Spine

Anatomy

  • Cord —> from medulla oblongata to L1-L2
    • 43-45cm
  • Spine is enclosed in the bony vertebral column
  • Periphery —> white matter
    • sensory and motor tracts
  • Central butterfly shape —> gray matter
    • nerve cell bodies
  • Columns:
    • Posterior-Dorsal
      • Sensory
        • Touch
        • Proprioception
        • Vibration
    • Anterolateral System (ALS )
      • Sensory
        • Pain
        • Temperature
    • Lateral (Pyramidal)
      • Motor
    • Anterior (Extrayramidal)
      • Motor

Layers of Meninges:

From inside to out —> pia matter, arachnoid mater, dura mater

  • pia matter envelopes cord and blood vessels
  • dura matter terminates @ conus medullaris at the film terminale

Three layers of meninges, the innermost pia mater, arachnoid mater, and outer dura mater, cover the elliptically shaped spinal cord and are continuous with the brainstem and brain. The delicate pia mater envelops the spinal cord and blood vessels. From this layer extend the denticulate ligaments, which connect with the dense, protec- tive dura mater to stabilize the cord within the spinal canal. The dura mater terminates beyond the conus medullaris at the filum terminale, a strand of fibrous tissue that attaches to the coccyx, providing longitudinal support to the cord. Between these two layers lies the arachnoid, which is filled with cere- brospinal fluid (CSF).
The spinal cord is responsible for transmitting motor and sensory neural signals between the peripheral nervous system and the brain and contains its own independent path- ways for coordinating certain reflexes (Fig. 28-1). Functionally, the cord is divided into 31 segments. At each level, a pair of spinal nerves exits: 8 cervical, 12 thoracic, 5 lumbar, and 5 sacral pairs and 1 coccygeal pair. In the cervical region, the spinal nerves exit above the corresponding vertebrae, whereas from the thoracic region and downward, the spinal nerves exit below the equivalent named vertebrae. Although the vertebral column continues to lengthen until adulthood, the canal and the cord are actually much shorter than the column because both stop lengthening at approximately 4 years of age. This growth differential is responsible for the formation of the cauda equina, a collection of the lower lumbar, sacral, and coc- cygeal nerves that fills the lower spinal column beyond the conus medullaris.