Biomedical Engineering Reference
In-Depth Information
5.3
Angie is carrying 70N at 36.5 cm from the elbow joint. The weight of her fore-
arm and hand is 20N with a radius of gyration of 18 cm. She has a complete
lesion of the musculocutaneous nerve, so only the brachioradialis can produce
a flexion when the elbow is 90
of flexion. The brachioradialis is attached to
the forearm at a distance of 26 cm from the elbow joint, and the angle of inser-
tion is such that the vertical distance at the elbow joint is 7.8 cm.
°
(a) Identify the class of lever operating during the isometric elbow flexion.
(b) Calculate the resistance torque and the effort force.
(c) Calculate the resistance joint force and its angle of application.
5.4
Sayed is carrying a 50-pound load in his hand. His forearm is at a 45
°
angle to
the ground and his upper arm is at a 30
angle to the ground. The distance of
the weight from the elbow joint is 14 inches and the distance from the elbow
to the shoulder joint distance is 12 inches. Ignoring the weights of forearm and
upper arm, (a) draw the free body diagram, and (b) determine the moment
exerted about the elbow joint and about the shoulder joint.
°
5.5
The illustration shows the abdominal skeletal structure of person (upper body
weight
250 pounds) standing on the right lower extremity. The right hip ab-
ductor muscles must contract to counteract the force of gravity and keep the
pelvis level. Note that the hip abductor muscle force is acting at an angle of
70° relative to the horizontal plane.
=
(a) How much force must the right hip abductor muscles generate to keep the
pelvis level?
(b) If the muscle contraction
Δ
L
/
L
=
10%, and the average cross-sectional area
is 14 cm
2
,
what is the elastic modulus of the muscle (assume Hooke's
law)?
