Balance Flashcards
Balance a state of physical equilibrium / maintenance and control of the center of gravity/ achieving and maintaining an upright posture.
All definitions assume integrated somatosensory, visual and vestibular information within the central nervous system. Balance is best assessed through investigation of all three components of balance.
Somatosensory input
Somatosensory receptors are located in the joints, muscles, ligaments, and skin to provide proprioceptive information regarding length, tension, pressure, pain and joint position. Proprioceptive and tactile input from the ankles, knees, hips, and neck provide balance information to the brain.
Challenging the somatosensory system
Examination of pressure and vibration; observation of a patient when changing the surface they are standing on. Examples: slopes, uneven surfaces, standing on foam.
Visual input
Visual receptors allow for perceptual acuity regarding verticality, motion of objects and self, environmental orientation, postural away, and movements of the head/neck. Children rely heavily on this system for maintenance of balance.
Challenging the visual system
Examination of quiet standing with eyes open; observing balance strategies to maintain center of gravity with and without visual input. Assessment of potential visual field cuts, hemianopsia, pursuits, saccades, double vision, gaze control, and acuity is necessary.
Vestibular input
The vestibular system provides the central nervous system with feedback regarding the position and movement of the head with relation to gravity. The labyrinth consists of three semicircular canals filled with endolymph and two otolith organs. Semicircular canals respond to the movement of fluid with head motion. Otoliths measure the effects of gravity and movement with regard to acceleration/deceleration.
Challenging the vestibular system
Examination of balance with movement of the head; testing such as Dix-Hallpike maneuver, bithermal carolic testing, assessment for nystagmus, head thrust sign; testing of the vestibulocular reflex.
Balance reflexes. Vestibuloocular Reflex (VOR)
VOR allows for head/eye movement coordination. This reflex supports gaze stabilization through eye movement that counters movements of the head.
Balance reflexes. Vestibulospinal Reflex (VSR)
VSR attempts to stabilize the body and control movement. The reflex assists with stability while the head is moving as well as coordination of the trunk during upright postures.
Automatic Postural Strategies.
Automatic Postural Strategies are automatic motor responses that are used to maintain the center of gravity over the base of support. These responses always react or respond to a particular stimulus.
Ankle strategy
The ankle strategy is the first strategy to be elicited by a small range and slow velocity perturbation when the feet are on the ground. Muscle groups contract in a distal to proximal fashion to control postural sway from the ankle joint.
Hip strategy
The hip strategy is elicited by a greater force, challenge or perturbation through the pelvis and hips. The hips will move (in the opposite direction from the head) in order to maintain balance. Muscle group contract in a proximal to distal fashion in order to counteract the loss of balance.
Suspensory strategy
The suspensory strategy is used to lower the center of gravity during standing or ambulation in order to better control the center of gravity. Examples of this strategy include knee flexion, crouching or squatting. This strategy is often used when both mobility and stability are required during a task ( such as surfing).
Stepping strategy
The stepping strategy is elicited through unexpected challenges or perturbations during static standing or when the perturbation produces such a movement that the center of gravity is beyond the base of support. The lower extremities step and/or upper extremities reach to regain a new base of support.
