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176 ANATOMY.
inferior oblique, arises from the floor of the anterior portion of the
orbit. They are named as follows
The Levator Palpebrse,
The Superior Rectus,
The Inferior Rectus,
Straight muscles of the eye.
The External Rectus,
The Internal Rectus,
The Superior Oblique,
The Inferior Oblique.
The Levator Palpebne is thin, flat, and triangular in shape. It arises
by a narrow ribbon-like band from the under surface of the lesser wing
of the sphenoid bone above and in
P^IG. 91.
front (jf the optic foramen. It passes
forward over the eyeball, expanding
as it does so, and is inserted in the
OKitfiuis Suvcrinr fibrous tissue on the anterior surface
of the superior tarsal cartilage.
Relatione.—Between the muscle and
the roof of the orbit are situated the
frontal nerve (branch of the ophthal-
mic or first division of the fifth), the
fourth nerve, and the supraorbital ves-
Reetus Infc Jiowtr Mead Below it is the superior rectus
sels.
The Relative Pus ition and Attachiuent of the and the globc of the cve wlicrc it joins
^Muscles of the Left Eveball. ,i t i , • •, , i" i i • 1,1 ^
the lid it is situated behind the pal-
;
pebral ligament, and its deep surface rests on the conjunctiva. A small
branch of the third nerve controls its action and enters its under sur-
face.
The Four Recti or Straight 3Iusdes of the eye are straight, flattened
bands which arise from the borders of the optic foramen ; they then
pass forward, as their names indicate, to be inserted into the sclerotic
coat three or four lines from the cornea. With the exception of the
su])erior rectus they may be said to have one common origin, which is
in the form of an oval ring, the ligament of Zinn, which commences
above, passing downward on the inner side to the lower margin of the
ojitic foramen, thence transversely across the anterior lacerated foramen,
where it is attached to the great wing of the sphenoid bone ; from this
it ])asses again to the lesser wing on the outer side of the optic foramen.
The Superior Rectus is the weakest of the four straight muscles. It
has its origin between the levator palpebrpe and the ring or ligament
of Zinn, some of its fibres having their origin in the ring.
The Inferior Rectus principally arises from the ligament of Zinn on
the inner margin of the anterior lacerated foramen.
The Infernal Rectus arises from the ligament of Zinn on the inner
and lower margin of the optic foramen.
The External Rectus is the strongest muscle of its group. It usually
arises by two heads. The louier head is the stronger, and arises from the
ligament of Zinn and a spine on the lower margin of the anterior lace-
rated foramen, and also joins the inferior rectus muscle at its origin. The
upper head is the weaker, and arises between the anterior lacerated and
176 ANATOMY.
inferior oblique, arises from the floor of the anterior portion of the
orbit. They are named as follows
The Levator Palpebrse,
The Superior Rectus,
The Inferior Rectus,
Straight muscles of the eye.
The External Rectus,
The Internal Rectus,
The Superior Oblique,
The Inferior Oblique.
The Levator Palpebne is thin, flat, and triangular in shape. It arises
by a narrow ribbon-like band from the under surface of the lesser wing
of the sphenoid bone above and in
P^IG. 91.
front (jf the optic foramen. It passes
forward over the eyeball, expanding
as it does so, and is inserted in the
OKitfiuis Suvcrinr fibrous tissue on the anterior surface
of the superior tarsal cartilage.
Relatione.—Between the muscle and
the roof of the orbit are situated the
frontal nerve (branch of the ophthal-
mic or first division of the fifth), the
fourth nerve, and the supraorbital ves-
Reetus Infc Jiowtr Mead Below it is the superior rectus
sels.
The Relative Pus ition and Attachiuent of the and the globc of the cve wlicrc it joins
^Muscles of the Left Eveball. ,i t i , • •, , i" i i • 1,1 ^
the lid it is situated behind the pal-
;
pebral ligament, and its deep surface rests on the conjunctiva. A small
branch of the third nerve controls its action and enters its under sur-
face.
The Four Recti or Straight 3Iusdes of the eye are straight, flattened
bands which arise from the borders of the optic foramen ; they then
pass forward, as their names indicate, to be inserted into the sclerotic
coat three or four lines from the cornea. With the exception of the
su])erior rectus they may be said to have one common origin, which is
in the form of an oval ring, the ligament of Zinn, which commences
above, passing downward on the inner side to the lower margin of the
ojitic foramen, thence transversely across the anterior lacerated foramen,
where it is attached to the great wing of the sphenoid bone ; from this
it ])asses again to the lesser wing on the outer side of the optic foramen.
The Superior Rectus is the weakest of the four straight muscles. It
has its origin between the levator palpebrpe and the ring or ligament
of Zinn, some of its fibres having their origin in the ring.
The Inferior Rectus principally arises from the ligament of Zinn on
the inner margin of the anterior lacerated foramen.
The Infernal Rectus arises from the ligament of Zinn on the inner
and lower margin of the optic foramen.
The External Rectus is the strongest muscle of its group. It usually
arises by two heads. The louier head is the stronger, and arises from the
ligament of Zinn and a spine on the lower margin of the anterior lace-
rated foramen, and also joins the inferior rectus muscle at its origin. The
upper head is the weaker, and arises between the anterior lacerated and
