Anatomical planes and axes: understanding the fundamental landmarks of the human body

Written by: Axel Devillard - Proofread by: Tristan Hiller Imagine having to explain to a student in medicine, physiotherapy, osteopathy, or an artist how to depict elbow flexion, head rotation, or shoulder abduction. Without a common language, it is impossible to precisely describe the position of a hand and the bones that compose it—which is the entire function of planes—and difficult to explain the movement of limbs, the abduction or adduction movements of a joint, and what might limit them in the body region involved. This is why it is important to establish references in anatomy, and why it is necessary to describe and then understand the main anatomical planes and anatomical axes. In this article, I will describe to you: The reference anatomical planes Sagittal plane and median plane Frontal plane (or coronal) Horizontal plane (or transverse) Prefer the term "horizontal" because "transverse" is the name of an axis. However, "transverse" is sometimes used incorrectly. The reference anatomical axes Longitudinal axis (cephalocaudal) Transverse axis (mediolateral) Anteroposterior axis (sagittal) A small clarification: the longitudinal axis is relative. The longitudinal axis of the foot is not vertical, but anteroposterior. It refers to the long axis of the structure being considered. It is not an "absolute" axis like the vertical axis. "Sagittal" being the name of a plane, it is better to prefer the term "anteroposterior." Although longer, it is more explicit (the vertical, or longitudinal, axis is also contained within the sagittal plane). Thanks to them, every human movement—hand extension, palm supination, thigh flexion, foot rotation—can be described with accuracy, in relation to the right, left, top, or bottom of the body. In the remainder of this article, you will discover how these imaginary lines and surfaces structure human anatomy and facilitate orientation in space. The corresponding charts Human skeleton + musculature pack To check your anatomical knowledge, I have created these two labeled charts, skeleton and musculature. At a reduced price, available laminated so you can draw on them! Happy revising! See the set Set of 2 starting from €35 · Free shipping in France How to use the anatomical reference position to understand planes and axes? What is the anatomical reference position? Before talking about a plane or axis, you first need a common frame of reference. The anatomical reference position corresponds to the standard posture used to describe all structures of the human body and allows for providing anatomical landmarks. It is defined by a subject standing: Body straight, standing, vertical, facing the observer. Arms at the sides of the body, slightly apart, palms facing forward. Legs straight, feet parallel and slightly apart at hip-width. Head straight, gaze horizontal. It is from this position that we can draw anatomical planes and define anatomical axes. Without it, every anatomical description would become relative and therefore subject to confusion. However, it is still possible to study structures in motion without referencing this anatomical reference position. How to orient yourself in the human body? In this complete guide, you will find anatomical orientations (coming soon), how to orient yourself, to know what is up or down, lateral or medial, if something far away is proximal or distal, if something is anterior or posterior, superficial or deep, and all the terms to orient yourself among all the structures and anatomical zones such as the abdomen, the leg which is not the thigh, the lower limb and upper limb, and in which quadrant a specific organ is located. The reference anatomical planes: how to understand and visualize them The frontal or coronal plane The frontal plane, also called coronal, is a vertical surface perpendicular to the sagittal plane that divides the body into two parts: anterior (front) and posterior (back). It constitutes a fundamental directional reference for studying the structure, systems, and movements induced by muscles in anatomy. There is an infinite number of frontal planes. Joint movements in the frontal plane In this plane, the described and observed movements are: Abduction: moving a limb away (like lifting the arm laterally away from the median axis). Adduction: moving the same limb toward the median axis. These movements in this plane are all linked to an axis because they occur around an anteroposterior axis, that is to say, an imaginary line oriented from front to back (longitudinally perpendicular to the frontal plane), described below. Mnemonic device to remember it To remember where this plane is located, you can associate "frontal" with "forehead"; indeed, this plane is parallel to that of our forehead. To remember that this frontal plane is also called coronal, you can remember that you place a crown above the forehead. It provides the front and back direction. The idea of using the coronal suture is also particularly relevant. Why is this plane so useful? It helps describe the structure of the human body in relation to the front or ventral and the back or posterior: for example, the face is in the anterior part, while the back is posterior, the glutes are posterior, the organs are anterior to the spine. It allows for the analysis of lateral limb movements—very useful in sports biomechanics, where hip or arm abduction is measured. It is used to locate anatomical slices in imaging (e.g., CT, MRI), especially when you want to visualize the front or back of certain structures. The sagittal plane: dividing the body into left and right The sagittal plane is a vertical plane, which can be referred to as the median plane, that divides the human body into two parts: the right part and the left part. When this plane passes exactly through the median line of the body, it is called the median sagittal plane or mid-sagittal plane. Other planes parallel to this one are simply called sagittal or parasagittal planes, but they do not touch the center of the body. It is a fundamental directional reference for describing structures and analyzing movements in anatomical space. Joint movements in the sagittal plane The movements observed in this plane are mainly: Flexion: decrease in the angle between two parts of the body (e.g., elbow or knee flexion). Extension: increase of this angle, return to the anatomical position; finger extension is exactly this example. Hyperextension: extension beyond the reference position (e.g., arching the back, or hypermobility of the knees). All these movements occur around a transverse axis (mediolateral), that is to say, a horizontal line going from left to right, which I detail below. Some use the term "frontal axis," but I have never read that in a reference work. Mnemonic device to remember the sagittal plane To remember the sagittal plane, imagine the Sagittarius, that mythological archer. When he draws his bow, the bow represents the associated plane, and to remember the movements, imagine the right foot moving forward and backward in a flexion-extension motion, exactly in the sagittal plane. Interest of the sagittal plane It allows for the description of sections separating the right side from the left side. It is a reference plane for medical examinations (MRI, CT), particularly for observing the spine, brain, or pelvic organs. In sports biomechanics, it helps analyze movements such as squatting, running, and especially sprinting, crunches, or push-ups. The horizontal plane: separating top and bottom The horizontal plane, also improperly called transverse or axial, is a surface perpendicular to the sagittal and frontal planes. It divides the human body into two parts: a superior (above) and an inferior (below).It is a plane particularly used in medical imaging (MRI, CT), as it allows for visualizing the body as if it were cut into "horizontal slices." Joint movements in the transverse plane The typical associated movements are: Internal (medial) rotations: movement that brings the front side of a body part toward the median axis (e.g., internal rotation of the shoulder or hip). External (lateral) rotations: movement that brings the front side of a body part away from the median axis (e.g., turning the foot outward). Pronation and supination: at the forearm, pronation turns the palm backward (downward if the elbow is flexed at 90°), supination turns it forward (upward, elbow flexed). Axial rotation: head and trunk movements (e.g., turning the head from right to left). These movements occur around a longitudinal axis (cephalo-caudal), a vertical line that passes through the body from top to bottom. Mnemonic device to remember it Imagine you are holding a tray in front of you; this tray is the horizontal plane. You can raise or lower the tray from head to toe, as done during an MRI. To remember the associated axis, imagine throwing a spinning top onto the tray; that is the vertical axis that I describe to you below. Use of the horizontal plane In anatomy, it allows for the description of sections separating the head from the trunk, or the thorax from the abdomen. In medicine, it is the reference plane for MRI and CT images to visualize internal organs (brain, liver, lungs). In sports biomechanics, it is used to analyze all rotations of the trunk, hips, and shoulders (e.g., golf swing, javelin throw). Anatomical axes: understanding them and associating them with their reference planes Antero-posterior axis: associated with the frontal plane The antero-posterior axis, or sagittal axis, passes through the body from front to back. It is perpendicular to the frontal plane and allows for the analysis of lateral movements. Movements around the antero-posterior axis Abduction (moving a limb away from the midline axis, e.g., raising the arm laterally in glenohumeral abduction). Adduction (bringing a limb closer to the midline axis, e.g., bringing the legs toward the midline in coxofemoral adduction). Lateral tilts (e.g., leaning the trunk or head to the side). All these movements occur in the frontal plane around the antero-posterior axis. Mnemonic device to remember the antero-posterior axis Think of an umbrella you are holding in front of you and spin it: the fabric represents the frontal plane, the handle of the umbrella represents the antero-posterior axis. Transverse axis associated with the sagittal plane The transverse axis, also called the mediolateral axis, passes through the body from left to right like a horizontal line. It is perpendicular to the sagittal plane and serves as a reference for movements that take place forward and backward. Movements associated with the transverse axis Flexion (decreasing the angle between two segments, such as elbow flexion, hip flexion). Extension (increasing the angle, such as straightening the knee, extension of the vertebral column). Hyperextension (going beyond the anatomical position, such as arching the back). All these movements occur in the sagittal plane around the transverse axis. Mnemonic device to remember the transverse axis Imagine a unicycle moving in a straight line! The axis around which the wheel turns is the transverse axis and the wheel is the sagittal plane. Vertical axis associated with the horizontal plane The vertical axis or longitudinal axis, also called the vertical or cephalo-caudal axis, passes through the body from top to bottom. It is perpendicular to the horizontal plane and allows for the analysis of all rotational movements. Movements associated with the vertical axis Internal (medial) and external (lateral) rotations (e.g., rotation of the coxofemoral joint, glenohumeral joint). Axial rotation (e.g., turning the head from right to left, trunk rotation). Pronation/supination of the forearm (palm facing backward/forward). All these movements occur in the horizontal plane around the vertical or longitudinal axis. Mnemonic device to remember the vertical axis Imagine a carousel: its axis passes through its center from top to bottom, and it rotates around this axis. Just like a rotation. Conclusion - anatomical planes and axes: understanding the fundamental reference points of the human body The planes and axes form a true reference system: they make it possible to unify the language of medicine, physical therapy, osteopathy, as well as sports and art.Thanks to them, it becomes possible to analyze a movement, locate a structure, or interpret a medical image with precision. By mastering these fundamental reference points, you have a solid foundation to progress in the study of the body, understand the logic of movement, and better apply your knowledge in practice. FAQ – Anatomical planes and axes 1. What are the main anatomical reference planes used to describe the human body? There are three fundamental planes: The median sagittal plane: it separates the body into a right half and a left half. The frontal (or coronal) plane: it divides the organism into an anterior face (front) and a posterior face (back). The transverse (or horizontal) plane: it cuts into a superior part (above) and an inferior part (below). They serve as a reference system to orient any anatomical description and locate the main structures. 2. What is the difference between a plane and an axis in anatomy? A plane is an imaginary surface that separates the body into parts or regions (sagittal, frontal, transverse). An axis is an imaginary line around which a movement occurs. The axis passes through the plane perpendicularly.For example: elbow flexion occurs in the sagittal plane around a transverse (mediolateral) axis. 3. What is the standard anatomical reference position and why is it essential? The standard anatomical reference position corresponds to: organism standing, face oriented toward the observer, arms along the trunk, palms facing forward, feet parallel, and head straight.This universal posture allows for the precise description of the relationships between body regions (up/down, left/right, anterior/posterior). Without this reference point, any orientation would be relative and a source of confusion. 4. Which movements can be associated with the planes and axes of the human body? In the sagittal plane: flexion and extension (e.g., tilting the head, straightening the back). In the frontal plane: abduction and adduction (moving a limb away and toward, like raising the arm laterally), as well as tilts (leaning to the sides). In the horizontal plane: internal and external rotations (e.g., hip rotation, pronation/supination of the hand) or right and left rotations for the spine. Each movement corresponds to a directional axis perpendicular to the plane concerned. 5. Why are anatomical planes and axes essential in medicine and biomechanics? They allow for: Accurately describing the location of a structure or organ in a region using a chosen view. Analyzing a movement from different views and in different professions (sports, physical therapy, osteopathy). Standardizing medical images (MRI, CT scan) using frontal, sagittal, and horizontal sections of different regions of the body. In short, they provide a common base for all health and movement professionals.

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Anatomical planes and axes: understanding the fundamental landmarks of the human body