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.