Lecture Notes - Deep Back & Spinal Cord

THE BACK AND SPINE

1. The Back
   1. Superficial back muscles: really limb muscles - anterior rami of spinal nerves
   2. True or Deep back muscles (Paraspinal muscles - posterior rami of spinal nerves)
      1. Erector spinae - main bulk of back muscles - from sacrum to skull
      2. Transversospinal group - multifidus, etc.the shortest and the deepest layers
      3. Others: splenius, suboccipital muscles, interspinales, rotators, etc.
      4. Function - to keep the spine erect, bend it laterally, and rotate it.
2. Vertebral Column
   1. Vertebrae
      1. 33: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), 4 coccygeal (fused)
      2. Parts:
         1. body - weight bearing part;
         2. vertebral arch - muscle attachment, etc.
         3. vertebral, spinal foramen - between body and vertebral arch, contains spinal cord
         4. vertebral notches - adjacent notches form intervertebral foramen to transmit spinal nerve
      3. Regional variations - vertebrae each region are different, some special
   2. Joints - join vertebrae
      1. Intervertebral Disks (cartilagenous joints)
      2. Facet joints (synovial joints - zygopophyseal joints)
   3. Ligaments - join vertebrae, longitudinal (ant., post), ligamenta flava, supraspinal
   4. Curvatures - Thoracic and sacral - primary ; cervical and lumbar - secondary
   5. Blood Supply - segmental and vertebral vessels - see spinal cord vessels
   6. Nerve Supply - to meninges, vertebrae, disks, ligaments and joints
   7. Abnormalities or defects, etc.
      1. fused or missing vertebrae
      2. scoliosis, lordosis, kyphosis, herniated disks
3. Gross Spinal Cord and Meninges
   1. Spinal Cord - CNS from medulla oblongata of brain to tip of conus medullaris (L2),
      1. Same regions as vertebral column - cervical, thoracic, lumbar, sacral, coccygeal
      2. Segment - section of spinal cord giving rise to a specific spinal nerve; 31 segments
      3. Enlargements - cervical and lumbosacral - cord larger where nerves to limbs arise
      4. Conus medullaris - terminal tapered end of cord, tip of which is at L2
      5. Cauda equina - free floating spinal nerve rootlets (lower L2 - S2) in CSF
      6. Spinal nerve rootlets - not really parts of spinal cord, but of spinal nerves
   2. Meninges and Spaces - contents of vertebral canal from outside in:
      1. Epidural space - contains fat and vertebral plexus of veins
      2. Dura mater - outer covering - "durable" dural sac ends at S2
      3. Subdural space - a potential space between dura and arachnoid
      4. Arachnoid mater - looks like a "spider web" attached to pia by trabeculae
      5. Subarachnoid space - between arachnoid and pia ends at S2, contains cerebrospinal fluid (CSF) to bathe and cushion the brain and spinal cord,
      6. Pia mater - outer layer of CNS, forms dentate ligaments and filum terminale
   3. Blood Supply of Vertebrae and Spinal Cord
      1. Arterial - segmental arteries from which arise: branch to the vertebra, radicular which join to form anterior spinal and posterior spinal arteries.
      2. Venous - vertebral venous plexus - connects to segmental veins inf. vena cava.
   4. Functional Considerations
      1. Lumbar puncture (Spinal tap) - to remove CSF for analysis
      2. Anesthesia - spinal; epidural (extradural); caudal
      3. Herniated disks - radiculopathies
      4. Developmental defects - spina bifida, meningocele, myelomeningocele