Post on 14-Feb-2020
INNERVATION OF THE TONGUE
NERVE
SUPPLY OF
TONGUE
Intrinsic muscles: Hypoglossal
nerve
Extrinsic muscles: All supplied by
the hypoglossal nerve, except the palatoglossus
The palatoglossus
supplied by the pharyngeal plexus
anterior 2/3 of the tongue:
general sensation: lingual nerve - branch of the mandibular nerve (with cell bodies in the trigeminal ganglion)
taste: chorda tympani (with cell bodies in the geniculate ganglion of facial nerve)
parasympathetic secretomotor fibres to the anterior lingual gland run in the chorda tympani from the superior salivary nucleus, and relay in the submandibular genglion
posterior 1/3 of the tongue: innervated by the glossopharyngeal nerve (both general sensation and taste), with cell bodies in the glossopharyngeal ganglia in the jugular foramen
posterior most part of the tongue: innervated by the vagus nerve through the internal laryngeal branch (with cell bodies in the inferior vagal ganglion)
SENSORY:
SENSORY NERVE
SUPPLY Mostly by the maxillary nerve
through its branches:
Greater palatine nerve
Lesser palatine nerve
Nasopalatine nerve
Glossopharyngeal nerve supplies
the region of the soft palate
Sensory supply is derived from
lesser palatine branches of the
sphenopalatine ganaglion and from
the branches of glossopharyngeal
nerve.
Motor Innervation
All the muscles, except tensor veli palatini, are supplied by the:
Pharyngeal plexus
Tensor veli palatini supplied by the:
Nerve to medial pterygoid, a branch of the mandibular division of the trigeminal nerve
NERVE SUPPLY OF PHARYNX
Pharyngeal plexus of nerves formed by-
Pharyngeal branch of vagus nerve which includes the cranial root of the accessory. This provides the motor supply to the muscles except for the tensor palati which is supplied by the mandibular division of the trigeminal. Motor fibres-Vagus N. – supply all muscles of pharynx
except Stylopharyngeus (glossopharyngeal N.)
Pharyngeal branches of glossopharyngeal nerve.
The glossopharyngeal nerve, which provides the sensory supply to the pharynx.
Pharyngeal branches of superior cervical sympathetic ganglion
• Branches from the sympathetic trunk.
Sensory fibres-Glossopharyngeal N. and Vagus N.
Thoracic part of the
vagus nerve
Vagus nerve branches in
the neck consist of the
following:
Pharyngeal branches
Superior laryngeal
nerve
Recurrent laryngeal
nerve
Superior cardiac nerve
Vagus nerve branches in the abdomen
The gastric branches supply the stomach.
The right vagus forms the posterior gastric plexus
The left forms the anterior gastric plexus.
The celiac branches are derived mainly from the
right vagus nerve. They join the celiac plexus and
supply the pancreas, spleen, kidneys, adrenals, and
intestine.
The hepatic branches originate from the left vagus.
They join the hepatic plexus and through it are
distributed to the liver.
The abdominal viscera are innervated by the
autonomic nervous system.
The parasympathetic innervation is delivered by the
vagus primarily, with help from the pelvic splanchnic
nerves.
The sympathetic innervation comes primarily from the
thoracic splanchnic nerves, greater, lesser, and least,
with help from the upper lumbar splanchnic nerves.
Generally, parasympathetic innervation results in
digestion, by stimulating peristalsis in the gut and
secretion by associated glands.
Sympathetic innervation, on the other hand, decreases
blood flow to the abdominal viscera and inhibits
digestion. Blood flow is diverted to the trunk and limbs,
to aid the body in "fight or flight".
THE SYMPATHETIC NERVOUS SYSTEM
The central part of the sympathetic system is
located in the lateral horns of the spinal cord
between the level of C7 and Th1-L3 in the
intermediolateral nucleus.
It give rise to fibres innervating the smooth muscles of
the viscera and the sensory organs (eyes), and the
glands. Vasomotor, pilomotor and respiration centres are
also located here.
The peripheral part of the sympathetic system is
formed by two symmetrical right and left sympathetic
trunks stretching on either side of the spinal from the
base of the skull to the coccyx where the caudal ends of
both trunks meet to form a single common ganglion
The peripheral part of the sympathetic system
Each sympathetic trunk is composed of a series of nerve
ganglia of the first order connected by longitudinal
interganglionic branches that consist of nerve fibres.
The processes of cells located in the lateral horns of the
thoracolumbar part of the spinal cord emerge from it
through the anterior roots and pass in the white
communicating branches to the sympathetic trunk.
From the white communicating branches the processes
of the cells join by means of synapsis with the cells of
the sympathetic trunk ganglia or pass through the
ganglia without interruption and reach one of
intermediate ganglia. This is the preganglionic
pathway.
From the ganglia of the sympathetic trunk or from the
intermediate ganglia arise non-medullated fibres of the
postganglionic pathways and pass to the blood
vessels and viscera.
Thus, the SNS is connected with the somatic system by two types
of communicating branches, white and grey.
The white communicating branch (medullated) are the
preganglionic fibres; they stretch from the centres of the
sympathetic nervous system through the anterior roots of the
ganglia of the sympathetic trunk.
The centres are situated at the level of the thoracic and upper lumbar
segments.
The grey communicating branch, the postganglionic fibres,
provide the vasomotor and trophic processes in the soma.
They connect the sympathetic trunk with the spinal nerves for its entire
length. The cervical part of the sympathetic trunk is also connected with
the cranial nerves.
All the plexuses of the somatic nervous system contain therefore fibres of
the sympathetic system in their bundles and nerve trunks.
The cervical part stretches from the base of the
skull to the neck of the first rib, lies behind the
carotid arteries on the deep muscles of the neck. It
has three cervical sympathetic ganglia: superior,
middle and inferior.
Superior cervical ganglion
Middle cervical ganglion
Inferior cervical ganglion
Each can be divided into an
Ascending group passing to the head
Descending group stretching to the heart,
The thoracic part:
The Greater and lesser splanchnic nerves:
The Great: Originates as several roots from the 5th to 9th
thoracic group ganglia, which pass medially to the level of the
9th thoracic vertebra where they fuse into one common trunk
which is transmitted through the space between the muscular
bundles of the diaphragmatic crura into the abdominal cavity in
which becomes a component of the CELIAC PLEXUS.
The Lesser: arises from the 10th and 11th thoracic ganglia,
penetrates the diaphragm together with the greater splanchnic
nerve or is separated from it by a few muscular bundles, and
also becomes a component of the CELIAC PLEXUS.
The lumbar (or abdominal) part
consists of four ganglia. Both sympathetic trunks come
closer to each other in the lumbar part, as a result of which
the ganglia lie on the anterolateral surface of the lumbar
vertebrae on the medial border of the psoas major muscle.
Along its entire distance the lumbar part sends off a
great number of branches which, together with the
greater and lesser splanchnic nerves and the
abdominal segments of the vagus nerve, form the
largest unpaired coeliac plexus.
The coeliac plexus lies on the anterior
semicircunference of the abdominal aorta behind the
pancreas and surrounds the initial parts of the coeliac
trunk and the superior mesenteric artery.
CELIAC TRUNK
Occupies an area between the renal arteries, the suprarenal glands, and the aortic opening of the diaphragm and includes the paired ganglion of the celiac artery – celiac ganglion, and sometimes the unpaired ganglion of the superior mesenteric artery- superior mesenteric ganglion lying under the root of this artery.
The 2nd main source of innervation of the abdominal organs is the aortic plexus, formed by two trunks arising from the celiac plexus and branches running from the lumbar ganglia of the sympathetic trunk.
Aortic plexus gives rise to: The inferior mesenteric plexus for the transverse, descending, and
sigmoid colon, and upper part of the rectum. At the origin of the inferior mesenteric plexus lies the inferior mesenteric ganglion whose postganglionic fibres pass to the pelvis as components of the hypogastric nerves
Aortic plexus is continuous with the unpaired hypogastric plexus which bifurcates at the promontory of the sacrum and is in turn continuous with the pelvic plexus.
Fibres derived from the superior lumbar segments are functionally vasomotor (vasoconstrictor) in relation to the penis and motor in relation to the uterus and the sphincter urethrae muscle.
The stomach receives innervation from several sources:
(1) sympathetic fibers via the splanchnic nerves and celiac
ganglion (synapse) supply blood vessels and musculature,
(2) parasympathetic fibers from the medulla travel in the gastric
branches of the vagi,
(3) sensory vagal fibers include those concerned with
gastric secretion.
THE STOMACH NERVE SUPPLY
There are two types of nerve supply of the stomach; sympathetic
and parasympathetic.
The sympathetic constricts the sphincters, however the
parasympathetic is a secreto-motor and stimulate smooth muscles
for peristaltic movement and induce evacuation.
To empty the pyloris, the sympathetic stimulation must be
inhibited and the parasympathetic excited.
Distribution of the vagus innervation to the stomach;
The right vagus nerve innervates the posterior portion of the
stomach
The left vagus supplies the anterior part of the stomach
(posterior gastric and posterior gastric, respectively).
Parasymathetic innervation of the stomach:
I-The anterior gastric nerve(left vagus):
1. mainly supplies the anterior portion of the body,
2. it also innervates the liver(hepatic branch),
3. and the laterjet nerve to the pyloris(which is
specific to the pyloris to increase control on the
emptying of the stomach).
II-The posterior gastric nerve(right vagus):
1. innervates a small portion of the anterior body,
2. a main fiber innervates the posterior body,
3. and another celiac branch which innervates all
the small intestines, up until the lateral third of the
transverse colon(innervates the medial two thirds),
along with the pancreas
The small intestine: is supplied by autonomic and sensory fibers from the celiac
and superior mesenteric plexuses. The sensory fibers
include those for pain, the intestine being sensitive to
distension ("cramps").
The large intestine Autonomic and sensory fibers travel in continuations of the
celiac and mesenteric plexuses that accompany the colic
arteries. The parasympathetic supply to the sigmoid colon
and to at least a part of the descending colon, however, is
from the pelvic splanchnic nerves by way of the hypogastric
nerves and the inferior hypogastric plexuses. Distension
activates pain fibers in the splanchnic nerves.