▁These ▁signals ▁travel ▁along ▁the ▁opt ic ▁n erve ▁fib ers ▁to ▁the ▁brain , ▁where ▁they ▁are ▁interpreted ▁as ▁vision ▁in ▁the ▁visual ▁cor tex . ▁ ▁Prim ates ▁and ▁many ▁other ▁verte br ates ▁use ▁three ▁types ▁of ▁volunt ary ▁eye ▁movement ▁to ▁track ▁objects ▁of ▁interest : ▁smooth ▁purs uit , ▁ver gence ▁sh ifts ▁and ▁s acc ades . ▁These ▁types ▁of ▁movements ▁appear ▁to ▁be ▁initi ated ▁by ▁a ▁small ▁cort ical ▁region ▁in ▁the ▁brain ' s ▁front al ▁lo be . ▁This ▁is ▁cor ro bor ated ▁by ▁removal ▁of ▁the ▁front al ▁lo be . ▁In ▁this ▁case , ▁the ▁ref lex es ▁( such ▁as ▁ref lex ▁sh ifting ▁the ▁eyes ▁to ▁a ▁moving ▁light ) ▁are ▁int act , ▁though ▁the ▁volunt ary ▁control ▁is ▁ob liter ated . ▁ ▁An atom y ▁ ▁Mus cles ▁▁ ▁Six ▁extra oc ular ▁mus cles ▁facil itate ▁eye ▁movement . ▁These ▁mus cles ▁arise ▁from ▁the ▁common ▁tend in ous ▁ring ▁in ▁the ▁orbit , ▁the ▁eye ▁cav ity , ▁and ▁attach ▁to ▁the ▁e y eb all . ▁The ▁six ▁mus cles ▁are ▁the ▁later al , ▁med ial , ▁inferior ▁and ▁superior ▁rect us ▁mus cles , ▁and ▁the ▁inferior ▁and ▁superior ▁ob lique ▁mus cles . ▁The ▁mus cles , ▁when ▁contract ing , ▁cause ▁movement ▁of ▁the ▁e y eb all , ▁by ▁pulling ▁the ▁e y eb all ▁towards ▁the ▁mus cle . ▁For ▁example , ▁the ▁later al ▁rect