- Brainstem—Part One 151
Cortico-
nuclear
tractCortico-
spinal
tract
Fronto-
pontine
tractAddl.
cortico-
pontine
tracts(Crus
cerebri)Substantia
nigraRed
nucleus
(mid-/upper
midbrain)Periaqueductal
grayCerebral
aqueductSuperior cerebellar peduncle
fiber decussation
(lower midbrain)NUCLEI TRACTSPosterior
Left
AnteriorRight(Red
nucleus)LL = Lateral lemniscus
ALS = Antero-
lateral system
Medial
lemniscusAT = Ant. trigemino-
thalamic tractATLL
ALSTegmentumBasisTectumDRAWING 9-2 Th e Midbrain — Partial