Tag: divisions of nervous system

The Hypoglossal nerve (CN XII) is a motor nerve that primarily controls the muscles of the tongue.

The Vagus nerve is the tenth cranial nerve and is classified as a mixed nerve because it contains both sensory and motor fibers.

In higher vertebrates (reptiles, birds, mammals) there are 12 pairs of cranial nerves- olfactory (I), optic (II), oculomotor (III), trochlear (IV), trigeminal (V), abducens (VI), facial (VII), vestibulocochlear (VIII), glossopharyngeal (IX), vagus (X), accessory (XI), and hypoglossal (XII).

The vagus nerve historically cited as the pneumogastric nerve, is the tenth cranial nerve or CN X, and interfaces with parasympathetic control of the heart, lungs, and digestive tract. The vagus nerves are paired but are normally referred to in the singular. It is the longest nerve of the autonomic nervous system in the human body.

The Vagus nerve is the tenth cranial nerve (CN X).

• The autonomic nervous system(ANS) is the part of the nervous system responsible for the control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
• Sympathetic ganglia deliver information to the body about stress and impending danger and are responsible for the familiar fight-or-flight response.
  
• There are usually 22-23 pairs of sympathetic ganglia present in ANS: 3 in the cervical region (cervical ganglia), 11 in the thoracic region (note the presence of the stellate cervicothoracic ganglia), 4 in the lumbar region and 4-5 in the sacral region.
  
• So, the correct answer is '22'.

The autonomic nervous system is a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs. 

• The autonomic nervous system has three branches: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system.
  
• The autonomic nervous system is unique in that it requires a sequential two-neuron efferent pathway; the preganglionic neuron must first synapse onto a postganglionic neuron before innervating the target organ.
  
• So, the correct answer is 'Acts on skeletal muscles'.

• The hypothalamus is a small region of the brain. It's located at the base of the brain, near the pituitary gland. 
  
• The hypothalamus is the link between the endocrine and nervous systems. The hypothalamus produces releasing and inhibiting hormones, which stop and start the production of other hormones throughout the body.
• Hence Hypothalamus integrates Nervous and endocrine system.
• So, the correct answer is 'Hypothalamus'.

Vagus is $10^{th}$ cranial nerve. It originates from the sides of medulla oblongata. In vertebrates it consists of sensory and motor fibres.

The central nervous system includes brain and spinal cord. It integrates and stores the sensory information from external and internal sense organs and commands different organs to respond accordingly. This makes option A incorrect. Peripheral nervous system lies outside the central nervous system. It serves to carry the sensory information from external sensory receptors to CNS and motor signals from CNS to skeletal muscles via its somatic division (the voluntary actions). The autonomous division of peripheral nervous system controls the cardiac and smooth muscles and glands, thereby the functioning of internal organs, without our conscious control (the involuntary actions). This makes option B incorrect and option C correct. The 12 pairs of cranial nerves are part of peripheral nervous system and are mostly concerned with head, neck and facial region of the body (vagus nerve X being the part of autonomous division serves as an exception). Option D is incorrect.  Correct answer is C.