Spinal Cord
Spinal cord – medulla spinalis.
Surface
Spinal cord is located in spinal canal. It weighs 34-38grams , is 40-45cm long and 1 cm in diameter. Spinal cord is cylinder shaped with conus shaped ending- conus medullaris, which ends at second lumbar vertebras upper edge.
Down from conus medullaris stretches rudimental part - filum terminale, which contains meninges. Filum terminale is 25cm long and ends anchoring spinal cord at os coccygis bone membrane. Next to filum terminale are located spinal nerve bundles forming horse tail - cauda equina.
Down from conus medullaris stretches rudimental part - filum terminale, which contains meninges. Filum terminale is 25cm long and ends anchoring spinal cord at os coccygis bone membrane. Next to filum terminale are located spinal nerve bundles forming horse tail - cauda equina.
Spinal cord is divided into 31 segments(each segment is a part of the cord that has one spinal nerve pair). Therefor spinal cord has part the same as spine with number of segments in them:
Cervical cord- 8 segmenta cervicalia,
Thoracical cord- 12 segmenta thoracica,
Lumbar cord- 5 segmenta lumbalia – at 10th, 11th thoracical vertebras level,
Sacral cord- 5 segmenta sacralia- 12th.thoracical and 1st lumbar vertebras level,
Coccygeal cord- 1 segmentum coccygeum.- 12th.thoracical and 1st lumbar vertebras level.
At 5th and 6th cervical segments level cord has cervical enlargement - intumescentia cervicalis. Widening from 1st lumbar vertebras to 3rd sacral vertebras level is lumbar enlargement - intumescentia lumbosacralis.
Spinal cords grooves:
Ventral median fissure- fissura mediana anterior-deepest groove on spinal cords surface.
Dorsal median sulcus- sulcus medianus posterior.
Anterolateral sulcus- sulcus anterolateralis dexter et sinister. From this sulcus in each segment comes out ventral root of spinal nerve -radix anterior s. motoria.
Posterolateral sulcus- sulcus posterolateralis dexter et sinister. In this sulcus at each segment enters dorsal root of spinal nerve - radix posterior s. sensoria. On this root is located sensory dorsal root ganglion- ganglion sensorium s. spinalis.
Internal anatomy.
Spinal cord consists of grey matter - substantia grisea (cell bodies of neurons and glia) and white matter - substantia alba (nerve fibers).
In middle of spinal cord is central canal- canalis centralis, which is filled with cerebro spinal fluid -liquor cerebrospinalis (diameter 1mm). Canalis centralis upper end connects with brains fourth ventricle but down it ends blindly with widening -ventriculus terminalis at conus medullaris level.
In middle of spinal cord is central canal- canalis centralis, which is filled with cerebro spinal fluid -liquor cerebrospinalis (diameter 1mm). Canalis centralis upper end connects with brains fourth ventricle but down it ends blindly with widening -ventriculus terminalis at conus medullaris level.
Substantia grisea transverse section shows that its layed out in butterfly, H shape around canalis centralis with two wide horns at front - cornu anterius, 2 narrow horns at back– cornu posterius and 2 horns at side starting from first thoracical segment till second lumbar segment- cornu laterale.
Horns form colummns as long as the cord. Cornu anterius forms columna anterior dextra et sinistra. Cornu posterius forms columna posterior dextra et sinistra. Between both columns is columna intermedia dextra et sinistra.
Around canalis centralis located grey matter is substantia intermedia centralis. Substantia grisea is dividend in 10 laminae- laminae spinales. First till sixt laminae forms cornu posterius. Seventh laminae forms columna intermedia. Eight and ninth laminae forms cornu anterius, but tenth laminae is substantia intermedia centralis. Between Anterior and posterior horn at lateral side of grey matter at cervical and upper thoracical segments is located formatio reticularis spinalis net which also penetrates white matter and controls brains alertness. In grey matter neuron bodies with certain location form nuclei.
Horns form colummns as long as the cord. Cornu anterius forms columna anterior dextra et sinistra. Cornu posterius forms columna posterior dextra et sinistra. Between both columns is columna intermedia dextra et sinistra.
Around canalis centralis located grey matter is substantia intermedia centralis. Substantia grisea is dividend in 10 laminae- laminae spinales. First till sixt laminae forms cornu posterius. Seventh laminae forms columna intermedia. Eight and ninth laminae forms cornu anterius, but tenth laminae is substantia intermedia centralis. Between Anterior and posterior horn at lateral side of grey matter at cervical and upper thoracical segments is located formatio reticularis spinalis net which also penetrates white matter and controls brains alertness. In grey matter neuron bodies with certain location form nuclei.
Cornu anterius contains somatical nervous system motorical nuclei from whom fibers go to skeletal muscles.
Columna intermedia contains:
Vegetative parasympatical nuclei - nuclei parasympathici sacrales, which are located at second to fourth sacral segment. Their fibers are vegetatives nervous system peripheral parts part.
Vegetative sympathetic nucleus - nucleus intermediolateralis, is located at cornu laterale.
Intermediolateral nucleus- nucleus intermediomedialis, locates in matter around central canal at thoracical and upper lumbar segments.
Dorsal nucleus of Clarke- nucleus thoracicus posterior s. dorsalis at base of cornu posterior.
Cornu posterius contains sensory nuclei:
Marginal zone nucleus- nucleus marginalis locates at cornu posterius tip in first laminae.
Substantia gelatinosa– substantia gelatinosa lays next to nucleus marginalis, in second laminae
Chief sensory nucleus- nucleus proprius locates in cornu posterius center in 3rd and 4th laminae.
Substantia alba is divided in columns in which are located tracts (bundle of nerve fibers). Tracts are ascending ( tractus ascendentes s.afferentes), which carry information from spine to brain and descending (tractus descendentes s. efferentes), which carry information from brain to spinal cord. Substantia alba 6 columns are funiculus anterior (between fissura mediana anterior and sulcus anterolateralis), funiculus lateralis (between sulcus anterolateralis and sulcus posterolateralis) and funiculus posterior ( between sulcus posterolateralis and sulcus medainus posterior).
Funiculus anterior tracts:
Intersegment nerve fibers- fasciculus proprius- connects segments with each other.
Ascending tracts:
1.Paleospinothalamic tract- tractus spinothalamicus anterior- sends pain, temperature and crude touch information from somatic and visceral structures from nucleus proprius to thalamus.
Descending tracts:
1.Tractus tectospinalis- reflectory vision and hearing tract from subcortical vision center to motorical nuclei in spinal cord.
1.Tractus tectospinalis- reflectory vision and hearing tract from subcortical vision center to motorical nuclei in spinal cord.
2.Tractus olivospinalis- Reflectory balance tract from brainsteam to motorical nuclei in cornu anterius.
3. Tractus corticospinalis anterior- voluntary movement regulation from cortex to motorical nuclei.
4.Vestibulospinal tract- tractus vestibulospinalis (medialis and lateralis) refelctory coordination tract from vestibular nuclei in brainsteam to motorical nuclei cornu anterius.
5. Reticulospinal tract- tractus reticulospinalis from formatio reticularis in brainsteam to formatio reticularis spinalis and motorical nuclei.
6.Fasciculus longitudinalis medialis- from 3rd, 4th, 6th and 11th head nerve motorical nuclei to motorical nuclei in cervical segments. Coordinates eye movements with head and neck movements.
Funiculus lateralis tracts:
Intersegment nerve fibers- fasciculus proprius- connects segments with each other.
Ascending tracts:
1.Dorsal spinocerebellar tract- tractus spinocerebellaris posterior- unconscious proprioception information from muscles and joints of the lower extremity to the cerebellum. From nucleus thoracicus posterior to cerebellum.
2.Ventral spinocerebellar tract- tractus spinocerebellaris anterior- unconscious proprioception information from muscles and joints of the lower extremity to the cerebellum from nucleus intermediomedialis to cerebellum.
3.Neospinothalamic tract -Tractus spinothalamicus lateralis- sends pain, temperature and crude touch information from somatic and visceral structures from substantia gelatinosa to thalamus.
Descending tracts:
1.Rubrospinal tract- tractus rubrospinalis- carries information about voluntary movement, automatical movements. From midbrain to motorical nuclei in spinal cord.
2. Lateral corticospinal tract- tractus corticospinalis lateralis- Carries information about voluntary movements. From cortex to motorical nuclei in cornu anterius.
Funiculus posterior tracts :
Intersegment nerve fibers- fasciculus proprius- connects segments with each other.
Ascending tracts:
1.Fasciculus gracilis- carries information of conscious proprioception, tactile, pressure, position, movement sense. Goes to nuclei in brainstem. Carries information from lower extremities and bodies down part from fifth thoracic till first coccygeal segment. Located medially.
2. Fasciculus cuneatus- carries information of conscious proprioception, tactile, pressure, position, movement sense. Goes to nuclei in brainstem. Carries information from upper extremities and bodies upper part from first cervical till fifth thoracic segment. Located laterally.
