Examples of motor root in the following topics:
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- Each has three roots entering the ganglion (motor, sympathetic, and sensory roots) and a variable number of exiting branches.
- The motor root carries presynaptic parasympathetic nerve fibers (general visceral efferent fibers) that terminate in the ganglion by creating a synapse for the postsynaptic fibers traveling to target organs.
- The sympathetic root carries postsynaptic sympathetic fibers (general visceral efferent fibers) that traverse the ganglion without creating a synapse.
- The sensory root carries general sensory fibers (general somatic afferent fibers) that also do not create a synapse in the ganglion.
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- The trigeminal nerve (cranial nerve V), and it contains both sensory and motor fibers.
- The motor function activates the muscles of the jaw, mouth, and inner ear.
- The mandibular nerve has both sensory and motor functions.
- From the trigeminal ganglion, a single large sensory root enters the brainstem at the level of the pons.
- Immediately adjacent to the sensory root, a smaller motor root emerges from the pons at the same level.
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- Thirty-one pairs of spinal nerves (sensory and
motor) branch from the human spinal cord.
- The
posterior root is the sensory (afferent) root that carries sensory information
to the brain from other areas of the body.
- The anterior root is the motor
(efferent) root that carries motor information to the body from the
brain.
- The swelling found in the
posterior root is the posterior (dorsal) root ganglion, which contains the cell
bodies of sensory neurons.
- The anterior (ventral) root contains axons of motor
neurons that conduct nerve impulses from the CNS to other parts of the body
such as the muscles.
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- The grey matter, in the center of the cord, is shaped like a butterfly and consists of cell bodies of interneurons and motor neurons, as well as neuroglia cells and unmyelinated axons.
- The axons of dorsal root ganglion neurons are known as afferents.
- Ventral roots consist of axons from motor neurons, which bring information to the periphery from cell bodies within the CNS.
- Dorsal roots and ventral roots come together and exit the intervertebral foramina as they become spinal nerves.
- Describe the grey matter and spinal roots of the spinal cord
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- Each spinal nerve is formed by the combination of nerve fibers from the dorsal and ventral roots of the spinal cord.
- The dorsal roots carry afferent sensory axons, while the ventral roots carry efferent motor axons.
- The dorsal ramus contains nerves that serve the dorsal portions of the trunk; it carries visceral motor, somatic motor, and somatic sensory information to and from the skin and muscles of the back (epaxial muscles).
- Its anterior root helps form the coccygeal
plexus.
- Spinal nerves arise from a combination of nerve fibers from the dorsal and ventral roots of the spinal cord.
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- The somatosensory pathway is composed of three neurons located in the dorsal root ganglion, the spinal cord, and the thalamus.
- The first always has its cell body in the dorsal root ganglion of the spinal nerve.
- This is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex; namely, the portion of the human brain directly responsible for the movement and exchange of sensory and motor information of the body.
- Sensory nerves of a dorsal root ganglion are depicted entering the spinal cord.
- The formation of the spinal nerve from the dorsal and ventral roots.
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- The motor unit is the functional unit of muscle contraction and includes the motor nerve fiber and the muscle fibers it innervates.
- A motor unit consists of the motor neuron
and the grouping of muscle fibers innervated by the neuron.
- Thus, small motor units can
exercise greater precision of movement compared to larger motor units.
- Groups of motor units are innervated to
coordinate contraction of a whole muscle and generate appropriate movement; all
of the motor units within a muscle are considered a motor pool.
- These multiple motor units of different
sizes within a motor pool allow for very fine control of force either spatially
or temporally.
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- The spinothalamic tract is a somatosensory tract and the corticospinal tract is a motor tract.
- In both pathways, primary sensory neuron cell bodies are found in the dorsal root ganglia, and their central axons project into the spinal cord.
- It contains mostly motor axons.
- The primary purpose of the corticospinal tract is to maintain voluntary
motor control of the body and limbs.
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- SCI can have a number of causes; examples include motor vehicle accidents, falls, sports injuries, and violence.
- Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence.
- A indicates a "complete" spinal cord injury where no motor or sensory function is preserved in the sacral segments S4-S5.
- This is typically a transient phase and if the person recovers any motor function below the neurological level, that person essentially becomes a motor incomplete, i.e.
- E indicates "normal" where motor and sensory scores are normal.
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- The motor areas of the brain are located in both hemispheres of the cortex.
- The right half of the motor area controls the left side of the body, and the left half of the motor area controls the right side of the body.
- Premotor cortex: Located anterior
to the primary motor cortex and responsible for some aspects of motor
control.
- Various experiments
examining the motor cortex map showed that each point in motor cortex
influences a range of muscles and joints, indicating significant overlapping in
the map.
- $$Topography of the human motor cortex, including the premotor cortex, SMA, primary motor cortex, primary somatosensory cortex, and posterior parietal cortex.