Somatic neural system (SNS): It is the neural system that controls the. The PNS is then subdivided into the autonomic nervous system and the somatic nervous system. Human Nervous System Diagram Central Nervous System Peripheral Nervous System. For example the vagus nerve has sensory axons leading to the brain as well as motor axons leading to the heart and smooth muscles of visceral organs in the thorax and abdomen. This information is sent to the CNS via afferent sensory nerves. This diagram shows the structure of the cochlea in the inner ear. Others contain sensory and motor axons and are termed mixed nerves. The somatic nervous system is traditionally considered a division within the. optic nerve contains only sensory axons which carry signals to the brain. Somatic Nervous System (SNS) the part of the peripheral nervous system that controls voluntary movement of skeletal muscles. Fishes and amphibians have only 10 pairs. ![]() Reptiles birds and Mammals have 12 pairs of cranial nerves. Cranial nerves: In addition to paired spinal nerves peripheral nervous system of vertebrates includes paired cranial nerves.By contrast a snake, which moves by lateral undulations of its long trunk and tail has several hundred pairs of spinal nerves. The somatic nervous system uses motor neurones that have thick myelination and end in specific powerful synapses called neuromuscular junctions. ![]() For example a frog has evolved strong hind legs for swimming or jumping, a reduced trunk and no tail in the adult. ![]() The principal neurotransmitters, acetylcholine(ACh). Generally the number of spinal nerves is directly related to the number of segments in the trunk and tail of a vertebrate. Schematic representation of the somatic motor nerves and the efferent nerves of the autonomic nervous system. Spinal nerves: Extending from spinal cord are paired spinal nerves containing both motor and sensory fibres.Difference between cranial nerve and spinal nerve
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