Peripheral nervous systemThe peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brain and the spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs, essentially serving as a relay between the brain and spinal cord and the rest of the body. Unlike the CNS, the PNS is not protected by the vertebral column and skull, or by the blood–brain barrier, which leaves it exposed to toxins.
Enteric nervous systemThe enteric nervous system (ENS) or intrinsic nervous system is one of the main divisions of the autonomic nervous system (ANS) and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract. It is capable of acting independently of the sympathetic and parasympathetic nervous systems, although it may be influenced by them. The ENS is nicknamed the "second brain". It is derived from neural crest cells.
Parasympathetic nervous systemThe parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system. The autonomic nervous system is responsible for regulating the body's unconscious actions.
Autonomic nervous systemThe autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the nervous system that supplies internal organs, smooth muscle and glands. The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, its force of contraction, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is the primary mechanism in control of the fight-or-flight response.
Sympathetic nervous systemThe sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system. The autonomic nervous system functions to regulate the body's unconscious actions. The sympathetic nervous system's primary process is to stimulate the body's fight or flight response.
Vagus nerveThe vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that carries sensory fibers that create a pathway that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right vagus nerves—but they are typically referred to collectively as a single subsystem. The vagus is the longest nerve of the autonomic nervous system in the human body and comprises both sensory and motor fibers.
Trigeminal nerveIn neuroanatomy, the trigeminal nerve (lit. triplet nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves. Its name (trigeminal, ) derives from each of the two nerves (one on each side of the pons) having three major branches: the ophthalmic nerve (V_1), the maxillary nerve (V_2), and the mandibular nerve (V_3).
Afferent nerve fiberAfferent nerve fibers are axons (nerve fibers) of sensory neurons that carry sensory information from sensory receptors to the central nervous system. Many afferent projections arrive at a particular brain region. In the peripheral nervous system afferent nerve fibers are part of the sensory nervous system and arise from outside of the central nervous system. Sensory and mixed nerves contain afferent fibers.
Dorsal column nucleiIn neuroanatomy, the dorsal column nuclei are a pair of nuclei in the dorsal columns in the brainstem. The name refers collectively to the cuneate nucleus and gracile nucleus, which are situated at the lower end of the medulla oblongata. Both nuclei contain second-order neurons of the dorsal column–medial lemniscus pathway, which convey fine touch and proprioceptive information from the body to the brain. The dorsal column nuclei project to the thalamus.
GanglionA ganglion (: ganglia) is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system there are both sympathetic and parasympathetic ganglia which contain the cell bodies of postganglionic sympathetic and parasympathetic neurons respectively. A pseudoganglion looks like a ganglion, but only has nerve fibers and has no nerve cell bodies.
Neural pathwayIn neuroanatomy, a neural pathway is the connection formed by axons that project from neurons to make synapses onto neurons in another location, to enable neurotransmission (the sending of a signal from one region of the nervous system to another). Neurons are connected by a single axon, or by a bundle of axons known as a nerve tract, or fasciculus. Shorter neural pathways are found within grey matter in the brain, whereas longer projections, made up of myelinated axons, constitute white matter.
Central nervous systemThe central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts. It is a structure composed of nervous tissue positioned along the rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain.
Somatic nervous systemThe somatic nervous system (SNS), or voluntary nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles. The somatic nervous system consists of nerves carrying afferent nerve fibers, which relay sensation from the body to the central nervous system (CNS), and nerves carrying efferent nerve fibers, which relay motor commands from the CNS to stimulate muscle contraction. The a- of afferent and the e- of efferent correspond to the prefixes ad- (to, toward) and ex- (out of).
Spinal cordThe spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae.
DysautonomiaDysautonomia or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. A number of conditions can feature dysautonomia, such as Parkinson's disease, multiple system atrophy, dementia with Lewy bodies, Ehlers-Danlos syndromes, autoimmune autonomic ganglionopathy and autonomic neuropathy, HIV/AIDS, autonomic failure, and postural orthostatic tachycardia syndrome.
Motor cortexThe motor cortex is the region of the cerebral cortex involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus. The motor cortex can be divided into three areas: 1. The primary motor cortex is the main contributor to generating neural impulses that pass down to the spinal cord and control the execution of movement. However, some of the other motor areas in the brain also play a role in this function.
Efferent nerve fiberEfferent nerve fibers refer to axonal projections that exit a particular region; as opposed to afferent projections that arrive at the region. These terms have a slightly different meaning in the context of the peripheral nervous system (PNS) and central nervous system (CNS). The efferent fiber is a long process projecting far from the neuron's body that carries nerve impulses away from the central nervous system toward the peripheral effector organs (mainly muscles and glands).
Motor neuronA motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands. There are two types of motor neuron – upper motor neurons and lower motor neurons. Axons from upper motor neurons synapse onto interneurons in the spinal cord and occasionally directly onto lower motor neurons.
Motor controlMotor control is the regulation of movement in organisms that possess a nervous system. Motor control includes reflexes as well as directed movement. To control movement, the nervous system must integrate multimodal sensory information (both from the external world as well as proprioception) and elicit the necessary signals to recruit muscles to carry out a goal. This pathway spans many disciplines, including multisensory integration, signal processing, coordination, biomechanics, and cognition, and the computational challenges are often discussed under the term sensorimotor control.
Cardiac conduction systemThe cardiac conduction system (CCS) (also called the electrical conduction system of the heart) transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through the body's circulatory system. The pacemaking signal travels through the right atrium to the atrioventricular node, along the bundle of His, and through the bundle branches to Purkinje fibers in the walls of the ventricles. The Purkinje fibers transmit the signals more rapidly to stimulate contraction of the ventricles.
