|Location||Ventral horn of the spinal cord|
|Function||Excitatory projection (to NMJ)|
|Neurotransmitter||UMN to LMN: glutamate; LMN to NMJ: ACh|
|Presynaptic connections||M1 via the Corticospinal tract|
|Postsynaptic connections||Muscle fibers and other neurons|
In vertebrates, the term motor neuron (or motoneuron) classically applies to neurons located in the central nervous system (CNS) that project their axons outside the CNS and directly or indirectly control muscles. The spinal cord is a long thin tubular bundle of Nerves that is an extension of the Central nervous system from the brain and is enclosed in and protected A neuromuscular junction ( NMJ) is the Synapse or junction of the Axon terminal of a Motoneuron with the motor end plate, the Glutamic acid (abbreviated as Glu or E) is one of the 20 Alpha Amino acids It is not among the human Essential amino acids Its A neuromuscular junction ( NMJ) is the Synapse or junction of the Axon terminal of a Motoneuron with the motor end plate, the The Chemical compound acetylcholine (often abbreviated ACh) is a Neurotransmitter in both the Peripheral nervous system (PNS and Central The term morphology in Biology refers to the outward appearance ( Shape, Structure, Colour, Pattern) of an Organism The primary motor cortex (or M1) works in association with pre-motor areas to plan and execute movements The corticospinal or pyramidal tract is a massive collection of Axons that travel between the Cerebral cortex of the Brain and the Spinal Skeletal muscle is a type of Striated muscle, which usually attaches to tendons Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information In Vertebrates the central nervous system ( CNS) is the part of the Nervous system which is enclosed in the Meninges. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell Muscle (from Latin musculus, diminutive of mus "mouse" is contractile tissue of the body and is derived from the Motor neuron is often synonymous with efferent neuron, primary neuron, or alpha motor neuron. In the Nervous system, efferent nerves – otherwise known as motor or effector Neurons – carry nerve impulses away from the
|Branch of NS||Position||Neurotransmitter|
|*Except fibers to sweat glands and certain blood vessels|
According to their targets, motoneurons are classified into three broad categories:
"Somatic motoneurons", which directly innervate skeletal muscles, involved in locomotion (such as muscles of the limbs, abdominal, and intercostal muscles). The skin contains two different groups of sweat glands: Apocrine sweat glands and Merocrine sweat glands. The blood vessels are part of the Circulatory system and function to transport Blood throughout the body Skeletal muscle is a type of Striated muscle, which usually attaches to tendons Intercostal muscles are several groups of Muscles that run between the Ribs, and help form and move the Chest wall.
“Special visceral motoneurons” — also called “branchial motoneurons”— which directly innervate branchial muscles (that motorize the gills in fish and the face and neck in land vertebrates). Special visceral efferent ( SVE) refers to Efferent nerves which supply muscles which derived from the Branchial arches. Branchiomeric muscles are striated muscles of the head and neck A gill is an anatomical structure found in many aquatic organisms Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes
“General visceral motoneurons” — "visceral motoneurons" for short — which indirectly innervate smooth muscles of the viscera (like the heart, and the muscles of the arteries): they synapse onto neurons located in ganglia of the autonomic nervous system (sympathetic and parasympathetic), located in the peripheral nervous system (PNS), which themselves directly innervate visceral muscles (and also some gland cells). The general visceral efferent fibers ( GVE or sympathetic efferent fibers) probably arise from cells in the Lateral column or the base of the anterior column Smooth muscle is a type of non- Striated muscle, found within the Tunica media layer of large and small Arteries and Veins, the bladder In Anatomy, a viscus (ˈvɪskəs ( Plural: viscera /ˈvɪsərə/ is an internal organ of an animal (including humans in particular an internal The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic Arteries are Blood vessels that carry blood away from the Heart. Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands In Anatomy, a ganglion (pl ganglia) is a tissue mass. Neurology In neurological contexts ganglia are composed mainly of &trade The autonomic nervous system ( ANS) (or visceral nervous system) is the part of the Peripheral nervous system that acts as a Control The Sympathetic Nervous System ( SNS) is a branch of the Autonomic nervous system along with the Enteric nervous system and Parasympathetic nervous The parasympathetic Nervous system ( PSNS) is a division of the Autonomic nervous system (ANS along with the Sympathetic nervous system The peripheral nervous system ( PNS) resides or extends outside the Central nervous system (CNS which consists of the Brain and Spinal cord.
In other words:
It could be argued that, in the command of visceral muscles, the ganglionic neuron — parasympathetic or sympathetic — is the real “motoneuron”, being the one that directly innervates the muscle (whereas the “general visceral motoneuron” is, strictly speaking, a “preganglionic” neuron). The parasympathetic Nervous system ( PSNS) is a division of the Autonomic nervous system (ANS along with the Sympathetic nervous system In the Autonomic nervous system, fibers from the CNS to the ganglion are known as preganglionic fibers. But, for historical reasons, the term motoneuron is reserved for the CNS neuron.
All motoneurons are cholinergic, that is, they release the neurotransmitter acetylcholine. A receptor is cholinergic if it uses Acetylcholine as its Neurotransmitter. The Chemical compound acetylcholine (often abbreviated ACh) is a Neurotransmitter in both the Peripheral nervous system (PNS and Central Parasympathetic ganglionic neurons are also cholinergic, whereas most sympathetic ganglionic neurons are noradrenergic, that is, they release the neurotransmitter noradrenaline. Norepinephrine ( INN) (abbreviated norepi or NE) or noradrenaline ( BAN) (abbreviated NA or NAd) is a Norepinephrine ( INN) (abbreviated norepi or NE) or noradrenaline ( BAN) (abbreviated NA or NAd) is a (see Table)
The interface between a motoneuron and muscle fiber is a specialized synapse called the neuromuscular junction. Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands A neuromuscular junction ( NMJ) is the Synapse or junction of the Axon terminal of a Motoneuron with the motor end plate, the Upon adequate stimulation, the motoneuron releases a flood of neurotransmitters that bind to postsynaptic receptors and triggers a response in the muscle fiber. See Chemical synapse for an introduction to concepts and terminology used in this article In Biochemistry, a receptor is a Protein molecule embedded in either the Plasma membrane or Cytoplasm of a cell to which a mobile signaling
Somatic motoneurons are further subdivided into two types: alpha efferent neurons and gamma efferent neurons. (Both types are called efferent to indicate the flow of information from the central nervous system (CNS) to the periphery. In Vertebrates the central nervous system ( CNS) is the part of the Nervous system which is enclosed in the Meninges. The peripheral nervous system ( PNS) resides or extends outside the Central nervous system (CNS which consists of the Brain and Spinal cord. )
In addition to voluntary skeletal muscle contraction, alpha motoneurons also contribute to muscle tone, the continuous force generated by noncontracting muscle to oppose stretching. In Physiology, Medicine, and Anatomy, muscle tone (aka residual muscle tension or tonus) is the continuous and passive partial When a muscle is stretched, sensory neurons within the muscle spindle detect the degree of stretch and send a signal to the CNS. Sensory neurons are Neurons that are activated by sensory input (vision touch hearing etc Muscle spindles are Sensory receptors within the belly of a Muscle, which primarily detect changes in the length of this muscle The CNS activates alpha motoneurons in the spinal cord, which cause extrafusal muscle fibers to contract and thereby resist further stretching. This process is also called the stretch reflex. A stretch reflex is a muscle contraction in response to stretching within the muscle
Gamma motoneurons regulate the sensitivity of the spindle to muscle stretching. With activation of gamma neurons, intrafusal muscle fibers contract so that only a small stretch is required to activate spindle sensory neurons and the stretch reflex.
A single motoneuron may synapse with one or more muscle fibers. The motoneuron and all of the muscle fibers to which it connects is a motor unit. A motor unit is a single α-motor neuron and all of the corresponding muscle fibers it innervates.