Presentation on theme: "Inha University Hospital Professor Yoon SH"— Presentation transcript:
1Inha University Hospital Professor Yoon SH Spinal Cord AnatomyInha University HospitalProfessor Yoon SH
2Spinal Cord Anatomy Spinal cord is covered by pia, arachnoid, and dura Cord suspended in dural sheath by denticulate ligament on each sideAttached along lateral surface of cord midway between dorsal and ventral roots
3Spinal cord anatomyCord is enlarged in cervical (C4-T1) and lumbosacral regions (L2-S3)Cord contains grey matter, white matter tracts, and central canalCentral canal lined by ependyma
4Spinal cord anatomy Gray matter Dorsal root entry zone White matter Vascular anatomy
5Cross-section of the spinal cord with laminae of Rexed . From G. Paxinos & C. Watson
6Lamina of RexedGray matter of spinal cord divided into ventral (anterior) and posterior (dorsal) hornsPosterior horn contains laminae 1-6Lamina 1 gives origin to the pathway relaying information about pain to the thalamusLamina 2 and 3 (substantia gelatinosa) functions in regulating afferent input to the spinal cord.
7Lamina of RexedLamina 4 projects to the lateral cervical nucleus, the posterior column nuclei, and the thalamus (spinothalamic tract)Lamina 5 and 6 receives proprioceptive input AND sensory information relayed by lamina 4. These are the sites of origin of ascending projections to higher centres.From T1 to L3 is Clarke’s column, which is within lamina 6 and contains projections to the cerebellum via the dorsal spinocerebellar tract
8Lamina of Rexed Anterior horn: Lamina 9 contains motor neurons supplying the limbs and lamina 9M contains motor neurons supplying the trunk and neck. 9M is medial to 9.Is further subdivided into flexor and extensors (flexors are dorsal) and into distal and proximal (distal is more lateral).
9Lamina of RexedLaminae 7 and 8 contain interneurons involved in motor control and motor neurons that project to brain.Lamina 8 is highly related to lamina 9M, and participates in movements of muscles in the head and neck.Lamina 7 is related to lamina 9 and participates in limb muscle movementLamina 8 and 9M are highly developed in high cervical and thoracic segments controlling neck and trunk, whereas laminae 7 and 9 are highly developed in the spinal enlargements controlling the arms and legs
10Lamina of RexedIntermediolateral cell column is present in thoracic and sacral segments, and is not considered part of the anterior or posterior hornContains neurons of origin of pre-ganglionic autonomic fibresLamina 10 surrounds central canal, and contains neurons that project to the opposite side of the cord.
11White matter Divided into dorsal, lateral and ventral funiculi Dorsal funiculus mostly comprised of ascending fibres whose bodies are located in dorsal root gangliaFibres are ipsilateralProprioception and fine discrimination (note that vibration is carried in both dorsal and lateral funiculi)
12White matter – dorsal funiculus Fasciculus gracilis medial to fasciculus cuneatusF. gracilis from lower limbs and cuneatus from upper limbsNote that lowest segmental innervation is most medial in gracilis and highest innervation is most lateral in cuneatusNucleus gracilis and cuneatus in medullaThere are descending fibres in dorsal funiculus which modify sensory input to the cord
13White matter – lateral funiculus Dorsolateral and lateral parts (fasciculi)Dorsolateral contains lateral corticospinal tract (axons from contralateral frontal and parietal lobes); frontal fibres end in ventral hornLower limbs are lateral in tract and head is medialDistal muscles are posterior to proximal musclesRubrospinal tract (from contralateral red nucleus) is rudimentary in humans; involved in increasing flexor tone
14Lateral funiculusRaphespinal tract in dorsal part of lateral funiculus; modifies painful stimuli from dorsal horn; fibres may begin in reticular formation of medullaHypothalamospinal tract arises from paraventricular nucleus of hypothalamus and end in pre-ganglionic autonomic segments T1-L3 and S2-S4
15Lateral funiculusspinocervical tract ascends and terminates in lateral cervical nucleus, which is rudimentary in humans (significance is unknown)Dorsal spinocerebellar tract is present above L3; arises from Clarkes column and terminates in ipsilateral cerebellum; forms part of pathway of conscious proprioception from lower limb
16Lateral funiculus Ventrolateral fasciculus Spinothalamic tract has its nuclei in lamina 4,5,6 mostly.Axons cross midline in ventral white commissure and traverse the ventral hornEnd in thalamusCollateral branches to reticular formationPain and thermal sensationsFibres from lower limb are most superficial and from upper limb are deepest
17Lateral funiculusVentral spinocerebellar tract arises from dorsal horn and border cells of ventral horn of lumbosacral cordCrossed fibresAscends to midbrain, enters superior cerebellar peduncle, and decussates again, and enters cerebellar cortexConcerned with proprioception
18Lateral funiculusSpinotectal tract fibres from same part as spinothalamic tract end in superior colliculus and reticular formation (fibres are crossedSpinoreticular tract originates in laminae 4-8 ends in reticular formation; is important in perception of pain and other modalities originating in internal organs
19Lateral funiculus Spino-olivary tract has uncertain role in humans Ventrolateral fasciculus also contains descending medullary reticulospinal tract, which controls motor activities that do not require conscious effort
20Ventral funiculusVentral corticospinal tract contains uncrossed fibresVestibulospinal tract is uncrossed pathway from the lateral vestibular nucleus of medulla; axons terminate in lamina 8Mediates reflexes of equilibrium
21Ventral funiculus Pontine reticulospinal tract Medial longitudinal fasciculus (only in cord to upper cervical levels) is involved in movements of head required for equilibriumTectospinal tract from contralateral superior colliculus
22Fasciculus propriusPresent in all funiculi immediately adjacent to gray matterContains propriospinal fibres which connect different segmental levels of gray matterAscend and descend variable lengths and provide functional equivalent of interneurons
23Dorsal root entry zone Each dorsal root branches into 6-8 rootlets Axons segregated into two divisions within each rootlet: lateral and medialLateral contains unmyelinated (type C) fibres and enters dorsolateral tract of LissauerMedial contains larger, myelinated axons, and enter white matter medial to dorsal horn
24Vascular anatomy - Arterial Cord is supplied by multiple radicular arteries, which form the anterior and posterior spinal arteryRadicular arteries arise from adjacent arteries at each vertebral segmentPass through intervertebral foramina to supply nerve roots, but most do not reach the cordLarger radicular arteries which also supply cord are called radiculomedullary arteries
25Vascular anatomy - arterial Anterior spinal artery originates in upper cervical region, from anterior spinal branches of vertebral artery.6-10 anterior radicular arteries contribute to it throughout its length.Supplies anterior two thirds of cord, via central branches and penetrating branches of pial plexus
26Vascular anatomy – arterial territories Cervical and first two thoracic segments of cord are supplied by radicular a. that arise from subclavian a. or branches thereofHigh degree of variabilitymid-dorsal region of cord (T3-T7) is supplied from radicular a. accompanying T4 or T5 rootT8 to conus supplied by artery of Adamkiewicz
27Vascular anatomy - Adamkiewicz Arises from left sided lumbar (segmental) artery in 80%85% reaches cord between T9-L2; 15% between T3-T8 (in these cases it is supplemented by a radicular artery arising more inferiorly)Has large anterior and small posterior branchAnterior branch ascends, then gives off a small ascending branch and larger descending branchDescending branch goes inferior (to conus) and makes an anastomotic loop with posterior spinal a.
28Vascular anatomy – arterial Cauda equina also supplied by branches from lumbar, iliolumbar, and lateral and median sacral a.
29Vascular anatomy – posterior spinal artery Paired arteriesRun along posterolateral cordSometimes discontinuousOriginates from verterbral arteryHas contribution from posterior radicular a.Supplies posterior one third of cord
30Vascular anatomyAnterior spinal a. gives off central branches and branches to pial plexusCentral branches run in anterior median fissure and supply central cordPial plexus is formed from both anterior and posterior spinal a.Give penetrating branches which supply outer cordSome overlap between supply of central and pial branches
31Vascular anatomy - venous Internal and external vertebral venous plexusesForm rings around each vertebraFreely anastomose with each other
32Vascular anatomy - venous External plexus has anterior part (anterior to vertebral body) and posterior part (over posterior elements including laminae and spinous processes)Anterior and posterior parts freely anastomose
33Vascular anatomy - venous Internal plexus: anterior part is on each side of PLL, posterior to vertebral body; posterior part is interior to ligamentum flavumVertebral body drained by basivertebral veins which enter anterior external plexus
34Vascular anatomy - venous Veins of cord mirror related arteries in distributionVenules drain into anterior and posterior veins, which drain into two median longitudinal veins, and into anterolateral and posterolateral longitudinal veins lying adjacent to the nerve rootsRadicular veins join branches from internal plexus forming intervertebral veins (have valves), which exit intervertebral foramina and join their respective segmental veins