PANCE Blueprint Neurology (7%)

Cranial Nerve Palsies

Muscles Innervated by Cranial Nerves
Cranial Nerve Muscle(s) Lesion(s)
Oculomotor nerve (CN III)
  • Extraocular muscles innervated by CN III are
    • superior rectus (SR)
    • inferior rectus (IR)
    • medial rectus (MR)
    • inferior oblique (IO)
  • Levator palpebrae superioris
  • Ciliary muscle
  • Sphincter pupillae
  • Diplopia
  • Ptosis
  • Loss of accommodation
  • Pupillary involvement
    • in compressive lesions the pupil becomes dilated and non-reactive
    • in ischemic lesions (e.g., diabetes mellitus) the pupil is spared
Trochlear nerve (CN IV)
  • Superior oblique
  • Difficulty looking down
  • Head tilt away from the side of the lesion
Mandibular branch of the trigeminal nerve (CN V3)
  • Muscles of mastication include
    • masseter
    • temporalis
    • lateral and medial pterygoid
  • Anterior belly of the digastric muscle
  • Mylohyoid muscle
  • Tensor palati
  • Tensor tympani
  • Jaw deviation towards the side of the lesion
Abducens nerve (CN VI)
  • Lateral rectus
  • Horizontal diplopia
Facial nerve (CN VII)
  • Muscles of facial expression
  • Posterior belly of digastric muscle
  • Stylohyoid muscle
  • Stapedius muscle
  • Bell's palsy
  • Loss of blink reflex
  • Hyperacusis (when the stapedius is involved)
Glossopharyngeal nerve (CN IX)
  • Stylopharyngeus muscle


Vagus nerve (CN X)
  • Muscles of the palate and pharynx except
    • tensor palati muscle (CN V3)
    • Stylopharyngeus muscle (CN IX)
  • All muscles of the larynx
  • alate droop
  • Dysphagia
  • Deviation of the uvula away from the side of the lesion
  • Loss of gag reflex (the sensory component of this reflex is mostly via CN IX)
Accessory nerve (CN XI)
  • Sternocleidomastoid muscle
  • Trapezius muscle
  • Weakness with turning of the head
  • Shoulder droop
Hypoglossal nerve (CN XII)
  • Muscles of the tongue except for the
    • palatoglossus muscles
  • Tongue deviation towards the side of the lesion
osmosis Osmosis
IM_MED_CranialNerve1_v1.3_ Cranial nerve I, also known as the olfactory nerve, is a special sensory nerve that is responsible for smell. It travels through the olfactory tract and bulb and exits through the foramina in the cribriform plate of the ethmoid bone.

Cranial Nerve Function Picmonic

CN I Picmonic

IM_MED_CranialNerveII_v1.4_ Cranial nerve II, also known as the optic nerve, is a special sensory nerve responsible for vision. It partially decussates in the optic chiasm and exits the cranium through the optic canal.

CN II Picmonic

IM_MED_CranialNerve3_v1.6_ Also known as the oculomotor nerve. It is a motor neuron that controls most of the eye's movements, along with accommodation, eyelid opening and pupillary constriction.

CN III Picmonic

IM_MED_CranialNerve4_v1.4_ Also known as the trochlear nerve. It is a motor nerve that controls the superior oblique extraocular muscle.

CN IV Picmonic

IM_MED_CNV_v1.2_ Also known as the trigeminal nerve. CN V is the largest cranial nerve and has both motor and sensory functions.

CN V Picmonic

IM_MED_CranialNerve6_v1.3_ Also known as the abducens nerve. CN VI controls the lateral rectus extraocular muscle.

CN VI Picmonic

IM_MED_CN7_2.2_ CN VII (Seven) is also known as the facial nerve and it has both motor and sensory functions. It's sensory functions include being responsible for taste from the anterior 2/3 of the tongue. It's motor functions include control of the muscles of facial expression, the stapedius muscle in the middle ear and closing of the eyelid

CN VII Picmonic

IM_MED_CranialNerve8_v1.6_ CN VIII is a sensory nerve that is also known as the vestibulocochlear nerve. It divides into the vestibular nerve which is responsible for balance/equilibrium and visual fixation during movement and the cochlear nerve which is responsible for hearing.

CN VIII Picmonic

IM_MED_CranialNervesIX_v1.5_ CN IX is also known as the glossopharyngeal nerve. It is a motor and sensory nerve that has various functions including swallowing and taste sensation for the posterior 1/3 of the tongue. It is also important for regulation of heart rate via baroreceptors in the carotid sinus and regulation of respiratory drive via chemoreceptors in the carotid body.

CN IX Picmonic

IM_MED_CranialNerve10_v1.3_ CN X is also known as the vagus nerve. it is a motor, sensory and visceral nerve with several functions such as heart rate regulation, respiratory drive regulation, palate elevation, swallowing and talking. It is clinically assessed by checking for ability to swallow, elevate the palate and maintain a midline uvula.

CN X Picmonic

IM_MED_CranialNerveXI_v1.3_ Also known as the accessory nerve. This is a motor nerve that is responsible for head turning and shoulder shrugging via innervation of the sternocleidomastoid and trapezius muscles.

CN XI Picmonic

IM_MED_CranialNerve12_v1.2_ CN XII is also known as the hypoglossal nerve. This is a motor nerve that is responsible for tongue movement. It should be noted that unilateral damage will lead to tongue deviation TOWARD the affected side.

CN XII Picmonic

Traumatic brain injury (Prev Lesson)
(Next Lesson) Encephalopathic disorders
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