CNS pt 2

Dura matter

thickest layer, means tough mother, highly vascularized and innervated

Arachnoid matter

thin, intermediate layer

pia matter

adhered to surface of brain and sc

CSf

produced by chroid plexus, surrounds brain and sprinal chord

choroid plexus

ventricles

spaces within brain, usually filled with csf, has choroid plexus producing csf

subarachnoid space

between arachnoid and pia matter of brain and spinal cord. filled with csf.

csf drains to

venous system, processed

Where is gray matter located in the brain?

Gray matter is located superficially in the cerebral cortex and in deep brain nuclei such as the basal ganglia and thalamus

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Where is white matter located in the brain?

White matter lies beneath the cerebral cortex, between superficial gray matter and deep gray matter regions, and contains myelinated axons

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What is the function of gray matter?

Contains neuron cell bodies and is involved in processing and integrating information

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What is the function of white matter?

Transmits signals between different brain regions via axonal pathways

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What is the role of the medulla in autonomic control?

Regulates respiration, cardiovascular activity (cardioinhibitory & vasomotor centers), and reflexes for vomiting, coughing, sneezing, and swallowing

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What higher and lower CNS regions does the medulla connect?

It connects the spinal cord to higher brain centers, and all ascending and descending tracts pass through it

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What is the nucleus gracilis responsible for?

Relays fine touch and proprioception from the lower limb

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What is the nucleus cuneatus responsible for?

Relays fine touch and proprioception from the upper limb

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What is the dorsal vagal motor nucleus?

Contains preganglionic parasympathetic neurons whose axons travel in the vagus nerve (CN X) to supply thoracic and abdominal viscera

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What does the pyramidal tract in the medulla do?

Contains descending motor fibers from the cerebral cortex; most cross to the opposite side at the pyramidal decussation

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What does the lateral spinothalamic tract carry?

Pain and temperature sensations from the body

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What does the medial lemniscus carry?

Fine touch and proprioceptive sensations from the body

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What autonomic functions does the pons control?

Sleep, arousal, respiration, and bladder control via the micturition center

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How does the pons act as a relay center?

Connects the cerebrum to the cerebellum and integrates sensory input

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Which fiber tracts are present in the pons?

Pyramidal tract, medial lemniscus, and lateral spinothalamic tract

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Are pons fiber tracts continuations from the medulla?

Yes — they are direct continuations of medullary tracts

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What sensory systems are processed in the midbrain?

Vision and hearing

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What other roles does the midbrain have?

Motor control, sleep, arousal, alertness, and temperature regulation

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What are the major fiber tracts in the midbrain?

Pyramidal tract, medial lemniscus, lateral spinothalamic tract

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Are midbrain tracts continuations from the pons and medulla?

Yes — they continue through the brainstem to the cerebrum

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Where is the reticular formation located?

Scattered nuclei throughout the brainstem

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What is its role in consciousness?

Maintains arousal and alertness

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What is its role in sensory processing?

Filters repetitive, non-meaningful stimuli while allowing focus on important stimuli

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What other body functions does it regulate?

Pain modulation, cardiovascular control, posture, and balance

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10. Cerebellum

What is the cerebellum's primary motor role?

Coordinates movement for smooth execution

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How does the cerebellum control movement selection?

Selectively activates desired movements and suppresses unwanted ones

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What does the cerebellum regulate in movement?

Rate, force, and synergy of movement

Where are the basal ganglia located?

Deep within the white matter of the cerebral hemispheres

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What structures make up the basal ganglia?

Caudate nucleus, putamen, globus pallidus

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What is their function in motor control?

Facilitate voluntary movement and prevent unwanted movement

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12. White Matter Connections

What separates the cerebral hemispheres?

Longitudinal sulcus

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What connects the two hemispheres?

Corpus callosum

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What connects the cerebrum to the brainstem?

Internal capsule

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Frontal lobe functions?

Problem-solving, planning, voluntary movement, personality, concentration, and social interaction

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Parietal lobe functions?

Sensory perception, spatial awareness, speech comprehension

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Temporal lobe functions?

Hearing, memory, language recognition, emotion

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Occipital lobe function?

Visual processing

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Insular lobe functions?

Taste, smell, vestibular integration, pain perception, autonomic control

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Location of precentral gyrus?

Posterior frontal lobe, anterior to central sulcus

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Function of precentral gyrus?

Primary motor cortex — controls contralateral voluntary movements

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What is somatotopic organization?

Mapping of body regions onto specific cortical areas (motor homunculus)

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How is the motor homunculus arranged?

Inferolateral = head, superolateral = upper limb, medial = lower limb

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Location of postcentral gyrus?

Parietal lobe, posterior to central sulcus

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Function of postcentral gyrus?

Primary somatosensory cortex receiving contralateral touch, pain, and temperature

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Sensory homunculus arrangement?

Same as motor — head (inferolateral), upper limb (superolateral), lower limb (medial)

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16. Broca's & Wernicke's Areas

Broca's area location?

Inferior frontal gyrus of left hemisphere

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Broca's function?

Motor speech planning

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Broca's lesion symptoms?

Non-fluent speech, word-finding difficulty, intact comprehension

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Wernicke's area location?

Postero-inferior parietal lobe & superior temporal lobe

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Wernicke's function?

Comprehension of spoken language

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Wernicke's lesion symptoms?

Fluent but nonsensical speech, poor comprehension

Function of VL & VA nuclei?

Motor function control

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Function of VPL nucleus?

Relays somatosensory info from body to cortex

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Function of VPM nucleus?

Relays somatosensory info from head to cortex

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Function of medial geniculate nucleus?

Auditory processing

Function of lateral geniculate nucleus?

Visual processing

Main hypothalamus function?

Maintains homeostasis and regulates hormones

Hypothalamus connections?

Endocrine system (pituitary), autonomic nervous system, reticular formation

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Limbic system structures?

Hypothalamus, thalamic nuclei, hippocampus, amygdala, cingulate gyrus, insula, nucleus accumbens

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Limbic system functions ?

Homeostasis, Olfaction, Memory, Emotion & drives

Which fiber tracts are found in the medulla?

Pyramidal tract (motor, decussates at pyramids)

Lateral spinothalamic tract (pain & temperature)

Medial lemniscus (fine touch & proprioception)

Which fiber tracts are found in the pons?

Pyramidal tract

Lateral spinothalamic tract

Medial lemniscus

(continuations from medulla)

Which fiber tracts are found in the midbrain?

Pyramidal tract

Lateral spinothalamic tract

Medial lemniscus

(continuations from pons & medulla)

Which nuclei are located in the medulla?

Nucleus gracilis (fine touch lower limb)

Nucleus cuneatus (fine touch upper limb)

Which major nuclei are associated with the thalamus?

Ventral lateral (VL) nucleus — motor control

Ventral anterior (VA) nucleus — motor control

Ventral posterior lateral (VPL) nucleus — body somatosensory relay

Ventral posterior medial (VPM) nucleus — head somatosensory relay

Medial geniculate nucleus — auditory relay

Lateral geniculate nucleus — visual relay

Which brain regions contain pyramidal tract fibers?

Medulla, Pons, Midbrain

Which brain regions contain medial lemniscus fibers?

Medulla, Pons, Midbrain

Which brain regions contain lateral spinothalamic tract fibers?

Medulla, Pons, Midbrain

Which regions are part of the brainstem?

Medulla, Pons, Midbrain

Which regions are part of the diencephalon?

Thalamus, Hypothalamus

Which lobes contain language-related areas?

Frontal lobe — Broca's area (motor speech)

Which regions make up the limbic system?

Hypothalamus, some thalamic nuclei, hippocampus, amygdala, nucleus accumbens, cingulate gyrus, insula