The Brain

Key questions

1. Q1Where does the brain sit in the nervous system?

   The brain plus the spinal cord make up the central nervous system (CNS); everything else is the peripheral nervous system (PNS).
2. Q2Name the meninges from outside in, with one fact about each.

   Dura mater: two thick layers with four infoldings (e.g., falx cerebri) that hold the venous sinuses. Arachnoid mater: web-like, cushions the brain; below it is the subarachnoid space with CSF. Pia mater: delicate, stuck to the brain surface.
3. Q3Which space contains CSF?

   The subarachnoid space, between the arachnoid and the pia.
4. Q4Which adult structures come from each embryonic division?

   Prosencephalon → telencephalon (cerebrum) + diencephalon. Mesencephalon → midbrain. Rhombencephalon → metencephalon (pons + cerebellum) + myelencephalon (medulla).
5. Q5Name the three section planes and the landmark to use.

   Coronal, sagittal and horizontal (axial). Use the corpus callosum as your landmark.
6. Q6What does white matter do, and how is it imaged?

   It is made of axon tracts connecting gray matter structures throughout the nervous system. Diffusion tensor imaging (DTI) shows tracts (but not their direction).

Key questions

1. Q7What makes up the telencephalon?

   Two hemispheres. Gray matter: cerebral cortex (frontal, parietal, temporal, occipital lobes; includes the hippocampus in the temporal lobe) and subcortical nuclei (amygdala, basal ganglia such as the caudate). White matter: tracts (internal capsule) and commissures (corpus callosum).
2. Q8What does the telencephalon do?

   Cognitive and affective functions (language, memory, thought, emotion), sensory functions (vision, hearing, taste, smell, touch, pain) and motor functions.
3. Q9Name the four parts of the diencephalon and their main functions.

   Thalamus: relay and gatekeeper to the cortex (sensory, motor, cognitive, limbic). Hypothalamus (+ pituitary): feeding, feelings, fever, mating, sleep. Subthalamus: subthalamic nucleus, functionally part of the basal ganglia. Epithalamus: habenula (diverse behaviors) + pineal gland (circadian rhythms).
4. Q10Tectum vs tegmentum of the midbrain?

   Tectum (roof): inferior colliculus (hearing) and superior colliculus (vision). Tegmentum: nuclei including reticular formation, red nucleus, PAG, raphe, VTA and substantia nigra.
5. Q11Give the function of each midbrain tegmental nucleus in lecture.

   Reticular formation: motor and cardiovascular control, pain modulation, sleep and consciousness. Red nucleus: motor coordination, gait. PAG: autonomic function, pain modulation. Raphe: thermoregulation. VTA: reward-based learning. Substantia nigra: motor, memory, language (works with the basal ganglia).
6. Q12What lives in the pons, and what does it do?

   Cranial nerve nuclei V–VIII and the locus coeruleus (main source of norepinephrine). Functions: breathing, equilibrium, hearing, taste, facial touch and pain, eye movement, facial expression, chewing, swallowing, saliva and tears.
7. Q13What lives in the medulla, and why is it vital?

   Cranial nerve nuclei IX, X, XI and the arcuate nucleus (breathing rate). It runs autonomic functions: breathing, heart rate, blood pressure, swallowing, vomiting, sneezing, coughing, sleep cycle.
8. Q14Describe the cerebellum's anatomy.

   Two hemispheres, each with anterior, posterior and flocculonodular lobes; the midline vermis; cerebellar cortex; four deep nuclei — fastigial, globose, emboliform, dentate ("Fat Guys Eat Donuts").
9. Q15Is the cerebellum only a motor structure?

   No. The lecture's function map shows many functions beyond motor, including cognitive ones.

Key questions

1. Q16Broca's aphasia: what is damaged, and what are the deficits?

   Broca's area (inferior frontal gyrus) and surrounding tissue. Speech and language impairments, plus memory, executive and motor impairments.
2. Q17Huntington disease: what degenerates, and what are the deficits?

   The basal ganglia (caudate nucleus) and other structures. Motor dysfunction (chorea) plus memory, executive and language problems.
3. Q18Pituitary adenoma: how common, and what does it cause?

   About 17% prevalence; benign or malignant. Compressing the optic chiasm → bitemporal hemianopsia; excess ACTH → Cushing syndrome (too much cortisol from the adrenals).
4. Q19Parkinson disease: who, what degenerates, and what are the symptoms?

   1% of people over 60, 4% over 80. Starts with loss of dopaminergic neurons in the substantia nigra pars compacta. Motor (tremor, hypokinesia), cognitive (memory, executive, language), mood, sensory (especially smell) and sleep problems.
5. Q20What is the hallmark of a pontine stroke?

   Various deficits from the pontine nuclei and tracts — including weakness on both sides of the body.
6. Q21Medulloblastoma: who, where, symptoms and outcome?

   A common primary malignant brain tumor in children (14.5% of new pediatric brain tumors), in the cerebellum. Walking, balance, motor and cognitive problems; if it blocks the 4th ventricle → hydrocephalus (headache, vomiting, sleepiness). Surgery + chemo; ~70% 5-year survival.

Key questions

1. Q22What are the four principles of brain dysfunction?

   1) Damage to different structures often impacts different functions. 2) Which structure or pathway is damaged matters more than what causes the damage. 3) Damage to a given structure often affects more than one function. 4) Damage to distinct structures can impact the same function (networks).
2. Q23A stroke and a tumor in Broca's area cause the same deficits. Which principle?

   Principle 2: which structure is damaged matters more than the cause.
3. Q24Huntington damages the caudate and causes chorea, memory, executive and language problems. Which principle?

   Principle 3: damage to one structure affects more than one function.
4. Q25A white matter lesion and a cortical lesion cause the same language deficit. Which principle?

   Principle 4: networks — distinct structures (gray matter regions and the tracts connecting them) support the same function.
5. Q26What is a brain network?

   Different brain structures working together to support a function, including gray matter regions and the white matter tracts that link them — spanning the brain and even the whole nervous system.