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Central Nervous System - Anatomy & Physiology

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  • Main components of the central nervous system (CNS)

    The brain and spinal cord are the major components of the CNS, responsible for receiving information, integrating it, and directing responses.

  • Difference between gray matter and white matter

    Gray matter contains neuron cell bodies, dendrites, and unmyelinated processes for integration and processing. White matter consists mostly of myelinated axons for communication between regions.

  • Gray and white matter organization in the spinal cord

    Gray matter forms a central H-shaped region, surrounded by white matter on the outside.

  • Gray and white matter organization in the cerebrum and cerebellum

    Gray matter forms the outer cortex and deep nuclei, while white matter lies internally.

  • Definition of cortex, nucleus, and tract in the CNS

    Cortex: outer layer of gray matter; nucleus: deep cluster of neuron cell bodies; tract: bundle of axons within the CNS.

  • Brain stem divisions from superior to inferior

    Midbrain → pons → medulla oblongata.

  • Major functions of the medulla oblongata

    Regulates cardiac activity, vasomotor tone, respiratory rhythm, and reflexes like swallowing, coughing, sneezing, and hiccupping.

  • Role of pontine nuclei in the pons

    Relay information from the cerebral cortex to the cerebellum via the middle cerebellar peduncles.

  • Functions of the superior and inferior colliculi

    Superior colliculi mediate visual reflexes; inferior colliculi mediate auditory reflexes.

  • Significance of the substantia nigra

    Contains pigmented neurons linked to basal nuclei and voluntary movement; loss of dopamine here is associated with Parkinson disease.

  • Three-step process by which the cerebellum fine-tunes movement

    1. Receives motor plan from cerebral cortex.
    2. Compares plan with current body position.
    3. Sends corrective feedback to adjust motor commands.

  • Main parts of the diencephalon

    Thalamus, hypothalamus, and epithalamus surround the third ventricle.

  • Function of the thalamus

    Acts as a relay gateway for sensory and other signals traveling to the cerebral cortex.

  • Six key functions of the hypothalamus

    Autonomic control, emotional responses, thermoregulation, hunger/thirst, behavior, sleep–wake cycle, endocrine regulation, and memory involvement.

  • Hormone secreted by the pineal gland and its role

    Melatonin is secreted and helps regulate the circadian rhythm.

  • Difference between fissure, sulcus, and gyrus

    Fissure: deep groove; sulcus: shallow groove; gyrus: raised ridge between sulci.

  • Location of the insula lobe

    Hidden deep within the lateral sulcus of the cerebrum.

  • Types of cerebral white-matter fibers and their connections

    Commissural fibers connect hemispheres; association fibers connect areas within one hemisphere; projection fibers connect cortex with lower CNS regions.

  • Typical adult spinal cord length and end point

    Extends from the foramen magnum to approximately the L1–L2 vertebral level.

  • Definitions of conus medullaris, filum terminale, and cauda equina

    Conus medullaris: tapered end of spinal cord.
    Filum terminale: connective tissue anchor to coccyx.
    Cauda equina: bundle of spinal nerve roots below conus.

  • Functions of ascending and descending spinal pathways

    Ascending pathways carry sensory information to the brain.
    Descending pathways carry motor commands from brain to spinal cord.

  • Order of meninges from superficial to deep

    Dura mater → arachnoid mater → subarachnoid space (with CSF) → pia mater.

  • Where and how is cerebrospinal fluid (CSF) produced?

    Produced by choroid plexuses in all four brain ventricles via filtration from blood.

  • Four main functions of cerebrospinal fluid (CSF)

    Provides buoyancy and cushioning, nourishes CNS tissue, removes waste, and facilitates chemical signaling.

  • Complete pathway of CSF circulation

    Lateral ventricles → interventricular foramina → third ventricle → cerebral aqueduct → fourth ventricle → median/lateral apertures → subarachnoid space → arachnoid granulations → dural venous sinuses.

  • How is CSF returned to venous blood?

    Via arachnoid villi/granulations that drain CSF into dural venous sinuses.

  • What forms the blood–brain barrier (BBB) and why is it selective?

    Tight junctions between brain capillary endothelial cells form the BBB. It is selective because it allows oxygen and nutrients through but blocks many toxins and pathogens.