SpinalCord

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.

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:

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• 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