来源：特蕾西 A.Milligan，MD;塔玛拉 · B.卡普兰，MD;神经病学、 布里格姆和妇女 / 美国马萨诸塞州波士顿，马萨诸塞州总医院
颅神经检查遵循神经学检查中的心理健康状况评价。然而，在考试开始时问候病人作陈辞。例如，面部的肌肉 （这支配的颅神经七） 弱点可以在病人第一次接触的过程中会很明显。颅神经七 （面神经） 也有感官的分支，支配味蕾上前三分之二的舌头和外耳道内侧。因此，寻找同侧味觉功能障碍患者面部的弱点证实七颅神经受累。此外，神经解剖学知识有助于临床医师进行本地化的病变水平： 低的面部肌肉单方面无力建议性病变在另一侧，而病变涉及核或周围性面神经的部分清单与所有的面部肌肉在包含的边侧瘫痪。颅神经八 （听神经） 有两个部门： 听力 （人工耳蜗） 司和前庭司，支配半规管和维持平衡有重要作用。在常规的神经学检查，特别对前庭神经是通常不进行测试。
颅神经九 （舌咽神经） 和 X （thevagus 神经） 颅神经出现髓质，以及喉咽的功能;其功能是通过评估演讲和软腭运动测试。因为脑神经九和 Xform 的压制的感觉和运动四肢反射，引起的呕吐反射还可以测试其功能。颅神经溪 （副神经） 支配胸锁乳突肌和斜方肌的上半部分。这些肌肉控制一边到另一边转动头部和肩膀的耸了耸肩。颅神经考试结束的测试脑神经十二 （舌下神经），提供电机控制舌头的肌肉。
在神经系统评估时，临床医师应该总是试图联系在一起的考试才能洞察潜在疾病调查结果。重要的诊断线索可能包括多个颅神经介入的迹象和单方面与双边颅神经功能障碍。它将帮助临床医师制定要知道是否病人的症状发生突然 （作为预期与脑卒中），在关于一天 （如贝尔氏麻痹） 或逐渐超过周至数月 （与不断扩大的肿块） 的鉴别诊断。
颅神经六、 评估在此集合的另一个视频覆盖。该视频演示了脑神经第七至十二 (表 1) 进行系统的检查。
| 我 | 嗅觉 | 气味 |
| 二 | 光纤 | 传入的瞳孔反应视力 |
| 三 | 动眼神经 | 眼球水平 （引用） 传出瞳孔反应 |
| 四、 | 滑车 | 向下垂直眼球运动，内部旋转的眼睛 |
| V | 三叉神经脊束 | 面部感觉，下颌运动 |
| 六 | 外展神经 | 眼球水平运动 （绑架） |
| 七 | 面部护理 | 面部运动和强度，尝尝，抑制的响亮的声音，感觉;前壁的外耳道表面 |
| 八、 | 声学 | 听，前庭功能 |
| 九 | 舌咽神经痛 | 运动的咽、 咽、 舌头后部 （包括舌头后部的味道），和大多数的耳道的感觉 |
| X | 迷走神经 | 动作和腭、 咽、 咽反射，喉音听起来的感觉 |
| 西 | 脊柱的配件 | 胸锁乳突和斜方肌的肌肉的力量 |
| 十二、 | 舌下神经 | 舌头突出和侧方运动 |
表 1。12 颅神经和它们的基本功能
An examiner should develop an orderly approach to going through each nerve in numerical order, and document what test is performed and any findings. Abnormalities found in the cranial nerve exam may impact the remainder of the examination, requiring the examiner to look for other signs of diseases, such as multiple sclerosis (MS), myasthenia gravis, or amyotrophic lateral sclerosis (ALS) on the motor examination. For example, motor dysfunction of the lower cranial nerves, often called bulbar weakness, can be an early sign of muscle weakness, as seen in diseases such as ALS or myasthenia gravis. These findings on the cranial nerve examination will help the clinician focus the rest of the neurologic exam to help reach a possible diagnosis. Knowledge of the anatomy of the cranial nerves, head, and neck is important in both localization and diagnosis.
Systematic cranial nerve testing can sometimes give a clinician early and detailed information about specific pathologic processes affecting the brain. Anatomically, the twelve cranial nerves arise from distinctive locations in the brain and innervate various head and neck structures, as well as several organs in the thorax and abdominal cavity.
The cranial nerve exam part one focused of nerves one through six. In this installment we will briefly review the functions of nerves seven through twelve, followed by demonstration of specific tests that can provide valuable diagnostic information associated with the damage of these specific nerves.
We will start with a short discussion of the anatomy and physiology of cranial nerves VII to XII.
The cranial nerve VII is predominantly composed of motor fibers that supply muscles of facial expression. The facial nerve also carries taste information from the anterior two-thirds of the tongue and provides parasympathetic supply to the lacrimal, sublingual and submandibular glands. Cranial nerve VIII, the vestibulocochlear nerve, consists of cochlear and vestibular divisions, which relay sound and equilibrium information, respectively, from the inner ear to medulla.
Cranial nerve IX, the glossopharyngeal nerve arises from medulla and innervates the posterior one-third of the tongue and soft palate. It also stimulates the parotid gland to secrete saliva, and supplies the stylopharyngeus muscle, which helps in swallowing. Therefore, damage to this nerve may lead to the absence of the normal gag reflex. On the other hand, cranial nerve X, the vagus nerve, which also rises from the medulla, is a widely distributed, complex nerve that innervates various structures in head, neck, thorax and abdomen. However, all the functions of this nerve are not tested during a routine physical exam.
Cranial nerve XI, the spinal accessory nerve, innervates the sternocleidomastoid muscles and the upper portion of the trapezius. These muscles control turning the head to the side and shrugging of the shoulders. The cranial nerve exam concludes by testing cranial nerve XII, the hypoglossal nerve, which provides motor control of the muscles of the tongue involved in speech control and swallowing.
Now let’s review the systematic approach to examine this set of cranial nerves. Begin with the assessment of the facial nerve. Observe the patient’s face for signs of weakness, such as smoothing of nasolabial folds or widening of a palpebral fissure. Then have the patient raise their eyebrows and look for an inability to wrinkle their forehead on the involved side that can be seen in peripheral facial palsy, or the Bell’s palsy, which occurs due to facial nerve damage and manifests with unilateral weakness of both-the upper and lower facial muscles. This differs from the central facial palsy – seen in stroke patients with supranuclear lesion – which only affects the lower portion of one side.
Next, ask the patient to smile. Note an asymmetry in the contour of the smile, which can result from inability to fully raise the lip on the affected side in patients with either peripheral or central facial nerve palsy. Following that, instruct the patient to close their eyes tightly and assess if they “bury” their lashes equally on both sides. Then ask them to close their eyes again, and keep it closed while you try to open them. And, finally, have the patient blow up their cheeks while you try to push the air out of their pursed lips.
The next step is to assess the taste sensation, for which you will need cotton-tipped applicator, sugar water solution, and water for rinsing the mouth. Tell the patient to stick out their tongue, so that you can swab the sides with the sugar solution. Ask the patient to identify the taste. After getting the patient’s response have them rinse their mouth and repeat the testing on the other side of tongue. Then, ask the patient to compare the sense of taste on each side of the tongue.
The next group of tests evaluates the cochlear division of the cranial nerve VIII, the acoustic nerve. The assessment of hearing function starts with observing whether or not the patient can hear you during the interview. Note if they are wearing hearing aids. First perform a quick hearing assessment by holding your fingers a few inches away from the patient’s ear and softly rubbing them together. Ask the patient if they can hear the finger rub, then repeat on the other side, and inquire if the perceived sound is same for both sides.
Next, if the patient shows signs of hearing impairment, move onto the Weber and Rinne tests, also known as the tuning fork tests. These are performed to distinguish between conductive hearing loss and sensorineural hearing loss. Conductive hearing loss results from the external or middle ear disorders, such as otitis media or perforation of the eardrum. And sensorineural hearing loss occurs due to the damage of the cochlear nerve or the auditory pathways in the brain, which may result from aging, acoustic neuroma, or constant exposure to loud noises.
First let’s review the Weber test. Hit tuning fork tines with the heel of your hand and place the stem at the vertex of the patient’s head. Now ask the patient where they hear the sound. The sound produced by a tuning fork is conducted through both-air and vibration in the bones. Patients with normal hearing will hear the sound in the center of their head and equally in both ears. If the patient is experiencing hearing loss on one side, and if the nature of loss is sensorineural, then the sound lateralizes, or is perceived louder on the “good” side. Whereas, if the nature of loss is conductive, then the sound lateralizes to the “bad” side, since the well-functioning inner ear on this side might pick up the sound transmitted by the skull bones, causing it to be perceived as louder than the unaffected side.
If the Weber test is abnormal, move onto performing the Rinne test. For this, hit the tuning fork tines and place stem on the mastoid bone. Instruct the patient to say “now” when they no longer hear the tone and quickly move the tines adjacent to the outer ear canal. Ask the patient if they can still hear the sound. In the case of conductive hearing loss, the patient will hear the sound for a longer time when the tuning fork is on the bone, compared to when it is in the air near the external ear canal.
Next, evaluate the cranial nerves IX, the glosspharyngeal nerve and cranial nerve X, the vagus nerve, together. Begin by asking the patient to say one full sentence to determine if their speech has nasal quality, which is characteristic to palatal weakness.
After that, ask the patient to open their mouth and say, “AAH”. While the patient is doing so, observe the elevation of their soft palate and note if any asymmetry is present. In the cranial nerve X paralysis, the soft palate fails to rise and the uvula deviates towards the opposite side.
Following that, move to cranial nerve XI or the spinal accessory nerve evaluation. Start by asking the patient to shrug their shoulders upward. Then instruct them to repeat the movement, while you provide resistance by pushing the shoulders down to check for weakness or asymmetry. Next, instruct the patient to turn their head to one side, and ask them to resist your attempt to push their chin in the opposite direction. Repeat the test with the patient turning their head to the opposite side. This is done to assess the strength of the sternocleidomastoids muscle.
Conclude the examination by testing cranial nerve XII, the hypoglossal nerve. For this, ask the patient to open their mouth and first observe their tongue at rest. Look for fasciculations, as may be seen with amyotrophic lateral sclerosis and other motor neuron diseases. Then instruct the patient to stick their tongue out straight; it should be in midline. Unilateral weakness may cause it to deviate towards the weak side.
For the final test assessing the strength of tongue muscles, ask the patient to push their tongue against their cheek, and instruct them to resist while to try to push it back in. Repeat on the other side, each time looking for weakness or asymmetry. This concludes the examination of all the cranial nerves.
You’ve just watched a JoVE video on examination of the cranial nerves from VII to XII. You should now have an understanding of the orderly approach that a clinician should follow while going through a comprehensive cranial nerve exam. The practice of tying together the findings of this exam with the patient history can help a physician gain an insight into the underlying neurological disease. As always, thanks for watching!
