Orbicularis Oculi

This muscle is supplied by the zygomatic portion of the facial nerve. 

Two Parts The central, which travels within the eyelids, and the orbital, which is larger and thicker, encircle the central and insert in the medial palpebral ligament, the bone above and below the ligament, spread around the eyebrows, the temporal region and the cheek. 

The patient is supine with the head in neutral position. 

Palpate the lateral portion of the eye fossa (bone) and direct the tip of tibe electrode at a 25-30 degree angle with the skin, in a medial and downward direction. It will penetrate the lower lip portion of the orbicularis oculi. 

Ask the patient to wink or blink very gently. This maneuver should not be repeated too often because the motion of the electrode can produce some soft tissue damage which may lead to swelling and/or hemorrhage (black eye) due to the extreme looseness of the tissues in the infraorbital area. 

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Facial nerve—monitor contraction of the orbicularis oculi muscle... 

Fig. 7.2 Horizontal section of the eyeball via the fovea centralis (Some extraocular structures are mentioned). 1, Levator muscle 2, Orbicularis oculi muscle 5, Eyelid skin 4, Palpebral conjunctiva 5, Bulbar conjunctiva 6, Superior tarsal plate 7, Upper eyelid margin 8, Cornea 9, Conjunctival sac 10, Sclera...

Strength of the orbicularis oculi muscle can be easily tested by instructing the patient to close the eyes forcefully while the examiner attempts to open the eyelids manually. Because the orbicularis oculi muscle is often affected in mj thenics, the eyelids may offer little resistance and open easily. 

Benign essential blepharospasm (BEB) is a dystonia characterized by involuntary sustained (tonic) and spasmodic (rapid or clonic) repetitive contractions involving the orbicularis oculi, procerus, and corrugator musculature (Figure 22-15). When the muscles of facial expression that are innervated by the fecial nerve are similarly involved on only one side of the fece, a hemifacial spastic dystonia occurs. 

Hemifecial spasm differs from blepharospasm in that the former is unilateral when fully developed. Hemifecial spasm may begin in the orbicularis oculi... 

Without previous anesthesia and avoiding penetration of the orbital septum, the diluted Botox typically is injected subcutaneously or intramuscularly, using a 27- or 30-gauge needle. The most commonly used dilution is 2.5 units per 0.1 ml of volume at each injection site. In patients with blepharospasm, the initial injection sites should include the medial and lateral pretarsal orbicularis oculi of the upper eyelid and the lateral pretarsal orbicularis oculi of the lower eyelid (Figure 22-16). Patients with hemifecial spasm should receive similar injections to any affected muscles of the lower fece (Figure 22-17). The cumulative dose of Botox in a 30-day period should not exceed 200 units. 

Muscle mass affects the toxin s response. More toxin is needed locally to produce a desired effect in areas of increased muscle mass. Histologic examination of orbicularis oculi musculature after treatment with botulinum toxin shows no evidence of alteration of muscle fiber diameter, disruption of internal muscle architecture, or pathologic changes in the motor end plates. 

In FES it is thought that sleeping with an everted eyelid causes the pretarsal orbicularis oculi and skin to override the lid margins, which causes the eyelashes to point downward (eyelash ptosis). Because some patients with FES also have keratoconus, an underlying connective tissue disorder may be implicated. 

Gills JP, Loyd TL. A technique of retrobulbar block -with paralysis of orbicularis oculi. J Am Intraocul Implant Soc 1983 9(3) 339 0. 

Figure 112.1 EMG recording from the left orbicularis oculi showing five doublet discharges firing regularly and continuously in a hypothyroid patient with ptosis. Vertical gain and sweep speeds are indicated in the tracing.

Figure 112.2 Stimulated SFEMG recordings of a patient investigated for ptosis obtained from the right orbicularis oculi muscle. Superimposed tracings are shown. Respective jitter values of 30, 38 and 69 (is (upper normal limit should be <30 (is) suggest ocular myasthenia as an underlying etiology. Sweep speeds and vertical gain are as shown in the tracings.

RNS (at 3 Hz with square-wave pulses 0.3 ms in duration) of the facial nerve to the orbicularis oculi and orbicularis nasalis, accessory nerve to the trapezius, and median nerve to the abductor pollicis brevis muscles can be studied. Hand-held bipolar electrodes and adhesive surface electrodes are used for stimulation and recording, respectively. Routine nerve conduction studies (NCS) of all four limbs, including the VII nerve, can also be performed. 

Lo, Y.L., chan, L.L., Pan, A. and Ratnagppal, P. (2004). Acute opthalmoparesis with anti-GQlb antibody electrophysiological evidence of neuromuscular transmission defection the orbicularis oculi. J. Neurol. Neurosurg Psychiatry. 75, 436 40. Macfaul, R., Dorner, S., Brett, E.M. and Grant, D.B. (1978). 

Cheek raiser Orbicularis oculi, pars palebralis... 

Retroauricular Frontalis Orbicularis oculi Elevator nostril Orbicularis oris... 

It descends over the frontal bone to the edge of the orbital margin where it interlaces with the fibers of the orbicularis oculi without having any bone attachment. 

If inserted too close to the external eye orbit, it could be in the orbicularis oculi. If inserted too close to the zygomatic arch, it could be in the tendinous portion of the temporal muscle. 

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