Rami Communicans

Ramus communicans (plural rami communicantes) is the term used for a nerve which connects two other nerves.

When used without further definition, it almost always refers to a communicating branch between a spinal nerve and the sympathetic trunk. More specifically, it usually refers to one of the following:

  • Gray ramus communicans
  • White ramus communicans
Nerves – autonomic nervous system (sympathetic nervous system/ganglion/trunks and parasympathetic nervous system/ganglion) (TA A14.3, GA 9.968)
Head/
cranial
Sympathetic
  • Ciliary ganglion: roots
    • Sensory
    • Sympathetic
  • Short ciliary
Parasympathetic
  • Ciliary ganglion: roots
    • Sensory
    • Parasympathetic
  • Short ciliary
  • Pterygopalatine ganglion: deep petrosal
  • nerve of pterygoid canal
  • branches of distribution: greater palatine
    • inferior posterior nasal branches
  • lesser palatine
  • nasopalatine
    • medial superior posterior nasal branches
  • pharyngeal
  • Submandibular ganglion
  • Otic ganglion
Neck/
cervical
Sympathetic
  • paravertebral ganglia: Cervical ganglia
    • Superior
    • Middle
    • Inferior
  • Stellate ganglion
  • prevertebral plexus: Cavernous plexus
  • Internal carotid
Chest/
thorax
Sympathetic
  • paravertebral ganglia: Thoracic ganglia
  • prevertebral plexus: Cardiac plexus
  • Esophageal plexus
  • Pulmonary plexus
  • Thoracic aortic plexus
  • splanchnic nerves: cardiopulmonary
  • thoracic
  • cardiac nerves: Superior
  • Middle
  • Inferior
Abdomen/
Lumbar
Sympathetic
  • paravertebral ganglia: Lumbar ganglia
  • prevertebral ganglia:
    • Celiac ganglia
    • Aorticorenal
  • Superior mesenteric ganglion
  • Inferior mesenteric ganglion
  • prevertebral plexus:
  • Celiac plexus
    • Hepatic
    • Splenic
    • Pancreatic
  • aorticorenal
    • Abdominal aortic plexus
    • Renal/Suprarenal
  • Superior mesenteric
    • Gastric
  • Inferior mesenteric
    • Spermatic
    • Ovarian
  • Superior hypogastric
    • hypogastric nerve
    • Superior rectal
  • Inferior hypogastric
    • Vesical
    • Prostatic / Cavernous nerves of penis
    • Uterovaginal
    • Middle rectal
  • splanchnic nerves: Lumbar splanchnic nerves
Enteric
  • Meissner's plexus
  • Auerbach's plexus
Pelvis/
sacral
Sympathetic
  • paravertebral ganglia: Sacral ganglia
  • Ganglion impar
  • splanchnic nerves: Sacral splanchnic nerves
Parasympathetic
  • splanchnic nerves: Pelvic splanchnic nerves

M: PNS

anat (h/r/t/c/b/l/s/a)/phys (r)/devp/prot/nttr/nttm/ntrp

noco/auto/cong/tumr, sysi/epon, injr

proc, drug (N1B)

Histology: nervous tissue (TA A14, GA 9.849, TH H2.00.06, H3.11)
CNS
General Grey matter · White matter (Projection fibers · Association fiber · Commissural fiber · Lemniscus · Funiculus · Fasciculus · Decussation · Commissure) · meninges
Neuroglia

Myelination: Oligodendrocyte

Astrocyte (Radial glial cell) · Ependymal cells (Tanycyte) · Microglia
Other

Pyramidal · Purkinje · Granule

Neuropil
PNS
General Posterior (Root, Ganglion, Ramus) · Anterior (Root, Ramus) · rami communicantes (Gray, White) · Autonomic ganglion (Preganglionic nerve fibers · Postganglionic nerve fibers)
Connective tissues epineurium · perineurium · endoneurium · nerve fascicle
Neuroglia

Myelination: Schwann cell (Neurolemma, Myelin incisure, Myelin sheath gap, Internodal segment)

Satellite glial cell
Neurons/
nerve fibers
Parts

Perikaryon (Axon hillock)

Axon (Axon terminals, Axoplasm, Axolemma, Neurofibril/neurofilament)

Dendrite (Nissl body, Dendritic spine, Apical dendrite/Basal dendrite)
Types Bipolar · Unipolar · Pseudounipolar · Multipolar · Interneuron (Renshaw)
Afferent nerve fiber/
Sensory nerve
GSA · GVA · SSA · SVA
fibers (Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain)
Efferent nerve fiber/
Motor nerve
GSE · GVE · SVE
Upper motor neuron · Lower motor neuron (α motorneuron, γ motorneuron, β motorneuron)
Termination
Synapse Electrical synapse/Gap junction · Chemical synapse (Synaptic vesicle, Active zone, Postsynaptic density) · Ribbon synapse · Neuromuscular junction
Sensory receptors Meissner's corpuscle · Merkel nerve ending · Pacinian corpuscle · Ruffini ending · Muscle spindle · Free nerve ending · Olfactory receptor neuron · Photoreceptor cell · Hair cell · Taste bud

M: CNS

anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp

noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr

proc, drug (N1A/2AB/C/3/4/7A/B/C/D)

M: PNS

anat (h/r/t/c/b/l/s/a)/phys (r)/devp/prot/nttr/nttm/ntrp

noco/auto/cong/tumr, sysi/epon, injr

proc, drug (N1B)