# planes and axes by keralaguest

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```									                                   The Skeletal System
Planes of Motion and Axes
Biomechanics is the study of human movements through the use of physics. As such,
biomechanics has its own language and terminology. The language of biomechanics establishes
a common reference system of standard terms. Planes and axes of motion are an important part
of this language.

Planes of Motion

   a plane of motion can be defined as the two dimensional space cut by a moving body or the
plane along which movements occur. There are generally three planes used to describe
segmental and body movements in physical activity. These are:

1. Sagittal plane
 a vertical plane that cuts the body into right and left sides

2. Frontal plane
 vertical plane that cuts the body into anterior (front) and posterior (back) parts

3. Transverse plane
 horizontal plane that cuts the body into superior and inferior parts

Anatomical Axes

   an axis is the point about which rotation of a body or of a body segment occurs. There are
three axes of rotation. Each axis is associated with a plane of motion and the axis is
perpendicular to that plane.

1. Horizontal axis (…think East and West)
 passes through the body from side to side
 perpendicular to the sagittal plane

2. Antereoposterior axis (axis)
 passes through the body from front to back
 perpendicular to the frontal plane

3. Longitudinal axis (…think North and South pole)
 passes through the body from top to bottom
 perpendicular to the transverse plane
Movements in the sagittal plane around a horizontal axis
(e.g. front roll, back roll, cycling, running)

1. Flexion
 flexion at a joint results in a decrease of the angle between the two segments that
meet at that joint

2. Extension
 extension at a joint results in an increase of the angle between the two segments that
meet at that joint
 if the movement occurs beyond the extended position, the action is called
hyperextension

Examples of flexion and extension

   shoulder flexion and extension
   elbow flexion and extension
   wrist flexion and extension
   fingers flexion and extension
   hip flexion and extension
   knee flexion and extension
   ankle dorsi flexion and plantar flexion
   tilt of pelvis under

Dorsi flexion: bringing the toes toward the shin
Plantar flexion:      pointing the toes away from the shin (toward the floor)
Movements in the frontal plane around a antereoposterior axis
(e.g. cartwheel, jumping jacks, galloping)

1. Abduction
 occurs when a body part is moved away from the midline of the body
 e.g. shoulder, hip, fingers

 occurs when a body part is moved toward the midline of the body
 e.g. shoulder, hip, fingers
 e.g. shoulder, hip, fingers

3. Inversion
 Turning the sole of the foot inward at the ankle (so the sole of the foot faces toward
the midline)

4. Eversion
 turning the sole of the foot outward at the ankle (so the sole of the foot faces away
from the midline)

5. Elevation
 raising a part to a superior position

4. Depression
 lowering a part to an inferior position
 e.g. lowering your shoulders to normal or lower than normal position; lowering your
jaw to an open position

5. Protraction
 Sticking jaw out (pouting)

6. Retraction
 Bringing jaw back to anatomical position

7. Lateral bending
 bending of the spinal column in the frontal plane to the left or right
 e.g. bending side to side at the waist
Movements in the transverse plane around a longitudinal axis
(e.g. twist, pirouette)

1. Rotation
 the movement of a bone around its own axis; this is also known as a pivot
 e.g. the head, neck, and trunk can pivot around the longitudinal axis

2. Internal (medial) rotation
 Rotation towards the midline
 E.g. turning forearn in towards body

3. External (lateral) rotation
 Rotation away from midline
 E.g. turning forearm away from body

4. Pronation
 rotation of the forearm and hand to the palms down position

5. Supination
 rotation of the forearm and hand to the palms up position (remember holding a cup of
“soup”)

6. Protraction
 Shoulder rounding (hunching shoulders)

7. Retraction
 Bringing shoulders back to anatomical position, or squeezing shoulder blades
together at back

Special movements
1. Circumduction
 a combination of abduction, adduction, flexion and extension
 this action describes a circle
 e.g. moving the shoulder in a circle (swimming, windmill throw in baseball); can
also be done at the hip joint

2. Opposition
 Bringing thumb towards fingers

3. Reposition
 Returning thumb back to anatomical position

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