Chapt 11: Central Nervous System (CNS)

Vocabulary flashcards covering CNS anatomy, major brain regions, spinal cord organization, cellular components, neural pathways, and basic neurophysiology relevant to anesthesia.

Central Nervous System (CNS)

The brain and spinal cord; the main command center for consciousness, sensation, movement, and autonomic regulation.

Dura mater

The tough, outermost meningeal layer protecting the brain and spinal cord.

Arachnoid mater

The web-like middle meninx with the subarachnoid space containing CSF.

Pia mater

The delicate innermost meningeal layer that adheres closely to the brain surface.

Cerebrospinal fluid (CSF)

Fluid circulating in ventricles and subarachnoid space; acts as a shock absorber and helps maintain intracranial pressure.

Circle of Willis

Arterial ring at the base of the brain formed by vertebral and internal carotid arteries; distributes cerebral blood flow.

Gray matter

Regions containing neuronal cell bodies (e.g., cerebral cortex) where processing occurs.

White matter

Myelinated axonal tracts that transmit signals between brain regions.

Occipital lobe

Brain region specialized for visual processing; damage can impair sight.

Temporal lobe

Involved in auditory perception, memory (hippocampus), and language processing (Wernicke’s area).

Parietal lobe

Processes somatosensation, spatial relationships, and sensory-language integration.

Frontal lobe

Governs executive functions, planning, attention, and voluntary motor control; contains primary motor cortex.

Broca's area

Speech production area located in the left frontal lobe.

Wernicke's area

Language comprehension area located in the left temporal lobe.

Basal ganglia

Subcortical nuclei that modulate motor control and movement coordination.

Thalamus

Sensory relay station for most senses (except smell) before cortical processing.

Hypothalamus

Regulates autonomic and endocrine functions: hunger, thirst, temperature, circadian rhythms, emotions.

Pituitary gland

Master endocrine gland controlling peripheral hormonal outputs.

Cerebellum

Coordinates smooth, precise movements; important for balance and procedural memory.

Brainstem

Midbrain, pons, and medulla; controls autonomic/vital functions and houses cranial nuclei.

Meninges

Three-layer coverings of the CNS: dura mater, arachnoid mater, and pia mater.

Intracranial pressure (ICP)

Pressure within the skull; increases threaten perfusion and can cause herniation.

Spinal anesthesia

Subarachnoid injection into CSF for rapid, dense neural block; needle passes through ligamentum flavum and dura/arachnoid.

Epidural anesthesia

Injection outside the dura with catheter placement for gradual, titratable anesthesia.

Spinal cord termination

Originates below the brainstem and typically ends near L1 vertebra (conus medullaris).

Segmental organization of the spinal cord

Cervical (7), Thoracic (12), Lumbar (5), Sacral (5)—plus coccygeal segments.

Neural cell body

Soma; the metabolic center of a neuron where the nucleus resides.

Dendrite

Neuron branch that receives signals from other neurons.

Axon

Long nerve fiber that transmits action potentials to downstream neurons or effectors.

Synapse

Junction where neurotransmitter is released to communicate with the postsynaptic cell.

Glia

Supportive CNS cells (including oligodendrocytes) that myelinate, recycle neurotransmitters, clear debris, and provide immune support.

Myelin

Lipid-rich sheath surrounding axons to speed electrical conduction; produced by oligodendrocytes in the CNS and Schwann cells in the PNS.

Nodes of Ranvier

Gaps in myelin along the axon that enable saltatory conduction.

Lemniscal pathway

Dorsal column–medial lemniscus system for fine touch and vibration.

Spinothalamic pathway

Ascending tract for pain and temperature transmission.