IV. RESULTADOS
4.1. Descripción
4.1.1. Resultados obtenidos de Desempeño Docente
In attempting to elucidate the symptom-complexes ofver
tebral degenerative joint disease, autonomic nerve distri
bution and function, and visceral reflex activity, are of more than passing importance, e.g. in the syndrome of vertebral artery insufficiency, the dysequilibrium and nausea which often accompany upper cervical joint prob
lems, the distressing sequelae of acceleration and decelera
tion trauma, the group of conditions represented by the shoulder-hand syndrome, involvement and entrapment of splanchnic nerves in anterior osteophytes of the thora
columbar spine, and in the cold sciatic leg.
Further, serious disease of thoracic and abdominal viscera can simulate the referred pain of benign vertebral joint problems ; some of these factors are discussed under 'Referred Pain'.
A glance at the intimate involvement of autonomic nerve pathways, sharing the innervation of spinal muscu
loskeletal tissues (Figs 1 . 14-1 . 19) with somatic nerves, will indicate the necessity of understanding this innerva
tion and its implications.
The many descriptions of this innervation are not new.
Simplified mechanical concepts, of the cause and effect of vertebral treatment techniques, are plainly an in
adequate basis for discussion of treatment methods.
While the classical concept is that the autonomic ner
vous system regulates physiological activities at an in
voluntary level, below consciousness, evidence is acCumu
lating that control of some autonomic functions can be learned, both by animals and humans.))2
The autonomic part of the nervous system has acquired a large and steadily growing importance in neurology as well as in several other clinical disciplines ... there is good reason to believe that the autonomic nervous system is involved in producing some of the symptoms in a multitude of diseases which do nO[ primarily affect the system itself. 110
'Autonomic' means operating in isolation, but this is a misnomer since there is the greatest possible integration between the autonomic and the somatic system; the autonomy of the system is non-existent, but the old dis
tinction does have some value in the sense that this division of the nervous system proceeds by itself, yet wholly and intimately related to the rich volume of
afferent traffic from both the somatic and visceral receptors.
The division of the autonomic nervous system into sympathetic and parasympathetic systems rests on the anatomical, functional and pharmacological differences between them.4J1
I. ANATOMICAL
1 . The sympathetic system comprises a demonstrable system of ganglionated trunks with their branches of dis
tribution. The parasympathetic system, like a cuckoo in
F
- - _ _ ' - - - -
9
... .......... , - - - -9
..... .... .... �,I ... , .... , , .... " ' ,' \ \ \
'��
Fig. 2. t 7 Gel/eral plan of autonomic ntrtJous system. On left: Cranial and sacral autonomic (parasympathetic) system. Thick lines from ttl, VII. I X , X , and S.2, 3 are preganglionic (connector) fibres. A , ciliary ganglion; B, sphenopalatine ganglion; C, submaxillary and sublingual ganglia. 0, otic ganglion; E, vagus ganglion cells in nodes of heart; F, vagus ganglion cells in wall of bowel; G, sacral autonomic ganglion cells in pelvis; thin lines beyond = postganglionic (excitor) fibres to organs.
On r ight: Sympathetic nervous system. Dotted lines from T I -12, L t , 2 are preganglionic fibres; H, superior cervical ganglion; J. middle and inferior cervical ganglia (the latter fused with the 1st thoracic ganglion to form the stellate ganglion); K, coeliac and other abdominal ganglia (note preganglionic fibres directly supplying the adrenal medulla); L, lower abdominal and pelvic sympathetic ganglia; continuous lines beyond = postganglionic fibres. (Reproduced, with legend, from Samson Wright'S Applied Physiology, 1971, 12 edn, by kind permission of C. A. Keele and the Oxford University Press.)
APPLIED ANATOMY�ENERAL 65 the nest, utilises cranial and spinal nerves for its pathways, and is therefore difficult to demonstrate.
2. In classical descriptions, sympathetic fibres emerge from the central nervous system via thoracolumbar somatic nerves, i.e. segments T I-L2 (but see p. 10), while parasympathetic fibres emerge via cranial nerves I I I , VII, IX, X and sacral somatic nerves S234, i.e. a cranio-sacral outflow.
3. Sympathetic fibres have short pregangliontc neurones, synapse in proximal paravertebral ganglia, and have long postganglionic fibres. Parasympathetic fibres have long preganglionic neurones, synapse in peripheral ganglia located close to, and often in, the viscus or organs they serve, and thus postganglionic neurones are very short (Fig. 2 . 1 7).
4. Arterioles, glands and arrectores pilorum muscle of the body surface are supplied with sympathetic nerves ; the innervation of various regions of the skin of trunk and limb girdles has the same segmental representation as the splanchnic supply to large viscera. These skin areas are Head's zones of cutaneous hyperalgesia (see p. 178 and 'Referred pain').
There is no parasympathetic supply to the arterioles of skin or to musculoskeletal tissues.
2. FUNCTIONAL OR PHYSIOLOGICAL D IFFERENCES (Table 2.3)
In general terms, the sympathetic nervous system is organised to mobilise the body's resources for rapid ex
penditure of energy in emergencies ('fright, fight, flight'), i[ dilates the eye, bronchi and bronchial vessels, coronary vessels and skeletal muscle vessels, raises pulse rate and thus blood pressure and reduces blood flow for all activi
ties which are, at that time, non-essential, i.e. peristalsis, digestive activity and blood supply to the skin, etc. Blood is therefore diverted for the vital functions. Also there is a widespread discharge of sympathetic impulses during physiological stress, such as : severe muscular work, danger, extreme temperature, asphyxia, rage, haemor
rhage, fear, pain.
Conversely, the parasympathetic system is generally directed to the conservation and restoration of the energy resources of the body, and is organised as the effector for visceral motor systems and, one might say, some of the pleasures of life, distributing blood for the functions of the digestive tube, the skin, and so on.
Further, sympathetic reactions are mass responses of the whole animal, whereas parasympathetic effects are localised reactions, e.g. salivation.
3. THE PHARMACOLOGICAL DI FFERENCES ARE :
1 . The chemical transmitter (except in four cases, i.e.
sweat glands, muscle arterioles, the uterus, the adrenal
66 COMMON VERTEBRAL JOINT PROBLEMS
Table 2.1 Sympathetic
Organs supplied Site of Site of ganglion cells conntttor
cells
Head and neck TI.2 Superior cervical ganglion I . Eye
2. Face
3. Skin of head ..
and neck
4. Cerebral vessels Superior and inferior cervical ganglia
{
SUI"',io" middle and Thoracic viscera T3. 4 inferior cervical ganglia(man,
Stellate: ganglion (animals) Fore: limb T5--9 Middle: and inferior
(sometimes cervical, first and second also 1'2-4) thoncic ganglia (man)
Stellate: ganglion (animals) Hind limb TIQ-L2 Lumbar and sacral ganglia
Abdomen T6-U
I. Viscera of T6-12 Upper abdominal ganglia
abdomen (su�rior mesenteric,
prO�r (chieRy) coeliac, etc.)
{
lnbiO' mesenle,ic ganglia 2. Pelvic viscera L t . 2 (animals)(chiefly) Hypogastric ganglia (man)
Thoracic and TH2 Ganglia of lateral abdominal pariefes sympathetic chain
Route of postganglionic fib ...
Along internal carOlid arlC�ry Along external carotid arlcry With cervical plexus Along internal carotid and
\'c:rtc:bral artcries Cardiac branches of sympathetic
With brachial plexus
With lumbosacral plexus
Along blood vessels
Along blood vessels and in hypogastric nerves
With intercostal nerves
Tables 2.1-2.3 arc reproduced from Samson Wright'S Applied Physiology, 1971, 1 2 edn, by kind permission of C. A. Keele and the Oxford University Press.
gland itself) at postganglionic sympathetic nerve endings is noradrenalin, consequently they are 'adrenergic' end
ings, while that liberated by parasympathetic postgan
glionic endings is acetycholine, hence they are termed 'cholinergic'.615
2. In general, drugs which affect the sympathetic sys
tem have no effect on the parasympathetic system, and vice versa, e.g. atropine is a parasympathetic inhibitor, acting directly on the effector organs. Pilocarpine has the opposite effect, in general stimulating cholinergically in
nervated organs and increasing glandular secretion by in
hibiting acetylcholinesterase ; eserine (physostigmine) has the same general effect.
All preganglionic autonomic fibres liberate acetylcho
line, whether sympathetic or parasympathetic.
The chemistry of autonomic postganglionic transmit
ters appears to be linked to receptor substance, and in
volves complex enzymatic reactions. 11o
Sympathetic fibres are very widely distributed and the number of postganglionic fibres from the paravertebral
ganglia exceeds that of preganglionic fibres, e.g. at the superior cervical ganglion, the ratio of preganglionic to postganglionic is given as 1 : 196, hence the system is very diversified.01
So far as intra- and extracranial, and cervical, structures are concerned, interconnections with cranial nerves and somatic roots are very complex indeed. Via the three cervi
cal sympathetic ganglia, the paravertebral ganglia and the coeliac and two mesenteric ganglia, fibres are distributed to eye, glands and arterioles of skin, and arterioles of voluntary muscle in limbs and trunk, to cardiac, respira
tory and digestive system, 10 bladder, sphincters and geni
talia, e.g. each of the five sacral nerves and the coccygeal nerve receive a grey rami communicans from the corre
sponding ganglion of the sympathetic trunk.
The parasympatheric system, while having a very limited origin from cranial and sacral nerves, also has a large, but less wide, distribution, e.g. the vagus (X cranial nerve) supplies the heart, bronchi, digestive tube, genitalia, bladder and sphincters, all of the neurones synapsing in
Table 2.2 Parasympathetic
Cranial Site of connector Site of ganglion Structures
nerve cells cells supplied
I I I Cranial part of Ciliary ganglion Sphincter
I I I rd nerve nucleus pupillae
Ciliary muscle VII Dorsal nucleus of Sphenopalatine Lacrimal
V l l th nerve ganglion gland (Superior salivary In salivary Submaxillary
nucleus) glands. and
of sacral cord ganglia intestine
Nervi engentes Bladder
Prostate Blood vessels of penis
ganglia silUated peripherally, many of them lying in the walls of the viscera, glands and vessels supplied, and most only microscopically visible.
Preganglionic neurones are distributed in the cranial nerves ..
3rd (oculomotor), i.e. to the intrinsic eye muscles 7th (facial---<:horda tympani branch)
9th (glossopharyngeal) 10th (vagus)
and the macroscopic parasympathetic ganglia are:
Ciliary (in orbital fat) efferent fibres to the iris and ciliary muscle of the eye
Sphenopalatine (in pterygopalatine fossa)
Submandibular (in hyoglossus muscle, just above man
dibular gland)
Otic (just below the foramen ovale)
The latter three are concerned with efferent impulses to lacrimal and salivary glands.
APPLIED ANATOMY-GENERAL 67
Table 2.3 Responses of effector organs to autonomic nerve impulses Organ (responses influenced by female sex hormones and by pregnancy)
Ejaculation in male Vasodilatation and
Contraction
erection (penis, clitoris)
Secretion
Secretion of Ad and NA
68 COMMON VERTEBRAL JOINT PROBLEMS
The nuclei of the cranial nerves arc more or less sur
rounded by the reticular formation oj the brain srem, and have intimate functional relations with this. 129
Sacral parasympathetic fibres emerge with sacral roots 2, 3 and 4, thus comprising the pelvic splanchnic nerves (or visceral branches of the pudendal nerve) and unite with branches of the sympathetic pelvic plexuses.
SYMPATHETIC EFFERENT NEURONES
The sympathetic system is larger than the parasympath
etic system, because of its additional rich supply to the skin and to the blood vessels of voluntary muscle and the connective tissues of the locomotor system. All somatic spinal nerves have postganglionic fibres, but only a limited number of roots carry preganglionic fibres.
Over a period of 10 years, Continental anamrnis(s (Tine I ( 1 937),1220 Laruelle ( 1940)"', Guerrier ( 1944)<61 , Delmas ( 1947)'<7, have reported the cell bodies of pre
ganglionic sympathetic neurones in the cervical segments C5-C6-C7-C8 and joining these somatic roots, although most authors give the uppermost as T l .
The French authors stated that the rami communicans from these neurones also make synaptic junctions with the small sympathetic ganglia developed around the vertebral artery in the foramen transversarium between C4 and C6.
Operative findings indicate that many individuals do not have a symmetrical arrangement to the upper limb, and it is known that prefix at ion and postfix3rion occurs, as in the somatic limb plexuses.
Swarms of fibres accompany all the vessels, and especi
ally those accompanying the I I I and V cranial nerves, probabl y joining them in the cavernous sin us.
Further, (a) the external carotid plexus helps give fibres to the orbit, and also accompanies the lacrimal and frontal (supratrochlear) arteries and (b) the vertebral artery plexus accompanies, among others, the vascular supply to the vestibular structures, the equilibratory organs.
Some organs 3fC innervated by one division only, i.e.
most arterioles, the uterus and the adrenal medulla by sympathetic neurones (the latter organ singularly without synapses of the efferent pathway), and the glands of pan
creas and stomach by parasympathetic neurones only.6J5 The arrangement whereby both autonomic and somatic efferents are supplied to muscle, as in the anal and urethral sphincters, also occurs in the diaphragm;540 in addition to somatic fibres from phrenic and intercostal nerves, fila
mentS of sympathetic neurones derived from the coeliac plexus ramify on the inferior surface of the muscle to supply il.
Segmental distribution (Tables 2. 1 , 2.2)
The salient factors of sympathetic fibre distribution are set out in Table 2. 1 , and those of parasympathetic distribution
in Table 2.2, although authors give slightly different values for the segmental derivation of sympathetic neurones to head and neck, upper limb and thoracic
Visceral afferent pathways resemble those of the somatic afferent neurones, the unipolar cells of the peripheral fibres lying in cranial and posterior root ganglia.'&)7
For example, the peripheral processes (dendrites) of the vagus nerve converge on the superior and inferior vagal ganglia; other peripheral processes approach the dorsal spinal roots through autonomic plexuses or ganglia, and possibly through somatic nerve trunks, without synapse.
Hence the dorsal roots of spinal nerves contain mixed somatic and visceral (so-called Cautonomic') afferent fibres, and after entering the posterior horn they and their ramifications and divisions, via synapses within the cord substance, are diversified up and down the spinal cord to numerous other segments, thereby having available a very rich potential of connector pathways.
Apart from special visceral afferents, e.g. those subserv
ing taste, general visceral afferents form part of the vagus, glossopharyngeal and possibly other cranial nerves, of the thoracic and upper lumbar spinal nerves, and of the second, third and fourth sacral nerves. For example, sen
sory receptors are found at all levels in the wall of the bladder.4)7 The peripheral processes may be unmyeli
nated or myelinated fibres of assorted diameter, and share the distribution of efferent sympathetic and parasympath
etic fibres occurring in the rami communicantes and in pathways for the efferent sympathetic innervation of viscera and blood vessels, with the difference that they do not have synaptic interruptions in the autonomic ganglia.
Terminals are described, for example, in tongue, tonsils, pharynx and oesophagus, in the heart and walls of great vessels (as pressor- and chemoreceptors), pul
monary vessels, bronchial mucosa and smooth muscle, interalveolar connective tissue of lung and in the visceral pleura. Vagal afferent fibres have terminals in the sto
mach, intestines and digestive glands, and in the kidney, ureters and urethra. Afferent neurones of the pelvic splanchnic nerves innervate the distal colon and pelvic viscera, including the uterus and ovary, although none
have been demonstrated in the testes and these may there
fore reach the C.n.S. by different routes. Visceral afferent neurones have generally the same segmental arrangement as the pre- and postganglionic sympathetic fibres, ending in the same spinal cord segments giving rise to the efferent pathways to the region or viscus.
Visceral reflexes are initiated by impulses conducted along the pathways described, most not reaching consciousness, with some initiating organic visceral sensations like hunger, nausea, sexual sensation and bladder and rectal distension.
The general visceral afferent neurones entering via the dorsal roots of the thoracic and upper lumbar segments are, in the main, nociceptors, and visceral pain, produced by stretching and excessive contractions of visceral muscle (spasm), pathological changes in viscera and vascular engorgement probably also follow these afferent path
ways.
The pain may be felt in the region of the organ itself
so-called 'true' visceral pain-and/or in regions of the body wall and skin, sometimes remote from the seat of initiation of pain, e.g. the pain of cardiac ischaemia is commonly presternal and also referred to left neck, jaw, occiput and inner side of left arm. Conversely, the pain of renal colic occurs more usually in the posterolateral loin of the same side, over the obstructed ureter.
Referred pain is considered on page 189.
CENTRAL AUTONOM IC CONTROL
Regulation of blood pressure, body temperature, glandu
lar secretion and similar visceral functions are integrated at the medulla and the pons, the hypothalamus and
cere-Table 2.4
APPLIED ANATOMY-GENERAL 69 bral cortex, particularly the cortical and subcortical structures which form a ring around the brain stem.
Autonomically regulated responses, similar to those pro
duced on stimulation of the hypothalamus, can be pro
voked by stimulation of the tegmentum of mid-brain and the periaqueductal grey matter; the three areas are ana
tomically so adjacent that little functional distinction can be made when stimulation effects are compared.
Autonomic ganglia are only synaptic stations and have no independent activity, yet spinal cord connector cells show a degree of tonic activity, keeping up a level of va so
constrictor tone after complete section of the cord and thus maintaining a low but stable blood pressure.b1'i