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nerves_autonomic

Anatomy of the autonomic nervous system

Parasympathetic (P/S):

  • NB. No P/S fibres to limbs, gonads or suprarenal glands!

Efferent fibres:

Cranial
  • III: pregang. bodies in E-W oculomotor nuclei → ciliary ganglion;
  • VII: pregang. bodies in inf & sup. salivary nuclei → pterygopalatine ganglion;
  • IX: pregang. bodies in salivary nuclei? → otic ganglion;
  • X: pregang. bodies in dorsal motor nucleus of the vagus nerve and vagal tone
    • ⇒ terminal ganglia near/in target
    • ie. in walls of heart, lungs, gut;
Sacral
  • 2,3,4: pregang. bodies in lat. grey horns S2-4 → pelvic splanchnic Nn
    • ⇒ inf. hypogastric plexus (pelvic plexus as with symp.)
    • → pelvic viscera via blood vessels or retroperitoneally with post-gang.
    • cell bodies in visceral walls as for vagus:
      • ⇒ supply GIT distal to L colic flexure
      • ⇒ bladder, penis erection;

Parasympathetic afferents:

  • glossopharyngeal N & vagus N: cell bodies in inf. ganglia of those nerves
  • pelvic splanchnic nerves: cell bodies in post. root ganglia of S2-4
  • similar to symp.afferents
Cranial parasympathetic ganglia detail:
  • only contain:
    • cell bodies for post-gang. p/s efferents
    • fibres in transit:
      • sensory from trigeminal ganglion cell bodies
      • sympathetic from vascular plexuses
      • afferents?
  • Ciliary ganglion:
    • p/s root: from Edinger-Westphal part of oculomotor nucleus
      • via branch of inf. division of oculomotor nerve
    • sensory root: from branch of nasociliary nerve
    • symp. root: from internal carotid plexus
    • branches: short ciliary N to eye
  • Pterygopalatine:
    • p/s root: from sup. salivary nucleus
      • ⇒ N. intermedius part of facial N
      • ⇒ N. of pterygoid canal (with symp. roots)
    • sensory root: from branch of maxillary N
    • symp.root: from int. carotid N → deep petrosal N
      • ⇒ N. of pterygoid canal
    • branches:
      • zygomatic & lacrimal Ns → lacrimal gland
      • maxillary N branches
        • ⇒ mucous glands of nose, nasopharynx & palate
      • greater petrosal N → taste (palate)
    • NB. cell bodies in geniculate ganglion of facial N!!
  • Submandibular:
    • p/s root: from sup. salivary nucleus
      • ⇒ N. intermedius part of facial N
      • ⇒ chorda tympani → joining lingual N
    • sensory root: branch of lingual N
    • symp. root: via facial artery plexus
    • branches: branches of lingual N → submand/sublingual glands
  • Otic:
    • p/s root: inf. salivary nuclei → glossopharyngeal N
      • ⇒ tympanic branch → tympanic plexus
      • ⇒ lesser petrosal N
    • sensory: auriculotemporal N
    • symp. root: via mid. meningeal artery plexus
    • SOMATIC MOTOR ROOT: from N. to med. pterygoid
    • branches:
      • auriculotemporal N filaments → parotid gland
      • somatic motor → tensor tympani & tensor palati

Sympathetic:

Efferents:

  • Pregang. cell bodies in lat.horn cells of T1 → L2 spinal segments
    • ⇒ white myelinated fibres to paravert. symp. ganglia via white rami communicans
    • ⇒ cell bodies post-gang. in either:
      • symp. (paravertebral) trunk
      • collateral ganglia eg. coeliac ganglia
      • suprarenal gland (modified ganglia)
paravert. ganglia efferent fibres (mostly post-gang. grey unmyelinated) pass via:
  • grey rami communicans to spinal N - ALL limb symp. fibres
  • visceral or splanchnic branches to visceral plexuses
    • (cardiac/coeliac/pelvic)
  • vascular branches to form plexuses on major arteries
    • (int&ext.carotid/aorta)
  • NB. NO sympathetics hitchhike on arteries to limb targets
Spinal level of pre-gang. cell bodies:
  • T1-3 → sup. cervical ganglion (C1-4 position) → H&N
    • ⇒ int.carotid N & plexus
    • ⇒ through p/s ciliary ganglion (see above)
    • ⇒ deep petrosal N → N of pterygoid canal
    • ⇒ through pterygopalatine p/s ganglion (above)
    • ⇒ ext. carotid N & plexus
    • ⇒ facial artery plexus
    • ⇒ through submandibular p/s ganglion (above)
    • ⇒ middle meningeal artery plexus
    • ⇒ through otic p/s ganglion (above)
  • T2-7 → upper T, inf & middle Cx paravertebral ganglia
    • ⇒ upper limb; HENCE T2-3 ganglia destroyed in Cx sympathectomy.
    • ⇒ cardiac visceral branches
    • ⇒ cardiac plexus (T1-5) - joined by p/s vagal fibres
    • ⇒ coronary part - vasomotor to coronary arteries
    • ⇒ cardiac part - SA & AV nodes, bundle, myocardium
    • ⇒ pulmonary part (pulm. plexus) ⇒ lung (T2-7);
    • ⇒ oesoph. (T4-6);
    • ⇒ vascular branches to carotids as above??
  • T5-12 → lower thoracic paravetebral ganglia
    • ⇒ 3 splanchnic nerves which pierce the diaphragm → coeliac plexus
      • greater splanchnic N (T5-10)
        • ⇒ stomach/liver/panc.(T6-10)
        • ⇒ gall bladder (T4-10);
        • ⇒ small intestine (T8-11);
      • lesser spl. N (T10,11)
        • ⇒ prox.colon → L.flex.(T10-L1)
      • lowest spl. N (T12)
  • T10-L2 → upper lumbar paravertebral ganglia
    • ⇒ 4 lumbar splanchnic Nn → sup. & R&L inf. hypogastric plexuses which are together called the plevic plexus
    • ⇒ distal colon → rect. (L1-2)
    • ⇒ suprarenal gland (T10-L2)
    • ⇒ kidney (T11-L2), ureter (L1-2), via renal plexus?
    • ⇒ bladder trigone, ejacul.(T11-L2)
    • ⇒ vascular branches to common iliac art & med. sacral artery
  • L2-S3 paravertebral ganglia
    • ⇒ lower limb HENCE L3/4 ganglia destroyed in Lx sympathectomy.
  • sacral paravertebral ganglia
    • ⇒ sacral splanchnic nerves (NOT pelvic splanchnic nerves - P/S!!)
    • ⇒ pelvic plexus as above.
    • ⇒ vascular branches to lat & med sacral arteries
Sympathetic Afferent fibres (unconscious reflexes, visceral pain - all white):
  • from sensory end travel to paravert. ganglia then via white rami communicans to cell body in post. root ganglia of spinal nerve with the cell's central process then passing either:
    • to synapse with interneurons in spinal cord as part of a reflex arc
    • ascend to hypothalamus, etc
    • pass up spinal cord as for somatic pain afferents (visceral pain fibres)
  • Hence, whereas grey rami communicans carry ONLY post-ganglionic efferents and occur on ALL paravertebral ganglia, white rami communicans carry a mix of pregang. efferents and afferents, and occur ONLY on T1-L2 ganglia.
nerves_autonomic.txt · Last modified: 2015/05/27 15:06 (external edit)