Anatomy

Basic Anatomy Everyone Should Know

A grasp of basic anatomy is necessary to take good care of one's health. This page is intended to explain terms used elsewhere on my site, as well as provide a quick intro to the topic.

Disclaimer: I could have items in this page wrong. I do my best, but more complete and reliable sources are widely available. No claims of accuracy are made.

Anatomical Terms

Anatomical Planes

Wikipedia Pic of Anatomical Planes

Frontal, or Coronal, Plane

The coronal plane splits the body's front from its rear. It is a 90 degree rotation of the sagittal plane. If you stand in a doorway, the plane of the doorway is the frontal plane of your body. It bisects your body from the center of your left side to the center of your right side. Your nose, chest and toes are in front of it, and your back and heels are behind it. This plane is vertical when one stands. It has two names, frontal and coronal.

Sagittal, or Median, Plane

The sagittal plane bisects the body between left and right. Your left side is on one side of the plane. Your right side is on the other. The sagittal plane is vertical when one stands. It has two names: sagittal and median.

Transverse, or Axial, Plane

The transverse plane splits the upper body from the lower body. This plane is horizontal when one stands. It has two names, transverse and axial.

Anatomical Directions

Wikipedia Page

Medial & Lateral

Medial is toward the center of the body, and lateral toward the outside of the body, all within the coronal plane.

• For any appendage attached to the body's right side, the medial side of that appendage is toward the left, and the lateral side is toward the right.
• For an appendage attached to the body's left side, the medial side of the appendage is toward the right, and the lateral side is toward the left.

Anterior & Posterior

Anterior is toward the front of the body. Posterior, the opposite of anterior, is toward the back.

Example: The patella (kneecap) is at the anterior of the knee.

Proximal & Distall

Proximal is toward the body, along the axis of an appendage. Distal, the opposite of proximal, is away from the body:

Examples:

• The distal end of a finger is the fingertip.
• The tibia (shin bone) joines, at its proximal end, the humorus (thigh bone) at its distal end.

Dorsal & Ventral

Dorsal is like a fish's back, and ventral like its belly.

Examples:

• The dorsal side of a foot is the top. However, the sole of the foot is called the plantar side, instead of ventral.
• The dorsal side of a hand is "the back of the hand." However, the palm is not called the ventral side; it is called palmer.
• The fin on a fish's back is its dorsal fin. However, the fins on the ventral side are called pectoral, not ventral.
• Despite the fact that other terms are frequently used instead of ventral, ventral is the opposite of dorsal.

Joint Motion: Abduction, Adduction, Extension, Flexion, Inward Rotation, Outward Rotation

Extension: increase the joint's angle. - opposite of - Flexion: decrease the joint angle.

Abduction: increase the joint's angle as if opening scissors. - opposite of - Adduction: decrease the angle, like closing scissors to make the cut.

Rotation: rotate a bone along its axis. The angle between the joint's bones remains constant. - Internal rotation is the opposite of external rotation.

In some cases, it can seem ambiguous what constitutes increasing vs. decreasing an angle, especially for joints with many degrees of freedom. Here are examples:

• Flexion
  • Elbow Flexion = bending the elbow
  • Knee Flexion = bending the knee
  • Hip Flexion = pulling the thigh upward, so that the knee rises (assuming a standing position)
  • Neck Flexion = nodding the head forward.
  • Back Flexion = bending foward.
• Extension
  • Knee Extension = straightening the knee
  • Hip Extension = lowering the thigh, so that the knee lowers (assuming a standing position)
  • Neck Extension = tilting the head backward
  • Back Extension = bending backward
• Abduction & Adduction
  • Shoulder abduction is raising the arms sideways. A 90 degree abduction will make you look like a T. More than 90 degrees will make you look like a Y. Lowering the arms back down is adduction.
  • Hip abduction is spreading the legs apart, like opening scissors in preparation to make a cut. Putting the legs back together is
• Rotation
  • Hip inward rotation is to spin the leg on its axis such that the knee points toward the center of your body. The hip can only rotate a little bit.
  • Shoulder inward rotation is spinning the arm counterclockwise from an overhead view.
  • Ankle inward rotation pivots the foot so as to point the toes medially. I.e., the right toes point left, and/or the left point right.
  • Outward rotations are the opposite of inward rotations.
  • The knee can rotate, but only to a very small degree. Rotating the knee is not recommended.