Question

Skeletal muscles are controlled by?

Answer 1

Hint: Muscular tissue plays an important role in all the movement of the body. Myofibrils are the functional unit of muscles; they contract and relax on stimulation. We, in general, have \[3\] types of muscles viz, skeletal, smooth and cardiac. Skeletal muscles are voluntary whereas smooth muscles are involuntary in nature while cardiac muscles are only present in the heart and are involuntary. Different muscles are regulated by different parts of the nervous system.

Complete answer:
The nervous system is composed of highly specialized cells called ‘neurons’, which are the structural and functional units of the nervous system and are able to detect, receive and transmit different kinds of stimuli.
Humans have a well-developed neural system. It is divided into two parts namely, central nervous system (CNS) and peripheral nervous system (PNS).
1. Central Nervous System-
It includes the brain and spinal cord.
Brain is the central information processing organ of the body and acts as the ‘command and the control system’. It controls most of the functions of the body like voluntary regulations, balance of the body, functioning of various involuntary organs, thermoregulation, hunger and thirst, \[24\]-hour rhythmic cycle of body, activities of endocrine glands and human behavior, also the site for processing of vision, hearing, memory, intelligence, emotions and thoughts. All these functions are performed by different parts of the brain. The brain is divided into forebrain, midbrain and hindbrain. All these parts are further divided to properly organize these different functions. Forebrain includes cerebrum, olfactory lobe and diencephalon; midbrain includes the corpora- quadrigemina and crura-cerebri; the hindbrain includes cerebellum, pons and medulla.
Spinal cord is the extension of medulla via foramen magnum and has a neural canal that contains CSF/neurocoele and it itself is protected by the vertebral column. It forms a bridge between the brain and organs of the body. It provides a relay path for impulses coming from the brain. The most important function of the spinal cord is that it regulates the Reflex action. Reflex action is the involuntary action of voluntary muscles.
2. Peripheral Nervous System-
It includes all the body's nerves linked to the CNS. There are \[12\] pairs of cranial nerves that arise from the brain which are further divided into sensory, motor and mixed and \[31\] pairs of spinal nerves that arise from the spinal cord. The nerve fibers are of two types: Afferent nerve fibers that transmit the impulse from organs/tissues to CNS and Efferent fibers that transmit the regulatory impulses accordingly from CNS to the particular tissue or organ. The PNS is further divided into Somatic nervous system and Autonomic nervous system.
i) Somatic Nervous System: It relays impulses from the CNS to skeletal muscles (voluntary organs). The Ramus dorsalis and Ramus ventral is part of the spinal nerve forms SNS.
ii) Autonomic Nervous System: It transmits the impulses from the CNS to the smooth muscles and other involuntary organs of the body. The Ramus communicans part of the spinal nerves from ANS. It is further classified into Sympathetic Nervous system (Thoraco-lumbar outflow), has short preganglionic and longer post ganglionic neurons, increases the heart rate and respiratory rate and Parasympathetic Nervous System (Cranio-sacral outflow) which has longer preganglionic and short post ganglionic neurons, decreases the heart rate and respiratory rate.

Hence, Skeletal muscles are controlled by the somatic nervous system part of the peripheral nervous system.

Note:
Skeletal muscle is attached to skeletal bones. These are striated/striped in structure because of the presence of alternate light and dark bands, cylindrical in shape, unbranched and multinucleated, voluntary and fatigue in nature. Smooth muscles are non-striated/non-striated, fusiform in shape, unbranched and uninucleate, involuntary in nature and do not fatigue. They are present in walls of visceral organs. As the name suggests cardiac muscles are heart muscles, and are short, cylindrical, branched and pseudo syncytial (uninucleate). These are structurally similar to skeletal muscles and functionally to smooth muscles i.e., they are striated/striped but are involuntary and do not fatigue.