Midbrain

Question 1

Mention contents of tegmentum

Answer 1

Cranial nerve nuclei (III & IV), reticular formation, red nucleus, ascending & descending tracts

Question 2

Mention fibers of crus cerebri

Answer 2

1. Fronto-pontine fibers most medial
2. Corticospinal & corticonuclear middle
3. Tempro-,partieto-,occipito-pontine fibers most lateral

Question 3

Describe connections if inferior colliculi

Answer 3

Afferent: lateral leminiscus, opposite inferior colliculus, sup colliculus of same side, cortical auditory areas.
Efferent: medial geniculate body, opposite inferior colliculus, sup colliculus of same side.

Question 4

Maximum level of substantia nigra size is at….
Mention its parts with description

Answer 4

Superior colliculus
1. Pars compacta: melanin containing cells having high dopamine content

2. Pars reticularis: it is formed of large neurons.

Question 5

Describe layers if superior colliculus

Answer 5

1. Stratum zonale
2. Stratum cinereum
3. Stratum opticum
4. Stratum leminisci

Question 6

Describe connections of superior colliculus

Answer 6

Afferent: retino-, cortico-, spinal-tectal fibers. Inferior colliculus of same side, auditory relay nuclei, commissurak fibers from opposite side.
Efferent: tectospinal, tectopontine, tectoreticular

Question 7

Mention parts of oculomotor nucleus with function

Answer 7

Paired lateral cell columns & caudal central nucleus supply all extra-ocular muscles except (SO4LR6)
Edinger-Westphal nucleus: parasymp to ciliary muscle for accomodation & sphincter pupillae for lighet reflex

Question 8

Mention other brain stem nuclei connected to III nucleus

Answer 8

Abducent nucleus
Vestibular nuclei

Question 9

Describe structure of red nucleus

Answer 9

Two parts:
1. Caudal part: which is magnocellular (motor function)
2. Rostral part: parvicellular (motor learning)

Question 10

Describe the components of tegmental decussation

Answer 10

1. At superior level: dorsal & ventral tegmental decussations
2. At inferior level: decussation of SCP & Trochlear nerve

Question 11

Mention contents of SCP

Answer 11

Afferents: anterior spinocerebellar, tecto-cerebellar tracts
Efferents: fastigio-reticular, cerebello-rubral & dentato-thalamic or dentato-rubro-thalamic