Whether or not you consider yourself a “science nerd,” it can be helpful to understand the basics of human anatomy and movement. Understanding anatomy can help you be a better-informed fitness enthusiast and it may help you understand and incorporate different exercise variations into your fitness routine. In my experience teaching anatomy, gym-goers often pick up anatomical information fairly easily since they are already used to applying this type of information via different exercises.
With that said, here is the basic terminology you should be familiar with. I’ve tried to keep this brief and stick to the essentials, but don’t feel like you need to sit down and read this all at once. Feel free to just use this page to reference specific items. The most useful part of this page may be the “movement terms” section – this is where the rubber meets the road.
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Anatomical position is the standard reference position when talking about the human body. This position describes and individual who is standing erect, facing forwards, with the arms at the sides and the palms of the hands facing forwards. The lower limbs are close together and face forward.
Having a reference position is important for clarity when describing the relative position of body parts. Here is a visualization of anatomical position:
There are 4 categories of planes of the body that are important to understand. While many exercise movements occur almost exclusively in one plane (e.g. – biceps curls in the sagittal plane), sports often incorporate movements that occur in multiple planes simultaneously (e.g. – throwing a football or baseball).
The median (midsagittal) plane passes vertically through the body and divides the body into perfectly equal left and right halves (i.e. – this plane defines the midline of the body). There is only one median plane, which is why this is the only singular plane (the other terms are plural because multiple planes can exist in every other category).
Sagittal planes pass vertically through the body parallel to the median plane. They also divide the body into left and right halves, but the halves are not equal (if they were, we would be talking about the median plane).
Frontal (coronal) planes pass vertically through the body and divide the body into front (anterior) and back (posterior) parts. You can think about this plane dividing your body like a doorway would divide your body if you stopped partway through it.
Transverse (horizontal) planes pass horizontally through the body and divide the body into upper (superior) and lower (inferior) parts.
These planes (except a true sagittal plane) are illustrated in the image below. Note that the “sagittal plane” below should either be labeled “midsagittal” or “median,” but not just sagittal since it appears to be on the midline.
These terms come in pairs that have opposite meanings. Remember that these terms assume the body is in anatomical position unless otherwise specified. Here are the major terms you should be aware of:
Superior/Inferior: Superior refers to closer to the top of the head and inferior refers to closer to the sole of the foot.
Anterior/Posterior: Anterior refers to the front of a structure or closer to the front and posterior refers to the back of a structure or closer to the back.
Medial/Lateral: Medial means nearer to the median plane of the body and lateral means further from the median plane.
Dorsal surface/Palmar or Plantar surface: Dorsal can take on several meanings, but the important one for now is superior portion of a protruding structure (for example, the “top” or “back” of your foot is called the dorsal surface of the foot – the same is true for the hand). The surface that is opposite of the dorsal surface is called the palmar surface (for the hand) or plantar surface (for the foot).
Internal/External: These are fairly general terms. Internal means closer to the center of something and external means further from the center.
Proximal/Distal: These terms are primarily used to describe structures on the limbs. Proximal means closer to the torso and distal means further from the torso (e.g. – the elbow is distal to the shoulder, but the shoulder is proximal to the elbow).
Superficial/Deep: These terms relate to the surface of the body and underlying/overlying structures. Superficial means nearer to the surface and deep means further underlying a structure.
Bilateral refers to a structure that occurs on both sides of the body (left and right).
Unilateral refers to a structure that occurs on only one side of the body (e.g. – your spleen).
Ipsilateral means same side. For example, your right knee and right hip are ipsilateral.
Contralateral means opposite side. For example, your right knee and left hip are contralateral.
Flexion/Extension: Flexion is bending at a joint or decreasing the angle between two bones or body parts. Extension is straightening at a joint or increasing the angle between two bones or body parts.
Pronation/Supination: Pronation is rotating the radius bone so that the dorsum (back) of the hand faces anteriorly. Supination is the opposite movement – rotating the laterally to return the hand to anatomical position (with the palm facing anteriorly). Note: with the elbow flexed at 90 degrees, pronation will result in the dorsum of the hand facing superiorly and supination will result in the palm of the hand facing superiorly.
Adduction/Abduction: Adduction means moving towards the median plane (e.g. – moving your arms from a horizontal position to anatomical position by your side) and abduction means moving away from the median plane (e.g. – performing the concentric portion of a lateral raise). Note: for the fingers and toes (digits), these two terms are a little bit different.
Medial (internal) rotation/Lateral (external) rotation
Dorsiflexion/Plantarflexion: dorsiflexion is moving your toes closer to your shin and plantarflexion is moving your toes further from your shin (e.g. – performing a calf raise).
Elevation/Depression: Elevation moves a structure superiorly (e.g. – the upward phase of a shrug) and depression is moving a structure inferiorly (e.g. – the downward phase of a shrug).
Protraction/Retraction: These terms are often used to describe the movement of the shoulder blade (scapula). Protraction is moving the scapula anteriorly and laterally and retraction is moving the scapula posteriorly and medially (i.e. – squeezing your shoulder blades together).
Circumduction is a rotational movement that combines flexion, abduction, extension, and adduction (or the opposite order). Doing “arm circles” is an example of circumduction.
Origin: usually the proximal end of the muscle; remains fixed during muscular contraction
Insertion: usually the distal end of the muscle; is movable
Note: there are some exceptions to these definitions of origin and insertion. For example, when performing a closed kinetic chain exercise like the push-up, the distal part of the limb is fixed, but the proximal part of the limb is moving. It is more important to simply understand the attachments of a muscle rather than determine which is the origin and which is the insertion. If the attachments are known, the function can be understood.
Agonist/Prime Mover: the main muscle responsible for producing a specific movement in the body
Antagonist: a muscle that opposes the action of another muscle (e.g. – opposes the prime mover)
Synergist: a muscle that complements the action of a prime mover by either directly assisting the movement or by serving as a fixator
Fixator: a muscle that steadies the proximal part of a limb via isometric contraction while movement occurs distally
Types of Muscular Contractions
Muscle contractions can be grouped into three categories: reflexive, tonic, and phasic. Reflexive contractions are involuntary (e.g. – the diaphragm or the knee-jerk reflex). Tonic contractions are the slight contraction of muscle when it is “relaxed.” Tonic contractions can help maintain posture and readiness to respond to stimuli around us. Phasic contractions are the most important to understand for fitness. Phasic contractions include isotonic and isometric contractions.
Isotonic: contractions in which the muscle changes length and movement is produced
Concentric: an isotonic contraction in which the muscle shortens (e.g. – the “up” phase of a biceps curl involves the concentric contraction of the biceps brachii muscle)
Eccentric: an isotonic contraction in which the muscle lengthens, often as a controlled and gradual relaxation or lowering (e.g. – the “down/lowering” phase of a biceps curl involves the eccentric contraction of the biceps brachii muscle)
Isometric: contractions in which the muscle length stays the same and no movement occurs, but muscle tension is increased above normal resting tone.