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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)

SPINAL CORD SENSORY AND MOTOR ROOTS NEURONS

• Fibers by thickness*:

• *A-alpha motor/sensory (Ia, Ib)*: 12-22 mcm, 70-120 m/sec, low theshold, 2ms after stimulus (motoneurons, touch, position and velocity, Meissner's corpuscles)

* *A-alpha-Ia motor/sensory*: 
 * muscle spindle primary sensory endings (skin, two-point discrimination, extrafusal muscles, Meissner's corpuscles)
 * alpha motoneurons (extrafusal muscle fibers, skeletal movements, brainstem/spinal cord)
  * FF-type alpha motoneurons - biggest motoneurons, type IIB extrafusal muscle fibers (generate large force, poor efficiency, affected by static beta motoneurons)
  * FR alpha motoneurons - type IIA extrafusal muscle fibers (affected by static beta motoneurons)
  * S-type alpha motoneurons - type I muscle fibers (little force, metabolically efficient, affected by dynamic beta motoneurons)
* *A-alpha-Ib sensory*:
 * sensory Golgi tendon organs
 * sensory Ruffini endings in skin

• *A-beta motor/sensory (II)*: 8-13 mcm, 40-70 m/sec, higher theshold, 4ms after stimulus (fine touch, kinesthesia, muscle spindle secondary endings)

* Merkel disks (weak position and strong velocity - irregular discharge, type I, hairy/hairless skin)
* Ruffini's corpuscles (strong position and weak velocity receptors - regular discharge, type II, hairy/hairless skin)
* Hairy skin velocity receptors (large hair follicles, slow and rapid movement of hairs and deflection of the skin)
* Pacinian corpuscles (transient receptors, connective tissue, vibration, intrafusal muscles, tonic proprioceptive endings, flower-spray type)
* beta motoneurons (skeleto-fusimotor, intrafusal fibers and collaterals to extrafusal muscle fibers, muscle spindles, increase dynamic sensitivity of ending)
 * beta dynamic motoneurons - type I extrafusal muscle fibers and the intrafusal bag1 fiber (slow contracting motor units)
 * beta static motoneurons - type IIA or IIB extrafusal fibers and the intrafusal bag2 fiber (fast contracting motor units)

• *A-gamma motor*: 4-8 mcm, 15-40 m/sec, 6ms after stimulus

* intrafusal muscle fibers (skeletal muscle tone, contract muscle spindles from both ends, fusimotor gamma neurons, affect Ia/II)
 * gamma static motoneurons - intrafusal bag2 fiber and the nuclear chain fibers
 * gamma dynamic motoneurons - intrafusal bag1 fiber

• *A-delta sensory (III)*: 1-4 mcm, 5-15 m/sec, 20ms after stimulus

* noxious receptors (first/fast, sharp, well-localized pain)
* cold receptors (temperature, high-threshold mechano/heat, phasic)
* pressure (rapidly adapting mechanosensitive, directional selectivity, crude touch)

• *B motor*: 1-3 mcm, 3-14 m/sec, preganglionic autonomic, myelinated, ACh (sympathetic only in T1-L3, IML)

* preganglionic paravertebral sympathetic (short to paravertebral sympathetic ganglia, close to vertebral, fibers ascend/descend to reach all spinal cord levels)
* preganglionic prevertebral sympathetic (long to prevertebral sympathetic ganglia, celiac, superior/inferior mesenteric ganglia)
* preganglionic parasympathetic spinal (spinal cord long fibers to parasympathetic ganglia, splantic nerves, abdominal organs)
* preganglionic parasympathetic cranial (cranial nerves III, VII, IX and X long fibers to parasympathetic ganglia, eye iris, lacrimal/submandibular/subingual glands, thorax, abdomen, GI tract)

• *C motor/sensory (IV)*: 0.1-1 mcm, 0.2-2 m/sec, 60ms after stimulus (pain, touch, pressure, temperature, postganglionic autonomic)

* C fiber nociceptors (responsible for the second, burning pain)
* C fiber warming specific receptors (responsible for warmth)
* ultra-slow histamine-selective C fibers (responsible for itch)
* tactile C fibers (sensual touch, includes CT fibres, also known as C low-threshold mechanoreceptors (CLTM), which are unmyelinated afferents found in human hairy skin, and have a low mechanical threshold < 5 milliNewtons. They have moderate adaptation and may exhibit fatigue on repetitive stimulation and "afterdischarges" for several seconds after a stimulus)
* C mechano- and metabo- receptors in muscles or joints (responsible for muscle exercise, burn and cramp)
* postganglionic sympathetic C fibers (muscles and skin, pre/post - temporal summation and spatial summation, one-to-many, wide-spread, long and unmyelinated, NE)
* postganglionic parasympathetic C fibers (from ganglia in/on wall of organ, visceral activity and repose, short, local)

• Sensory neurons*:

• *Classification by receptor*:

* *proprioceptors*: LI,LV, also LII (fast pain/temperature senses), A-delta fibers
* *nociceptors*: LII,LI (slow pain/temperature senses, unmyelinated), C fibers
* *mechanoreceptors*: LIII,LIV (touch/position/kinesthetic/vibration senses), A-alpha-Ia/A-beta fibers

• *Proprioception*

* receptors origin: muscle spindle (intrafusal fibers), Golgi tendon organ, A-alpha-Ib/A-beta fibers
* intrafusal fiber types:
 * *nuclear chain fibers* - report static length of muscle (aligned in a single row), A-alpha-Ia/A-beta/A-gamma fibers
 * *static nuclear bag fibers* - report static length of muscle (bundle in fiber middle), A-alpha-Ia/A-beta/A-gamma fibers
 * *dynamic nuclear bag fibers* - report rate of change of muscle length (bundle in fiber middle), A-alpha-Ia/A-gamma fibers
* roman number fiber classification:
 * *Ia* - primary afferents, annulospiral endings, length and velocity, A-alpha-Ia fibers
 * *Ib* - Golgi tendon organ, report load being applied to muscle, A-alpha-Ib fibers
 * *II* - secondary afferents, flower spray endings, length only, A-beta fibers

• *Sensory endings*

* 
* *Hair follicle receptors*: touch (slowly adapting, low threshold), A-beta fibers
* *Merkel disk receptors*: vibration 5-15 Hz (high resolution tactile discrimination, static touch/pressure, mechanoceptors in hairless skin and mucosa, pressure and texture, slowly adapting, sustained response, low threshold), A-beta fibers
* *Meissner's corpuscles*: vibration 20-50 Hz (tactile, dynamic touch/pressure, texture, rapidly adapting, superficial papillary receptor, low threshold, especially sensitive to light touch - like fingers and lips), A-alpha-Ia fibers
* *Pacinian corpuscles*: vibration 60-400 Hz (deep receptors, subcutaneous tissue, viscera, rapidly adaptng, low threshold), A-beta fibers
* *Ruffini's corpuscles*: stretching of skin (deep receptors, slowly adapting, low threshold), A-alpha-Ib/A-beta fibers
* *Free nerve endings*: pain, temperature, crude touch, A-delta/C fibers
* *Golgi tendon organs*: muscle tension (slowly adapting, low threshold), A-alpha-Ib fibers
* *Muscle spindles*: skeletal muscle, stretch by muscle length (fast), A-alpha-Ia/A-beta

• Motoneurons*:

• *alpha-motoneuron*: extrafusal muscle fibres (voluntary movement), A-alpha-1a fibers
• *beta-motoneuron*: intrafusal/extrafusal muscle fibres (voluntary movement), A-beta fibers
• *gamma-motoneuron*: intrafusal muscle fibers (muscle tonus, additional contracts to maintain sensitivity in stretched state), A-gamma fibers
• *preganglionic autonomic*: B fibers
• *postganglionic autonomic*: C fibers
• *renshaw cell*: axon collateral of alpha-motoneuron -> renshaw cell -> alpha-motoneuron (negative feedback)

• 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 NUCLEI

• outer:*
• Lateral Cervical Nucleus (LCN) (lateral horn, low-threshold fast-conducting, tactile/pressure relay); sensory, tract of Lissauer/spinocervical tract; A-alpha-Ib/A-beta/A-delta sensory data
• Lateral Spinal Nucleus (LSN) (lateral horn, relay in unmyelinated pathways between the periphery and brain, intersegmental integrator); sensory, spinohypothalamic tract/spinosolitary tract; A-delta/C sensory data

• sensory:*

• Marginal Nucleus (MN), Apex of Posterior Horn, Nucleus Posteromarginalis - LI (A-delta/C, somatic sensory, non-modulatable pain and temperature sensations, joint nociception); sensory, tract of Lissauer/spinomesencephalic tract; modulatory, dorsolateral tract (from RVM); interneurons from SG; interneurons to NPR,IML; A-delta/C sensory data
• Substantia Gelatinosa (SG), Rolando's Substance - LII (C, somatic sensory, short - pain, temperature, long - mechanoreceptors; long inhibits short); sensory, tract of Lissauer; modulatory, dorsolateral fasciculus (from VTA); interneurons to MN, CLN; C sensory data
• Nucleus Proprius (NPR), Main Sensory Nucleus, Proper Sensory Nucleus - LIII,LIV (A-beta, visceral sensory, crude and pressure, 2-point discrimination, vibration); sensory: lateral spinothalamic tract/spinocervical tract/spinotectal tract/spinoolivary tract; A-alpha-Ib/A-beta/A-delta sensory data
• Clarke's Nucleus (CLN), Nucleus Dorsalis, Posterior Thoracic Nucleus, Clarke's Column - LV, LVI (A-alpha/A-delta, visceral sensory, secondary visceral afferents, unconscious proprioception): sensory, tract of Lissauer/anterior spinothalamic tract/spinoreticular tract/dorsal spinocerebellar tract; interneurons from SG, NPR; A-alpha-Ia/A-alpha-Ib/A-delta sensory data
• *Central Nucleus* (unconscious proprioception)

* Central Cervical Nucleus (CCN) - LVII (spinocerebellar sensory, relays neck proprioception to cerebellum, locomotion); sensory, spinoolivary tract/spinovestibular tract; A-alpha-Ia/A-alpha-Ib sensory data
* Centrobasalis Nucleus (CBN) - LVII (spinocerebellar sensory, relays forelimb proprioception to cerebellum); sensory, rostral spinocerebellar tract; A-alpha-Ia sensory data

• Intermediomedial Nucleus (IMM) - LVII (visceral sensory); sensory, ventral spinocerebellar tract; A-alpha-Ia sensory data

• motor:*
• *Medial Motor Nuclei* (axial muscles motor neurons)

* Posteromedial Nucleus (PMN), Dorsomedial Nucleus - LIX (axial trunk flexors, T1-L2); flexor motor, lateral vestibulospinal tract/medullary reticulospinal tract; A-alpha-Ia/A-beta/A-gamma motor data
* Ventromedial Nucleus (VMN), Anteromedial Nucleus - LVIII (axial trunk extensors, inhibit flexors, all segments); extensor motor, ventral corticospinal tract; A-alpha-Ia/A-beta/A-gamma motor data

• *Lateral Motor Nuclei* (distal muscles motor neurons)

* Posterolateral Nucleus (PLN), Dorsolateral Nucleus - LIX (distal flexors, C4-C8/L2-S1, hand/leg, distal muscles of forearm, hand, leg, foot); flexor/extensor motor, lateral corticospinal tract/rubrospinal tract/lateral vestibulospinal tract; A-alpha-Ia/A-gamma motor data
* Ventrolateral Nucleus (VLN), Anterolateral Nucleus - LIX (distal extensors, C4-C8/L2-S1, shoulder/hip, distal muscles of shoulder girdle, arm, hip, thigh); extensor motor, pontine reticulospinal tract; A-alpha-Ia/A-gamma motor data
* Spinal Accessory Nucleus (SAN) - LIX (neck, control neck to rotate head); flexor motor, tectospinal tract/medial vestibulospinal tract; A-alpha-Ia/A-beta/A-gamma motor data
* Phrenic Nucleus (PHN) - LIX (diaphragm, conscious and autonomic control of breathing); visceral motor, ventral corticospinal tract; autonomic motor, solitariospinal tract; A-alpha-Ia/A-beta/A-gamma motor data
* Retroposterolateral Nucleus (RPL), Retrodorsolateral Nucleus - LIX (fingers, C8-T1/S1-S3, distal large motor neurons to small arm and leg finger muscles); flexor motor, lateral corticospinal tract/rubrospinal tract; A-alpha-Ia/A-gamma motor data

• Onuf's Nucleus (ONN), Gert's Nucleus, Lumbosacral Nucleus - LIX (dorsomedial: urination, dorsolateral: defecation, external sphincters; orgasmic muscular contractions); flexor motor, dorsolateral tract; interneurons from Sacral Parasympathetic Nucleus; A-alpha-Ia/A-gamma motor data
• Dorsal Commissural Nucleus (DCN) - LX (integrate direct/indirect excitatory and inhibitory fast inputs, modulate by slow excitatory responses); interneurons from Intermediolateral Nucleus

• autonomic:*
• *Intermediolateral Cell Column*, Intermediate Zone:

* Intermediolateral Nucleus (IML) - LVII (autonomic, visceral structures); sympathetic, visceral motor; dorsolateral tract; interneurons from Marginal Nucleus; B motor data
* Ciliospinal Center (CSC) - LVII (autonomic, visceral structures); sympathetic motor, tectospinal tract/hypothalamospinal tract; B motor data
* Sacral Parasympathetic Nucleus (SPS) - LVII (S1-S3, psym. to large intestine; pelvic nerve); sympathetic motor, dorsolateral tract; interneurons to Onuf's Nucleus; B motor data

SPINAL CORD LAMINAE AND LEVELS

(generated)

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

SUBCORTICAL SENSORY SYSTEMS

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

SPINAL CORD CONNECTIVITY

SPINAL CORD TRACTS

• ASCENDING*:

• *dorsal column*, posterior column, medial lemniscus (well-localized discriminative fine touch and proprioception, alpha/beta mechanoreceptors, conscious):

* *fasciculus gracilis*, tract of Goll (A-beta, tactile and pressure, thoracic-toward-contralateral and cervical slices): receptors of thoracic and lower limbs to Dorsal Root Ganglion (N1) to BrainRegionBMA_HM_GR Gracile Nucleus (N2) to BrainRegionSMA_FD_TH_VPL Ventral Posterolateral Nucleus (N3) to BrainRegionSMA_NC_PG_S1 Somatosensory Cortex (BA 3b)
* *fasciculus cuneatus*, tract of Burdach (A-beta, fine touch, fine pressure, vibration, and proprioception, sacral-toward-contralateral and lumbar slices): receptors of C1-T6 dermatomes to Dorsal Root Ganglion (N1) to BrainRegionBMA_HM_CU Cuneate Nucleus (N2) to 
 * Ventral Posterolateral Nucleus (neck, trunk, and extremities) (N3) to BrainRegionSMA_NC_PG_S1 Somatosensory Cortex (BA 3b)
 * Ventral Posteromedial Nucleus (head) (N3) to BrainRegionSMA_NC_PG_S1 Somatosensory Cortex (BA 3b)

• *dorsolateral column*, dorsolateral fasciculus, dorsolateral funiculus:

* *tract of Lissauer*, fasciculus of Lissauer, tract/zone of Lissauer (DLF, intraspinal, discriminative pain and temperature information - location, intensity and quality)
 * A-delta (fast, pain duration equals to stimulus duration) pain fibers to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_MG Marginal Nucleus (N2) to BrainRegionBMA_SC_LH_LCV Lateral Cervical Nucleus (N3) (initial sharp localization of pain) to:
  * Gracile Nucleus (from medial LSN) (N3) to fasciculus gracilis
  * Cuneate Nucleus (from lateral LSN) (N3) to fasciculus cuneatus
 * C (slow, pain duration exceeds simulus duration, substance P) pain fibers to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_SG Substantia Gelatinosa (N2) to BrainRegionBMA_SC_PH_CL Clarke's Nucleus to anterior spinothalamic tract
* *spinocervical tract*, Morin's tract: A-alpha,A-beta receptors (static position, Ruffini endings) to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_NP Nucleus Proprius (N2) to BrainRegionBMA_SC_LH_LCV Lateral Cervical Nucleus (N3) to 
 * Periaqueductal Gray Matter
 * Ventral Posterolateral Nucleus (N4) to neocortex

• *lateral sensory tracts*:

* *anterolateral system*:
 * *spinothalamic tract* (STT, conscious):
  * *trigeminothalamic tract*, neospinothalamic tract (TTT):
   * head, face and intraoral structures nociceptors to Trigeminal Ganglion (N1) to BrainRegionHMA_HM_TGM_STR Spinal Trigeminal Nucleus (N2) to BrainRegionSMA_FD_TH_VPM Ventral Posteromedial Nucleus (N3) to BrainRegionSMA_NC_PG_S1 Somatosensory Cortex (BA 1,2)
   * nociceptors of cranial nerves 7,9,10 to Trigeminal Ganglion, BrainRegionAVA_PN_SG_JUG Jugular Ganglion, BrainRegionAVA_PN_SG_NOD Nodose Ganglion (N1) to spinal trigeminal nucleus (N2) to BrainRegionSMA_FD_TH_VPM Ventral Posteromedial Nucleus (N3) to BrainRegionSMA_NC_PG_S1 Somatosensory Cortex (BA 1,2)
   * C-fibers of face dull, burning pain, deep, aching pain, temperature and crude touch to Principal Trigeminal Nucleus (N1) to BrainRegionHMA_HM_TGM_STR Spinal Trigeminal Nucleus (N2) to BrainRegionBGA_FD_TH_CM Centromedian Nucleus of Thalamus and BrainRegionBGA_FD_TH_PF Parafascicular Nucleus of Thalamus (N3) to BrainRegionSMA_NC_PG_S1 Somatosensory Cortex (BA 3)
  * *paleospinothalamic tract* (cervical-anterior-toward-contralateral, thoracic, lumbar, sacral-lateral slices):
   * *anterior spinothalamic tract*, anterolateral tract (ASTT, both sides, non-discriminative touch & pressure): tract of Lissauer to Substantia Gelatinosa to BrainRegionBMA_SC_PH_CL Clarke's Nucleus (N1) to BrainRegionSMA_FD_TH_VPL Ventral Posterolateral Nucleus (N2) to BrainRegionSMA_NC_PG_S1 Somatosensory Cortex
   * *lateral spinothalamic tract* (LSTT, pain & thermal sense-temperature): free nerve endings (pain and temperature, A-delta/C fibers) to Dorsal Root Ganglion (N1) to 
    * Marginal Nucleus (N2) to 
     * Ventral Posteroinferior Nucleus (N3) to BrainRegionPHA_NC_INS_PIC Posterior Insular Cortex
     * Mediodorsal Nucleus of Thalamus (N3) to BrainRegionCGA_NC_DACG Dorsal Anterior Cingulate Area
     * Nucleus Proprius (N3) to BrainRegionSMA_FD_TH_VPL Ventral Posterolateral Nucleus
 * *spinolimbic pathways*
  * *spinohypothalamic tract*: A-delta,C fibers to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_LH_LSN Lateral Spinal Nucleus (N2) to hypothalamus (endocrine, motivational responses to stimuli):
   * Lateral Nucleus
   * Dorsomedial Hypothalamic Nucleus
   * anterior nuclei
    * Paraventricular Nucleus
    * Suprachiasmatic Nucleus
    * Supraoptic Nucleus
  * *spinomesencephalic tract*: A-delta/C fibers to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_MG Marginal Nucleus (N2) to BrainRegionFBA_MM_PAG Periaqueductal Gray Matter
  * *spinoreticular tract*: free nerve endings (crude touch, temperature, pain, afferent for RF, conscious) to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_CL Clarke's Nucleus (N2) to:
   * Medullary Reticular Formation
   * Pontine Reticular Formation (Gigantocellular Reticular Nucleus, BrainRegionHMA_HP_PRF_RPO Oral Pontine Reticular Nucleus, BrainRegionHMA_HP_PRF_CRF Caudal Pontine Reticular Nucleus) (N3) to BrainRegionBGA_FD_TH_CM Centromedian Nucleus of Thalamus (N4)
   * Cuneiform Nucleus (N3) to BrainRegionBGA_FD_TH_CM Centromedian Nucleus of Thalamus (N4)
  * *spinosolitary tract*: C fibers to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_LH_LSN Lateral Spinal Nucleus (N3) to BrainRegionHMA_HM_SOL Solitary Nucleus
  * *spinotectal tract*: free nerve endings (ST, crude touch, temperature, pain, spinovisual reflexes, head/eye movement toward stimulus source) to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_NP Nucleus Proprius (N2) to BrainRegionMBA_MM_SC_DEEP Deep Superior Colliculus (N3)
 * *spinometencephalic pathways*
  * *spinoolivary tract*, Helweg's tract (SOT, lateral, proprioceptive and cutaneous organs to cerebellum): proprioception information, cutaneous impulses from muscles and tendons to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_NP Nucleus Proprius, BrainRegionBMA_SC_IZ_CCV Central Cervical Nucleus (N2) to BrainRegionBMA_HM_IO Inferior Olivary Nucleus (N3) to BrainRegionMBA_HP_CR Cerebellum (automatic movements of head, neck & upper limb)
  * *spinovestibular tract*: C1-C4,neuromuscular spindles and Golgi tendon organs to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_IZ_CCV Central Cervical Nucleus (N2) to BrainRegionBMA_HP_VB Vestibular Nucleus
* *spinocerebellar tracts* (proprioceptive sensation, subconscious, very lateral slice):
 * *cuneocerebellar tract*: C1-C7,proprioceptive/fine touch/vibration to Dorsal Root Ganglion (N1) to BrainRegionBMA_HM_ACU Accessory Cuneate Nucleus (N2) to BrainRegionMBA_HP_CR Cerebellum
 * *dorsal spinocerebellar tract*, posterior spinocerebellar tract (PSCT): neuromuscular spindles and Golgi tendon organs (trunk and lower limb) to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_CL Clarke's Nucleus (N2) to (unilaterally) BrainRegionMBA_HP_CR Cerebellum
 * *ventral spinocerebellar tract*, anterior spinocerebellar tract, Gower's tract (ASCT): C8-L3,proprioceptive/fine touch/vibration (body, legs) to Dorsal Root Ganglion (N1) to BrainRegionAVA_SC_IZ_IMM Intermediomedial Nucleus (N2) to (bilaterally in C8-L3) BrainRegionMBA_HP_CR Cerebellum (to cortex and globose, emboliform nuclei)
 * *rostral spinocerebellar tract* (RSCT): C8-L3,proprioceptive/fine touch/vibration (body, legs) to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_IZ_CBS Centrobasalis Nucleus (N2) to BrainRegionMBA_HP_CR Cerebellum (bilaterally)

• DESCENDING*:

• *dorsolateral tract*, posterolateral tract

* Periaqueductal Gray Matter (N1) to 
 * RVM (Raphe Nucleus of Medulla, BrainRegionHMA_HP_PRF_GCR Gigantocellular Reticular Nucleus) (N2) to BrainRegionBMA_SC_PH_MG Marginal Nucleus (N3) (inhibit pain, serotonine)
 * Barrington's Nucleus (N2) to BrainRegionAVA_SC_IZ_SPS Sacral Parasympathetic Nucleus, BrainRegionAVA_SC_VH_ONF Onuf's Nucleus (N3) to colon, rectum, bladder, penis, vagina
* Ventral Tegmental Area (N1) to BrainRegionBMA_SC_PH_SG Substantia Gelatinosa (N2) (inhibit pain, dopamine, reward, placebo)
* Locus Coeruleus (N1) to BrainRegionAVA_SC_IZ_IML Intermediolateral Nucleus (N2) (inhibit pain, norepinephrine - physiological responses to stress and panic)

• *lateral motor tracts*:

* *lateral corticospinal tract* (LCST, flexor motor, pyramidal tract, conscious, cervical-medial, thoracic, lumbar-lateral, distal muscles, decussating to contralateral and ipsilateral): cortex BA 1-4,6 (N1) to
 * Retroposterolateral Nucleus (N2) to distal limb finger muscles
 * Posterolateral Nucleus interneuron to motoneuron (N2-N3) to distal limb flexors muscles
* *rubrospinal tract*, tract of Monakow (flexor motor, upper limbs, subconscious): Red Nucleus (magnocellular neurons) (N1) to (mediation of voluntary movement by cerebelum):
 * Retroposterolateral Nucleus (N2) to distal limb finger muscles
 * Posterolateral Nucleus (N2) to distal limb flexors muscles
* *solitariospinal tract*: (subconscious motor tract, see http://www.slideshare.net/LawrenceJames/regulation-of-respiration, from corticobulbar, corticonuclear tract)
 * Solitary Nucleus (autonomic respiration, start) (N1) to BrainRegionHMA_HM_AMB Ambiguus Nucleus, BrainRegionHMA_HM_RA Retroambiguus Nucleus (expiratory cencer, active when forced breathing) (N2) to nucleus ambiguus (inspiratory center) (N3) to
  * Phrenic Nucleus (N4) to diaphragm, intercostal nerves to intercostal muscles
 * Parabrachial Nucleus (pacemaker, controls rate and pattern of breathing) (N1) to BrainRegionHMA_HM_AMB Ambiguus Nucleus (N2) to 
  * Phrenic Nucleus (N3) to diaphragm, intercostal nerves to intercostal muscles

• *ventral motor tracts*:

* *ventral corticospinal tract*, anterior/medial corticospinal tract, direct pyramidal tract, anterior cerebrospinal fasciculus (VCST, extensor motor, pyramidal tract, conscious, axial, proximal muscles, ipsilateral): cortex BA 1-4,6 (N1) to:
 * Posteromedial Nucleus (N2) to axial muscles
 * Phrenic Nucleus (N2) to diaphragm, intercostal nerves to intercostal muscles
* *lateral vestibulospinal tract* (LVST, flexor motor, anti-gravity muscles, lateral, inferior, trunk/legs extensors, arm flexors, subconscious): Vestibular Nucleus (giant cells of Deiters) (N1) to 
 * Ventromedial Nucleus (N2) to trunk and ipsilateral limbs
 * Posterolateral Nucleus (N2) to arms, legs (modulates muscle tone to maintain equilibrium)
* *tectospinal tract*, colliculospinal tract (TST, flexor motor, reflex postural movementa - coordinate head, neck, and eye movements by visual and auditory stimuli): Deep Superior Colliculus (N1) to 
 * Spinal Accessory Nucleus (C1-C4) (N2) to axial muscles of neck
 * Ciliospinal Center (N2) to BrainRegionAVA_PN_SYM_SCG Superior Cervical Ganglion (N3) to muscles of iris
* *reticulospinal tract* (RST, extensor motor, control by hypothalamus of sympathetic and sacral parasympathetic outflow, subconscious):
 * *medullary reticulospinal tract*, lateral reticulospinal tract (LRST, flexor motor, inhibiting excitatory axial extensor muscles of movement, excite flexors): 
  * Gigantocellular Reticular Nucleus (N1) to BrainRegionBMA_SC_VH_PL Posterolateral Nucleus (N2) to distal muscles (exciting anti-gravity, inhibit stretch reflexes)
  * Caudal Pontine Reticular Nucleus (N1) to BrainRegionBMA_SC_VH_PM Posteromedial Nucleus (N2) to axial muscles
  * Oral Pontine Reticular Nucleus (N1) to BrainRegionBMA_SC_VH_PM Posteromedial Nucleus (N2) to axial muscles
 * *pontine reticulospinal tract*, medial reticulospinal tract (MRST, extensor motor, facilitates flexor spinal reflexes): 
  * Medullary Reticular Formation (N1) to BrainRegionBMA_SC_VH_VL Ventrolateral Nucleus (N2) to distal muscles (extensor muscles)
 * *hypothalamospinal tract*, oculosympathetic pathway (HTST, sympathetic motor): Paraventricular Nucleus (N1) to BrainRegionVBA_SC_IZ_CSC Ciliospinal Center (N2) to BrainRegionAVA_PN_SYM_SCG Superior Cervical Ganglion (N3) to dilator muscle of iris
* *medial longitudinal fasciculus* (MLF): 
 * *medial vestibulospinal tract* (MVST, extensor motor, subconscious): 
  * Vestibular Nucleus (medial) (N1) to 
   * Spinal Accessory Nucleus (N2) to neck muscles (ensures neck and trunk movements coordinated with eye movements)
   * Abducens Nucleus to BrainRegionVBA_MM_OCN Oculomotor Nucleus to muscles of eye
   * Oculomotor Nucleus to muscles of eye
   * Trochlear Nucleus to muscles of eye
  * Cajal Nucleus to BrainRegionVBA_MM_OCN Oculomotor Nucleus to muscles of eye

• INTRASPINAL*:

• A-alpha receptors to Dorsal Root Ganglion (N1) to

* alpha motor neurons (N2) to the same agonist muscles (myotatic/stretch reflex to support increased load)
* Substantia Gelatinosa GABA interneurons (N2) to alpha motor neurons (N3) to antagonist muscles (reciprocal inhibition in stretch reflex)

• A-delta receptors to Dorsal Root Ganglion (N1) to

* Marginal Nucleus (N2) to BrainRegionBMA_SC_PH_NP Nucleus Proprius
* Nucleus Proprius

• C receptors to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_SG Substantia Gelatinosa (interneurons) (N2) to

* Marginal Nucleus 
* Clarke's Nucleus

• viscerosensory information to Dorsal Root Ganglion (N1) to BrainRegionBMA_SC_PH_MG Marginal Nucleus (N2) to BrainRegionAVA_SC_IZ_IML Intermediolateral Nucleus (IML) to white rami (sympathetic tract, preganglionic fibers)
• Sacral Parasympathetic Nucleus to BrainRegionAVA_SC_VH_ONF Onuf's Nucleus
• C fibers of intestine and bladder to Dorsal Root Ganglion (N1) to BrainRegionAVA_SC_VH_ONF Onuf's Nucleus (N3) to BrainRegionAVA_SC_IZ_SPS Sacral Parasympathetic Nucleus (N4) to

* Pelvic Peripheral Ganglion (bladder ganglion) (N5) to detrusor muscle of bladder (via pelvic nerve, excite bladder, relax uretra)
* colon, rectum

• A-delta/C sacral fibers to Dorsal Root Ganglion (N1) to BrainRegionAVA_SC_IZ_IML Intermediolateral Nucleus (N2) to BrainRegionAVA_SC_CC_DCN Dorsal Commissural Nucleus (N3) to

* hypogastric nerve
* Pelvic Peripheral Ganglion

SENSORY NUCLEI CONNECTED TO SPINAL CORD

• *Forebrain Telencephalon*

* Somatosensory Cortex - sensory, fasciculus cuneatus/fasciculus gracilis/trigeminothalamic tract/anterior spinothalamic tract
* Posterior Insular Cortex - sensory, lateral spinothalamic tract
* Dorsal Anterior Cingulate Area - sensory, lateral spinothalamic tract

• *Forebrain Diencephalon*

* *Hypothalamus*
 * Dorsomedial Hypothalamic Nucleus - sensory, spinohypothalamic tract
 * Lateral Nucleus - sensory, spinohypothalamic tract
 * Preoptic Area - sensory, spinohypothalamic tract
 * Suprachiasmatic Nucleus - sensory, spinohypothalamic tract
 * Supraoptic Nucleus - sensory, spinohypothalamic tract
* *Thalamus*
 * Centromedian Nucleus of Thalamus - sensory, trigeminothalamic tract/spinoreticular tract
 * Mediodorsal Nucleus of Thalamus - sensory, lateral spinothalamic tract
 * Parafascicular Nucleus of Thalamus - sensory, trigeminothalamic tract
 * Ventral Posteroinferior Nucleus - sensory, lateral spinothalamic tract
 * Ventral Posterolateral Nucleus - sensory, fasciculus cuneatus/fasciculus gracilis/spinocervical tract/anterior spinothalamic tract
 * Ventral Posteromedial Nucleus - sensory, fasciculus cuneatus/trigeminothalamic tract

• *Midbrain Mesencephalon*

* Cuneiform Nucleus - sensory, spinoreticular tract
* Periaqueductal Gray Matter - sensory, spinocervical tract/spinomesencephalic tract

• *Hindbrain Metencephalon*

* Cerebellum - sensory, cuneocerebellar tract/dorsal spinocerebellar tract/ventral spinocerebellar tract/rostral spinocerebellar tract/spinoolivary tract
* Principal Trigeminal Nucleus - sensory, trigeminothalamic tract

• *Hindbrain Myelencephalon*

* Accessory Cuneate Nucleus - sensory, cuneocerebellar tract
* Cuneate Nucleus - sensory, tract of Lissauer/fasciculus cuneatus
* Gracile Nucleus - sensory, tract of Lissauer/fasciculus gracilis
* Inferior Olivary Nucleus - sensory, spinoolivary tract
* Spinal Trigeminal Nucleus - sensory, trigeminothalamic tract/trigeminothalamic tract

MOTOR NUCLEI CONNECTED TO SPINAL CORD

• *Forebrain Telencephalon*

* *neocortex, BA 1-4,6* - motor, lateral corticospinal tract/ventral corticospinal tract

• *Midbrain Mesencephalon*

* Cajal Nucleus - motor, medial longitudinal fasciculus
* Oculomotor Nucleus - motor, medial longitudinal fasciculus
* Red Nucleus - motor, rubrospinal tract
* Trochlear Nucleus - motor, medial longitudinal fasciculus
* Ventral Tegmental Area - modulatory, dorsolateral fasciculus

• *Hindbrain Metencephalon*

* Abducens Nucleus - motor, medial longitudinal fasciculus
* Locus Coeruleus - modulatory, dorsolateral fasciculus
* Parabrachial Nucleus - motor, solitariospinal tract

• *Hindbrain Myelencephalon*

* *Expiratory Center*
 * Ambiguus Nucleus - motor, solitariospinal tract
 * Retroambiguus Nucleus - motor, solitariospinal tract
* Raphe Nucleus of Medulla - modulatory, dorsolateral fasciculus

NUCLEI RECIPROCALLY CONNECTED TO SPINAL CORD

• *Forebrain Diencephalon*

* *Hypothalamus*
 * Paraventricular Nucleus - sensory, spinohypothalamic tract; modulatory, hypothalamospinal tract

• *Midbrain Mesencephalon*

* Deep Superior Colliculus - sensory, spinotectal tract; motor, tectospinal tract

• *Hindbrain Metencephalon*

* Barrington's Nucleus - sensory, dorsolateral fasciculus; motor, dorsolateral fasciculus
* *Pontine Reticular Formation*
 * Gigantocellular Reticular Nucleus - sensory, spinoreticular tract; modulatory, dorsolateral fasciculus; motor, pontine reticulospinal tract
 * Oral Pontine Reticular Nucleus - sensory, spinoreticular tract; motor, pontine reticulospinal tract
 * Caudal Pontine Reticular Nucleus - sensory, spinoreticular tract; motor, pontine reticulospinal tract
* Vestibular Nucleus - sensory, spinovestibular tract; motor/modulatory, medial longitudinal fasciculus/lateral vestibulospinal tract/medial vestibulospinal tract

• *Hindbrain Myelencephalon*

* Medullary Reticular Formation - sensory, spinoreticular tract; motor, medullary reticulospinal tract
* Solitary Nucleus - sensory, spinosolitary tract; motor, solitariospinal tract

GANGLIA CONNECTED TO SPINAL CORD

• Dorsal Root Ganglion (DRG): sensory, all tracts except medial longitudinal fasciculus/trigeminothalamic tract; A-alpha-Ia/A-alpha-Ib/A-beta/A-delta/C sensory data
• Inferior Mesenteric Ganglion (IMG): motor, sympathetic
• Jugular Ganglion (JUG): sensory, trigeminothalamic tract; A-beta/A-delta/C sensory data
• Nodose Ganglion (NDG): sensory, trigeminothalamic tract; A-beta/A-delta/C sensory data
• Pelvic Peripheral Ganglion: intraspinal; B/C motor data
• Superior Cervical Ganglion (SCG): motor, tectospinal tract; modulatory, hypothalamospinal tract; B/C motor data
• Trigeminal Ganglion (TRG): sensory, trigeminothalamic tract; A-alpha-Ia/A-alpha-Ib/A-beta/A-delta/C sensory data

FUNCTIONAL GROUPS

SENSORY NUCLEI FROM DRG TO VPL/VPM

• DRG -> Cuneate Nucleus -> VPL - upper body
• DRG -> Gracile Nucleus -> VPL - lower body
• DRG -> Principal Trigeminal Nucleus -> VPM - head and face

SENSORY NUCLEI FROM SPINAL CORD TO VPL/VPM

• DRG -> Spinal Trigeminal Nucleus -> VPM - head and face deep pain/temperature
• DRG -> Marginal Nucleus -> VPL - fast pain/temperature
• DRG -> Substantia Gelatinosa -> VPL - slow pain/temperature

SENSORY NUCLEI FROM SPINAL CORD TO CR

• DRG.CX -> Accessory Cuneate Nucleus -> CR - upper extremity (to C7)
• DRG.TX,LX -> Clarke's Nucleus -> CR - from C8

INTERSPINAL SENSORY TO MOTOR

• vessel/gland (GVA) -> DRG -> Substantia Gelatinosa -> BrainRegionAVA_SC_IZ_IML Intermediolateral Nucleus -> (GVE) vessel/gland
• muscle (GSA) -> DRG -> Posteromedial Nucleus/BrainRegionBMA_SC_VH_VM Ventromedial Nucleus/BrainRegionBMA_SC_VH_PL Posterolateral Nucleus/BrainRegionBMA_SC_VH_VL Ventrolateral Nucleus -> (GSE) muscle
• muscle (GSA) -> DRG -> Substantia Gelatinosa -> BrainRegionBMA_SC_VH_PM Posteromedial Nucleus/BrainRegionBMA_SC_VH_VM Ventromedial Nucleus/BrainRegionBMA_SC_VH_PL Posterolateral Nucleus/BrainRegionBMA_SC_VH_VL Ventrolateral Nucleus -> (GSE) muscle