part 1 brainstem

• It is stalk like in shape and connects the narrow spinal cord with the expanded forebrain

• Made up of the medulla oblongata, the pons, and the midbrain and occupies the posterior cranial fossa of the skull •

Three broad functions:

1. It serves as conduit for the ascending tracts and descending tracts

2. It contains important reflex centers associated with the control of respiration and the cardiovascular system and with the control of consciousness

3. It contains the important nuclei of cranial nerves III through XII.

Brainstem

olives are two small oval lumps posterolateral to the pyramids produced by the underlying _______

inferior olivary nuclei

• It is stalk like in shape and connects the narrow spinal cord with the expanded forebrain

Brainstem

• Made up of the medulla oblongata, the pons, and the midbrain and occupies the posterior cranial fossa of the skull •

Brainstem

The brainstem is divided longitudinally into two sections: the ______ and the ______

basilar section; tegmentum

is located anteriorly and contains predominantly motor system structures

o Descending axons from the cerebral cortex: corticospinal, corticobrainstem, corticopontine, and corticoreticular tracts

o Motor nuclei: substantia nigra, pontine nuclei, and inferior olive

o Pontocerebellar axons

• Basilar section

• Basilar section is located ______ and contains predominantly ______ system structures

anteriorly; motor

basilar section: descending axons from the cerebral cortex include the?

corticospinal, corticobrainstem, corticopontine, and corticoreticular tracts

basilar section: motor nuclei include the?

substantia nigra, pontine nuclei, and inferior olive

is located anteriorly and contains predominantly motor system structures

Basilar section

The ______, located posteriorly, includes the following:

o The reticular formation, which adjusts the general level of activity throughout the nervous system

o Sensory nuclei and ascending sensory tracts

o Cranial nerve nuclei

o The medial longitudinal fasciculus, a tract that coordinates eye and head movements

tegmentum

The ______, which adjusts the general level of activity throughout the nervous system

reticular formation

a tract that coordinates eye and head movements

o The medial longitudinal fasciculus,

The ______ has a longitudinal section, posterior to the tegmentum, called the tectum. The tectum includes the structures:

• Pretectal area

• Superior and inferior colliculi

midbrain

The midbrain has a longitudinal section, posterior to the tegmentum, called the ______. This structure includes the structures:

• Pretectal area

• Superior and inferior colliculi

tectum

• is a functional unit that spans all three divisions of the brainstem.

• Complex neural network that includes the reticular nuclei, their connections, and ascending and descending reticular pathways

• Integrates sensory and cortical information

• Regulates somatic motor activity, autonomic function, and consciousness

• Modulates nociceptive/pain information

reticular formation

• is a functional unit that spans all three divisions of the brainstem.

reticular formation

• Complex neural network that includes the reticular nuclei, their connections, and ascending and descending reticular pathways

reticular formation

• Integrates sensory and cortical information

reticular formation

• Regulates somatic motor activity, autonomic function, and consciousness

reticular formation

______ regulate neural activity throughout the central nervous system

__________ all slow acting or neuromodulating, although the same transmitter may be fast acting in other neural subsystems.

Reticular nuclei regulate neural activity throughout the central nervous system

The transmitters released by the reticular nuclei are all slow acting or neuromodulating, although the same transmitter may be fast acting in other neural subsystems.

______ regulate neural activity throughout the central nervous system

reticular nuclei

__________ all slow acting or neuromodulating, although the same transmitter may be fast acting in other neural subsystems.

transmitters released by the reticular nuclei

the major reticular nuclei are:

o Ventral tegmental area (Dopamine)

o Pedunculopontine nucleus (Acetylcholine)

o Raphe nuclei (Serotonin)

o Locus coeruleus and the Medial reticular area (Norepinephrine)

among the major reticular nuclei, which produces dopamine?

ventral tegmental area

among the major reticular nuclei, which produces norepinephrine

o Locus coeruleus and the Medial reticular area

among the major reticular nuclei, which produces serotonin

raphe nuclei

among the major reticular nuclei, which produces dopamine

ventral tegmental area

what does ventral tegmental produce

dopamine

what does peduculopontine nucleus produce

acetylcholine

what does raphe nuclei produce

serotonin

what do locus coeruleus and medial reticular area produce

norepinephrine

whats does ARAS stand for

Ascending Reticular Activating System

• Regulation of consciousness

• Consciousness system governs alertness, sleep, and attention

• Axons of _____ project to components of the consciousness system: basal forebrain, thalamus, and cerebral cortex

• Sleep: a periodic loss of consciousness, is actively induced by activity of areas within the ____

ARAS (Ascending Reticular Activating System)

Axons of ARAS project to components of the consciousness system:

basal forebrain, thalamus, and cerebral cortex

this is a periodic loss of consciousness, is actively induced by activity of areas within the ARAS

Sleep:

• Lowermost part of the brainstem

• Connects the pons superiorly with the spinal cord inferiorly

Medulla Oblongata

• Lowermost part of the brainstem

Medulla Oblongata

• Connects the pons superiorly with the spinal cord inferiorly

Medulla Oblongata

Medulla oblongata connects the _______ superiorly with the _______ inferiorly

Medulla oblongata connects the pons superiorly with the spinal cord inferiorly

o major part of MO; two vertical bulges anteriorly

o Formed by the descending axons of corticospinal tract and some corticonuclear (corticobrainstem) fibers

o About 80% (80-90%) of LCST cross the pyramidal decussation

o Most impressive fibers in the pyramidal tract originate from giant pyramidal cells found in primary motor cortex called Betz cells. It has also the most rapid rate of transmission from brain to spinal cord

Pyramids:

o major part of MO; two vertical bulges anteriorly

Pyramids:

o Formed by the descending axons of corticospinal tract and some corticonuclear (corticobrainstem) fibers

Pyramids:

o About 80% (80-90%) of LCST cross the pyramidal decussation

Pyramids:

o Most impressive fibers in the pyramidal tract originate from giant pyramidal cells found in primary motor cortex called Betz cells. It has also the most rapid rate of transmission from brain to spinal cord

Pyramids:

Most impressive fibers in the pyramidal tract originate from giant pyramidal cells found in primary motor cortex called ______. It has also the most rapid rate of transmission from brain to spinal cord

Betz cells

two small oval lumps posterolateral to the pyramids produced by the underlying inferior olivary nuclei

o CN 12 connects to medulla in between pyramids and olives

o CN 9, 10, 11 are connected lateral to the olives

• Olives:

two small oval lumps posterolateral to the pyramids produced by the underlying inferior olivary nuclei

olives

Olives:

o CN 12 connects to ______ in between ______ and ______

o CN 9, 10, 11 are connected ______ to the ______

medulla; pyramids; olives

lateral; olives

What are the prominent features on posterior medulla?

inferior cerebellar peduncle (aka restiform body)

4th ventricle

• Contains the connections between cerebrum and spinal cord at the central canal:

• Corticospinal tracts (Anterior)

• Spinothalamic tracts (Anterolateral)

• Dorsal column: nucleus gracilis and cuneatus (Posterior) § After midline decussation → Medial lemniscus (posterior to the pyramids)

• Contains cranial nerve structures

• Spinal trigeminal nucleus: pain and temp on face

• Medial longitudinal fasciculus (MLF): coordination of eye and head movement via connections between vestibular nuclei, spinal accessory nucleus, and the nuclei that control eye movements (3,4,6

Lower Medulla

enumerate the connections between cerebrum and spinal cord at the central canal. include their laterality

• Corticospinal tracts (Anterior)

• Spinothalamic tracts (Anterolateral)

• Dorsal column: nucleus gracilis and cuneatus (Posterior) § After midline decussation → Medial lemniscus (posterior to the pyramids)

What do you call nucleus gracilis and cuneatus after decussating in the midline

Medial lemniscus

enumerate the cranial nerve structures that the lower medulla contains

• Spinal trigeminal nucleus: pain and temp on face

• Medial longitudinal fasciculus (MLF): coordination of eye and head movement via connections between vestibular nuclei, spinal accessory nucleus, and the nuclei that control eye movements (3,4,6

pain and temp on face

• Spinal trigeminal nucleus:

coordination of eye and head movement via connections between vestibular nuclei, spinal accessory nucleus, and the nuclei that control eye movements (3,4,6

Medial longitudinal fasciculus (MLF):

What is the upper part of medulla

Fourth ventricle

enumerate the cranial nerve nuclei in dorsal section (Medial to Lateral)

o Hypoglossal nucleus (CN 12)

o Dorsal motor nucleus (PSP of CN 10)

o Solitary nucleus (Visceral afferents/taste from CN 7, 9, 10)

o Vestibular nuclei (CN 8)

located more anteriorly and contributes motor fibers to striated muscles in the pharynx, larynx, and upper esophagus via CN 9 and 10.

• Nucleus ambiguus:

Between medulla and pons:

o Cochlear and Vestibular nuclei (CN 8)

shaped like a wrinkled paper bag, this nucleus receives input from most motor areas of the brain and spinal cord

Inferior olivary nucleus:

Axons from the __________ project to the contralateral cerebellar hemisphere via the olivocerebellar tract

inferior olivary nucleus

Axons from the inferior olivary nucleus project to the contralateral cerebellar hemisphere via the ___________

olivocerebellar tract

The medulla sends many fibers (spinocerebellar, olivocerebellar, vestibulocerebellar, and reticulocerebellar) to the cerebellum via the ________

inferior cerebellar peduncle

Located between the midbrain and the medulla

Only the corticopontine tracts and some corticobrainstem tracts synapse in the here

pons

Pons is located between ______ and _____

midbrain and medulla

In pons, only the __________ and some ________ tracts can synapse

corticopontine tracts; corticobrainstem

synapse on pontine nuclei leave the pons to enter the cerebellum via the middle cerebellar peduncle (aka. brachium pontis)

Corticopontine tracts:

synapse with neurons in the trigeminal motor nucleus and the facial nucleus

Corticobrainstem tracts:

The cranial nerves located in pons involved the following:

o Processing sensation from the face (CN 5)

o Controlling lateral movement of the eye (CN 6)

o Facial and chewing muscles (CN 5 and 7, respectively

Internal structure of pons include:

Motor nucleus of the trigeminal nerve (CN5)

. Main/Chief sensory nucleus of the trigeminal nerve

An internal structure of pons that is situated beneath the lateral part of the fourth ventricle within the reticular formation

Motor nucleus of the trigeminal nerve (CN5)

An internal structure of pons that is situated on the lateral side of the motor nucleus. It is also continuous inferiorly with the nucleus of the spinal tract.

Main/Chief sensory nucleus of the trigeminal nerve

The ______ initiates rapid eye movement (REM) sleep and help control respiratory movements.

The _____ processes motor information from the cerebral cortex and forwards the information to the cerebellum

pons

The ______ initiates rapid eye movement (REM) sleep and help control respiratory movements.

pons

The _____ processes motor information from the cerebral cortex and forwards the information to the cerebellum

pons

The uppermost part of the brainstem, connects the diencephalon and the pons.

midbrain

The midbrain is the uppermost part of the brainstem, the midbrain, connects the ______ and the _____.

diencephalon; pons

major structure; a small canal through the midbrain, joins the third and fourth ventricles. It is filled with cerebrospinal fluid

Cerebral aqueduct:

Midbrain comprises of 2 lateral halves called the?

cerebral peduncles

The midbrain has cerebral peduncles, the anterior cerebral peduncle and posterior cerebral peduncle. Name them.

Anterior cerebral peduncle: Crus cerebri

Posterior cerebral peduncle: Tegmentum

The midbrain can be divided into 3 regions, from anterior to posterior. These are:

basis pedunculi

tegmentum

tectum

contains important descending tracts: corticospinal, corticonuclear, and corticopontine tracts

Crus cerebri

Serves as a visual reflex center