Orbicularis muscle

Infiltrative anesthesia is the major type of local anesthesia used in eyelid surgery. It can be subdivided into two forms a pretarsal subcutaneous block and a retrotarsal block. A pretarsal subcutaneous block provides excellent anesthesia to the anterior lamella, including skin, orbicularis muscle, orbital septum, and the anterior tarsal surlace.When anesthesia is needed for surgery on the palpebral conjimctiva or posterior tarsal surface, a retrotarsal block is indicated. 

Eyelid myokymia or benign eyelid twitching is a common localized form of facial myokymia. It is a transient condition in which mild to moderate fine undulating contractions of the orbicularis muscle occurs, causing an annoying... 

The integration of bomlinum toxin into the orbicularis muscle can cause reduced blinking and lead to corneal exposure and ulceration. 

Holds, J.B., Alderson, K., Fogg, S.G. and Anderson, R.L. (1990) Motor nerve sprouting in human orbicularis muscle after botulinum A injection. Invest. Ophthalmol. Vis. Sci. 31 964-967. 

Kissing. Orbicularis muscles control the lips, and for the Romans osculum was a peck on the cheek hasium was a lip-to-lip juxtaposition and saviolum was a passionate kiss that involved the tongue. 

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

A twitching or spasmodic contraction of the orbicularis occuli 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. 

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. 

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. 

Figure 9.12 Mold for cleft lip model and orbicularis oris muscle.

Two types of equation are needed to compute the network myoelastic eqmtions that describe the physical behaviour of the walls of the pipes and aerodynamic eqmtions that describe the evolution of the movements and pressures of the air in the network. The variables for these equations are specified by means of 29 parameters that metaphorically describe the actions of the vocal tract muscles and organs, such as cricothyroid, styloglossus, orbicularis oris and masseter, to cite but four. This s)mthesiser is capable of producing utterances with an... 

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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