Peripheral Distribution of Cranial Nerves Flashcards
What supplies the majority of the extraocular muscles?
Oculomotor nerve (CN III)
Which nerve innervates the superior oblique muscle?
CN IV (trochlear)
Which nerve innervates the lateral rectus muscle?
CN VI (abducens)
Which nerve is sensitive to the sclera of the eye?
Ophthalmic division of trigeminal (CN V1)
Which nerve innervates the ciliary muscle and sphincter pupillae?
Oculomotor (CN III)
What is Horner’s syndrome caused by?
Lack of sympathetic innervation to the eye, usually due to damage of the cervical sympathetic chain
Outline the symptoms of trochlear palsy
There is paralysis of the superior oblique –> eye elevation, hardest to diagnose (but is rarest) and the patient may attempt to minimise double vision by tilting their head (tilted to opposite side than affected eye)
What is the motor function of the mandibular nerve (CN V3)?
Has postsynaptic parasympathetic fibres to the muscles of mastication
What is the sensory function of the mandibular nerve (CN V3)?
To lower dentition (inferior alveolar) and tongue
What is the function of the ophthalmic branch (CN V1)?
Sensory to the lacrimal glands, forehead and nasociliary region
What is the function of the maxillary branch (CN V2)?
Sensory to the infraorbital foramen, upper dentition (superior alveolar), palate and gums
What are the two main divisions of the facial nerve?
Large motor division and smaller intermediate nerve
Describe the motor function of the facial nerve (CN VII)
Travels through internal auditory meatus and exits in the stylomastoid foramen to supply the muscles of facial expression
Describe the special sensory function of the facial nerve (CN VII)
Taste to anterior 2/3 of tongue by travelling with the chorda tympani
Describe the parasympathetic function of the facial nerve (CN VII)
Gives off the branch of the greater petrosal nerve and causes secretions at the lacrimal, submandibular and sublingual glands
Name the 5 branches of the somatic portion of the facial nerve (CN VII)
Temporalis, zygomatic, buccal, marginal mandibular and cervical
Describe the passage and function of the vestibulocochlear nerve (CN VIII)
Passes through the internal auditory meatus and is involved in hearing (cochlear portion)
Describe the function of the glossopharyngeal nerve (CN IX)
Sensory to pharynx and larynx (stimulates gag reflex if touched), supplies taste to posterior 1/3 of tongue, parasympathetic innervation to the parotid gland (via otic ganglion) and provides somatic sensory information to the carotid sinus
Describe the sensory function of the vagus nerve (CN X)
Lower pharynx, larynx and aortic body
Describe the motor function of the vagus nerve (CN X)
Muscles of palate, pharynx, larynx, oesophagus, and parasympathetic to thoracic and abdominal viscera
Describe the function of the spinal accessory nerve (CN XI)
Fibres to underside of SCM muscles and to lateral trapezius
What are the symptoms of spinal accessory nerve injury?
Weakened shoulder shrugging
Describe the function of the hypoglossal nerve (CN XII)
Motor to the tongue
What are the symptoms of hypoglossal nerve injury?
Paralysis of the ipsilateral side of the tongue –> deviation of the tongue towards side of lesion
Which nerves ‘hitch a lift’ with the hypoglossal nerve?
C1 and C2 hitch a lift to the infrahyoid muscles
Name the 4 cranial nerves with parasympathetic modalities
Oculomotor, facial, glossopharyngeal and vagus
What is the parasympathetic function of the oculomotor nerve?
Pupil constriction and accommodation reflex
What is the parasympathetic function of the facial nerve?
lacrimal glands, mucosal glands of nose/palate, submandibular and sublingual glands
What is the parasympathetic function of the glossopharyngeal nerve?
Parotid gland
What is the parasympathetic function of the vagus nerve?
Heart and gut to 2/3 along transverse colon
