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Motor Pathways - Anatomy & Physiology

2011-01-27T17:34:57Z

Ewahlberg: /* Pyramidal System (Corticospinal) */

{{review}}

==Introduction==
Motor pathways carry signals from the brain to the [[Muscles - Anatomy & Physiology#Skeletal Muscle|skeletal muscle]]. The system consists of upper and lower motor neurones. Upper motor neurones are located mainly within the neopallium of the [[Hindbrain - Anatomy & Physiology#Cerebellum|cerebellum]]. They govern the excitation or inhibition of lower motor neurones. Connections of upper motor neurones with lower motor neurones are grouped into two pathways.

===Pyramidal System (Corticospinal)===
[[Image:pyramidalsystem.jpg|thumb|right|150px|Pyramidal System © Sarah Hamilton]]
*Produces fine movements associated with skill, e.g. writing and playing a musical instrument.
*Most developed in primates, although may exist in other species such as the cat, where it aids in grooming.
*Nerve fibres of the pyramidal system originate in the cerebral cortex and then pass to the [[Forebrain - Anatomy & Physiology#Thalamus|thalamus]], and [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]].
*Some fibres decussate in the [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]], whilst others remain ipsilateral until they leave the [[Spinal Cord - Anatomy & Physiology|spinal cord]] where they cross the midline of the body.
**Nevertheless, all fibres cross the midline at some point, so that the left side of the brain controls the right side of the body and vice versa.

===Extrapyramidal System===
[[Image:Extrapyramidal system.jpg|thumb|right|150px|Extrapyramidal System © Sarah Hamilton]]
*Distinguishable from the pyramidal system as tracts do not run within the pyramids of the medulla.
*Earlier evolutionary development than the pyramidal system, so is a feature of lower animals and is the most important system in domestic species.
*More complex than the pyramidal system as involves various multisynaptic pathways that relay within several nuclei in the brain.
**Nuclei are dispersed from the telencephalon to the [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]] and may be visible grossly.
**Parts of it take origin from the motor cortex, others from the tectum and reticular formation.
**Neurones then relay within nuclei which include:
***Red nucleus
***Substantia nigra
***Caudate nucleus
***Subthalamic nuclei
***Olive in the [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]]
***Reticular formation
**Neurones that relay in the red nucleus and reticular formation relay directly onto LMNs, others relay to other nuclei.
* The main descending motor tracts from these two nuclei are:
** Rubrospinal tract - important in carnivores and ungulates. Modulates pattern generators in the [[Spinal Cord - Anatomy & Physiology|spinal cord]].
** Reticospinal tract
** Vestibulospinal tract
** Tectospinal tract

==Links==

*[[Nervous System - Pathology|Pathology of the Nervous System]]

[[Category:Nervous System - Anatomy & Physiology]]

Motor Pathways - Anatomy & Physiology

2011-01-27T17:31:33Z

Ewahlberg: /* Introduction */

{{review}}

==Introduction==
Motor pathways carry signals from the brain to the [[Muscles - Anatomy & Physiology#Skeletal Muscle|skeletal muscle]]. The system consists of upper and lower motor neurones. Upper motor neurones are located mainly within the neopallium of the [[Hindbrain - Anatomy & Physiology#Cerebellum|cerebellum]]. They govern the excitation or inhibition of lower motor neurones. Connections of upper motor neurones with lower motor neurones are grouped into two pathways.

===Pyramidal System (Corticospinal)===
[[Image:pyramidalsystem.jpg|thumb|right|150px|Pyramidal System © Sarah Hamilton]]
*Produces fine movements associated with skill, e.g. writing and playing a musical instrument.
*Most developed in primates, although may exist in other species such as the cat, where it aids in grooming.
*Nerve fibres of the pyramidal system originate in the [[Hindbrain - Anatomy & Physiology#Cerebellum|cerebellum]], and then pass to the [[Forebrain - Anatomy & Physiology#Thalamus|thalamus]], and [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]].
*Some fibres decussate in the [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]], whilst others remain ipsilateral until they leave the [[Spinal Cord - Anatomy & Physiology|spinal cord]] where they cross the midline of the body.
**Nevertheless, all fibres cross the midline at some point, so that the left side of the brain controls the right side of the body and vice versa.

===Extrapyramidal System===
[[Image:Extrapyramidal system.jpg|thumb|right|150px|Extrapyramidal System © Sarah Hamilton]]
*Distinguishable from the pyramidal system as tracts do not run within the pyramids of the medulla.
*Earlier evolutionary development than the pyramidal system, so is a feature of lower animals and is the most important system in domestic species.
*More complex than the pyramidal system as involves various multisynaptic pathways that relay within several nuclei in the brain.
**Nuclei are dispersed from the telencephalon to the [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]] and may be visible grossly.
**Parts of it take origin from the motor cortex, others from the tectum and reticular formation.
**Neurones then relay within nuclei which include:
***Red nucleus
***Substantia nigra
***Caudate nucleus
***Subthalamic nuclei
***Olive in the [[Hindbrain - Anatomy & Physiology#Medulla Oblongata|medulla oblongata]]
***Reticular formation
**Neurones that relay in the red nucleus and reticular formation relay directly onto LMNs, others relay to other nuclei.
* The main descending motor tracts from these two nuclei are:
** Rubrospinal tract - important in carnivores and ungulates. Modulates pattern generators in the [[Spinal Cord - Anatomy & Physiology|spinal cord]].
** Reticospinal tract
** Vestibulospinal tract
** Tectospinal tract

==Links==

*[[Nervous System - Pathology|Pathology of the Nervous System]]

[[Category:Nervous System - Anatomy & Physiology]]