The Ultimate Guide to Brain Nerves: Understanding The 12 Cranial Nerves and Their Functions

The human brain is a complex organ and one of the most intricate parts of the nervous system. It is responsible for a wide range of functions, including learning, memory, movement, and emotion. The brain is composed of many different nerves, each with its own unique function. In this article, we will explore the 12 cranial nerves and their functions, the symptoms of cranial nerve disease, how a brain MRI shows cranial nerves and more.

What are Nerves from the Brain Called?

The nerves that originate in the brain are called Cranial Nerves. These nerves are responsible for transmitting information between the brain and various parts of the body, including the head and neck. There are 12 pairs of cranial nerves in the human body, each with its own specific function.

What is the Main Nerve in the Brain?

One of the most important cranial nerves is the Olfactory Nerve or Cranial Nerve I. This nerve is responsible for the sense of smell, and it helps us detect the different scents in our environment. It is also responsible for sending signals to the Limbic system, which is the part of the brain that controls emotions and behaviors.

What are the 12 Cranial Nerves Names?

The 12 cranial nerves are named after their function, and they are usually numbered I to XII in Roman numerals. Their names, functions and distribution are as follows:

Cranial nerve I: Olfactory nerve

Function: Sense of smell
Distribution: Nasal mucosa

Cranial nerve II: Optic nerve

Function: Vision
Distribution: Retina

Cranial nerve III: Oculomotor nerve

Function: Eye movement
Distribution: Extraocular muscles

Cranial nerve IV: Trochlear nerve

Function: Eye movement
Distribution: Superior oblique muscle

Cranial nerve V: Trigeminal nerve

Function: Sensory for face; chewing muscles
Distribution: Face and mouth muscles, cornea, nose, and forehead

Cranial nerve VI: Abducens nerve

Function: Eye movement
Distribution: Lateral rectus muscle

Cranial nerve VII: Facial nerve

Function: Facial expressions, secretion of saliva and tears, taste
Distribution: Face muscles, salivary gland, tongue, and ear

Cranial nerve VIII: Vestibulocochlear nerve

Function: Hearing and balance
Distribution: Cochlea and vestibular apparatus

Cranial nerve IX: Glossopharyngeal nerve

Function: Swallowing, taste, saliva secretion
Distribution: Tongue, pharynx, salivary glands

Cranial nerve X: Vagus nerve

Function: Control of organs, sensation and movement of throat
Distribution: Muscles in the thorax, neck, and abdomen; the larynx, pharynx, and viscera

Cranial nerve XI: Accessory nerve

Function: Head movement, swallowing
Distribution: Sternocleidomastoid and trapezius muscles

Cranial nerve XII: Hypoglossal nerve

Function: Tongue movement
Distribution: Muscles of the tongue

What are the 12 Cranial Nerves and Their Functions Quizlet?

There are various ways to test and memorize the 12 cranial nerves and their functions. Quizlets and flashcards are some of the more effective and conventional methods. These methods provide a range of scenarios and problems, which help with memorizing the different cranial nerves and their corresponding functions.

What are the 12 Cranial Nerves and Their Functions?

  1. Olfactory Nerve: Sense of smell
  2. Optic Nerve: Vision
  3. Oculomotor Nerve: Eye movement and pupil dilation
  4. Trochlear: Superior Oblique movement
  5. Trigeminal Nerve: Sensory for face and chewing muscles
  6. Abducens Nerve: Lateral rectus movement
  7. Facial Nerve: Facial expressions and secretion of tears and saliva
  8. Vestibulocochlear Nerve: Hearing and balance
  9. Glossopharyngeal Nerve: Swallowing, saliva secretion, and taste
  10. Vagus Nerve: Control of organs, sensation and movement of throat
  11. Accessory Nerve: Movement of the head and shoulders
  12. Hypoglossal Nerve: Tongue Movement

Does Brain MRI Show Cranial Nerves?

Although MRI’s have a wide range of applications in medicine, not all MRIs show cranial nerves. However, in certain cases, doctors might request an MRI with contrast to help with identification and location of the cranial nerve abnormalities. This type of MRI is called an MRI with contrast or gadolinium-enhanced MRI. It is important to note that not all MRIs require the use of contrast, and this will be determined by your doctor.

What are the Symptoms of Cranial Nerve Disease?

Cranial nerve disease can cause a range of symptoms depending on the cranial nerve affected. Some symptoms may include:

  • Loss of vision
  • Difficulty hearing
  • Facial nerve paralysis
  • Difficulty swallowing
  • Weakness or paralysis in the face, tongue or throat
  • Headaches
  • Dizziness or unsteadiness
  • Loss of smell or taste

If you are experiencing any of these symptoms, it’s important to speak with a healthcare professional right away. They will be able to diagnose the problem and recommend the appropriate treatment.

How to Perform a Cranial Nerves Examination

There are several tests that doctors can perform to assess the function of the cranial nerves. These tests are called cranial nerve exams. Here’s what you can expect during a cranial nerve exam:

  • The doctor will first observe your face for any signs of weakness or asymmetry
  • They will then ask you to follow their fingers with your eyes
  • They may also ask you to identify different smells and tastes
  • The doctor will test your hearing by asking you to repeat words or sentences at different volumes
  • They may also test your gag reflex by touching the back of your throat


In conclusion, the human brain and its nerves are complex and vital for optimal functioning. By understanding the 12 cranial nerves and their functions, we can learn to identify symptoms of cranial nerve disease, perform proper tests and exams, and seek appropriate medical care. Whether you are a healthcare professional or a personal remark, understanding cranial nerves can potentially lead to saving lives.