There are three planes of motion in which we move. If you think about it, most of our movements are not straight up and down, or side to side etc, especially in sports. They tend to combine a mixture of movements in different planes.
The three planes of motion are:
The Sagittal plane passes through the body front to back, so dividing it into left and right. Movements in this plane are the up and down movements of flexion and extension
The frontal plane divides the body into front and back. Movements in this plane are sideways movements, called abduction and adduction
This plane divides the body into top and bottom. Movements in this plane are rotational in nature, such as internal and external rotation, pronation and supination
The anatomical position or neutral position is the starting position for describing any movement. It is important that you know this to be able to understand what is meant by certain movement patterns. It is sometimes also called the anatomical starting position or fundamental starting position.
Anatomical neutral is:
- Standing upright
- Legs together and knee straight
- Toes pointing straight forwards
- Arms by the side
- Palms facing forwards
Flexion and Extension
Flexion is a movement in the sagittal plane, which decreases the angle at the moving joint. Extension is the opposite movement, which increases the angle at the joint. Many types of synovial joint are capable of flexion and extension (hinge; ball and socket; saddle; condyloid) including the shoulder, elbow, wrist, hip and knee. Here are some examples:
In the videos above, shoulder flexion is the action of raising the arm above the head. Extension is then the downward movement. In the photo, the shoulder is in an extended position. For the knee, bending the knee is flexion, as the angle is reduced (as shown in the picture) and straightening it is called extension.
Flexion and extension at the ankle joint is called dorsiflexion and plantarflexion. Dorsiflexion is when you point your toes towards the ceiling and plantar flexion is when you point your toes away, towards the floor. Remember to start in the anatomical starting position!
Abduction and Adduction
These are movements in the frontal plane and involve moving the body part away or towards an imaginary centre line. Abduction is taking the body part away from the central line and adduction is moving it towards (remember this by thinking adduction adds the body part to the centre). Adduction can also be moving the body part across the centre line and to the other side of the body, shown in the hip abduction video below. Amongst the joints capable of abduction and adduction are the shoulder and hip.
Other abduction and adduction movements include the fingers. If you splay your fingers and move them apart, this is abduction as they are moving away from the centre position. When you bring the fingers back together, this is adduction, as you are adding them back to the centre line.
Rotation movements are in the transverse plane and include any twisting motion. Joints which permit rotation include the shoulder and hip. These are both ball and socket joints. We can also rotate our necks and backs due to a series of smaller joints, including the atlanto-axial joint which is a pivot joint in the neck between the first two vertebrae (C1 and C2).
Rotation of the hip and shoulder can be broken down into internal or external rotation (also sometimes known as medial and lateral rotation respectively). In the example of the shoulder video below, internal rotation is the movement of the hand either inwards towards the body (when the shoulder is adducted) or down to point towards the floor (when the shoulder is abducted). External rotation is therefore the opposite, when the hand moves away from the body (when the shoulder is adducted) or up towards the ceiling (when the shoulder is abducted).
Circumduction is a combination of all of the movements above. It is possible at ball and socket, condyloid and saddle joints such as the shoulder, hip, wrist and ankle. It involves moving the entire connecting limb through its full range of motion. Here is an example of shoulder circumduction:
Pronation, Supination, Inversion and Eversion
Pronation and supination are specialised movements of the forearm and ankle. In the forearm, pronation is the movement of turning the palm over to face downwards (or backwards if starting in anatomical neutral). Supination is the opposite movement, of turning the palm up or forwards. The movement here comes from the proximal radio-ulnar joint (the joint just below the elbow, between the Radius and Ulna bones) which is a pivot joint, allowing the Radius to move around the Ulna.
At the ankle, supination is the movement of turning the sole of the foot inwards. This is sometimes called inversion. Pronation is the movement of turning the sole of the foot outwards, sometimes called eversion. You will sometimes hear people saying they have over-pronated feet, meaning their sole turns outwards slightly more than it should when they walk or run, giving the appearance of a flat foot, without an arch.