Which tissue is not typically innervated by the autonomic nervous system?

Which tissue is not typically innervated by the autonomic nervous system?

• A. Cardiac muscle
• B. Smooth muscle
• C. Glands
• D. Skeletal muscle

Answer: (D)

Autonomic innervation governs involuntary actions: cardiac and smooth muscle contract or relax, and glands secrete, all under autonomic modulation. Skeletal muscle, however, is controlled by the somatic nervous system. Motor neurons in the spinal cord send signals directly to skeletal muscle fibers at the neuromuscular junction, releasing acetylcholine to produce voluntary contraction via nicotinic receptors. Therefore, skeletal muscle is not typically innervated by the autonomic system, making it the tissue that stands outside the usual autonomic control. The autonomic system can influence skeletal muscle indirectly, such as by adjusting blood flow or sweating in the skin, but the muscle fibers themselves aren’t autonomically innervated.

Autonomic innervation governs involuntary actions: cardiac and smooth muscle contract or relax, and glands secrete, all under autonomic modulation. Skeletal muscle, however, is controlled by the somatic nervous system. Motor neurons in the spinal cord send signals directly to skeletal muscle fibers at the neuromuscular junction, releasing acetylcholine to produce voluntary contraction via nicotinic receptors. Therefore, skeletal muscle is not typically innervated by the autonomic system, making it the tissue that stands outside the usual autonomic control. The autonomic system can influence skeletal muscle indirectly, such as by adjusting blood flow or sweating in the skin, but the muscle fibers themselves aren’t autonomically innervated.