_a_, Eyelids; _b_, bulbar fascia (Tenon’s capsule); _c_, _c′_,
retractor bulbi; _d_, rectus oculi inferior; _e_, obliquus oculi
inferior (in cross-section); _f_, rectus oculi superior; _g_,
levator palpebræ superioris; _h_, obliquus oculi superior (in
cross-section); _i_, lacrimal gland; _k_, _k′_, periorbita; _l_,
superficial fascia; _m_, deep fascia; _n_, skin; _o_, retrobulbar
fat; _p_, extraorbital fat; _q_, temporalis muscle; _r_,
supraorbital process; _s_, cranial wall; _1_, cornea; _2_, sclera;
_3_, chorioidea; _4_, ciliary muscle; _5_, iris; _6_, granula
iridis; _7_, retina; _7′_, optic papilla; _8_, optic nerve; _9_,
crystalline lens; _10_, capsule of lens; _11_, ciliary zone; _12_,
posterior chamber; _13_, anterior chamber; _14_, conjunctiva bulbi;
_15_, vitreous body. (After Ellenberger, in Leisering’s Atlas.)
]
The actual movements of the eyeball are by no means so simple as might
be inferred from the foregoing general statements. Practically all
movements are produced by the coördinated actions of several muscles,
involving combinations which are quite complex and difficult to
analyze accurately. Further complication is caused by the fact that
the recti are not inserted at equal distances from the equator and the
axes of rotation of the oblique muscles do not correspond to the
longitudinal axis of the eyeball.
=Nerve-supply.=—The oculomotor nerve supplies the foregoing muscles,
with the exception of the rectus externus and obliquus superior, which
are innervated by the abducens and trochlearis respectively.