Week 8 Cranial nerves Flashcards
How many cranial nerves are there?
12 pairs
How are the cranial nerves named?
By roman numerals in reference to their attachment to the brain in an anterior to posterior direction
They are named as cranial nerves as they emerge through the foramina or fissures in the cranium/ skull
What are the cranial nerves covered in?
Sheaths formed by the cranial meninges
Where do most of the cranial nerves arise?
Mainly off the brain stem
What portion of the brain stem do the cranial nerves arise?
The medulla, pons and midbrain
What is the brain stem?
The connecting link between the remainder of the brain and the spinal cord
What are the main functional components of cranial nerves?
motor: Somatic motor (efferent) Visceral motor (efferent) Sensory: General sensory (touch, pain and temperature) Visceral sensory (afferent) Special sensory
What do the cranial nerves innervate?
Structures in the head and neck and visceral organs of the trunk
What kind of nerve is the olfactory nerve and where does it originate and end?
Cranial nerve 1
Special sensory
Begins at the mucosa of the nasal cavity and ends at the olfactory bulb in the cerebral cortex
What is the olfactory nerve composed of and what do they respond to?
Both neurons and receptors
Respond to volatile chemicals
Where does the olfactory nerve run?
Through the foramina of the cribirform plate
pierce dura and arachnoid mata
enter olfactory bulb
then becomes the olfactory tract
What is the function of the olfactory nerve?
Sense of smell
Arousal of emotions
induce visceral responses through ANS
What kind of nerve is the optic nerve?
Cranial nerve 2
Special sensory
What is the optic nerves claim to fame?
The largest (thickest) cranial nerve
Where is visual information relayed to?
visual coriticies of the occipital lobes
What nerve fibres does the occulomotor nerve recieve?
Both parasympathetic and sympathetic fibres.
Where does the occulomotor nerve begin and end?
Cranial nerve 3
originates in the midbrain
it then leaves the cranial cavity
then enters the orbit through the superior orbital fissure
What are the functions of the occulomotor nerve?
Provides motor function to 4 extraocular muscles
motor supply to the upper eyelid
Supplies parasympathetics to the sphincter of the pupil and cillary muscle of the lens
Where does the trochlea nerve originate?
Cranial nerve 4
The midbrain, it emerges from its dorsally from the brainstem
What is the trochlea nerves claim to fame?
Longest intracranial course
What is the function of the trochlea nerve?
somatic motor nerve to one of the extraocular muscles and proprioception
Where does the trigeminal nerve originate from?
Cranial nerve 5
Originates from the pons and is the second largest cranila nerve
What fibres supply the trigeminal nerve?
Somatic motor fibres and somatic sensory fibres
How many components of the trigeminal nerve are there?
3:
opthalmic
maxillary
Mandibular
What does the trigeminal nerve supply through sensory innervation?
Face Teeth Mouth Nasal cavity Dura
Where does the abducens nerve emerge?
From the brain stem between the pons and the medulla
What is the function of the abducens nerve?
somativ motor nerve to an extraocular muscle and proprioception.
Also abducts the eye
Where does the facial nerve arise?
from the junction of the pons and medulla
What is the facial nerves pathway?
passes through internal acoustic miatus
through the facial canal within the temporal bone
exits through the stylomastoid foramen
It then enters the parotid galnd where it gives off terminal branches
What is the facial nerves claim to fame?
It is the longest interossues Cranial nerve
What nerve fibres does the facial nerve have?
Special sensory fibres
Somatic sensory fibres
Somatic motor fibres
Visceral motor fibres
What are the roots of the facial nerve and how many are there?
2 roots
Larger motor root:
supplies muscles of facial expression
Smaller intermediate root:
Carries taste, somatic sensory fibres and parasympathetics
What are the unctions of the facial nerve?
taste to the anterior 2/3rds of the tongue and softa palate
sensory to the external ear
motor to the muscles of facial expression, throat and middle ear
Proprioception to the above muscles
parasympathetic supply to submandibular and sublingual salivary glands icramal gland, glands of the nasal cavity and palate
What are the terminal branches of the facial nerve?
Posterior auricular Temporal Zygomatic Buccal Mandibular Cervical
Where does the Vestibulocochlea nerve arise?
Cranial nerve 8
between the pons and the medualla
What is the vestibulocochlea nerves claim to fame?
It is the only cranial nerve that does nt exit the skull
What are the functions of the vestibulochochlea nerve?
Special sensory supply
state of balance
hearing
Where does the glossopharyngeal nerve begin?
Cranial nerve 9
From the medulla
Where does the glossophrangeal nerve exit?
Through the jugular foramen
What are the functions of the glossophrangeal nerve?
Special sensory supply Taste Somatic sensory Visceral sensory somatic motor visceral motor Proprioception
What kind of nerve fibres does the glossopharangela nerve have?
Parasympathetic
What does vagus mean?
Cranial nerve 10
Wandering
What is the vagus nerves claim to fame
it is the longest cranial nerve
Where does the vagus nerve originate and leave the skull?
roots from the medulla
leaves the skull through the jugular foramen
What are the functions of the vagus nerve?
sensory to: Inferior pharynx Larynx Thoracic and abdominal organs special sensory
What does the vagus nerve have somatic motor supply to?
Soft palate Pharynx Intrinsic laryngeal muscle palaglotus muscle proprioception
What do the parasympathetic fibres of the vagus nerve supply?
Thoracic and abdominal viscera
How many roots does the spinal accessory nerve have?
2;
Cranial root
Spinal root
Where does the cranial root originate from on the spinal accessory nerve?
from the medulla
Where does the Spinal root originate from on the spinal accessory nerve?
upp 5-6 cervical segments, via passing through the foramen magnu,
What are the functions of the spinal accessory nerve?
motor supply to: soft palate pharynx SCM Trapezius
Where does the hypoglossal nerve arise from and where does it exit the cranium?
CN 12
The Medulla
exits through the hypoglossal canal
What are the functions of the hypoglossal nerve?
motor nerve to the muscles of the tongue
proprioceptive fibres for these muscles
