HEAD AND CERVICAL SPINE

Cranial Nerves

 

Cranial nerves are nerves that branch off directly from the brain and brainstem, as opposed to the spinal column. Each nerve is paired; it branches off and innervates both sides of the head and neck. There are twelve cranial nerves, each labeled by number. They could be sensory, motor or both sensory and motor. The function of cranial nerves should be evaluated any time a head injury is suspected, such as a concussion. It should be noted that these are guidelines, and that the AT test the nerves in different ways depending on available materials and environment.

 

In order to help remember cranial nerves, there are two common mnemonics: one to remember which order they go in, and the other to remember if they are sensory, motor.

 

On Old Olympus Towering Tops, A Finn And German Viewed Some Hops

 

Some Saps May Marry But My Brother Says Bad Business My Man

 

Olfactory (I)

• Sensory

• Smell and to a certain extent taste; the two senses interact

• Example Testing Protocols: Put IcyHot on a tongue depressor and have patient try to smell it out of each notstril individually with eyes closed. Have them put close their eyes and have them drink water and Gatorade separately and have them try to tell the difference. 

Optic (II) 

• Sensory

• Vision acuity

• Example Testing Protocol: First ask if the patient wears corrective lenses and whether or not they're wearing them right now. Ask patient if they are experiencing double or blurred vision (Can you read the scoreboard? Can you see what's on my shirt?). Snellen Chart; check one eye at a time both close and far away. 

Oculomotor (III)

• Motor

• Pupillary reaction to light, eyelid elevation, downward eye rolling

• Example testing: Cover both eyes and remove at the same time to see if pupils dilate equally (or at all); ask athlete to look downwards; "follow the finger" test, going downward.

Trochlear (IV)

• Motor

• Upward eye rolling

• Example testing protocol: "Follow the finger" test, going upwards

Trigeminal (V)

• Motor and Sensory

• Muscles of mastication (chewing); sensation in the nose, forehead, temples, scalp, lips, tongue, and lower jaw

• Example testing protocol: have them chew a piece of gum or clench their jaw on a tongue depressor; "dull/sharp" test

Abducens (VI)

• Motor

• Lateral eye movement

• Example testing protocol: "follow the finger" test with head staying forward and have only the eyes moving

  • ​It's important to look for nystagmus 

Facial (VII)

• Motor and Sensory

• Expression muscles, taste

• Example testing protocol: have patient smile or frown; have them close their eyes and taste water and Gatorade and differentiate between the two. 

Vestibulocochlear (VIII)

• Sensory

• Equilibrium, hearing

• Example testing protocol: have them balance on one foot; Romberg's test; stand behind them and snap your fingers on one side or the other of their head and have them tell you which side it was on.

Glossopharyngeal (IX)

• Motor and sensory

• Phanygeal muscles (swallowing); taste

• Example testing protocol: have them swallow and feel their throat as they do; Gatorade vs. water test

Vagus (X)

• Motor and sensory

• Pharynx and larynx (swallowing, speech); gag reflex

• Example testing protocol: have them swallow and feel their throat; have them speak; put a tongue depressor on the back of the tongue to test for a gag reflex.

Accessory (XI)

• Motor

• Trapezius and sternocleidomastoid muscles

• Example testing protocol: Manual muscle testing; have the patient shrug their shoulders and turn their head. 

Hypoglossal (XII)

• Motor

• Tongue movement

• Example testing protocol: stick out tongue, curl it, move it side to side.