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1. A 52 year old is diagnosed with having a tumor within the brain that is blocking action of the trigeminal
nerve prior to its division into the three main branches. Outline the key motor and sensory deficits that
might arise from such a lesion.
All three main branches will be affected.
Sensory deficits:
loss of general sensation to the upper, mid and lower face, the oral cavity and anterior two thirds of the tongue
Motor deficits:
weakness/paralysis of muscles of mastication – masseter, temporalis, medial and lateral pterygoid, anterior belly
of digastric and mylohyoid
weakness/paralysis of tensor veli palatine
2. How would these deficits differ if the tumor was blocking action of the most inferior of the three main
branches of the trigeminal nerve?
Sensory deficits:
Loss of general sensation to the lower face, lower portions of oral cavity and anterior two thirds of tongue
Motor deficits:
Same as Q1
3. You working on the neurology unit and are called to see a 42 year old with the sudden onset of some
head and neck deficits. You examine him and note that when he smiles, the left side of his mouth does
not move. He also complains of some diminished taste. You note no other obvious anomalies. The
attending neurologist is comes in just as you complete your examination. He tells you the patient has a
peripheral neuropathy (damage to a peripheral nerve). He asks you point blank what nerve is involved.
This is a no-brainer. Left cranial nerve VII (Facial Nerve). This nerve provides motor supply to the muscles of
the face and oris. Also the chorda tympani, a branch of CN VII branches off in the temporal bone and picks up
with V3 of CN.V and relays taste for the anterior two thirds of the tongue.
4. Later in the day you are called to the surgical unit. A 69 year old man is recovering from a deep surgery
to neck and has had “speech problems” since he woke up from the surgery. When you speak to him you
note that he has a soft very breathy voice, difficulty varying the pitch of his voice and his speech has a
nasal resonance quality. What cranial nerve do you think is involved? Do you think the damage to the
nerve occurred relatively high in the neck or relatively low in the neck?
Let’s review the signs and probable reason
Soft breathy voice: problems with vocal fold adduction – recurrent laryngeal nerve (branch of CN. X)
Difficulty varying pitch: problems with lengthening and tensing vocal fold – external branch of the superior
laryngeal nerve (branch of CN. X)
Speech with nasal resonance: problems with closing velopharyngeal port with relies heavily on the levator veli
palatine – pharyngeal branch of CN X.)
Therefore, there is CN X (vagus nerve) damage. It must be high in the neck since it involves all three branches
involved in speech and laryngeal muscle control.
5. You finish out your day on the stroke unit. Your referral describes a 49 year old woman with a severe
bilateral brainstem stroke. You see her and perform an examination of the oral mechanism. She
demonstrates problems moving her tongue, has a hoarse voice and demonstrates a unilateral facial palsy.
Jaw strength and motion is good. Based upon these results, what cranial nerves (actually their nuclei)
are affected by the stroke. What other motor signs might you look for? What kinds of sensory deficits
might you expect?
Tongue, lips/face and laryngeal involvement suggests damage to CN. VII, X, and XII. CN V is spared since
jaw movement is OK.
Other motor signs:
Problems with control of the velum (CN X)
Problems swallowing (tongue, lips and larynx)
Sensory deficits:
Loss of taste to anterior two thirds of tongue (CN VII)
Loss of sensation to the larynx (CN X)