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What are found in the tectum of the midbrain?

Superior colliculus
Inferior colliculus
Periaqueductal gray

What nuclei are found in the tegmentum of the midbrain?

CN III: Motor & Edinger-Westphal
CN IV
Mesencephalic Nuc. and Tract of CN V

What other structures are found in the midbrain?

Substantia nigra (dopamine producer)
Red nucleus (origin of rubrospinal tract)
Cerebral peduncle
Superior cerebellar peduncle
Anterolateral system
Lateral lemniscus (auditory fibers)
Medial lemniscus
MLF

What nucleus is tagged?

Edinger-Westphal

Edinger-Westphal

What nucleus is tagged?

Oculomotor nucleus

What nucleus is tagged?

Trochlear nucleus

Trochlear nucleus

What nucleus is tagged?

Mesencephalic nucleus of CN V

Mesencephalic nucleus of CN V

Where are the inferior colliculi and superior colliculi in the following midbrain sections?

...

Inferior colliculi (green)
Superior colliculi (red)

Observe the medial lemniscus "kicking out" dorsolaterally in the following midbrain sections.

What tract is seen adjacent to the medial lemniscus?

Anterolateral system.

What tract is seen dorsally to the anterolateral system, contacting the inferior colliculi?

Lateral lemniscus

Lateral lemniscus

What structure is tagged?

Brachium of the inferior colliculus

Brachium of the inferior colliculus
Connects the inferior colliculus to the medial geniculate body (part of the thalamus)

Where are the cerebellar peduncles in the following midbrain sections?

What is tagged? What comes through here?

Interpeduncular fossa. CN III.

Interpeduncular fossa. CN III.

What is tagged here, dorsal to the cerebral peduncle?

Substantia Nigra

Substantia Nigra
(a center for dopamine)

Observe the "owl" in the following image of midbrain.

What is tagged? (The "body" of the owl)

Decussation of the superior cerebellar peduncle.

Decussation of the superior cerebellar peduncle.

What is tagged? (The "eyes" of the owl)

Trochlear nucleus

Trochlear nucleus

Trochlear nucleus

What is tagged? (The "beak" of the owl)

MLF

MLF
(Ventral to the trochlear nucleus and dorsal to the decussation of the superior cerebellar peduncle)

What is tagged? (The "ears" of the owl)

Central tegmental tract
(tagged in black)

Where is the oculomotor nucleus in the following section (slightly more rostral in the midbrain)?

...

Oculomotor nucleus
(Edinger-Westphal is just dorsal to this, hard to distinguish)

What is tagged in this rostral midbrain section?

Red nucleus

Red nucleus

What is the function of the periaqueductal gray?

Pain system

Where on the neuraxis is this section?

Junction between the midbrain and the diencephalon

Junction between the midbrain and the diencephalon

What structure is tagged?

Red Nuclei

Red Nuclei
Origin of the rubrospinal tract

What is tagged?

Pineal gland

Pineal gland
(calcifications are visible)

What is tagged?

Superior colliculi

What is tagged?

Pretectal nuclei on either side of the posterior commissure

Pretectal nuclei on either side of the posterior commissure
(light reflexes)

What would be affected by a pineal tumor?

Superior colliculi
Causes Parinaud's Syndrome

What is the blood supply of the midbrain?

Posterior cerebral artery

Describe Parinaud's Syndrome

-A lesion of the superior colliculi
-Paralysis of upward gaze
-Can be caused by pineal tumor

Describe the effects of the following midbrain lesion.

Weber's Syndrome

LCST + CN III (fibers)
-Contra. body hemiparesis
-Ipsil. oculomotor palsy

LCST + CN III (fibers)
-Contra. body hemiparesis
-Ipsil. oculomotor palsy

Describe the effects of the following midbrain lesion.

Benedikt's Syndrome

CN III and Red Nucleus
-Contra. upper extremity tremor, chorea, athetosis
-Ipsil. ocular paresis.

CN III and Red Nucleus
-Contra. upper extremity tremor, chorea, athetosis
-Ipsil. ocular paresis.

What is tagged?

Substantia nigra

Substantia nigra
Site of dopaminergic neurons

What is tagged?

Locus ceruleus

Locus ceruleus
Source of norepinephrine

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