1. CNS 2 Brain Anatomy

What is the basic organisation of neuronal cells?

• Cell body (soma): Large structure with central nucleus

• Dendrites: Receive inputs from other neurones

• Axons: Transmit impulses away from the cell body

• Axon terminals: Form synapses with other neurones

What are the main types of glial cells & their functions?

• Astrocytes: Regulate the chemical environment of nerve cells

• Oligodendrocytes: Form myelin sheaths around axons to ↑ impulse efficiency

• Microglia: Primary immune cells of the CNS

What are the main components involved in brain protection?

• Skull: Supports facial structures & protects the brain

• Meninges: 3 layers – dura mater, arachnoid mater, pia mater

• Cerebrospinal fluid (CSF):

  • Made by choroid plexuses (capillaries + ependymal cells)

  • Formed via plasma filtration

  • Used to diagnose meningitis, bleeds, multiple sclerosis

• Blood-brain barrier (BBB):

  • Tight junctions between brain capillary endothelial cells

  • Highly selective transport mechanisms

What are the key anatomical terms for the PNS & CNS?

• PNS:

  • Ganglia: Neuronal cell bodies in PNS

  • Nerves: Axons in periphery

• CNS:

  • Brain & spinal cord

  • Nuclei: Neuronal cell bodies in CNS

  • Tracts: Axons in CNS

What do rostral, caudal, dorsal & ventral mean in brain anatomy?

• Rostral: Front

• Caudal: Back

• Dorsal: Top

• Ventral: Bottom

What are the main parts of the brain?

• Brainstem: Midbrain, Pons, Medulla oblongata

• Cerebellum

• Diencephalon: Thalamus, Hypothalamus

• Cerebrum: Two cerebral hemispheres

What are the functions of the medulla oblongata?

• Controls autonomic functions: respiration, heart rate, BP, digestion

• Controls movements via pyramidal tracts

• Relays somatic sensory info to cortex & cerebellum

• Regulates arousal & sleep

What are the functions of the medulla oblongata?

• Controls autonomic functions: respiration, heart rate, BP, digestion

• Controls movements via pyramidal tracts

• Relays somatic sensory info to cortex & cerebellum

• Regulates arousal & sleep

What are the functions of the pons?

• Connects the cerebellum & cerebrum

• Origin of cranial nerves, including Trigeminal (feeling in face, chewing, swallowing) & Facial (facial expressions)

• Regulates breathing depth & frequency

• Modulates brain activity through slow neurotransmitter systems

What are the functions of the midbrain?

• Involved in vision, hearing, motor control, sleep/wake, arousal & temperature regulation

• Contains dopaminergic nuclei (Substantia Nigra, Ventral Tegmental Area) that supply dopamine to the brain, regulating motor pathways & motivation

What are the functions of the cerebellum?

• Regulates motor control, coordination, timing & motor learning

• Involved in attention, language, fear & pleasure

• Receives input from spinal cord & other brain areas

• Loss of function causes coordination issues, dizziness, impaired speech

• Linked to cognitive disorders like autism, schizophrenia & dyslexia

What are the components of the diencephalon?

• Thalamus

• Hypothalamus

• Epithalamus (Pineal gland)

• Subthalamus (Subthalamic nucleus)

What are the functions and features of the thalamus?

• Relays sensory signals (except olfactory) to cortex

• Regulates sleep, wakefulness & consciousness

• Composed of two lobes

• Damage = coma, sensory/movement issues, sleepiness

• Linked to disorders like bipolar, ADHD, autism

What are the functions and features of the hypothalamus?

• Regulates temperature, hunger, thirst, & ANS

• Controls endocrine system via pituitary

• Manages emotions, behaviour, sleep-wake cycle

• Maintains metabolism & circadian rhythm

• Damage = hypothermia, lethargy, weight changes, stress

• Linked to depression, bipolar, schizophrenia, hormonal issues

What are the functions and features of the subthalamus?

• Small ventral anterior part of the diencephalon

• Main component is the subthalamic nucleus

• Connected to the basal ganglia region

What are the functions and features of the epithalamus?

• Small dorsal part of the diencephalon

• Contains the pineal gland, which produces melatonin at night to regulate sleep

Which neurological disorder is caused by the loss of neurones in the Substantia nigra?

Parkinson’s disease

What are the main components & functions of the basal ganglia?

• Includes striatum, globus pallidus, nucleus accumbens, subthalamic nucleus, substantia nigra

• Regulates motor function

• Needs dopamine from substantia nigra

• Nucleus accumbens = reward system

• Impairment = addiction, depression, schizophrenia

What are the roles of the basal ganglia & what happens when it's damaged?

• Controls voluntary movement, habits, eye movement, cognition, emotion

• Forms loops with cortex & thalamus for movement selection

• Damage = tremors, posture issues, difficulty starting movement

• Parkinson’s: ↓ dopamine = movement problems

• Huntington’s: striatum loss = uncontrolled movement

• Dyskinesia: often drug-induced

What are the functions of the hippocampus & what happens if it's damaged?

• In medial temporal lobe, part of limbic system

• Roles: memory consolidation, spatial navigation

• Damage = memory loss, disorientation

• Linked to Alzheimer’s, depression, bipolar, schizophrenia

What are the key components & functions of the cerebrum?

• Largest brain region

• Cerebral cortex (outer gray matter):

  • 2–4 mm thick

  • Neuronal cell bodies, dendrites, unmyelinated axons

• White matter: myelinated axons beneath the cortex

• Deep gray matter: includes basal ganglia

How are the cerebral hemispheres structured & divided?

• Divided into right & left by longitudinal fissure

• Central sulcus separates frontal & parietal lobes

What are the functions of the parietal lobe & its sensory areas?

• Posterior to central sulcus

• Detects, localizes & interprets sensory input

• Handles spatial attention & visual-spatial processing

• Damage = trouble recognizing or locating objects/body parts

What are the functions of the occipital & temporal lobes?

• Occipital lobe – processes vision

  • Damage → hallucinations, blindness, visual issues

• Temporal lobe – processes hearing & language

  • Damage → impaired language understanding, memory loss

What does fMRI show during speaking & hearing?

• Functional magnetic resonance imaging (fMRI)

• Measures brain activity via blood flow

• Cerebral cortex of person speaking & hearing

• Activity in frontal lobe (speaking)

• Activity in temporal lobe (hearing)

What are the main motor functions of the frontal lobe?

• Coordinates voluntary movement of skeletal muscles

• Coordinates planning of voluntary movement

• Specialized motor speech function

What are the functions of the prefrontal cortex?

• Cognition & learning

• Executive functioning

• Social skills & mood

• Mental flexibility & empathy

• Conscience & judgment

• Personality & impulse control

• Long-term planning

What is the role of cerebral white matter & its fiber types?

• Enables communication between:

  • Cortical areas

  • Cortex & brain stem/spinal cord

• Mostly myelinated axons in tracts:

  • Commissures – connect R & L hemispheres (e.g. corpus callosum)

  • Association fibers – connect parts of the same hemisphere

  • Projection fibers – run vertically to/from cerebral cortex