![]() ![]() Therefore there is no point of reference for finding the muscle if it is lost or slipped. Therefore, in traumatic cases where the lateral, superior, and inferior recti muscles are transected or must be detached for scleral exploration, these muscles should be isolated from their connective attachments so as not to advance or resect adjacent muscles unintentionally. The medial rectus is the only rectus muscle that does not have an oblique muscle running tangentially to it. The inferior rectus is attached to the lower eyelid retractors, the capsulopalpebral fascia, and the inferior tarsal muscle. The superior rectus is loosely attached to the LPS and connected to the superior oblique by a frenulum of the intermuscular septum. These connections are advantageous for globe and strabismus surgeons if a muscle is "lost." The lateral rectus is connected to the inferior oblique muscle by a frenulum of the intermuscular septum. It fuses anteriorly with the intermuscular septum about 2 mm posterior to the limbus and posteriorly to the optic nerve sheath. The Tenon capsule is an orbital fascia that envelopes the globe and anterior portion of the EOMs, forming a sleeve within which the eye can move. This fibroelastic pulley system stabilizes the EOM bellies in space, preventing deep retraction of the muscle should it be disinserted or lacerated anteriorly, and may preserve muscle function on initial examination. The EOMs are attached to check ligaments within an intermuscular membrane. Knowing this and the relationship of EOM globe insertion provides surgeons with an anatomical roadmap for globe exploration if an open wound is suspected but not obvious on the initial exam. ![]() Īccessory extraocular muscles or fibrotic structures have been described and may also be encountered during eyelid or orbital procedures. Patients with congenital fibrosis of extraocular muscles may have anomalously inserted tendons, thin tendons, or increased muscle tension. Insertion distances vary among individuals, but conventionally taught measurements for the medial, inferior, lateral, and superior rectus muscles from the limbus are 5.5 mm, 6.5 mm, 6.9 mm, and 7.7 mm, respectively. Notwithstanding breaks from the initial injury, sutures passing too deeply at or posterior to the rectus insertion site are at risk for scleral perforation and precipitating retinal breaks. The sclera is thinnest just posterior to the insertion of the rectus muscles (averaging about 0.3 mm in thickness), providing a potential site of rupture during globe trauma. They insert onto the globe near the globe's equator at varying distances from the limbus: the medial rectus inserts the closest to the limbus, and the inferior rectus, lateral rectus, and superior rectus muscles each insert progressively further away, yielding an imaginary coil termed the spiral of Tillaux. The rectus muscles originate from a fibrous ring termed the annulus of Zinn within the orbital apex. The EOMs of the eye include the medial, inferior, lateral, and superior rectus, the superior and inferior oblique, and the levator palpebrae superioris (LPS). The anatomy, actions, and innervation of EOMs. The goal of EOM management during acute ocular or orbital surgery is to limit the amount of fibrosis that could occur and result in strabismus. The presence or suspicion of an open globe injury and mechanical causes of strabismus or neurologic involvement guides the planning and timing of surgery. Contrarily, the EOMs may not be damaged but may need to be iatrogenically detached from the globe to explore and repair open globe injuries. Indirectly, EOM motility may be impaired from cranial nerve palsy or supranuclear injury associated with head and neck trauma. Direct EOM involvement can range from mild: minimal displacement from adjacent soft tissue edema or hemorrhage to moderate: contusion of the EOM itself to severe: disinsertion, laceration, or incarceration of the EOM from the traumatic blow or by an orbital fracture. These injuries are more commonly encountered when the body has sustained high-velocity forces, such as motor vehicle accidents or firearm assault.Īddressing EOM management in trauma can be conceptualized in two ways: one where there is damage to the EOMs and one where there is not. Recognition and treatment of life-threatening injuries following Advanced Trauma Life Support (ATLS) principles hold precedence over all others. In the known ocular or orbital trauma setting, elucidating the mechanism, type, and severity of the injury helps triage critical components of the physical exam. Extraocular muscle (EOM) management from ocular, orbital, and cranial trauma can be varied and complex. ![]()
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