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