Question

Which muscles have functionally multinucleated conditions?
A. Cardiac muscle
B. Smooth muscle
C. Voluntary muscle
D. All of these

Answer 1

Hint: Muscles are non-calcified tissues in the body. They arise from the mesoderm. Based on whether their movement is under one’s control, muscles can be voluntary and involuntary. The structure and histology of these two types of muscles differ in many ways.

Complete answer:
Option (a) is incorrect. Cardiac muscles are present in the heart. They are involuntary muscles since their contraction does not depend on the will of an individual. Cardiac muscles are composed of cardiomyocytes present on the walls of the heart. Though cardiac muscles are involuntary muscles, they are structurally related to the skeletal or voluntary muscles. The cardiomyocytes contain only one nucleus, but they are functionally syncytium, that is each cardiomyocyte works in a coordinated manner with the next cell to pump blood efficiently. The cardiomyocytes are connected to each other with the help of intercalated discs. Thus, cardiac muscles are not multinucleated and true syncytium but appear to be so.
Option (b) is incorrect. Smooth muscles are involuntary muscles. They are present in the esophagus, stomach, urinary bladder and uterus. Their movement is not under the control of an individual’s will. Smooth muscles lack striations and are therefore called non-striated muscles. The smooth muscles have an elongated structure with pointed ends. They contain only one nucleus and are called uninucleate structures.
Option (c) is correct. Voluntary muscles are skeletal muscles. The movement of skeletal muscles is under the will of one’s will. Skeletal muscles are composed of myofibrils, which in turn are composed of repeated units called sarcomeres. The skeletal muscles are formed by a process of myogenesis by the fusion of several uninucleate cells. Skeletal muscles are therefore multinucleate entities. Skeletal muscles are found attached to the bones. They help in the movement of body parts, protect the internal organs and maintain body shape.

So, the correct answer is option C.

Note: Muscles are softer tissues. They are formed during embryogenesis. There are three types of muscles based on the regulation of their movement and structures. Skeletal muscles are voluntary and striated, while cardiac muscles and cardiac muscles are involuntary muscles. Skeletal muscles are present on the bones connected to the latter by tendons, whereas smooth muscles are present in intestine and digestive organs, uterus, urinary bladders. Cardiac muscle, as the name suggests, is present in the heart.