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Spinal Cord

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This page is intended to discover component structure of spinal cord of biological human, sitting in between mind and peripheral organs.

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SPINAL CORD STRUCTURE

BASIC INFORMATIOIN

• regions - cervical (C1-C8), thoracic (T1-T12), lumbar (L1-L5), sacral (S1-S5), coccygeal (CX = CX1-CX3)
• width - 1 cm (thoracic/sacral) /2 cm (cervical-lumbar)
• height - 45 cm (men)/43 cm (women)

• dorsal horn and afferent connections:

• receptors classification: proprioceptors, nociceptors, mechanoreceptors

• spinal cord cross section - ascending and descending tracts

• motor interneurons:

• *interneurons of indirect supraspinal connections*: primary pathway for alpha-motoneurons
• *renshaw interneurons*: interneurons of direct monosynaptic connections with alpha-motoneurons, some fibers of CST/LVST/RST, negative feedback on the same alpha-neurons; stop firing to be ready for next supraspinal signal
• integrated rhythmic movements of upper and lower extremities like walking and running

* *intersegmental interneurons*: reciprocal inhibition (excite agonist muscles/ inhibit antagonist muscles), feedback inhibition (selectively inhibit LMN to proper pattern in agonist muscle group)
* *commissural interneurons*: to contralateral neurons (crossed extensor reflexes, alternate rhythms of both upper and lower extremities during running and walking)

SPINAL CORD LAMINAE AND LEVELS - REFERENCE

SPINAL CORD LAMINAE AND LEVELS

(generated)

|| *Level/Lamina* || *LO* || *LI* || *LII* || *LIII-IV* || *LV-VI* || *LVIIS* || *LVIIM* || *LVIII* || *LIX* || *LX* || || C1 || LCN || MG || SG || NPR || ACN || CCN || || VMN || SAN || || || C2 || LCN || MG || SG || NPR || ACN || CCN || || VMN || SAN || || || C3 || LCN || MG || SG || NPR || ACN || CCN || || VMN || SAN,PHN || || || C4 || LCN || MG || SG || NPR || ACN || CCN || || VMN || SAN,PHN,PLN,VLN || || || C5 || LCN || MG || SG || NPR || ACN || CBN || || VMN || SAN,PHN,PLN,VLN || || || C6 || LCN || MG || SG || NPR || ACN || CBN || || VMN || SAN,PLN,VLN || || || C7 || LCN || MG || SG || NPR || ACN || CBN || || VMN || PLN,VLN || || || C8 || LCN || MG || SG || NPR || CLN || CBN || RPL || VMN || PLN,VLN || || || T1 || LSN || MG || SG || NPR || CLN || IMM || RPL,IML,CSC || VMN || PMN || || || T2 || LSN || MG || SG || NPR || CLN || IMM || IML,CSC || VMN || PMN || || || T3 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T4 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T5 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T6 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T7 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T8 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T9 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T10 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T11 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || T12 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || || || L1 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN || DCN || || L2 || LSN || MG || SG || NPR || CLN || IMM || IML || VMN || PMN,PLN,VLN || DCN || || L3 || || MG || SG || NPR || CLN || || || VMN || PLN,VLN || || || L4 || || MG || SG || NPR || || || || VMN || PLN,VLN || || || L5 || || MG || SG || NPR || || || || VMN || PLN,VLN || || || S1 || || MG || SG || NPR || || || RPL,SPS || VMN || PLN,VLN,ONN || DCN || || S2 || || MG || SG || NPR || || || RPL,SPS || VMN || ONN || DCN || || S3 || || MG || SG || NPR || || || RPL,SPS || VMN || ONN || DCN || || S4 || || MG || SG || NPR || || || || VMN || || DCN || || S5 || || MG || SG || NPR || || || || VMN || || || || CX || || MG || SG || NPR || || || || VMN || || ||

SUBCORTICAL SENSORY SYSTEMS

• subcortical visual system
• somatosensory system
• subcortical auditory system
• gustatory system
• viscerosensory system
• humerosensory system

SPINAL CORD CONNECTIVITY

• see Spinal Cord Tract Details

FUNCTIONAL GROUPS

• *spinothalamocorticospinal cycle*:

* somatic body mechanical sensory -> {medial lemniscus system} -> VPL -> SI -> MI -> {lateral corticospinal tract} -> flexors (conscious motor)
* somatic head mechanical sensory -> {anterior trigeminothalamic tract} -> VPM -> SI (perception)
* somatic body pain sensory -> {paleospinothalamic system} -> VPI -> INS (conscious motivation)
* somatic head pain sensory -> {dorsal trigeminal tract} -> VPI -> INS (conscious motivation)
* PMC -> {lateral corticospinal tract} -> extensors (conscious motor)

• *spinohypothalamospinal cycle*: visceral pain -> LSN -> {spinohypothalamic tract} -> hypothalamus -> {hypothalamospinal tract} -> sympathetic/parasympathetic
• *spinomesencephalospinal cycle*:

* somatic pain -> MG -> {spinomesencephalic tract} -> PAG -> Gigantocellular Reticular Nucleus -> {medullary reticulospinal tract} -> extensors (reflexive)
* visceral pain -> IMM -> {spinomedulloreticular tract} -> Gigantocellular Reticular Nucleus

• *spinosolitariospinal cycle*: visceral pain -> LSN -> {spinosolitary tract} -> SOL -> Parabrachial Nucleus -> SOL -> {solitariospinal system} -> diaphragm
• *spinoponcoreticulocorticospinal cycle*: visceral pain -> IMM -> Medial Pontine Reticular Formation -> VA -> PMC -> {pontine reticulospinal tract} -> extensors
• *spinotectospinal*: visceral mechanical -> NPR -> {spinotectal tract} -> Superior Colliculus -> {tectospinal tract} -> oculomotor
• *spinocerebellorubrospinal cycle*:

* mechanical sensory -> {direct spinocerebellar system} -> CR -> RDN -> {corticobulbospinal system} -> flexors (automatic)
* mechanical sensory -> Inferior Olivary Nucleus -> {spinoolivary tract} -> CR

• *spinovestibulospinal cycle*:

* cutaneous sensory -> CCN -> {spinovestibular tract} -> VBN
* VBN -> {medial vestibulospinal tract} -> upper motor extensors
* VBN -> {lateral vestibulospinal tract} -> lower motor extensors