This section describes the spinal cord structures and function.

Spinal Cord

General Description

• l 42-45cm in length
• Continuous with medulla
• Larger at C4-5 & L3-S2- more gray matter
• Conus medullaris (distal tip) lies between T12 & L2 in adults

Cervical Vertebra

C1-C7 Smallest

Canal widest

• T1-T12
• Oblique spinous processes
• Articulate with ribs

L1-L5 Largest

Horizontal spinous processes

Sacrum

Fusion of 5 vertebrae

Coccyx

4 fused vertebrae

Fibro cartilaginous discs

Located between each vertebrae

Provide support and cushion

Spinal Cord Nerves

• C1-7 exit above vertebrae

• C8 exits below C7 vertebrae

• 12 thoracic exit below vertebrae

• 5 lumbar exit below vertebrae

• Sacrum- 5 corresponding nerves

• 1 coccygeal

Gray matter

• Central canal of cord
• Contains cell bodies of spinal neurons
• Shape of a butterfly

Dorsal horns

• Sensory function
• Pain
• Position sense
• Touch
• temperature

Ventral horns

• Motor functions
• Spinal reflexes

White Matter

• Myelinated & unmyelinated fibers
• Communicates with brainstem & cerebral cortex

Descending pathways

• Motor paths
• Corticospinal
• Vestibulospinal
• rubrospinal

Ascending pathways

• Sensory paths
• Dorsal column
• Spinothalamic
• Spinoreticular

Principal Dermatomes

Blood Supply

Arterial

• Posterior spinal arteries (2)-
  • supply posterior 1/3 of the cord-
    • arise from vertebrals
• Anterior spinal artery (1)-
  • supplies anterior 2/3 of the cord-
    • arise from vertebrals
• Radicular arteries-
  • enter every intervertebral foramen-
    • supplies nerve roots
  • Radiculospinal branches-
    • arise from vertebral artery and aorta
• Artery of Adamkiewicz-
  • largest radiculospinal -
  • much of blood flow to anterior spinal art. depends on Art of Adamkiewicz#13; 13;

Venous drainage

• Anterior spinal vein
• Posterior spinal vein

Anatomical distribution from outer to inner layers

• Epidural space
• Dura mater
• Subdural space
• Arachnoid mater
• Subarachnoid space
• Pia mater

Ligaments

Anterior longitudinal

• Anterior to vertebral column
• Attached to vertebral bodies
• Extends from skull & atlas to sacrum
• Provides extension/flexion stability

Posterior longitudinal

• Posterior to vertebral column
• Extends from skull & atlas to sacrum
• Provides extension/flexion stability

Supraspinous

• Joins adjacent spinous processes dorsally
• Most superficial
• Provides additional flexion stability

Interspinous

• Joins adjacent spinous processes on horizontal surface
• Provides additional flexion stability

Ligamentum flavum

• Deepest
• Covers dura mater
• Joins adjacent laminae

Additional Study Questions