

• Right Upper Quadrant (RUQ) – right lobe of liver, gallbladder, part of the transverse colon, part of pylorus, hepatic flexure, right kidney, and duodenum.
• Right Lower Quadrant (RLQ) – cecum, ascending colon, small intestine, appendix, bladder if distended, right ureter, right spermatic duct (men), right ovary and right tube and uterus if enlarged (women).
• Left Upper Quadrant (LUQ) – Left lobe of liver, stomach, small intestine, transverse colon, splenic flexure, pancreas, left kidney and spleen.
• Left Lower Quadrant (LLQ) – small intestine, left ureter, sigmoid flexure, descending colon, bladder if distended, left spermatic duct (men) left ovary and left tube and uterus if enlarged (women).