1.6 Anatomical terminology  (Page 2/44)

Directional terms

Certain directional anatomical terms appear throughout this and any other anatomy textbook ( [link] ). These terms are essential for describing the relative locations of different body structures. For instance, an anatomist might describe one band of tissue as “inferior to” another or a physician might describe a tumor as “superficial to” a deeper body structure. Commit these terms to memory to avoid confusion when you are studying or describing the locations of particular body parts.

• Anterior (or ventral    ) Describes the front or direction toward the front of the body. The toes are anterior to the foot.
• Posterior (or dorsal    ) Describes the back or direction toward the back of the body. The popliteus is posterior to the patella.
• Superior (or cranial    ) describes a position above or higher than another part of the body proper. The orbits are superior to the oris.
• Inferior (or caudal    ) describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column). The pelvis is inferior to the abdomen.
• Lateral describes the side or direction toward the side of the body. The thumb (pollex) is lateral to the digits.
• Medial describes the middle or direction toward the middle of the body. The hallux is the medial toe.
• Proximal describes a position in a limb that is nearer to the point of attachment or the trunk of the body. The brachium is proximal to the antebrachium.
• Distal describes a position in a limb that is farther from the point of attachment or the trunk of the body. The crus is distal to the femur.
• Superficial describes a position closer to the surface of the body. The skin is superficial to the bones.
• Deep describes a position farther from the surface of the body. The brain is deep to the skull.

Body planes

A section    is a two-dimensional surface of a three-dimensional structure that has been cut. Modern medical imaging devices enable clinicians to obtain “virtual sections” of living bodies. We call these scans. Body sections and scans can be correctly interpreted, however, only if the viewer understands the plane along which the section was made. A plane    is an imaginary two-dimensional surface that passes through the body. There are three planes commonly referred to in anatomy and medicine, as illustrated in [link] .

• The sagittal plane    is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane or less commonly a longitudinal section.
• The frontal plane    is the plane that divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. (“Corona” is Latin for “crown.”)
• The transverse plane    is the plane that divides the body or organ horizontally into upper and lower portions. Transverse planes produce images referred to as cross sections.