EXAM 2 - WRITTEN Flashcards
spine alignment
vertebral column has counterbalancing anterior-posterior curves; act as shock absorbers and reduce amount of injury
thoracic and sacral curves offset cervical and lumbar curves
- thoracic and sacral curves - concave anteriorly and convex posteriorly, in sagittal plane; lumbar and cervical curves - convex anteriorly and concave posteriorly; lateral curves - pathological - scoliosis.
at sagittal plane, anteriorly concave curve is primary curve - thoracic and sacral
- lift head and bilateral lifting of lower extremities - antigravity extension actions create secondary curves - cervical and lumbar
neutral position:
(1) ASIS and PSIS level with each other in transverse plane
(2) ASIS in same vertical plane as symphysis pubis
(3) lumbar curve has desired amount of curvature (pelvis tilts anteriorly, lumbar curvature increases (lordosis); pelvis tilts posteriorly, lumbar curvature decreases (flat back)
- lateral pelvic tilt controlled by hip abductors - gluteus medius / minimus, and trunk lateral benders (erector spinae and quadratus lumborum)
- hip abductors and trunk lateral benders hold pelvis level
antigravity muscles
keep body in upright position static / dynamic posture
- hip and knee extensors, trunk and neck extensors
- trunk and neck flexors / lateral benders, hip abductors and adductors, ankle pronators and supinators
postural sway
- ankle plantar flexors and dorsiflexors
- anterior-posterior motion of upright body caused by motion at ankles
- result of constant displacement and correction of center of gravity within base of support
- high center of gravity and small base of support increase amount of postural sway
good posture / alignment
- decreases amount of stress placed on bones, ligaments, muscles, and tendons
- improves function and decreases amount of muscle energy needed to keep body upright
posture - lateral
plumb line aligned to passes slightly in front of lateral malleolus; body segments aligned so plumb line passes through landmarks
posture - anterior
plumb line aligned to pass through the midsagittal plane , dividing body into 2 equal halves
posture - posterior
plumb line aligned to pass through midsagittal plane, dividing body into 2 equal halves
posture - sitting
- shifting weight onto front of vertebrae will increase pressure placed on intervertebral disks; leans forward, disk pressure increases; reaches forward or picks up a weight, disk pressure further increases as weight or length of lever arm increases
- disk pressure is least when lying supine; increases as you stand and increases more as you sit
- lumbar curve decreases when sitting with back unsupported, pressure on intervertebral disks and posterior structures increases; chair with seat inclined anteriorly / kneeling stool decrease disk pressure by tilting pelvis forward slightly; maintain lumbar curve; back is unsupported, increased and sustained muscle contraction is required to keep body upright; extended position more desirable.
- weight onto front part of vertebra, stresses placed on posterior vertebra (facet joints) decreases, here a flexed position is desirable
- chair with lumbar support and/or a slight forward angle to seat helps maintain lumbar lordosis and minimize pressure on the disks; helpful to have adjustable height work station and computer monitor, a keyboard tray, and a chair with adjustable height armrests; maintain vertebral curves, keeping feet flat on floor, low back supported, and upper body in good alignment
posture - supine
- resting, least amount of intervertebral disk pressure, surface avoid loss of lumbar curve, yet soft to conform and give support to normal curves
- In side-lying posi- tion, bottom leg is extended and top leg flexed; pillow between the legs increase comfort for hips in good alignment
- prone - increased pressure placed on neck
gait cycle / stride
- between one foot touches floor until same foot touches floor again
- stride length - distance traveled during
- step - one-half of a stride; two steps (a right and a left) to complete a stride / gait cycle; equal; walking speed / cadence - number of steps taken / minute; slow 70 steps / minute; fast 130 steps / minute
- step length - distance between heel strike of one foot and heel strike of other; increased or decreased walking speed, step length will increase or decrease; regardless of speed, step length remain equal
gait cycle phases:
- stance phase - when foot is in contact with ground; heel strike of one foot and ends when that foot leaves ground; 60% of the gait cycle
- swing phase - foot is not in contact with ground; foot leaves floor and ends when heel of same foot touches floor again; 40% of the gait cycle.
tasks
(1) weight acceptance - very beginning of stance - foot touches ground and body weight begins to shift onto that leg
(2) single-leg support - body weight shifts completely onto stance leg so opposite leg can swing forward
(3) leg advancement - during swing phase
periods of double support (both feet contact with ground at same time) - as one leg is beginning stance phase and other leg is ending stance phase
- as right leg is beginning stance phase and left leg is ending stance phase
- as right leg is ending stance phase and left leg is beginning stance phase
- each 10% of the gait cycle at average walking speed
periods of single support (only one foot is in contact with ground)
- right foot is on ground as left foot is swinging forward
- left foot bears weight and right leg swings forward
- each 40% of gait cycle
period of nonsupport - neither foot is in contact with ground - during running
gait terms
- traditional terms refer to points in time; key points within the gait cycle
- RLA terms refer to periods of time; moving or dynamic nature of gait
gait cycle events
stance phase
As defined earlier, stance is that period in which the foot is in contact with the floor. Traditionally, the stance phase has been broken down into five components: (1) heel strike, (2) foot flat, (3) midstance, (4) heel-off, and (5) toe-off (Fig. 22-3). Some sources give stance phase only four components by combining heel-off and toe-off into one and calling it push-off. Because signifi- cantly different activities occur during these two periods, it is best to keep them separated.
Heel strike signals the beginning of stance phase, the moment the heel comes in contact with the ground (Fig. 22-4). At this point, the ankle is in a neu- tral position between dorsiflexion and plantar flexion, and the knee begins to f lex. This slight knee f lexion provides some shock absorption as the foot hits the ground. The hip is in about 25 degrees of flexion. The trunk is erect and remains so throughout the entire gait cycle. The trunk is rotated toward the opposite (contralateral) side, the opposite arm is forward, and the same-side (ipsilateral) arm is back in shoulder hyperextension. At this point, body weight begins to shift onto the stance leg. In RLA, this is the period of initial contact.
The ankle dorsiflexors are active in putting the ankle in its neutral position. The quadriceps, which have been contracting concentrically, switch to con- tracting eccentrically to minimize the amount of knee f lexion. The hip f lexors have been active. However, the hip extensors are beginning to contract, keeping the hip from flexing more. The erector spinae are active in keeping the trunk from flexing. The force of the foot hitting the ground transmits up through the ankle, knee, and hip to the trunk. This would cause the pelvis to rotate anteriorly, flexing the trunk somewhat, if it were not for the erector spinae counteracting this force.
Foot flat, when the entire foot is in contact with the ground, occurs shortly after heel strike (Fig. 22-5). The ankle moves into about 15 degrees of plantar flexion with the dorsiflexors contracting eccentrically to keep the foot from “slapping” down on the floor. The knee moves into about 20 degrees of flexion. The hip is mov- ing into extension, allowing the rest of the body to begin catching up with the leg. Weight shift onto the stance leg continues. Foot flat is roughly comparable to the RLA period called loading response, which is that period between the end of heel strike and the end of foot flat.
The point at which the body passes over the weight- bearing foot is called midstance (Fig. 22-6). In this phase, the ankle moves into slight dorsiflexion. However, the dorsiflexors become inactive. The plantar flexors begin to contract, controlling the rate at which the leg moves over the ankle. The knee and hip continue to extend; both arms are in shoulder extension, essentially parallel with the body; and the trunk is in a neutral position of rota- tion. In RLA, midstance is the period between the end of foot flat and the end of midstance.
Following midstance is heel-off, in which the heel rises off the floor (Fig. 22-7). The ankle will dorsiflex slightly (approximately 15 degrees) and then begin to plantar flex. This is the beginning of the push-off phase, sometimes called the propulsion phase, because the ankle plantar flexors are actively pushing the body for- ward. The knee is in nearly full extension, and the hip has moved into hyperextension. The leg is now behind the body. The trunk has begun to rotate to the same side, and the arm is swinging forward into shoulder flexion. In RLA, terminal stance is that period between the end of midstance and the end of heel-off.
The end of the push-off portion of stance is toe-off (Fig. 22-8). The toes are in extreme hyperextension at the metatarsophalangeal joints. The ankle moves into about 10 degrees of plantar flexion, and the knee and
ip are flexing. The thigh is perpendicular to the ground. In RLA, preswing is the period just before and including when the toes leave the ground, signaling the end of stance phase and the beginning of swing phase.
swing phase
non–weight-bearing activities:
acceleration - leg is behind body and moving to catch up; ankle is dorsiflexing, and knee and hip continue to flex, moving leg forward
- initial swing - period between end of toe-off and end of acceleration
midswing - ankle dorsiflexors brought ankle to neutral position; knee - maximum flexion (approximately 65 degrees), hip - maximum flexion (at about 25 degrees of flexion); shorten leg, foot clear ground as it swings through; further hip flexion moves leg in front of body and puts lower leg in vertica
- midswing - period between end of acceleration and end of midswing
deceleration - ankle dorsiflexors active to keep ankle in neutral position preparation for heel strike; knee extending, hamstring muscles contracting eccentrically to slow down leg, keeping snapping into extension; leg swung as far forward as it is going to swing; hip remains in flexion
- terminal swing - period between end of midswing and end of deceleration
displacement
vertical displacement of center of gravity - normal amount ~ 2 inches, highest at midstance and lowest at heel strike (initial contact)
horizontal displacement of center of gravity - as body weight shifts from side to side; equal; greatest during single-support phase at midstance; represents the distance body’s center of gravity must shift horizontally onto one foot so that other foot can swing forward; side-to-side displacement ~ 2 inches
width of walking base
durng walk, place feet slightly apart - distance would range from 2 - 4 inches