Recording-2025-02-19T19:20:10.011Z

Overview of the Spinal Cord and Reflexes

Central Canal

  • The central canal is a fluid-filled space in the center of the spinal cord.

  • The fluid in this space is called cerebrospinal fluid (CSF).

Structure of the Spinal Cord

  • Gray Matter: Contains neuron cell bodies and is organized into:

    • Dorsal Horn (posterior)

    • Lateral Horn

    • Ventral Horn (anterior)

  • White Matter: Contains myelinated axons and organized into columns:

    • Dorsal Column

    • Ventral Column

    • Lateral Column

Spinal Nerves and Neuronal Pathways

  • Spinal Nerves: Carry sensory and motor information; consist of sensory neurons.

  • Ganglion: A cluster of neuron cell bodies in the peripheral nervous system.

Neural Pathways

  • The ascending pathway carries sensory information to the brain (via interneurons).

  • The descending pathway carries motor commands from the brain to effectors (muscles or glands).

Types of Motor Neurons

  • Autonomic Motor Neurons: Controls involuntary responses (e.g., heart, visceral organs).

  • Somatic Motor Neurons: Control voluntary movements (e.g., to skeletal muscles).

Reflexes

Definition and Function

  • Reflex: An involuntary reaction in response to a stimulus, which allows faster reaction than conscious thought.

  • Most reflexes occur in the spinal cord or brain stem rather than higher brain centers.

Components of a Reflex Arc

  1. Sensory Receptor: Detects the stimulus (e.g., pain, heat).

  2. Sensory Neuron: Sends sensory information to the spinal cord.

  3. Interneurons: Relay and process signals between sensory and motor neurons.

  4. Motor Neuron: Sends impulses to effectors (muscles or glands).

  5. Effector Organ: Carries out the response (muscle contraction or gland secretion).

Types of Reflexes

  • Stretch Reflex: e.g., knee-jerk reflex (involuntary muscle contraction in response to stretching).

  • Withdrawal Reflex: e.g., flexor reflex (removal of a limb from a painful stimulus); involves sensory receptors as pain receptors.

robot