Anatomy 2: SPINAL CORD

Anatomy of the Spinal CordPrepared by: Maria Michaela Valenzuela, PTRPExternal Anatomy of the Spinal CordStarts from foramen magnum to L1 or L2 Entirely enclosed with Spinal or Vertebral Bones

Upper border of L2 or lower border of L32 Dura MaterOutermostArachnoid MaterPia MaterInnermost

MENINGEAL COVERINGS OF THE SPINAL CORD Named based on the corresponding region of the Vertebral ColumnCervicalThoracicLumbarSacralCoccygeal

SEGMENTAL DIVISIONS OF THE SPINAL CORDEach spinal segment will have corresponding nerves emerging from it: SPINAL NERVES31 pairsConveys somatic sensory/motor & autonomic functionsLater will form the plexusesSPINAL CORD SEGMENTS AND SPINAL NERVESCervical: 8Thoracic: 12Lumbar: 5Sacral: 5Coccygeal: 15Each spinal nerve will exit via INTERVERTEBRAL FORAMENSPINAL CORD SEGMENTS AND SPINAL NERVESC1SKULLC2C6C7T1T2T11T12L1L2C1C2C3C7C6C8T1T2T10T11T12L1Note how cervical nerves exit above their corresponding vertebra while thoracic and lumbar exit below their corresponding vertebra6Other external structures of the spinal cordAt the End of the Spinal Cord:Conus MedullarisCauda EquinaAnchors of the Spinal CordFilum TerminaleDenticulate LigamentConus Medullaris structure at the end of the SC wherein it tapers from being a cylindrical structure (at the level of L1 or L2)Cauda Equina horsess tail; composed of lower level spinal nerves making its way from the conus medularis to their point of exit at their respective vertebral levelFilum Terminale connects the conus medularis to the end of the spinal canalDenticulate ligament anchors the SC to the side, derived from pia mater7

INTERNAL ANATOMY OF THE SPINAL CORDInternal aggregation of cell bodies in a distinct Butterfly ShapeGray MatterPeriphery comprised of axonsWhite MatterLaw of Bell & Magendie

Parts to be discussed:-dorsal horn, ventral horn- dorsal intermediate sulcus- spinal nerve-central canal- dorsal lateral sulcus, ventral lateral sulcus (better seen in next slide)- anterior, lateral, posterior columns (white mater)-dorsal median fissure, ventral median fissure- dorsal root, ventral root10

See how the internal anatomy differs from each segment but all segments have similar structures. See how white matter is more prominent in higher levels? This is because the axons from the lower levels ascend and combine with the axons from higher levels to go to the brain~ 11INTERNAL ANATOMY OF THE SPINAL CORD: gray matterGray Matter is further divided into 10 Rexeds LaminaLamina processed all received info from the brain or effector organsProcess either sensory or motor info depending on location

Points of emphasis: - Substantia Gelatinosa (RL 1&2): for pain sensation- Anterior Horn Cell (RL 9): for movement - Nucleus Proprius (RL 3&4): for proprioception- Central Canal (RL10): circulation of CSF- Nucleus Dorsalis (RL7): also proprioception 13INTERNAL ANATOMY OF THE SPINAL CORD: white matter3 Columns (Funniculi)Posterior: between Dorsal Median Fissure + Dorsal HornLateral: between Ventral Horn + Dorsal HornAnterior: between Ventral Median Fissure + Ventral HornEach containing various tracts to send/receive impulse to/from the braintracts OF THE SPINAL CORDWhite matter is divided/composed of 8 major tractsSensory : ascending tractsMotor: descending tracts

Descending Tracts of Emphasis: Corticospinal Tract, as for the rest, at least have the students know the function16TractsOriginTermDecusFunction/sLateralCorticospinalBA 4,6RL 8,9& inter-ineuronMOVol. moves distal musclesMedial/AntCorticospinalBA 4,6RL 8,9& inter-ineuronNoneVol. moves axial & proximal musclesTectospinalMBRL 8,9 inte-rneuronBSReflexly moves axial & proximal muscles in response to visual/auditory stimuliTractsOriginTermDecusFunction/sMedial Vestibulosp.PONSRL 8,9& inter-ineuronNone*BSReflexly adjust neck and back muscles-postureLateralVestibulosp.MOPONSRL 8,9& inter-neuronNoneReflexl moves limb extensors-postureRubrospinalMBRL 8,9 interneuronBSReflexly moves contralat Limb flexorsMedial Reticulospin.PONS

RL 8,9D.NoneBSModulation of pain & spinal refexes LateralReticulospin.MORL 8,9D. HornNoneBSPain/SCreflex modul.

Ascending tracts for emphasis: - dorsal column - anterior/lateral spinothalamic tract19TractsOriginTermDecusFunction/sDorsal ColumnRL 3,4,6BA 3,1,2,5,7MOconscious proprioception; cortical sens.Post/AntSpinocerbell.RL 3,4,6,7PaleoCerebelNoneAnt.-SCUnconsciousProprioceptionAnt/LatSpinothalamRL 1,2,5Thalam to BA 3,1,2,5,7SC Antpain/tempLat-touch/presSomatotopic Organization in the Spinal CordCorticospinal & Spinothalamic TractCervical fibers MEDIALSacral fibers LATERALDorsal Column Medial LemniscusCervical fibers LATERALSacral fibers MEDIALFor dorsal column tract, lumbar fibers are found more medial because they get pushed medially as cervical fibers enter from the lateral aspect of the SCFor spinothalamic tract, cervical fibers are found more medial because they push the lumbar fibers laterally as they decussate from the other sideFor corticospinal tract, cervical fibers are found more medial because they need to exit to the anterior horn first

-- this can be a factor for incomplete SCI21Blood supply to the spinal cord

Blood supply to the spinal cord1 Anterior Spinal ArterySupplies Anterior 2/3 of SC 2 Posterior Spinal Artery Supplies Posterior 1/3 of SCHere, we can infer that injury to ASA is more debilitating than injury to PSA because ASA supplies greater area and PSA also has 2 artery that may compensate23Blood supply to the spinal cord Radicular Arterybranch of Intercostal arteries supply T1-L1Great Ventral Radicular Artery: largest branch found entering T8 L4 (aka Artery of Adamkiewics)

T4 T6 have less blood supply: WATERSHED AREAS

Clinical applicationEVALUATION

DERMATOMEMYOTOMENEURO LEVELFUNCTIONAL PROGNOSISDEFINE THE REAL PROBLEMTREATMENT

PRECAUTION TO PHYSICAL AGENTS & OTHER SEQUELARX OF APPROPRIATE EXERCISE AND RETRAINING