White fibers are present in which
muscle?
a) Calf muscles
b) Back muscles
c) Gluteal muscles
d) Hand muscles
Correct Answer - D
Ans. D. Hand muscles.
[Ref Principles of medical physiology p.118]
Type of muscle fibers:
Type 1 (red) or type 2 (white).
Most of the muscle in human body contains both types of fibers, i.e.
most muscles in the body have both types of motor units.
But, some muscles have more type 1 fibers (type 1 motor units) than
type 2, and vice-versa.
Accordingly, skeletal muscles can be divided into :
Red muscles
These muscles contain more type 1 (red) fibers, therefore are slow
twitch muscles and contain more myoglobin content.
These are muscles which require prolonged contraction, for
example, muscles which help in maintaining posture, i.e. Back
muscles gluteus muscles (at back of hip) and calf muscles.
White (pale) muscles
These muscles contain more type 2 (white) fibers and are fast twitch
muscles.
These are muscles which help rapid contractions and finer
movements.
Examples are Hand muscles and extra ocular muscles.