Facial nerve examination Review of the facial nerve course & distribution.. How to examine the facial nerve ? abnormal findings.. Clinical tips..
Review of the facial nerve course & distribution.. Facial nerve examination
Review of the facial nerve course & distribution.. Motor nucleus in the lower pons (LMN). Motor Fibers of facial nerve wind around the VI CN nucleus in the pons. They leave at the pontomedullary junction to join nervous intermedius (carries taste, lacrymation & salivation fibers). Enters the internal acoustic meatus along with IIX CN. In the facial canal (in the temporal bone), VII nerve gives 3 branches 1.Greater superficial petrosal nerve (for lacrymation & salivation) 2.Nerve to stapedius muscle: in the middle ear, contracts in the presence of noise to dampen the movement of stapes at the cochlea. 3.chorda tympani: carries taste fibers from the anterior 2/3 of the tongue. Exits the skull through the stylomastoid foramen. Runs in the substance of parotid gland & divides into branches to supply the muscles of facial expression.
Facial nerve examination Review of the facial nerve course & distribution.. so facial nerve supplies : 1.Muscles of facial expression (Motor) 2.Lacrymation & salivation (parasympathetic) 3.Taste sensation for the anterior 2/3 of the tongue ( Special sense)
How to examine the facial nerve ? We have to assess the three major functions of the facial nerve. The motor by the examining the movements of the facial muscles. Taste by testing the patient’s ability to distinguish different flavors. lacrymation: Schirmer’s test Facial nerve examination
The motor function: Facial nerve examination How to examine the facial nerve ? 1.Putting the patient in comfortable position & inspected the patient’s face. It should appear symmetric (forehead wrinkles, nasolabial folds, corners of the mouth). 2.Ask the patient to wrinkle his forehead or look up above his head (frontalis muscle).
3.Ask the patient to close his eyes tightly & try to open them by applying gentle upwards pressure (orbicularis oculi). 4.Ask the patient to show his teeth & look for any deviation of the angle of the mouth (orbicularis oris). 5.Ask the patient to puff out his cheeks & tap your finger on his inflated cheek (buccinator). 6.Ask the patient to whistle. 7.Check the (platysma) by asking the patient to clench teeth. Facial nerve examination How to examine the facial nerve ?
Taste: 1.Instruct the patient not to speak during the test. 2.Ask the patient to put out his tongue. 3.Use cotton dipped in sugar (sweet), salt, vinegar (sour) & bitter solutions. Apply them on the anterior 2/3 of the tongue. 4.Ask the patient to point to sweet, salt, sour or bitter on a card to indicate the response. 5.Between each test ask the patient to rinse his mouth with water. Facial nerve examination How to examine the facial nerve ?
Hook small strips of notched plotting paper over the lower eyelids while the patient looks upwards. Ask him to close his eyes & sit comfortably for 5 minutes. Measure the distance that tears travel down the strip from the notch. >15 mm is normal 5-15 mm equivocal. <5 mm abnormal Lacrymation: Schirmer’s test Facial nerve examination How to examine the facial nerve ?
Facial nerve examination abnormal findings.. CN 7 has a precise pattern of innervations, which has important clinical implications. The right and left upper motor neurons (UMNs) each innervate both the right and left lower motor neurons (LMNs) that allow the forehead to move up and down. However, the LMNs that control the muscles of the lower face are only innervated by the UMN from the opposite side of the face.
Facial nerve examination abnormal findings..
Facial nerve examination abnormal findings.. UMN dysfunction: This might occur with a central nervous system event, such as a stroke. Right central CN7 dysfunction: Note preserved abiltiy to wrinkle forehead. Left corner of mouth, however, is slightly lower than right. Left naso-labial fold is slightly less pronounced compared with right
Facial nerve examination abnormal findings.. LMN dysfunction: This occurs most commonly in the setting of Bell’s Palsy, an idiopathic, acute CN 7 peripheral nerve palsy. Left peripheral CN7 dysfunction: Note loss of forehead wrinkle, ability to close eye, ability to raise corner of mouth, and decreased naso-labial fold prominence on left.
Facial nerve examination abnormal findings..
Facial nerve examination Clinical tips.. Be on the look out for those older patients with a sense of humour who when you say: ‘ show me your teeth ’ will point to their dentures in a denture pot. Do not get your patient to smile as a test of facial expression because descending pathways of expressing emotions are different to the upper voluntary motor neurons. Bilateral facial palsy is less common than unilateral facial palsy which is more easy to be observed. In bilateral facial palsy there is no asymmetry but you can observe that there is a very little movement of the facial muscles during the examination.
Facial nerve examination Clinical tips.. Hyperacusis : results from damage to the nerve to stapedius. In this case sounds appear louder than normal. In a severe LMN palsy the eyelid may fail to close altogether & you may see the eyeball turning upwards to display the white sclera. this is called Bell’s phenomenon. this is a normal process but the sclera is hidden behind the closed eyelid in narmal persons.
Facial nerve examination Greeted the patient and obtained permission Putting the patient in comfortable position & inspected the patient’s face. It should appear symmetric (wrinkles, nasolabial folds, corners of the mouth). (with description, he will perform) Ask the patient to wrinkle his forehead or look up above his head. Ask the patient to close his eyes tightly & try to open them by applying gentle upwards pressure. Ask the patient to show his teeth & look for any deviation of the angle of the mouth. Ask the patient to puff out his cheeks & tap your finger on his inflated cheek. Ask the patient to whistle Check the platysma by asking the patient to clench teeth. Test the taste sensation by asking the patient to taste various solutions. Schirmer’s test (with description only) Thanked the patient