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===Pyramidal System (Corticospinal)===

===Pyramidal System (Corticospinal)===

[[Image:pyramidalsystem.jpg|thumb|right|150px|Pyramidal System © Sarah Hamilton]]

[[Image:pyramidalsystem.jpg|thumb|right|150px|Pyramidal System © Sarah Hamilton]]

The pyramidal tract produces fine movements associated with skill, e.g. writing and playing a musical instrument. This tract is composed of direct connections that contain no synapses within the brain stem. Therefore the neurons pass directly through the medulla oblongata

The pyramidal tract produces fine movements associated with skill, e.g. writing and playing a musical instrument. This tract is composed of direct connections that contain no synapses within the brain stem. 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]]. Therefore the neurons pass directly through the ventral aspect of the [[Hindbrain_-_Anatomy_%26_Physiology#Medulla_Oblongata|medulla oblongata]] in a pyramidal shape providing the reason for the name of this tract. 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. The result of this is that 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.

*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.

Motor tracts within the pyramidal system are fundamental in the control and coordination of muscle groups that require concentration and concious thought to control. This is particularly true for movements of the hands and fingers and therefore these pyramidal tracts are most developed in primates, although may exist in other species such as the cat, where they aid in grooming. It is thought that the evolution of pyramidal tracts is closely associated with the development of concious and fine movements. In most domestic species that lack the ability to undertake fine movements the pyramidal tracts are primarily involved in control of the jaw, lips and aspects of the face.

**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===

===Extrapyramidal System===