Brainsteam
Medulla (bulbus)
Surface
Located in posterior cranial fossa against clivus. In front it conncets with pons and middle cerebellar peduncle. Medulla is conus shaped and is 2.5cm long with base directed towards pons.
Bulbus has ventral and dorsal surface:
Ventral surface contains:
Ventral median fissure - fissura mediana anterior- continuation with spinal cords fissura mediana anterior.
Anterolateral sulcus -sulcus anterolateralis dexter et sinister. From this groove comes out XII nerve (n.hypoglossus).
Posterolateral sulcus -sulcus posterolateralis dexter et sinister. From this groove comes out IX nerve (n.glossopharyngeus), X nerve (n.vagus) and XI nerve (n.accesorius).
Raised area- pyramis between fissura mediana anterior and sulcus anterolateralis
Raised area- oliva between sulcus anterolateralis and sulcus posterolateralis.
Dorsal surface contains:
Dorsal median sulcus - sulcus medianus posterior.
Sulcus intermedius posterior- at both sides of sulcus medianus posterior
Tuberculum gracile- at elevations made from fasciculus gracilis between sulcus medianus posterior and sulcus intermedius posterior end.
Tuberculum cuneatum- at elevations made from fasciculus cuneatus between sulcus intermedius posterior and sulcus posterolateralis end.
Inferior cerebellar peduncle- pedunculi cerebellares inferiores- made from thickened upper margin.
Internal structure
Substantia grisea contains:
1.Nucleus gracilis- located in tuberculum gracile. Conscious proprioception, tactile, pressure, position, movement senses second neurons.
2.Nucleus cuneatus- located in tuberculum cuneatum. Conscious proprioception, tactile, pressure, position, movement senses second neurons.
3.Nucleus olivaris- located in oliva.. Balance regulation.
4.Nuclei reticulares- scattered in white matter. Near middle line are located raphes. Regulate brain allertness.
5. VIII(part ) - XII head nerve nuclei.
Substantia alba contains:
Ascending tracts:
1.Fasciculus gracilis- carries information of conscious proprioception, tactile, pressure, position, movement sense. Carries information from lower extremities and bodies down part from fifth thoracic till first coccygeal segment to nucleus gracilis which axons form fibrae arcuatae internae, which crosses forming decussatio lemnisci medialis which further goes as medial loop (lemniscus medialis) to thalamus
2.Fasciculus cuneatus- carries information of conscious proprioception, tactile, pressure, position, movement sense. Carries information from upper extremities and bodies upper part from first cervical till fifth thoracic segment to nucleus cuneatus which axons make fibrae arcuatae internae. Further it goes the same as described above.
3. Tractus spinocerebellaris anterior- to cerebellum.
4.Tractus spinocerebellaris posterior- to cerebellum through pedunculi cerebellares inferiores.
5.Tractus olivocerebellaris- to cerebellum through pedunculi cerebellares inferiores.
6.Fibrae spinothalamicae- fibers from tractus spinothalamicus lateralis and anterior. Goes 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.Tractus olivospinalis- Reflectory balance tract from brainsteam nucleus olivaris to motorical nuclei in cornu anterius.
3.Tractus tectospinalis- reflectory vision and hearing tract from subcortical vision center to motorical nuclei in spinal cord.
4.Vestibulospinal tract- tractus vestibulospinalis (medialis and lateralis) refelctory coordination tract from nuclei vestibulares 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 III, IV, VI and XI head nerve motorical nuclei to motorical nuclei in cervical segments. Coordinates eye movements with head and neck movements.
7.Tractus pyramidialis, which is made from:
Fibrae corticospinales- voluntary movement regulation. 80% of fiber crosses forming decussatio pyramidum. Crossed fibers make tractus corticospinalis lateralis, uncrossed fibers tractus corticospinalis anterior.
Fibrae corticonucleares- voluntary movement regulation. From cortex to head nerve (IX, X, XI, XII) motoric nuclei.
