1 Cranial Nerves Originates from brain (mainly brain stem) and passes through foramina of skull...
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Transcript of 1 Cranial Nerves Originates from brain (mainly brain stem) and passes through foramina of skull...
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Cranial NervesOriginates from brain (mainly brain
stem) and passes through foramina of skull
There are 12 pairs of cranial nervesThey have both name and number
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There are mixed cranial nerves, sensory cranial nerves
and motor cranial nerves
All motor cranial nerves contain a small number of sensory fibers
that is proprioceptive
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Olfactory nerve Olfactory nerve II The axons that makes
the olfactory nerve starts from nasal mucosa.
They make 20 small bundles of fibers that pierce the cribriform plate
Olfactory nerve carry the sense of smell
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Optic nerve IIOptic nerve II Axons start in retina They carry visual
information to brain. Most of the optic
tract fibers terminate in thalamus.(lateral geniculate nucleus)
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Occulomotor nerve IIIOcculomotor nerve III Starts from
occulomotor nucleus in the ventral part of the midbrain.
Extends to various external eye muscles
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Trochlear nerve Trochlear nerve IVIVOriginates from
the midbrain They go to the
superior oblique muscle of the eye
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Trigeminal nerve VTrigeminal nerve V It splits into three large
branches It makes ophtalmic
nerve, maxillary nerve, mandibular nerve
Carry sensory information from face and teeth
Its motor nerve controls mastication
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Abducence nerve VIAbducence nerve VIIts fibers originate from pons
and extends to the lateral rectus muscle of the eye.
This muscle abducts the eye.
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CN VICN VI
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Facial nerve VIIFacial nerve VII
Arise from the lower part of the pons. Innervates superficial muscles of face
and skull. Its autonomic fibers innervate the
submaxillary and sublingual salivary glands and lacrimal glands.
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Vestibulocochlear nerveVestibulocochlear nerve
Has two distinct divisions:Vestibular and cochlear
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Vestibular branchVestibular branch
Arise from semicircular canals in internal ear and terminates in pons medulla and cerebellum.
Its function is to maintain equilibrium.
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Cochlear branchCochlear branch Starts from the organ of corti and
terminate between medulla and pons. Conduct the sense of hearing. Its some times called auditory or
acoustic nerve.
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Glossopharyngeal nerveGlossopharyngeal nerve IX
It is a mixed nerve. Supplies the tongue and pharynx It also supplies the carotid sinus Its fibers extend to medulla.
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Vagus nerve Vagus nerve XX Contains sensory and motor fibers It has many widely distributed branches Sensory fibers supply, pharynx, larynx, pharynx, larynx,
trachea, heart, carotid body, lungs, trachea, heart, carotid body, lungs, bronchi, esophagus, stomach, small bronchi, esophagus, stomach, small intestine and gall bladderintestine and gall bladder
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motor fibers of vagus nereve
Are mainly autonomic. They controls muscles for swallowing Most of them are parasympathetic. They also go to pharynx, larynx,
thoracic organs and abdominal organs.
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Accessory nerve XIAccessory nerve XI
Is a motor nerveIs considered an
accessory nerve to vagus.It was formerly called the
spinal accessory nerve
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Hypoglossal nerve XIIThe motor fibers supplies the
muscles of the tongue It also have sensory
(proprioceptive) nerves.
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Divisions of Divisions of peripheral nervous peripheral nervous systemsystemSensory divisionSensory division
Motor divisionMotor division
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Somatic motor nervous system
Includes all the voluntary movements outside the CNS
The end motor neuron stimulates the effector muscle by means of acetylcholineacetylcholine
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Somatic reflexes A reflex is a predictable response to an
stimulus Based on the center of a reflex we have
cranial and spinal reflexes. We also have somatic reflexes and
autonomic reflexes
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Autonomic reflexesAutonomic reflexes Is either muscle contraction or glandular
secretion Cause Smooth or cardiac muscle
contraction or secretion of a gland
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Important somatic reflexesImportant somatic reflexes
Knee jerk reflexAnkle jerk reflexBabinski reflexCorneal reflexAbdominal reflex
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Knee jerk reflexKnee jerk reflex Is extension of lower leg in response to
tapping patellar tendon It is also a spinal cord reflex, segmental spinal cord reflex, segmental
reflex, stretch reflex, extensor reflex and reflex, stretch reflex, extensor reflex and deep tendon reflex.deep tendon reflex.
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Ankle jerk reflexAnkle jerk reflex
It is called achilles reflex Cause plantar flexion Its center is in the first and second
segment of the cord
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Babinski reflexBabinski reflexIs extension of great toeInfants show this reflex up
to 1 ½ yrsAfter that it is considered
abnormal
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Corneal reflexCorneal reflex Is blinking in response to touching the
cornea It is mediated by the ophtalmic branch
of fifth cranial nerve Centers in the pons and motors in
seventh cranial nerve
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Abdominal reflexAbdominal reflex Is drawing in of the abdominal wall in
response to stroking the side of the abdomen
Its center is in 9th to 12th spinal nerves In pregnancy it is abscent.
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