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NEU 101: Anatomy I - Lecture Flashcards


  • The Human Nervous System has two main parts:

    • Central Nervous System (CNS): Brain and Spinal Cord.

    • Peripheral Nervous System (PNS): Nerves connecting to the body.

  • Nerves transmit information:

    • Afferent (sensory): TO the brain (e.g., Skin -> Spinal Cord -> Brain).

    • Efferent (motor): FROM the brain (e.g., Brain -> Spinal Cord -> Muscle).

Peripheral Nervous System (PNS) Subdivisions

  • Somatic Nervous System: Controls voluntary movement and sensory input from skin, muscles, bones, and joints (external world interaction).

  • Autonomic Nervous System: Regulates involuntary functions of internal organs like heart, stomach, lungs, bladder (internal world interaction).

Spinal Cord Anatomy & Function

  • Organized into cervical, thoracic, lumbar, and sacral segments, with spinal nerves exiting at corresponding levels.

  • Transmits sensory (afferent) information via the dorsal (posterior) horn and motor (efferent) information via the ventral (anterior) horn.

  • Contains the central canal, which runs its entire length and is filled with Cerebrospinal Fluid (CSF).

Autonomic Nervous System (ANS): Parasympathetic vs. Sympathetic

  • Parasympathetic (Rest & Digest): Promotes body maintenance and energy conservation.

    • Examples: Constricts pupils, stimulates salivation, slows heartbeat.

  • Sympathetic (Fight or Flight): Prepares the body for stress or action.

    • Examples: Dilates pupils, inhibits salivation, accelerates heartbeat, dilates bronchi, inhibits digestion, stimulates glucose release.

CNS Protection: Meninges

  • The CNS is protected by bone and three layers of meninges:

    • Dura Mater: Outermost, tough.

    • Arachnoid Mater: Middle, spider-web like.

    • Pia Mater: Innermost, delicate, adheres to brain/spinal cord.

  • Also includes the newly identified SLYM (Subarachnoidal LYmphatic-like Membrane).

Cerebrospinal Fluid (CSF) & Ventricles

  • CSF Role: Cushions and supports the CNS, filling the subarachnoid space, central canal, and brain ventricles.

  • Ventricles: CSF-filled cavities including lateral (right/left), third, cerebral aqueduct, fourth, and central canal.

  • Production & Absorption: Produced by the choroid plexus; absorbed by dural venous sinuses.

  • Hydrocephalus: Occurs when CSF flow is blocked, causing buildup, ventricular expansion, and potentially head enlargement; treated with shunts.

Brain's Metabolic Demand

  • The brain, less than 2%2% of body weight, consumes approximately 20%20% of the body's blood supply, highlighting its high energy needs.

Blood-Brain Barrier (BBB)

  • A protective barrier formed by specialized brain vasculature.

  • Components: Capillary endothelial cells with tight junctions and astrocyte endfeet.

  • Function: Regulates substance passage from blood to brain, maintaining neural homeostasis.

Anatomical Orientation: Directions and Planes

  • Cardinal Directions: Dorsal (top/back), Ventral (bottom/front), Anterior (front), Posterior (back), Medial (middle), Lateral (side).

  • Planes for Slicing: Coronal, Sagittal, Horizontal (axial).

Contralateral vs. Ipsilateral

  • Contralateral: Pertaining to the opposite side of the body.

  • Ipsilateral: Pertaining to the same side of the body.

Grey Matter vs. White Matter

  • Brain: Contains both grey and white matter. The cerebral cortex is a six-layered, highly folded sheet.

    • Unfolded, its area is about 1 m21m2 and its thickness is approximately 3 mm3mm.

  • Spinal Cord: Grey matter forms an H-shape internally, surrounded by white matter.

    • Sensory signals enter via the dorsal horn, motor signals exit via the ventral horn.

Major Brain Parts

  • Brainstem: Includes medulla, pons, midbrain (tectum & tegmentum), and sometimes thalamus.

  • Cerebellum: The "little brain," located at the back, crucial for coordination.

  • Cerebrum: The largest part, superior to other structures, containing basal ganglia and limbic system.

Cerebral Cortex Structure

  • The cortex, meaning "bark," is a six-layered, folded sheet.

  • Features:

    • Gyrus (gyri): Raised folds.

    • Sulcus (sulci): Grooves between gyri.

    • Fissure: A large, deep groove.