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Spinal Cord

Understanding Anatomy:

The spinal cord is a long, slender cylindrical structure between ¼ inch (thoracic) and ½ inch (cervical and lumbar) in thickness.  The spinal cord is between 17-18 inches long and begins immediately below the brain stem. It extends down to the first or second lumbar vertebra where it blends with the conus medullaris. Below the conus it becomes the cauda equina, a group of nerves resembling the tail of a horse.
The spinal cord serves three major functions:

  1. A conduit for motor function
  2. A conduit for sensory information
  3. Coordinating reflexes

The spinal cord is divided into 31 different segments. At each and every segment, right and left pairs of spinal nerves (sensory and motor) form. Small sensory and motor rootlets branch off from the spinal cord and combine to form spinal nerves (1 on each side). These spinal nerves, or nerve roots, exit the spinal canal through the intervertebral foramen, small hollows between each vertebra. A thin sac called the dural sac (dura mater) surrounds the spinal cord. Within the dural sac is a fluid called Cerebrospinal Fluid (CSF) that bathes the spinal cord and provides some protection to it.
The brain and the spinal cord make up the Central Nervous System (CNS).  The nerve roots that exit the spinal cord/spinal canal branch out into the body to form the Peripheral Nervous System (PNS).  

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Type of Neural StructureRole/Function
Brain StemConnects the spinal cord to other parts of the brain.
Spinal CordCarries nerve impulses between the brain and spinal nerves.
Cervical Nerves (8 pairs)These nerves supply the head, neck, shoulders, arms, and hands.
Thoracic Nerves (12 pairs)Connects portions of the upper abdomen and muscles in the back and chest areas.
Lumbar Nerves (5 pairs)Feeds the lower back and legs.
Sacral Nerves (5 pairs)Supplies the buttocks, legs, feet, anal and genital areas of the body.
DermatomesAreas on the skin surface supplied by nerve fibers from one spinal root.

Between the front and back portions of the vertebra (i.e. the midregion) is the spinal canal that houses the spinal cord and the intravertebral foramen.  The foramen are small hollows formed between each vertebra.  These hollows provide space for the nerve roots to exit the spinal canal and to further branch out to form the peripheral nervous system.

The spinal cord and brain are contained within special membranes called meninges that envelope the CNS and keep it separate from the rest of the body.
Dura Mater – the outermost layer and also the thickest
Arachnoid Mater – the middle layer
Pia Mater – the innermost layer and the most delicate

There are 3 anatomical or potential spaces of the CNS – each with different contents and each providing unique therapeutic benefits when targeted for treatments. For example, Epidural Steroid Injections are aimed at delivering steroidal medications into the Epidural Space, where as Intrathecal treatments deliver medication into the Subarachnoid Space. Each space is defined by its relation to the meninges and surrounding anatomy.

Epidural SpaceAbove the Dura Mater and under the bone of the spinal canalFat, lymphatics, spinal nerve roots, small arteries and a large network of thin-walled blood vessels called the epidural venous plexus
Subdural SpaceBetween the Dura and Arachnoid MaterNothing
Subarachnoid SpaceBetween the Arachnoid and Pia MaterCSF

Get Answers to Your Questions at the Ainsworth Institute
The key to finding the proper treatment for any type of pain is getting a proper diagnosis.  Not all types of pain respond to the same treatments and the window for improvement can be limited. The experts at Ainsworth Institute offer the most advanced pain management treatments available today, including advanced clinical trials that aren’t yet available to the general public. Call us today for an appointment so we can get you started on your road to recovery.