Spinal Cord Anatomy

Overview

• The spinal cord begins at the foramen magnum and concludes at the second lumbar vertebra (L2).
• It ends in a cone-shaped process called the conus medullaris.
• Extending from the spinal cord's inferior portion is a group of nerves known as the cauda equina ("horse's tail").
• The spinal cord's inferior portion is anchored by the filum terminale ligament.

Structure

• Cervical and Lumbar Enlargements: Bulges in the cervical and lumbar regions.
• 31 pairs of spinal nerves emerge from the spinal cord.
• The spinal cord is covered by three layers of meninges:
  • Dura mater: Tough, fibrous outer layer.
  • Arachnoid mater: Middle layer inside the dura mater.
  • Pia mater: Contacts the surface of the spinal cord.
• The subarachnoid space between arachnoid and pia mater is filled with cerebrospinal fluid.
• White Matter: Outer portion of the spinal cord, divided into funiculi—posterior, lateral, and anterior.
• Gray Matter: Inner portion of the spinal cord, divided into horns—posterior, lateral, and anterior.

Additional Structures

• Nerve Roots: Dorsal and ventral roots exit and combine to form a spinal nerve:
  • Dorsal root: Contains the dorsal root ganglion, a collection of cell bodies.
• Grooves: Posterior median sulcus and anterior median fissure.
• Gray Commissure: A bridge of gray matter uniting both sides of the spinal cord.
• Central Canal: Contains cerebrospinal fluid.

Functions and Pathways

• Spinal Tracts: Pathways for nervous system impulses:
  • Ascending (Sensory) Tracts: Carry information to the brain.
  • Descending Tracts: Carry information from the brain to effectors (muscles, organs, glands).
  • Most tracts cross to the other side of the spinal cord or brain.

Specific Tracts

• Fasciculus Gracilis and Cuneatus: Discriminative touch, vibration, pain, proprioception.
• Lateral Spinothalamic Tract: Pain and temperature information.
• Anterior Spinothalamic Tract: Light touch and pain information.
• Spinocerebellar Tracts (Anterior and Posterior): Coordination information.
• Corticospinal Tracts: Motor information to skeletal muscles.
• Rubrospinal Tract: Motor information to skeletal muscles.
• Reticulospinal Tract: Motor information to skeletal muscles and sweat glands.

These notes summarize the key aspects of spinal cord anatomy and function. Understanding these can provide insights into how nervous system signals are transmitted and processed.