Spine Anatomy

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  1. General Information
    33 Vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), 4 coccygeal (fused)
  2. Spinal Regions: Cervical
    • C1-C2: unique bones allow stabilization of occiput to spine and rotation of head
    • Motion: rotation and flexion/extension
  3. Spinal Regions: Thoracic
    • Relatively stiff due to costal articulations
    • Motion: rotation
    • Minimal flexion/extension
  4. Spinal Regions: Thoracolumbar
    • Facet orientation transitions from semicoronal to sagittal
    • Segments are mobile
    • Most common site of lower spine injuries
  5. Spinal Regions: Lumbar
    • Largest vertebrae
    • Common site for pain
    • Houses caudal equina
    • Motion: flexion/extension (minimal rotation)
  6. Vertebrae
    • Uniquely shaped bones that support the axial musculature and protect the spinal cord and nerve roots
    • Body (Centrum): Has articular cartilage on both superior and inferior surfaces; articulates with intervertebral discs and gets larger distally
    • Arch: Made up of pedicles and lamina. Develops from 2 ossification centers that fuse. Failure to fuse results in spina bifida. It forms the vertebral canal for the spinal cord 
    • Spinous Processes: ligament attachment site
    • Transverse Processes: rib (t-spine) and ligament attachment site
    • Vertebral Foramen: spinal cord/cauda equina
    • Neural Foramen: nerve roots exit via here
  7. Spinal Levels and Corresponding Structures
    • C2-3: Mandible
    • C3: Hyoid Cartilage
    • C4-5: Thyroid Cartilage
    • C6: Cricoid Cartilage
    • C7: Vertebral Prominens
    • T3: Spine of Scapula
    • T7: Xiphoid, Tip of Scapula
    • T10: Umbilicus
    • L1: Conus Medullaris (End of Cord) 
    • L3: Aorta Bifurcation
    • L4: Iliac Crest
  8. Sensory Testing
    • C5: Lateral Shoulder
    • C6: Thumb
    • C7: Middle Finger
    • C8: Ring & Small Fingers
    • T1: Ulnar Forearm & Hand
    • L3: Anterior & Medial Thigh
    • L4: Medial Leg & Ankle
    • L5: Dorsal Foot & 1st Web Space
    • S1: Lateral & Plantar Foot
    • S2-4: Perianal Sensation
    • Positive Test = cervical root compression/lesion
  9. Motor Testing
    • C5: Deltoid (resisted abduction)
    • C6: Biceps (resisted elbow flexion)
    • C7: Triceps (resisted elbow extension)
    • C8/T1: Intrinsics (resisted finger abduction)
    • L3-4: Quadriceps (knee extension)
    • L4: Tib Ant (Ankle DF)
    • L5: EHL (Toe DF)
    • S1: Gastroc (Ankle PF)
    • S2-4: Anal Sphincter (Anal Squeeze) 
    • Positive Test = cervical root compression/lesion
  10. Reflex Testing
    • Biceps = C5
    • Brachioradialis = C6
    • Triceps = C7
    • Patellar Tendon = L4
    • Achilles Tendon = S1
    • Positive = radiculopathy

    Babinski and ankle clonus= upper motor neuron/myelopathy
  11. Descending (Motor) Tracts
    • Anterior Corticospinal
    • Lateral Corticospinal
  12. Anterior Corticospinal
    • Function: innervates motor neurons - voluntary motor
    • Minor motor pathway
    • Injured in anterior cord syndrome
  13. Lateral Corticospinal
    • Function: innervates motor neurons - voluntary motor
    • Major motor pathway
    • Injured in Brown-Sequard Syndrome 
  14. Ascending (Sensory) Tracts
    • Anterior Spinothalamic
    • Lateral Spinothalamic
    • Dorsal Columns 
  15. Anterior Spinothalamic
    • Light touch sensation
    • Injured in anterior cord syndrome
  16. Lateral Spinothalamic
    • Pain and temperature sensation
    • Injured in Brown-Sequard Syndrome
  17. Dorsal Columns
    • Proprioception and Vibratory Sensation
    • Usually preserved, injured in posterior cord syndrome 
  18. Spinal Cord
    • Runs from brain stem to conus medullaris (termination at L1) within the spinal canal 
    • Terminale filum and cauda equina (lumbar and sacral nerve roots) continue in the spinal canal
    • Has layered covering (membranes) = dura mater, arachnoid mater, pia mater (outisde --> inside)
    • Made up of multiple ascending (sensory) and descending (motor) tracts and columns
    • Wider in the cervical and lumbar spines where roots for plexuses to innervate the upper and lower extremities 
    • Paired (R & L) nerve roots emerge from each level
    • Nerve roots made up of ventral (motor) and dorsal (sensory) roots 
  19. Spinal Nerves
    • Made up of a ventral (motor) root and dorsal (sensory) root
    • 31 pairs (L&R)
    • Cell bodies for sensory nerves are in the dorsal root ganglia
    • Motor nerve cell bodies are in the ventral horn of the spinal cord
    • Roots exit spinal column via intervertebral (neural) foramen (under pedicle)
    • C1-7 exit above their vertebrae, C8-L5 exit below their vertebrae 
    • Can be compressed by herniated discs, osteophytes, and hypertrophied soft tissues (ligamentum flavum, facet capsule) 
    • Spinal nerves divide into dorsal and ventral rami
    • Dorsal rami innervate local structures (neck & back mm, overlying skin, facet capsule, etc)
    • Ventral rami contribute to plexus and become peripheral nerves to the extremities
  20. Cervical Plexus
    C1-C4 Ventral Rami (behind IJ and SCM)

    • 1) Lesser Occipital Nerve
    • 2) Greater Auricular Nerve
    • 3) Transverse Cervical Nerve
    • 4) Supraclavicular Nerve
    • 5) Ansa Cervicales
    • 6) Phrenic Nerve 
  21. Lesser Occipital Nerve 
    • C2-3
    • Arise from posterior border of SCM
    • Sensory: superior region behind auricle
    • Motor: none
  22. Great Auricular Nerve
    • C2-3
    • Exits inferior to lesser occipital nerve, ascends on SCM
    • Sensory: over parotid gland & behind ear
    • Motor: none 
  23. Transverse Cervical Nerve
    • C2-3
    • Exits inferior to greater auricular nerve, then to anterior neck
    • Sensory: anterior triangle of the neck
    • Motor: none 
  24. Supraclavicular Nerve
    • C2-3
    • Splits into three branches = anterior, middle, and posterior
    • Sensory: over clavicle, outer trap and deltoid
    • Motor: none 
  25. Ansa Cervicales
    • C1-3
    • Superior (C1-2) and inferior (C2-3) roots form loop
    • Sensory: none
    • Motor: omohyoid, sternohyoid, sternothyroid 
  26. Phrenic Nerve
    • C3-5
    • On anterior scalene into thorax between subclavian artery and vein 
    • Sensory: pericardium & mediastinal pleura
    • Motor: diaphragm
Card Set:
Spine Anatomy
2015-02-08 23:19:39
Spine Anatomy
I3 Review
Netter's Anatomy: Spine
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