Anatomical Planes

The Sagittal Plane

The sagittal plane is a primary anatomical division that runs vertically through the body, extending from the anterior (front) to the posterior (back). This orientation effectively splits the body, or specific organs and structures, into distinct right and left portions. When this plane is situated precisely at the midline of the body, creating two symmetrical halves, it is strictly referred to as the midsagittal plane or the median plane. Conversely, any vertical plane situated parallel to the median plane but offset from the exact center, resulting in unequal right and left sections, is identified as a parasagittal plane. From a biomechanical and kinesiological perspective, the sagittal plane serves as the framework for movements occurring along an anterior-posterior axis. These include flexion, which is a movement that decreases the angle between two articulating bones, and extension, which increases that angle. For example, performing a bicep curl, a leg extension, or a forward lunge involves movements occurring almost entirely within the sagittal plane, where the limbs move forward or backward relative to the rest of the body.

The Coronal Plane

The coronal plane, which is frequently referred to as the frontal plane, is a vertical division that passes through the body from side to side. It is oriented at a $90^\circ$ angle relative to the sagittal plane, effectively separating the body or its parts into anterior (front or ventral) and posterior (back or dorsal) segments. This plane is critical in medical imaging and physical assessment for understanding the relationship and distance between structures from the front to the back of the organism. In terms of physical movement, the coronal plane is the domain of lateral or side-to-side actions. The most prominent movements occurring in this plane are abduction, which is the process of moving a limb away from the midline of the body, and adduction, which is the process of bringing a limb toward the midline. Lateral flexion, such as side-bending the torso, is another motion that takes place within the coronal framework. An example of an exercise performed in the coronal plane is the jumping jack, where both arms and legs move laterally away from and toward the center of the body.

The Transverse Plane

The transverse plane, also known as the axial or horizontal plane, operates at a right angle to both the sagittal and coronal planes, slicing horizontally across the body. This division creates a top-and-bottom orientation, separating the body into superior (upper or cranial) and inferior (lower or caudal) portions. This cross-sectional view is a fundamental reference point in diagnostics and clinical medicine, particularly for the interpretation of Computed Tomography (CT) scans and Magnetic Resonance Imaging (MRI), which display internal anatomy in axial slices. Biomechanical movements that occur within the transverse plane are primarily characterized by rotation around a vertical or longitudinal axis. This includes medial (internal) rotation and lateral (external) rotation of the shoulder or hip. Other movements within this horizontal context include the rotation of the head or neck to look over one's shoulder and the twisting of the torso. Forearm movements such as pronation and supination also describe rotational changes that occur within the transverse plane, allowing for complex multi-planar manual tasks.