oblongata + pons Flashcards
brainstem
is in descending order;
midbrain
pons
oblongata
m.oblongata
cranial half: open medulla
caudal part: closed p. of medulla
-caudally cont. w s.cord and alike s.cord
-cranial half is split open and forms the floor of the 4th ventricle
external features of oblongata
VENTRAL SURFACE
ventral surface:
-sulci and funiculi cont. on oblongata
-ant. median fissure crosssed by pyramidal decussation —>
marks transition point from s.cord to oblongata
-bulbopontine sulcus sep. pons and oblongata (VI, VII, VIII arise from there)
-ant. funiculi of s.cord terminate in pyramids of oblongata (contain corticospinal tracts)
-anterolateral sulcus: cranial n XII arises from there
-olive lies lateral to pyramids
(elevated by underlying oliv.nucleus)
-lateral funiculus cont. into inf. cerebellar peduncle (joins w cerebellum)
-posterolateral sulcus: IX, X, XI emerge from it
dorsal SURFACE oblongata
-lower p. of medulla
-post. median sulcus cont. from s.cord to dorsal surf oblongata
-gracile + cuneate fasiculi cont from s.cord to oblongata to terminate in:
Gracile tubercle (elev. by gracile nucleus)
Cuneate tubercle(elev. by cuneate nucleus)
(upper half of oblongata forms floor of 4th ventricle)
PONS ventral surface
very convex and marked by sulcus basilaris (basilar artery)
-laterally pons narrows, forms middle cerebellar peduncles, terminating in cerebellum
-cranial n. V emerges from anterolateral parts of pons
(DORSAL SURF PONS forms floor of 4th ventricle)
4th ventricle and rhomboid fossa
a upper expanded continuation of central canal of oblongata
-pyramidal shape
Rhomboid fossa:
upper (rostral part) formed by dorsal surf pons
lower (caudal part) formed by dorsal surf oblongata (open medulla)
rhomboid fossa marked by:
-median sulcus og sulci limitans
Elevations on median sulcus:
(in lower part):
-hypoglossal triangle (elev. by hypoglossal nucleus)
-vagal triangle (elev by…)
(in upper part):
-facial colliculus overlies abducent n. nucleus and facial n. fibers
-vestibular area og acoustic tubercle placed in lateral recess
interal structure oblongata og pons
under floor of 4th ventricle the oblongata og pons contain cranial nerves nuclei
(efferent motor nuclei and afferent sensory nuclei)
motor nuclei
*Motor nuclei (nuclei of somatic efferents cell column)
1) hypoglossal nucleus: in oblongata
2) abducent nucleus: in pontine part
*Motor nuclei (nuclei of branchiomotor cell column, supply voluntary muscles dev. from branchial arches)
1) nucleus ambiguus: in oblongata, laterally from hypoglossal nucleus. Is a motor nucleus of n. IX, X og XI
2) facial n nucleus: in pons
3) trigeminal (masticatory) nucleus: in pons
*parasymp. nuclei (nuclei of parasymp. cell column)
1) dorsal nucleus of vagus n: in oblongata
2) inf. salivary nucleus: ncl of glossopharyngeal n, in oblongata
3) sup. salivary nucleus: ncl of facial n, in pons
4) lacrimal nucleus: ncl of facial n, in pons
sensory nuclei
placed laterally from motor nuclei
1) nucleus solitarius (gustatory nucleus):
in oblongata + pons
-fær visceral afferents (incl taste fibers)
-visceral sensory afferents from IX og
gray matter in oblongata+pons also með
1) gracile og cuneate nuclei, sem fá n fibers from s.cord (gracile og cuneate fasiculi)
-axons from gracile and cuneate cells cross median plane as lemniscal decussation
-asc upwards to form medial lemniscus, terminates in thalamus
2) olivary nucleus:
folded mass of grey matter, open medially as hilum
Receives afferent from:
-c. cortex
-red nucleus
-s. cord
Sends efferents to:
cerebellum (inv. in olivocerebellar tract)
inv in control of movement
Accessory olivary nuclei:
placed near hilum of inferior olivary nucleus
3) pontine nuclei:
scattered in ventral p pons among the corticospinal tract fibers
-constitute important conn. milli c cortex og cerebellum
-fá corticopontine fibers
-senda pontocerebellar fibers
inv. in coordination of movements
4) reticular formation:
represented by numerous n cells located near midline
-receives og sends fibers from all parts of cns
white substance oblongata og pons
úr asc og desc tracts.
ASCENDING TRACTS:
1) spinothalamic tract (spinal lemniscus)
2) spinotectal tract
3) spinoolivary tract
4) spinoreticular tract
5) spinocerebellar tract
6) medial lemniscus (starts in gracile + cuneate nuclei)
7) trigeminal lemniscus (trigeminothalamic tract)
8) solitariothalamic tract (begins in ncl of tractus solitarius) -gustatory pathway viscerosensory
9) lateral lemniscus (starts in cochlear ncl, auditory pathway)
white substance oblongata og pons
DESCENDING TRACTS:
1) corticospinal tract
2) corticonuclear tract (terminate on motor nuclei of cranial nerves)
3) tectospinal tract
4) rubrospinal tract
5) reticulospinal tract
6) vestibulospinal tract
7) median longitudinal fasicle (m asc og desc fibers conn. some nuclei of cranial nerves, upper cervical segments and midbrain)
