Week 1- anatomy Flashcards
Describe the intracranial course of the trigeminal nerve
Attaches to the pons
Runs inferior to the tentorium cerebellum between the posterior and middle cranial fossa.
Which foramen do the trigeminal nerve branches exit the cranium by?
CN V1- superior orbital fissure
CN V2- foramen rotundum
CN V3- foramen ovale
Where does the first branch of the trigeminal nerve supply (sensory)? Include deep structures
It supplies the forehead, upper eyelid down to the tip of the nose.
Deep structures include all the paranasal sinus’s (minus maxillary), the upper anterior nasal cavity, the bones and soft tissues of the orbit and the anterior and posterior cranial fossa.
Where does the second branch of the trigeminal nerve supply (sensory)? Include deep structures?
The lower eyelid to the mid cheek and upper lip.
Deep structures- lower posterior nasal cavity, maxilla and maxillary sinus, floor of the nasal cavity and palate, maxillary teeth and associated soft tissue (gingival)
Where does the third branch of the trigeminal nerve supply (sensory)? Include deep structures
Supplies from the mid cheek to the chin. Does not supply the angle of the mandible.
Deep structures are the mandibular teeth, anterior 2/3rds of the tongue, floor of the mouth, buccal mucosa and middle cranial fossa.
What muscles does the motor division of the trigeminal nerve supply?
Muscles of mastication
Name the three jaw closing muscles and their attachments
Masseter- from the angle of mandible to the zygomatic arch
temporalis- coronoid process of mandible- lateral aspect of neurocranium
Medial pterygoid- angle of mandible to pterygoid plate of sphenoid bone
How would you clinically test the sensory division of the trigeminal nerve?
Ask the patient to close their eyes and touch a cotton bud to the areas of the face supplied by each division. Ask the patient to say when they can feel anything. Compare sides.
How would you clinically test the motor division of the trigeminal nerve?
Test the strength of the jaw closing muscles (specifically masseter and temporalis) by asking the patient to clench their teeth
Ask the patient to open their jaw against resistance (lateral pterygoid)
Describe the path of the facial nerve from intracranial to extracranial
Intracranially- originates at the pons-medullary junction. Travels straight into the internal acoustic meatus in the posterior cranial fossa. From here it travels through the facial canal (and gives off a branch to the chorda tympani) and then through the stylomastoid foramen.
Most motor fibres pass into the parotid gland and then exit via one of the 5 branches.
What does the chorda tympani branch supply and which nerve does it join?
The chorda tympani branch supplies taste to the anterior 2/3rds of the tongue and parasympathetic supply to the salivary gland. It joins the lingual nerve (a branch of CN V3)
What does the facial nerve supply (not the chorda tympani branch)?
The muscles of facial expression.
Name the muscles of facial expression
Frontalis, orbicularis oculi, orbicularis oris, elevator of the lips
How would you clinically test the facial nerve?
Ask the patient to frown, close eyes tightly, puff out cheeks and smile.
Describe the intracranial and extracranial course of the glossopharyngeal nerve?
Originates in the superior medulla. Passes straight into the jugular foramen. Extracranial axons go down to the pharynx and tongue.
What modalities of axons does the glossopharyngeal nerve contain?
General sensory Special sensory Somatic motor Parasympathetic Visceral afferent
Describe the general sensory supply of CN IX
Supplies the posterior 1/3rd of the tongue, most of the nasopharynx, all of the oropharynx and some of the laryngopharynx. Also supplies the palatine tonsil, Eustachian tube and middle ear.
Describe the special sensory supply of CN IX?
Special sensory to the posterior 1/3rd of the tongue. Via vallate papillae.
Describe the somatic motor supply of CN IX?
To one of the longitudinal muscles of the pharynx
Describe the parasympathetic supply of CN IX?
To the parotid gland
Describe the visceral afferent supply of CN IX?
To the carotid baroreceptors and chemoreceptors.
Describe the course of the vagus nerve intracranially to extracranially
Connects from the medulla just inferior to the CN IX. Goes directly towards jugular foramen.
Where does the vagus nerve sit in the neck?
Within the carotid sheath
What other structures are in the carotid sheath?
Deep cervical lymph nodes
Common carotid artery
Internal jugular vein
In the chest, where does the vagus nerve pass?
On the right- travels on the lateral aspect of the trachea
On the left- on the lateral aspect of the aortic arch
They then pass onto the posterior lung root and then onto the oesophagus. They pass through the diaphragm with the oesophagus.
Where in the abdomen does the vagus nerve supply?
-spleen, pancreas, stomach, foregut, midgut and renal.
How would you clinically test the vagus nerve?
Ask patent to say ‘ah’. Uvula should stay in the midline. If there is unilateral pathology- the uvula will point away from the side with it.
Ask patient to swallow water- spluttering suggest issues with larynx
Listen to speech- hoarseness may be due to an issue with the muscles
Ask patient to cough
Describe the path of the spinal accessory nerve?
Originates from the anterior rootlets of the cervical spinal nerves. Ascends through the foramen magnum and heads towards the jugular foramen. Passes down through the jugular foramen and supplies the sternocleidomastoid. Then passes through the posterior triangle to supply the trapezius muscle.
How would you clinically test the spinal accessory nerve?
Ask the patient to shrug their shoulders.
Ask them to turn to look up at the opposite side.
Describe the course of the hypoglossal nerve intracranially and extracranially?
Originates from several rootlets that attach to the lateral pyramids of the medulla.
Passes anteriorly towards the hypoglossal canal.
Descends in the neck lateral to the carotid sheath. At the level of the hyoid bone passes anteriorly towards the lateral aspect of the tongue.
What does the hypoglossal nerve supply?
Most of the tongue muscles.
How would you clinically test the hypoglossal nerve?
Ask patient to stick their tongue out. If there isn’t pathology- the tip of the tongue will remain in the midline. if there is pathology- the tongue will point towards the injured side.
Damage to a spinal nerve may cause these sensory symptoms (use both medical and laymans terms)
Paraesthesia (pins and needles) Neuralgia- pain Anaesthesia (numbness) Sensitivity (hyperaesthesia) Temperature perceptions Loss of co-ordination/balance/clumsiness
Damage to a spinal nerve may cause these motor symptoms
Muscle stiffness Muscle tightness or spasm (cramp) Loss of muscle tone (hypotonia) Muscle weakness Loss of co-ordination
How would you go about testing the sensory aspect of spinal nerves?
Using dermatomes
How would you go about testing the motor aspect of spinal nerves?
Using myotomes
How would you test the motor and sensory aspect of spinal nerves simultaneously?
Using spinal cord reflexes.
