Spinal cord anatomy: Difference between revisions
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== Introduction == | == Introduction == | ||
The Nervous System is divided into two main divisions.<ref name="Barker">Barker; Barasi; Neal. Neuroscience at a glance; Blackwell science Ltd; 1999</ref> | |||
These are: | |||
#Central Nervous System (CNS) | |||
#Peripheral Nervous System (PNS) | |||
[[Image:Nervous System.jpg|center|Nervous System]] | |||
== Anatomy of the Spinal Cord == | == Anatomy of the Spinal Cord == | ||
The spinal cord lies within the vertebral canal, extending from the foramen magnum to the lowest border of the first lumbar vertebra. It is enlarged at two sites, the cervical and lumbar region. The lower part of the spinal canal contains the lower lumbar and sacral nerves known as the '''Cauda Equina'''. | |||
* Sensory Nerve Fibres enter the Spinal Cord via the '''Dorsal (Posterior) Root'''. The cell bodies for these neurons are situated in the Dorsal Root Ganglia. | |||
*Motor and Preganglionic Autonomic Fibres exit via the '''Ventral (Anterior) Root.''' | |||
*Motor and | |||
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| [[Image:Cord.jpg|left|400px]] | | [[Image:Cord.jpg|left|400px]] | ||
| [[Image:Spinalnerves.jpg|left|400px]] | | [[Image:Spinalnerves.jpg|left|400px]] | ||
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This short video clip gives an overview of spinal cord anatomy. | This short video clip gives an overview of spinal cord anatomy. | ||
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== Associated Pathways == | == Associated Pathways == | ||
=== Ascending Sensory Pathway === | |||
==== [[Spinothalamic tract|Spinothalamic Tract]] ==== | |||
* From Dorsal horn laminae I,III,IV,V. crosses midline in spinal cord, projects to brain stem and contr-lateral thalamus. Conveys pain and temperature. | |||
==== Dorsal Column Medial Lemniscal Pathway ==== | |||
* Afferents from mechanoreceptors, muscle and joint receptors. terminates in dorsal column nuclei of medulla. Forms medial lemniscus at this level and synapses in ventroposterior nucleus of thalamus. Conveys proprioception, light touch and vibration. | |||
==== Spinocerebellar Tract ==== | |||
* From spinal cord interneurons. It has two tracts a) Dorsal SCT relays via inferior cerebellar peduncle and b) VCT relays via superior cerebellar peduncle to the cerebellum. It conveys proprioceptive information and on-going activity in the spinal cord interneurons. | |||
=== Descending Motor Pathways === | |||
== | ==== [[Corticospinal Tract|Corticospinal (Pyramidal) Tract]] ==== | ||
From the motor cortex, premotor cortex, and somatosensory cortex. Has a role in sensory processing and fractionated finger movements. | |||
==== [[Rubrospinal Tract]] ==== | |||
Originates from the magnocellular part of the red nucleus in the brain. It projects towards common structures with the CoST, particularly those involved with distal motor control. There is debate as to how significant this tract is. | |||
== | ==== [[Vestibulospinal Tract|Vestibulospinal Tract]] ==== | ||
Originates from Deiters nucleus in the medulla and innervates the extensor and axial muscles. It is involved in balance control and posture. | |||
==== [[Reticulospinal Tract|Reticulospinal Tract]] ==== | |||
This tract begins in the caudal reticular formation in the pons and medulla. Provides both excitable and inhibitory effects on the interneurons in the spinal cord, and to a lesser extent, it also acts on the motor neurons. Its main action is to dampen down activity in the spinal cord. without this pathway, there is increased extensor tone observed. | |||
== References == | == References == | ||
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Introduction[edit | edit source]
The Nervous System is divided into two main divisions.[1]
These are:
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
Anatomy of the Spinal Cord[edit | edit source]
The spinal cord lies within the vertebral canal, extending from the foramen magnum to the lowest border of the first lumbar vertebra. It is enlarged at two sites, the cervical and lumbar region. The lower part of the spinal canal contains the lower lumbar and sacral nerves known as the Cauda Equina.
- Sensory Nerve Fibres enter the Spinal Cord via the Dorsal (Posterior) Root. The cell bodies for these neurons are situated in the Dorsal Root Ganglia.
- Motor and Preganglionic Autonomic Fibres exit via the Ventral (Anterior) Root.
 |
 |
This short video clip gives an overview of spinal cord anatomy.
| [2] |
Associated Pathways[edit | edit source]
Ascending Sensory Pathway[edit | edit source]
Spinothalamic Tract[edit | edit source]
- From Dorsal horn laminae I,III,IV,V. crosses midline in spinal cord, projects to brain stem and contr-lateral thalamus. Conveys pain and temperature.
Dorsal Column Medial Lemniscal Pathway[edit | edit source]
- Afferents from mechanoreceptors, muscle and joint receptors. terminates in dorsal column nuclei of medulla. Forms medial lemniscus at this level and synapses in ventroposterior nucleus of thalamus. Conveys proprioception, light touch and vibration.
Spinocerebellar Tract[edit | edit source]
- From spinal cord interneurons. It has two tracts a) Dorsal SCT relays via inferior cerebellar peduncle and b) VCT relays via superior cerebellar peduncle to the cerebellum. It conveys proprioceptive information and on-going activity in the spinal cord interneurons.
Descending Motor Pathways[edit | edit source]
Corticospinal (Pyramidal) Tract[edit | edit source]
From the motor cortex, premotor cortex, and somatosensory cortex. Has a role in sensory processing and fractionated finger movements.
Rubrospinal Tract[edit | edit source]
Originates from the magnocellular part of the red nucleus in the brain. It projects towards common structures with the CoST, particularly those involved with distal motor control. There is debate as to how significant this tract is.
Vestibulospinal Tract[edit | edit source]
Originates from Deiters nucleus in the medulla and innervates the extensor and axial muscles. It is involved in balance control and posture.
Reticulospinal Tract[edit | edit source]
This tract begins in the caudal reticular formation in the pons and medulla. Provides both excitable and inhibitory effects on the interneurons in the spinal cord, and to a lesser extent, it also acts on the motor neurons. Its main action is to dampen down activity in the spinal cord. without this pathway, there is increased extensor tone observed.
References[edit | edit source]
References will automatically be added here, see adding references tutorial.
- ↑ Barker; Barasi; Neal. Neuroscience at a glance; Blackwell science Ltd; 1999
- ↑ Handwritten tutorials. Spinal Pathways 1 - Spinal Cord Anatomy and Organisation. Available from: http://www.youtube.com/watch?v=5B87zsAKmWc [last accessed 29/08/16]
