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Gross Anatomy of the Nervous System - Anatomy & Physiology

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  • Central Nervous System (CNS)

    The CNS consists of the brain and spinal cord, responsible for processing and integrating information.

  • Peripheral Nervous System (PNS)

    The PNS includes all nerves outside the CNS, subdivided into cranial and spinal nerves.

  • Sensory (afferent) neurons

    Neurons that carry information toward the CNS from sensory receptors.

  • Motor (efferent) neurons

    Neurons that transmit impulses away from the CNS to effector organs like muscles.

  • Somatic Nervous System (SNS)

    Controls voluntary movements by innervating skeletal muscles.

  • Autonomic Nervous System (ANS)

    Regulates involuntary functions by controlling heart, glands, and viscera. Divided into sympathetic and parasympathetic divisions.

  • Sympathetic Division of ANS

    Known as the "fight, flight, freeze" system; activates energy-expending responses during stress.

  • Parasympathetic Division of ANS

    Known as the "rest and digest" system; conserves and replenishes energy.

  • Spinal Cord - Grey Matter

    Inner region shaped like an "H" containing neuronal cell bodies and involved in processing.

  • Spinal Cord - White Matter

    Outer region composed of myelinated axons organized into columns and tracts for fast signal conduction.

  • Spinal Nerves

    31 pairs of nerves emerging from the spinal cord, each with an anterior (motor) root and a posterior (sensory) root.

  • Meninges

    Three protective layers around the brain and spinal cord: dura mater, arachnoid mater, and pia mater.

  • Cerebrospinal Fluid (CSF)

    Fluid in the subarachnoid space that cushions the CNS and maintains its environment.

  • Cerebrum

    The largest brain region, divided into two hemispheres and four lobes: frontal, parietal, temporal, occipital.

  • Cerebellum

    Located posterior to the cerebrum, it regulates muscle coordination, balance, and posture.

  • Diencephalon

    Contains the thalamus and hypothalamus, which process sensory information and regulate homeostasis.

  • Thalamus

    Relay center that directs sensory and motor signals to the cerebral cortex.

  • Hypothalamus

    Regulates circadian rhythm, hunger, thirst, body temperature, and controls the pituitary gland.

  • Brainstem

    Includes the midbrain, pons, and medulla oblongata; controls vital functions like heart rate and breathing.

  • Cranial Nerves

    Twelve pairs of nerves emerging from the brain, numbered I to XII, with sensory, motor, or mixed functions.

  • Olfactory Nerve (I)

    Sensory nerve for smell, originating in the nasal mucosa and terminating in the olfactory bulb.

  • Optic Nerve (II)

    Sensory nerve for vision, originating in the retina and passing through the optic chiasma.

  • Oculomotor Nerve (III)

    Motor nerve controlling eye movement, eyelid opening, pupil constriction, and lens shape.

  • Trigeminal Nerve (V)

    Mixed nerve for facial sensation and motor control of mastication and swallowing.