Page 28: Questions # 2, 3, 5, 6 [answers in bold print]
2. Describe the following instances and identify the relative motion characteristics of the situations:
a. A runner
is running by a fence.
b. A runner
is running along a sidewalk and is passed by a car moving twice as fast.
c. The
motion of the ankle relative to the knee when performing leg extensions
on a weight machine and when performing leg extensions during the squat
lift.
a. the fence is a stationary frame of reference, so the runner is moving relative to the fence.
b. the sidewalk is a stationary frame of reference, so the runner moves relative to it, say at 4 mph; the car passes the runner at 4 mph, so the car basses the sidewalk at 8 mph
c. the ankle forms a circular arc as it travels around the knee joint during leg extensions. During leg extension (knee extension) in a squat lift, the ankle is stationary relative to the ground while the knee forms a circular arc relative to the ankle, so the ankle's movement relative to the knee, not the ground, would be a circular arc.
3. Identify and describe the spatial reference directions for the right elbow of a long jumper during takeoff; the barbell of a lifter performing a bench press; the path of a curveball baseball pitch; the path of a ski jumper from takeoff to landing.
- the long jumper's elbow would travel primarily forward and upward.
- the barbell would move linearly upward as the arm segments rotated about their proximal joints.
- the curve ball would travel forward, downward, and sideward.
- the ski jumper would follow a curvilinear path upward and forward then downward and forward.
5. Using an arm and a hand and a foot and a leg, demonstrate
linear and rotary motion. Estimate the linear and angular displacements
of the parts used. What measurement units are used for each type
of motion?
If only a single segment is moved, it must rotate about a joint
axis and therefore, exhibit angular motion. For example, rotating
the hand from a position of extreme wrist flexion to extreme wrist extension
represents angular displacement of about 110 degrees. Other angular
measurement units are radians and revolutions.
If the hand were moved along the edge of a table (linearly) it would be seen that in order to do so, more than one segment must be rotated; for example, shoulder extension with elbow flexion will move the hand linearly. Similar examples may be performed with the lower extremity. Linear measurement units are meters, feet, kilometers, miles and fractions of those units.
6. Describe five examples in sport or dance in which something (a) moves linearly (rectilinearly or curvilinearly), (b) rotates about some axis, and (c) moves with both linear and rotary motion.
a. Something moving rectilinearly is anything that moves through space in a straight line. Most common examples are things that fall vertically, or roll or slide along a flat, straight surface. Curvilinear motion of a point on a segment or piece of equipment is a more common type of motion found in human movement; for example, the hand's curved motion path in throwing, the body's center of gravity moving forward and up and down in walking and running, and in all movements in which the body is not falling or rolling or sliding in a straight line. A point on the hand or racket follows a curvilinear path as one or more segments move it through space.
b. Any rotating or spinning body or object whose axis does not travel through space as it turns displays only rotary motion; for example, a spinning skater, a merrry-go-round, a bicycle ergometer wheel, a leg rotating about the knee joint of a person sitting, a gymnast swinging on a horizontal bar.
c. Any body that is projected through space and is rotating or spinning, such as a diver, or ball, or discus, displays both linear and rotary motion. Motion of body segments rotating as their axes also are moving through space are most common and easily observed in walking, throwing, jumping, turning, kicking, dancing, etc.
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Pages 41-42: Questions # 2, 6, 8 [answers in bold print]
2. Demonstrate the anatomical position and movements along each of the three anatomical planes and around each of three axes of the body.
Students should work in partners to demonstrate anatomical position and various segmental movements around each of the three anatomical axes and along each of the three anatomical planes.
6. For the following movements, list the axis and plane used during the force phase of the movement: (a) the breathing movement for the front crawl (neck), (b) the vertical jump (knee), (c) the elementary backstroke (shoulder joint), (d) the forehand drive in tennis (shoulder joint), (e) the placekick (knee), and (f) turning a door handle (radioulnar joint).
AXIS
PLANE
longitudinal
transverse
M-L
sagittal
A-P
frontal
Longitudinal
transverse
M-L
sagittal
Longitudinal
transverse
8. With the help of a partner, perform the following movements: (a) flex the knee 90 degrees, (b) abduct the hip 30 degrees, (c) transvers abduct the shoulder 60 degrees, (d) medially rotate the shoulder joint 20 degrees, (e) laterally rotate the hip 30 degrees, (f) pronate the radioulnar joint 180 degrees, (g) medially rotate the knee 10 degrees, (h) laterally rotate the knee 20 degrees, (i) invert the subtalar joint as far as possible, (j) flex the elbow 90 degrees and then flex the ingers as far as possible and move the wrist in radial and ulnar flexion.
Students perform movements listed while partners read the list. Partners should also check on the correctness of the movement. Instructors may have the students perform the following for additional practice:
a. Do the same movements from different total body positions such as lying on the back;
b. Perform the same movements from different initial segmental positions such as internally rotating the shoulder joint from an initial position of 90 degrees abduction;
c. Perform the movement with the more distal segment
flexed such as medial rotation of the right hip while right limb weight-bearing.