Axis and Planes By: Dr. M. Abbas Jamil

Cardinal planes:  Whenever a plane passes through the midline of a part, whether it is the sagittal, frontal, or transverse plane, it is referred to as a cardinal plane because it divides the body into equal parts. The point where the three cardinal planes intersect each other is the center of gravity. In the human body that point is in the midline at about the level of, though slightly anterior to, the second sacral vertebra.

Axis and Planes:  Axis: Axes are points that run through the center of a joint around which a part rotates. An axis is a line about which movement takes place.  Planes: Planes are fixed lines of reference along which the body is divided. A plane is the surface which lies at right angles to it and in which the movement takes place.  Sagittal axis (antero-posterior axis) z-axis: The sagittal axis is a point that runs through a joint from front to back. Sagittal axis lies parallel to the sagittal suture of the skull in an antero-posterior direction. Movement about the axis is in a frontal plane.  Frontal plane (coronal, or XY plane); Frontal plane is parallel, passes through the body from side to side and divides the body into front and back parts. Motions that occur in this plane are defined as sideward and vertical movements. Abduction, Adduction, Lateral Flexion, Elevation and Depression of shoulder girdle, Radial and Ulnar deviation occur in frontal plane and in sagittal axis.

 Frontal axis (medio-lateral axis) x-axis: The frontal axis runs through a joint from side to side. Frontal axis lies parallel to the transverse suture of the skull. It lies at right angles to the sagittal axis. Movement about a frontal axis is in a sagittal plane.  Sagittal plane: The sagittal plane (mid-sagittal, or YZ plane) is vertical, passes through the body from front to back and divides the body into right and left sides. Joint motions occurring in the sagittal plane are defined as forward and backward movements. Flexion, Extension, Hyperextension, Plantar and Dorsiflexion occur in frontal axis and sagittal plane.

 Vertical axis (longitudinal axis) y-axis: The vertical axis, also called the longitudinal axis, runs through a joint from top to bottom. Vertical axis lies parallel to the line of gravity and movement about it is in a horizontal plane.  Horizontal plane (transverse or XZ plane) transverse plane movements: Horizontal plane passes through the body horizontally and divides the body into upper and lower parts. Rotations occurs in this plane around the vertical y axis. Joint motions occurring in the horizontal plane are defined as internal rotation (inward or medial rotation), external rotation (outward or lateral rotation), supination, pronation, horizontal abduction and adduction.  Joint movement occurs in a plane and around an axis. A particular motion will always occur in the same plane and around the same axis. For example, flexion/extension will always occur in the sagittal plane around the frontal axis. Abduction/adduction will always occur in the frontal plane around the sagittal axis. Similar motions, such as radial and ulnar deviation of the wrist, will also occur in the frontal plane around the sagittal axis. The thumb is the exception because flexion/extension and abduction/adduction do not occur in these traditional planes.

PlaneAxisJoint Motion SagittalFrontalFlexion/Extension FrontalSagittalAbduction/Adduction Radial/Ulnar deviation Eversion/Inversion TransverseVerticalMedial/Lateral Rotation Supination/Pronation Horizontal Abduction/Adduction

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