This week we are continuing with the nervous system, one of our eleven organ systems. Cranial nerves are tricky to learn but they are essential as they control so many important body functions. We are going to try and explain these to you in relatively simple terms.
There are twelve pairs of cranial nerves. Cranial nerves can be shortened to CN and they are typically written in roman numerals.
CN I - Olfactory nerve - This is a special sensory nerve that functions in the sense of smell.
CN II - Optic nerve - This is another special sensory nerve that is the primary nerve for sight
CN III - Oculomotor - This is a motor nerve that functions in moving some of the muscles of the eye.
CN IV - Trochlear - This motor nerve also functions in moving one of the many eye muscles.
CN V- Trigeminal - This cranial nerve has both sensory and motor roots. It divides into the mandibular, ophthalmic, and maxillary nerves. It functions in moving the muscles of mastication (chewing food) and provides sensation to the face, scalp, and anterior ⅔’s of the tongue.
CN VI - Abducens - This a motor nerve that moves yet another muscle of the eye.
CN VII - Facial - This nerve has a mixed function. It provides motor function to the muscles of facial expression as well as sensation for the ears. It also innervates salivary glands.
CN VIII- Vestibulocochlear - This is a special sensory nerve that functions in balance and hearing.
CN IX - Glossopharyngeal - Another dual-functioning nerve. Its functions are swallowing, salivation, and taste sensation.
CN X - Vagus - This multifunctioning nerve is also called the wandering nerve as it is the only nerve that leaves the cranium. It provides sensation to the abdomen and is responsible for heart rate, and peristalsis and also moves some muscles of the larynx.
CN XI - Spinal accessory - This motor nerve moves laryngeal muscles as well as trapezius, a muscle for moving the head and neck.
CN XII - Hypoglossal - This motor nerve supplies the tongue, functioning in swallowing and speech.
This might seem like an overload of information but some mnemonics can help you remember :
This mnemonic is composed of the cranial nerves in order, using the first letter of each:
Oh, Oh, Oh, To Touch And Feel Very Good Velvet, Ah heaven
To remember the functions of the cranial nerves - this mnemonic tells you which is sensory, motor or both:
Some Say Money Matters But My Brother Says Big Brains Matter More.
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