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A-Branches of the facial nerve inside the facial canal :
1-greater petrosal nerve.
a-arise from geniculate ganglion ( mixed nerve ).
b- Emerges from the foramen lacerum after receive branch from carotid
sympathetic plexuses ( deep petrosal nerve ).
c- Then called the nerve of the pterygoid canal which ended in the
pterygopalatine plexus.
2- Lesser petrosal nerve : small branch arise from the geniculate ganglion with
the choradatympani and ended in the otic ganglion.
3- Stapedial nerve : short branch supply the stapedius muscle.
4-choradatympani :
a- small branch arise ventrally to the stapedial nerve .
B-pass through the tympanic cavity , then joins the lingual nerve .
C-gives branch supply the sublingual and mandibular salivary glands , and the
mm of the cranial third of the tongue ( to the last buds ).
5- Small branches unite with auricular branch of vagus at the mastoid foramen.
B- Branches of the facial nerve outside the stylomastoid foramen:
1-Caudal auricular nerve :
Arise from the facial nerve it emerge from the stylomastoid foramen and pass
with the caudal auricular artery under the parotid gland . It supplies the dorsal
auricular muscle and skin of the external surface of ear 2-Internal auricular
branch : supply the skin of internal surface of the ear .
3-Digastric branch : arise ventrally to the auricular branch , it supply the
caudal belly of the digastric and stylohyoidus and occipitohyoidus muscles .
4-Auriculopalpebral nerve : arise from the dorsal border of the facial nerve ,
near the caudal border of the ramus of the mandible and ended by divided into:
a-Rostral auricular : --supply the auricular and parotid auricularis muscles.
b-Zygomatic branch: ( temporal branch ) –directed cranially and medially
toward the angle of the eye and supply the orbicularis oculi, levator of the
medial angle of the eye and levator nasolabii muscles and gives palpebral
branch .
5-Cervical branch : small branch arise ventrally to the facial nerve pass toward
the neck , gives branch to the guttural pouch , parotid auricularis and cutanous
colli muscles.
6-Dorsal buccal nerve : directed cranially over the masseter muscle , then
pass toward the caninus muscle under the zygomaticus , supply the muscle of
the upper lip and nostrils .
7-Ventral buccal nerve : pass over the masseter muscle obliquely and
continuous cranially along the depressor labii inferior and supply these muscles
.
8th cranial nerve : Auditory nerve or vistibulocochlear nerve are sensory
responsible for hearing and balance .
1-arises from the lateral side of the medulla oblongata , and has two roots (
vestibular and cochlear ) .
2- The nerve enters the internal caustic meatus , with the facial nerve.
3- It divided into two branches , the dorsal –is the vestibular nerve which
responsible for mechanism of equilibration and the ventral –is the cochlear
nerve which responsible for the hearing .
a-Vestibular nerve: gives branches to the utricle , saccule, and the semicircular
canal of the internal ear. It is connected with the geniculate ganglion of the
facial nerve by small twigs and it has the vestibular ganglion at the base of the
internal caustic meatus , from which its branches are arise .
b-Cochlear nerve: gives fibers to the sacuule, the fibers pass through the
cribriform plate ( lamina cribrosa ) to reach to the labyrinth which distributes in
the spiral organ which called cortiorgan in the cochlea.
9th Cranial nerve: Glossopharyngeal nerves are mixed:
a- Arise from the lateral surface of the medulla oblongata by several fibers
bLeaves the cranium cavity through the jugular foramen cranially to the
vagus.
cIt have two ganglia, the proximal one called the jugular and the distal
called petrosal ganglion, cross the deep face of the external carotid artery and
divided into three branches .
1-Tympanic nerve : directed toward the tympanic cavity , and supply the mm
of the tympanic cavity and auditory tube.
2-Lingual nerve : is the largest one , is the continuous of the glossopharyngeal
nerve , pass under the glossohyoidus muscle and supply the last third of the
tongue by gustatory branches and gives branches to the soft palate , and tonsils.
10th Cranial nerve: Vagus nerves are mixed:
1-is the largest and most widely distributed of the cranial nerve .
2-Arise from the lateral aspect of the medulla oblongata by several filaments,
unites to form a trunk which pierce the dura mater.
3-It emerges from the cranium cavity through the jugular foramen and inside the
foramen bears the proximal jugular ganglion.
4-The vagus runs caudally and ventrally with accessory in the fold of the
guttural pouch(in equine ).
5-At the origin of the occipital artery , the nerves join with the cervical
sympathetic trunk and pass along the dorsal aspect of the common carotid artery
under the name of the vagosymphathetic trunk .
6-At the base of the neck they separated from each other and from this point and
caudally the relation of the right vagus nerve are differ than the left vagus .
A-The right vagus nerve : enter the thoracic cavity between the right
subclavian artery and the bicarotid trunk , then caudally on the brachiocephalic
artery and the right surface of the trachea, then the dorsal surface of the trachea.
At its bifurcation then divided into dorsal and ventral branches.
B-The left vagus nerve : enter the thoracic cavity on the lateral or ventral
surface of the esophagus , passing below the subclavian artery ,then caudal to
the greater cardiac nerve , then caudal at the lateral surface of the aorta until its
reach the dorsal surface of the left branches , then divided into dorsal and
ventral branches.
The dorsal branches :are united to make the dorsal vagus trunk.
The ventral branches : are united to make the ventral vagus trunk .
These trunks continue caudally in the caudal mediastinum with the
esophagus hiatus .
The dorsal vagus trunk: --in the abdominal cavity directed to the left to the
cardiac region of the stomach and divided into :
aGastric branch : -gives branches to the visceral surface of the stomach.
b- Celiac branch : ended in the celiac mesenteric ganglion.
The ventral vagus trunk (small ) :Directed to the kisser curvature of the
stomach on the parietal surface of the stomach to make cranial gastric plexus
from which m branches where emerge to innervate the duodenum, liver and
pancreas .
Branches of the vagus :
1)
Pharyngeal branch : arise near the cranial cervical ganglion and
contribute in the formation of the pharyngeal plexus )with glossopharyngeal ,
accessory and sympathetic branch .) Which innervated the pharyngeal muscles
and the soft palate except tenser veli palatine which innervated by mandibular
nerve.
2)
Cranial laryngeal nerve: large branch arises caudal to the pharyngeal
branch pass on the lateral surface of the pharynx, then enter the larynx through
the thyroid foramen and innervate the mm of the larynx, the floor of the
pharynx and the aditus esophagus and has small external branch to the
cricothyroid muscle .
3) Recurrent laryngeal nerve: varies in its origin from left to the right .
-Right one –arise against the second rib, turned around the cervicocostal trunk,
directed cranially , in the neck ventrally to the common carotid artery .
-Left one –
*-arise from the vagus , when the vagus crosses the aortic trunk
**-it pass on the ligamentum arteriosum , then turned around the concavity of
the aortic arch , then directed cranially in the neck, ventrally to the common
carotid artery.
*-Both when reach to the larynx, pass between the esophagus and the trachea .
*-gives branches to the dorsal cricoarytenoid , transverses arytenoid muscle ,
then enter to the larynx, to innervated all the internal laryngeal muscle except
cricothyroid muscle.
4)
Cardiac branches : unites with the sympathetic cardiac nerves and
caudal laryngeal nerve to make the cardiac plexuses.
5) Tracheal and esophageal branches : inside the thorax .
6)
Bronchial branches : at the root of lung ( hilus ) unites with sympathetic
branch to make pulmonary plexuses.
11thCranial nerve :accessory nerves are motor
1-Arise by two roots ( medullary root and spinal root ).
2-the medullary root –arise by several filaments from the medulla oblongata
caudal to the vagus.
3-The spinal root –arises by several filaments from the spinal cord in the first
five cervical vertebrae, then directed cranially along the lateral surface of the
spinal cord, and enters the cranium through the foramen magna and unites with
the medullary root to make the accessory nerve.
4-the accessory emerges from the cranium through the jugular foramen with the
vagus and glossopharyngeal and directed caudally
5-it is divided into two branches ventrally to the wing of atlas. The ventral
branch –end in the sternocephalicus muscle, the dorsal branch-end in the
trapezus muscle and give small branch to the brachiocephalicus muscle.
12thCranial nerve :Hypoglossal nerves are motor :
1-is the only motor nerve for the tongue muscle.
2-Arise from the medulla oblongata by small filaments.
3-Leave the cranium through the hypoglossal foramen and directed caudally and
ventrally then dorsally toward the tongue .
4-Gives branches to the lingual muscles and geniohyoidus muscle.
5-Also gives branch unites with the ventral branch of the 1st cervical nerve to
make loop called the loop of the hypoglossal nerve .
6-Gives another branch ( descending ) innervated the sternothyroidus ,
sternothyroidus and omohyoidus muscle.
7-Gives branch to the pharyngeal plexuses and another branch to the cranial
cervical sympathetic ganglion.
Blood supply of the brain : in horse
The blood supply of the brain of horse com from two arteries :
aThe internal carotid artery –which didn’t receive any branch from the
maxillary artery ( like in ox , dog , pig , sheep , goats , and cats ).
b-Basilar artery –the main arteries which supply the brain are found on the
ventral surface of the brain as a circle called circle of Willis or the cerebro
arteries circle , which are circle ( circulus arteriosus ) of the cerebro arteries
surrounded the infundibulum of the hypothalamus and the optic chiasma formed
by the anastomosis
of the cranial cerebral arteries with the caudal
communicating arteries .
The main branches of the circle of Willis:
1-Rostral cerebral artery : Is the continuation of the internal carotid artery.
The cerebral arterial circle unites infront of the optic chiasma to make the artery
of corpus callosum. The branches of this artery are :
a- Cranial meningeal artery –small branch arises near the union of the
cerebral arteries .
bInternal ophthalmic artery—small branch course with the optic nerve
1- Middle cerebral artery – arises at the optic chiasma and directs laterally to
the lateral groove of the cerebral hemispheres and ramify their. The choroid
artery is one of the middle cerebral artery and sometime arises from the
rostral cerebral artery , this artery follow the optic tract and ended in the
choroid reti of 3rd and lateral ventricles of the brain.
2- Caudal communicating artery – coursing between the internal carotid
artery and basilar artery, on each side the caudal communicating artery
directed caudally on the cerebral crus and anastomosis with the caudal
cerebral arteries of the basilar artery. The branches of this artery are ( deep
cerebral artery and rostral cerebral artery ).
3- Caudal cerebral artery – arises from basilar artery or from ( 3) and directs
laterally above the mesencephalon toward the caudal surface of the cerebral
hemispheres.
4- Basilar artery –is formed by union of caudal communicating artery and
directed caudally above the ventral surface of medulla oblongata, trapezoid
body and pons until the foramen magnum. This artery is single. The
branches of this artery are :
a- 6-10 medullary branches .
b- Caudal cerebellum artery –is the 1st major branch of this artery and
passes laterally around the medulla caudal to the pons, to the cerebellum
and extended to the choroid plexus of the 4th ventricle.
c- Rostral cerebellar artery—taker its origin from terminal portion of the
basilar artery .