Cranial Nerves
The other cranial nerves I - VII and IX - XII are intact.
CRANIAL NERVES
- Localization principle : cranial nerve nuclei in the brainstem mark the lesion level. If a cranial nerve deficit is on the opposite side to a hemiparesis, the lesion is at the level of that nerve's nucleus (brainstem).
- a) CNS pathways to/from cortex, diencephalon, cerebellum, or other brainstem parts
- d) Generalized nerve/neuromuscular junction/muscle problem
- Brainstem level of nuclei : Midbrain — III, IV · Pons — VI, VII · Medulla — XII (nuclei lie near the 4th ventricle/medial longitudinal fasciculus)
Read this in CNS History Taking & Neurological Exam Guide | Clinical Skills
What our notes say
- The other cranial nerves I - VII and IX - XII are intact. (CNS PATHOLOGY — Past Paper Questions & Answers)
- Mechanism of action: toxin binds to gangliosides at the neuromuscular junction, is taken up and transported retrograde along the axon to the CNS, then travels via cranial nerve/cranial pathway transsynaptically to reach the spinal cord/brainstem (Streptococcus Classification, S. pyogenes, Rheumatic Fever, AGN)
- Cephalic tetanus affects the cranial nerves and causes trismus and difficulty swallowing. (Paediatrics end of fourth year main exam: 1 July 2019, Paper One, 99 of 100 MCQs)
- Examine pupils and cranial nerves as indicated, and assess reflexes and sensation where feasible. (Paediatric History Taking and Physical Examination)
- Result: flaccid (descending) paralysis, starting with cranial nerves, progressing to respiratory muscles if untreated (Bacteriology and Entomology Supplementary Exam)
- Chronic ethanolism can lead to Wernicke disease, which may have an element of cranial nerve findings. (CNS PATHOLOGY — Past Paper Questions & Answers)
Study material on Cranial Nerves
- High-Yield Clinical Exam Notes: Cranial Nerves, Respiratory, Cardio
- Cranial Nerves, Eye Exam & Vital Signs: MBChB Clinical Revision
- MEDICAL PHYSIOLOGY II ESsays
- CNS PATHOLOGY
- CNS History Taking & Neurological Exam Guide | Clinical Skills
- cat 2 2014 — Source Paper Awaiting Edit
- MBChB Clinical Exam: Cranial Nerves, Resp & Abdominal Skills
- Weekly Year 1: Anatomy Exam - May 22, 2026 (Section A: MCQs)
Practice questions on Cranial Nerves
In the developing embryo, pharyngeal arches are formed. The second (branchial) arch gives rise to the stapedius, orbicularis oris, and posterior belly of the digastric muscles. Which of the following cranial nerves is also derived from this arch?
- III
- V
- VII
- IX
- XI
Answer: C. CN VII is the facial nerve, innervating muscles of facial expression. ---
Which of the following cranial nerves conducts sensory touch information from the skin of the forehead, cheeks and lower jaw and conducts motor signals to the muscles of mastication?
- Facial nerve
- Trigeminal
- Hypoglossal
- Abducens
- Vagus nerve ✅ Answer: B
Answer: A. The trigeminal nerve (CN V) is
What cranial nerve supplies taste innervation for the posterior tongue?
- V
- VII
- IX
- XI
- XII
Answer: C. ** The glossopharyngeal nerve (CN IX) provides taste innervation to the posterior third of the tongue. CN VII (facial) supplies taste to the anterior two-thirds, while CN V provides general sensation but not taste. --- ---
Which of the following cranial nerves conducts sensory touch information from the skin of the forehead, cheeks and lower jaw and conducts motor signals to the muscles of mastication?
- Facial nerve
- Trigeminal
- Hypoglossal
- Abducens
- Vagus ✅ Answer: B
Answer: A. The trigeminal nerve (CN V) is responsible for sensory innervation of the face and motor innervation of the muscles of mastication.
What cranial nerve supplies taste innervation for the posterior tongue?
- Facial nerve (CN VII)
- Glossopharyngeal nerve (CN IX)
- Vagus nerve (CN X)
- Trigeminal nerve (CN V)
Answer: B. The glossopharyngeal nerve (CN IX) is responsible for taste sensation from the posterior one-third of the tongue.
Which cranial nerve is primarily responsible for motor innervation to the muscles of facial expression?
- Trigeminal nerve (CN V)
- Abducens nerve (CN VI)
- Facial nerve (CN VII)
- Glossopharyngeal nerve (CN IX)
Answer: C. The Facial nerve (CN VII) is primarily responsible for motor innervation to all the muscles of facial expression. The Trigeminal nerve (CN V) (A) provides sensory innervation to the face and motor innervation to muscles of mastication. The Abducens nerve (CN VI) (B) innervates the lateral rectus muscle of the eye. The Glossopharyngeal nerve (CN IX) (D) is involved in taste, salivation, and sensation from the pharynx.