Anatomy 4: Anatomy of Cranial Nerves Flashcards
For CNI, give it’s extracranial and intracranial course and connection with CNS (if applicable)
In olfactory mucosa in nasal cavity
Synapse in olfactory bulb, and pass to olfactory tract
NO CONNECTION
Outline how you would go about testing CNI
Smell while covering contralateral side`
For CNII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Neurones of retina travel posteriorly via optic nerve to the orbit
Pass from the optic chiasm to the optic tract
Diencephalon
Outline how you would go about testing CNII
Visual acuity (Snellen) Colour (Ishihara plates) Fields (4 quadrants) Reflexes (Pupillary light reflexes) Fundoscopy
For CNIII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
SOF into orbit and supply all extraocular muscles except 2, PSs synapse in ciliary ganglion
Lateral wall of cavernous sinus (orbit)
Mesencephalon (midbrain)
Outline how you would go about testing CNIII
Light reflexes via a torch (PS)
For CNIV, give it’s extracranial and intracranial course and connection with CNS (if applicable)
SOF into orbit and supply SO muscle
Lateral wall of cavernous sinus (orbit)
Mesencephalon (midbrain)
Outline how you would go about testing CNIV
H test (in and down)
For CNVI, give it’s extracranial and intracranial course and connection with CNS (if applicable)
SOF into orbit and supply LR muscle
Cavernous sinus to orbit
Pontomedullary junction
Outline how you would go about testing CNVI
H test (out)
For CNVIII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Axons from cochlear and vestibular apparatus
Posteromedially from IAM to PM junction
Pontomedullary junction
Outline how you would go about testing CNVIII
Rinnie and Weber tests
For CNXI, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Axons supply SCMD, travel across posterior triangle to trapezius
Foramen magnum to jugular foramen
Cervical spinal cord
Outline how you would go about testing CNXI
Shrug shoulders (and resist) - TRAPEZIUS Turn head to flex neck (and resist) - SCMD
For CNXII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Descends lateral to carotid sheath (at hyoid turns anteriorly to tongue)
Pass anteriorly to hypoglossal canal
Many rootlets lateral to pyramids of medulla
Outline how you would go about testing CNXII
Stick tongue out and move side-side
Tip of tongue will point towards side of pathology
For CNV, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Sensory passes superficial to deep structures of face posteriorly to foramen
Motor from CNV3 travels from f. ovale to skeletal muscle
Inferior to tentorium cerebelli
Pons!
Give the superficial sensory divisions for the trigeminal supply to the face
CNVI: upper eyelid to tip of nose to forehead
CNV2: Lower eyelid to upper lip and nostril
CNV3: Lower lip and chin to TMJ/ mandible (except angle)
What gives sensory supply to the angle of mandible, and what are the roots of this nerve?
Great auricular nerve (C2, C3)
Give the deep sensory divisions for the trigeminal supply to the face
CNV1: orbit (not floor or lower eyelid), upper anterior nasal cavity, paranasal sinuses (not maxillary), anterior and posterior CF
CNV2: lower posterior nasal cavity, maxillary sinus, maxilla, floor of nasal cavity/ palate, maxillary teeth, soft tissues
CNV3: Middle CF, mandible A 2/3 of tongue, floor of mouth, buccal mucosa, mandibular teeth
Outline how you would go about testing the sensory divisons of CNV
Close eyes
Cotton wool - ‘Say when you feel me touching you’
Compare sides
Which nerve is the 1st part of afferent limb of blink/ corneal reflex?
Long ciliary nerve
Outline how you would go about testing the motor division of CNV
Palpate strength of masseter (clench teeth)
Open jaw against resistance
For CNVII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Somatic motor fibres to parotid gland and then facial expression muscles (1 out of 5)
Directly to IAM
Pontomedullary junction
The facial canal is located within what part of the temporal bone?
Petrous part
What is the function of chorda tympani, a branch of CNVII?
Taste to A 2/3 of tongue
PS to submandibular and sublingual glands (salvation)
What is the tiniest SkM in the body?
Stapedius
What is the role of the stapedius muscle, and what happens when you damage it?
Reduces stapes movement to dampen down excessive noise
Hyperacuisis
Outline how you would go about testing CNVII
Test the muscles of facial expression - raise eyebrows, close eyes tightly, smile, puff out cheeks and hold air
List the muscles of facial expression
Frontalis
Orbicularis oculi
Elevators of lips
Orbicularis oris
For CNIX, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Descends in pharynx in mouth to stylopharyngeus, parotid gland, pharyngeal muscosa, carotid body and sinus, posterior 1/3 of tongue
Directly to jugular foramen
Medulla oblongata
Outline how you would go about testing CNIX
Elicit afferent limb of gag reflex
What is the only muscle supplied by CNIX
Stylopharyngeus
Which muscles are supplied with motor innervation from CNV?
Tensor tympani
Tensor veli palatini
1 pair of jaw closing muscles - lateral pterygoid
3 pairs of jaw opening muscles - masseter, temporalis, medial pterygoid
For CNX, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Structures between pallate and midgut
Directly into jugular foramen
Medulla oblongata
Why is pain often referred from pharynx to ear and vice versa?
Both supplied by glosopharyngeal nerve
What two vessels is the carotid sheath located between? Which CN runs in the carotid sheath?
CCA and IJV
Vagus nerve
The left recurrent laryngeal nerve, branch of CNX, passes under…
Arch of aorta
The right recurrent laryngeal nerve, branch of CNX, passes under…
Right subclavian artery
Outline the route taken by both vagus nerves from the chest to abdomen
RIGHT: Lateral aspect of trachea LEFT: Lateral aspect of aortic arch Pass posterior to lung root on oesophagus Pass through diaphragm with oesophagus Pass onto surface of stomach Branches and travels to organs
List the branches of the vagus nerve in the abdomen
Celiac and superior mesenteric ganglia Foregut Renal Midgut (on mesenteries) Splenic Pancreatic
What vertebral level do the oesophagus and vagus nerve pass through the diaphragm?
T10
Where do the vagus nerves very last PS axons pass onto?
Splenic flexure of colon
Outline how you would go about testing CNX
MUSCLES OF PALATE (motor) - Say ‘aaah’ - uvula deviates to side that is functioning
PHARYNGEAL MUSCLES - Swallow water and see if they splutter
LARYNGEAL MUSCLES - Listen to speech and see if any hoarseness
Which CN is the only nerve to exit the brainstem posteriorly?
Trochlear nerve - EXIT POSTERIOR MIDBRAIN AT JUNCTION WITH PONS
If a patient has reduced sensation unilaterally on the face, including the forehead and lip, what does this suggest? Why?
More likely involves peripheral facial nerve (Bell’s palsy) than a central lesion (forehead sparing)
There is bilateral innervation of the upper facial nerve
Which cranial nerves are located within the cavernous sinus and can be damaged in thrombosis?
III, IV, VI, V2, V1
Outline the ‘rule of 4’ for cranial nerves
4 above the pons (1-4)
4 at the pons (5-8)
4 in medulla (9-12)
