There are 12 cranial nerves which supply the head and neck region and have varied functions of purely sensory, purely motor and mixed type. Vagus is the only nerve which supplies to parts other than head and neck region like Lungs, Heart, Intestine and Stomach.
I have divided the Functions of the 12 cranial nerves to make it easy to remember for you. and which is really helpful in National Boards exams and Entrance examinations.

Classification of Cranial Nerves based on their type and function:

  1. Purely Sensory cranial nerves: I, II, VIII
  2. Purely Motor cranial nerves: III, IV, VI, VII, XI, XII
  3. Mixed Motor and Sensory Nerve Fibers: IX, X
  4. Cranial nerves which absorb CSF: I, II, VII, VIII
  5. Cranial nerves which originate from medulla: IX, X, XI, XII
  6. Cranial nerves which are attached to Pons: V, VI, VII, VIII
  7. Smallest cranial nerve: Trochlear nerve
  8. Cranial nerve with longest intra cranial course: Trochlear nerve
  9. Only cranial nerve which emerges dorsally from the brainstem: Trochlear
  10. Longest extra cranial nerve course of cranial nerve: Vagus

Classification of Cranial nerves
Mnemonic to remember Sensory, Motor and Mixed Cranial Nerves: :

“Some say marry money but my brother says big brains matter more”

S: sensory (olfactory nerve – CN I)
S: sensory (optic nerve – CN II)
M: motor (oculomotor nerve – CN III)
M: motor (trochlear nerve – CN IV)
B: both (trigeminal nerve – CN V)
M: motor (abducens nerve – CN VI)
B: both (facial nerve – CN VII)
S: sensory (vestibulocochlear nerve – CN VIII)
B: both (glossopharyngeal nerve CN IX)
B: both (vagus nerve – CN X)
M: motor (spinal accessory nerve – CN XI)
M: motor (hypoglossal nerve – CN XII)
Source: Radiopaedia.org

12 cranial nerves if you are confused with the numbering of the cranial nerves: 

  1. Olfactory Nerve
  2. Optic Nerve
  3. Oculomotor Nerve
  4. Trochlear Nerve
  5. Trigeminal Nerve
  6. Abducent Nerve
  7. Facial Nerve
  8. Vestibulocochlear Nerve
  9. Glossopharyngeal Nerve
  10. Vagus Nerve
  11. Spinal Accessory Nerve
  12. Hypoglossal Nerve

There are Spinal nerves as well which should not be confused with cranial nerves as they arise from the Spinal Cord on both the left and right side which are 31 pairs in number. These 31 Spinal nerves are mixed type supplying to many parts of the body. These are further divided into 5 types Cervical, Thorasic, Lumbar, Saccral and Coccygeal nerves.