The orbit pdf - Head and Neck

552

CHAPTER 11

the maxilla and the frontal bone.

illa, and the medial margin is formed by the processes of

rior margin is formed by the zygomatic bone and the max

the processes of the frontal and zygomatic bones, the infe

above by the frontal bone, the lateral margin is formed by

is formed

orbital margin

apex posterior (Fig. 11.18). The

The orbit is a pyramidal cavity with its base anterior and its

forced up the duct into the lacrimal sac on blowing the

This prevents air from being

lacrimal fold.

known as the

The opening is guarded by a fold of mucous membrane

bony canal and opens into the inferior meatus of the nose.

The duct descends downward, backward, and laterally in a

emerges from the lower end of the lacrimal sac (Fig. 11.16).

is about 0.5 in. (1.3 cm) long and

nasolacrimal duct

The

nasolacrimal duct.

medial palpebral ligament and is the upper blind end of the

(Fig. 11.16), which lies in the lacrimal groove behind the

The Head and Neck

nose.

The Orbit

Description

-
-

superior oblique

lacrimal gland

levator palpebrae

superioris

superior rectus

lateral rectus

sclera

inferior rectus

inferior oblique

medial rectus

nasociliary nerve

lower division of

oculomotor nerve

infraorbital nerve

inferior oblique

ciliary ganglion

abducent nerve

lateral rectus

trochlear nerve

lacrimal nerve

upper division of
oculomotor nerve

superior rectus

levator palpebrae superioris

supraorbital nerve

trochlear nerve

supratrochlear nerve

optic nerve

trochlea

orbital plate of frontal

superior orbital

fissure

greater wing of

sphenoid

zygomatic

optic canal

lesser wing of

sphenoid

maxilla

ethmoid

lacrimal

medial rectus

optic nerve

ophthalmic artery

inferior rectus

lower division of
oculomotor nerve

inferior
orbital
fissure

abducent

nasociliary

upper division of

oculomotor nerve

trochlear nerve

frontal nerve

lacrimal nerve

ophthalmic vein

superior orbital

fissure

superior rectus

supraorbital nerve

supratrochlear nerve

levator palpebrae superioris

superior oblique

FIGURE 11.18

The optic canal and the superior and inferior orbital fissures on the left side.

forming the walls of the right orbit.

Bones

Muscles and nerves of the left orbit as seen from in front.

Right eyeball exposed from in front. B.

Basic Anatomy

the maxilla and the greater wing of the sphenoid

Located posteriorly between

Inferior orbital fissure:

(Fig. 11.16). It transmits the nasolacrimal duct.

it communicates with the inferior meatus of the nose

Located anteriorly on the medial wall;

Nasolacrimal canal:

maxillary nerve) and blood vessels.

transmit the infraorbital nerve (a continuation of the

orbit in the orbital plate of the maxilla (Fig. 11.19); they

Situated on the floor of the

Infraorbital groove and canal:

transmits the supraorbital nerve and blood vessels.

situated on the superior orbital margin (Fig. 11.18). It

The supraorbital notch is

Supraorbital notch (Foramen):

the walls of the orbit.

sixth of the eye is exposed; the remainder is protected by

Lies anteriorly (Fig. 11.18). About one

Orbital opening:

Figure 11.18.

The openings into the orbital cavity are shown in

from the ethmoid sinuses), and the body of the sphenoid

plate of the ethmoid (which separates the orbital cavity

tal process of the maxilla, the lacrimal bone, the orbital

Formed from before backward by the fron

Medial wall:

separates the orbital cavity from the maxillary sinus

Formed by the orbital plate of the maxilla, which

Floor:

wing of the sphenoid (Fig. 11.18)

Formed by the zygomatic bone and the greater

Lateral wall:

nial fossa and the frontal lobe of the cerebral hemisphere

which separates the orbital cavity from the anterior cra

Formed by the orbital plate of the frontal bone,

Roof:

The orbital walls are shown in Figure 11.18.

553

Openings into the Orbital Cavity

(Fig. 11.18); it communicates with the pterygopalatine

thalmic artery.

cranial fossa. It transmits the optic nerve and the oph

sphenoid (Fig. 11.18); it communicates with the middle

Located posteriorly in the lesser wing of the

Optic canal:

ophthalmic vein.

abducent nerve, the nasociliary nerve, and the superior

the oculomotor nerve (upper and lower divisions), the

the lacrimal nerve, the frontal nerve, the trochlear nerve,

communicates with the middle cranial fossa. It transmits

greater and lesser wings of the sphenoid (Fig. 11.18); it

Located posteriorly between the

Superior orbital fissure:

nerves.

branch, the inferior ophthalmic vein, and sympathetic

fossa. It transmits the maxillary nerve and its zygomatic

frontal sinus

superior oblique

levator palpebrae superioris

superior rectus

medial rectus

optic nerve

upper division of

oculomotor nerve

lower division of

oculomotor nerve

maxillary nerve

pterygopalatine ganglion

pterygopalatine fossa

greater and lesser

palatine nerves

posterior superior alveolar nerves

zygomatic nerve

maxillary sinus

middle superior alveolar nerve

anterior superior

alveolar nerve

infraorbital nerve

nerve to inferior oblique

lateral rectus

trochlea

short ciliary nerve

from ciliary ganglion

ciliary ganglion

inferior oblique

FIGURE 11.19

ed from the lateral side. The maxillary nerve and the pterygopalatine

Muscles and nerves of the right orbit view

ganglion are also shown.

554

CHAPTER 11

poral nerve, which later leaves it to enter the lacrimal gland

(Fig. 11.20). It is joined by a branch of the zygomaticotem

forward along the upper border of the lateral rectus muscle

part of the superior orbital fissure (Fig. 11.18) and passes

the trigeminal nerve. It enters the orbit through the upper

The lacrimal nerve arises from the ophthalmic division of

Lacrimal Nerve

back of the eyeball.

within the cranial cavity therefore is transmitted to the

as the eyeball. A rise in pressure of the cerebrospinal fluid

around the optic nerve, and through the optic canal, as far

spinal fluid extends forward from the middle cranial fossa,

so that the subarachnoid space with its contained cerebro

pole of the eyeball. Here, the meninges fuse with the sclera

cles and pierces the sclera at a point medial to the posterior

runs forward and laterally within the cone of the recti mus

pia mater, arachnoid mater, and dura mater (Fig. 11.25). It

lower lateral side. The nerve is surrounded by sheaths of

accompanied by the ophthalmic artery, which lies on its

fossa by passing through the optic canal (Fig. 11.20). It is

The optic nerve enters the orbit from the middle cranial

Optic Nerve

unknown.

It is supplied by sympathetic nerves, and its function is

of smooth muscle that bridges the inferior orbital fissure.

is a thin layer

orbitalis muscle,

muscle of Müller,

The

the periosteum covering the outer surfaces of the bones.

and is continuous through the foramina and fissures with

the walls of the orbit. It is loosely attached to the bones

The orbital fascia is the periosteum of the bones that form

The Head and Neck

Orbital Fascia

Nerves of the Orbit

maxillary nerve

nasociliary nerve

ciliary ganglion

superior oblique

trochlea

levator palpebrae superioris

superior rectus

lacrimal gland

long ciliary

nerves

short ciliary

nerves

abducent

nerve

left

lacrimal nerve

optic nerve

trochlear nerve

internal carotid artery

ophthalmic artery

cavernous sinus

anterior cerebral artery

optic chiasma

infundibulum

oculomotor nerve

trochlear nerve

abducent nerve

trigeminal nerve

trigeminal ganglion

mandibular nerve

middle meningeal artery

right

ophthalmic

nerve

medial rectus

nasociliary

nerve

lacrimal nerve

lacrimal gland

superior rectus

levator palpebrae

superioris

frontal nerve

supraorbital nerve

supratrochlear nerve

infratrochlear nerve

anterior ethmoidal nerve

ethmoid sinuses

FIGURE 11.20

wed from above. The roof of the orbit, formed by the orbital plate of the frontal

Right and left orbital cavities vie

have also been removed to expose the underlying structures.

bone, has been removed from both sides. On the left side, the levator palpebrae superioris and the superior rectus muscles

Basic Anatomy

off numerous branches, which accompany the nerves in the

the optic nerve to reach the medial wall of the orbit. It gives

with the optic nerve (Fig. 11.20). It runs forward and crosses

(see page 599). It enters the orbit through the optic canal

artery after that vessel emerges from the cavernous sinus

The ophthalmic artery is a branch of the internal carotid

Ophthalmic Artery

Blood Vessels and Lymph Vessels of the

without interruption.

carotid plexus into the orbit and run through the ganglion

A number of sympathetic fibers pass from the internal

ball and supply the sphincter pupillae and the ciliary muscle.

which enter the back of the eye

short ciliary nerves,

inferior oblique. The postganglionic fibers leave the ganglion

thetic fibers from the oculomotor nerve via the nerve to the

part of the orbit. It receives its preganglionic parasympa

size of a pinhead (Fig. 11.19) and situated in the posterior

The ciliary ganglion is a parasympathetic ganglion about the

lateral rectus muscle.

of the superior orbital fissure (Fig. 11.18). It supplies the

The abducent nerve enters the orbit through the lower part

Abducent Nerve

as the tip (see page 580).

nasal bone, and supplies the skin of the nose down as far

at the lower border of the

external nasal branch

ing an area of mucous membrane, it appears on the face

a slitlike opening alongside the crista galli. After supply

ethmoid (Fig. 11.20). It enters the nasal cavity through

fossa on the upper surface of the cribriform plate of the

rior ethmoidal foramen and enters the anterior cranial

passes through the ante

anterior ethmoidal nerve

The

part of the nose (Fig. 11.16).

of the medial part of the upper eyelid and the adjacent

ley of the superior oblique muscle and supplies the skin

passes forward below the pul

infratrochlear nerve

The

and sphenoidal air sinuses (Fig. 11.20).

supplies the ethmoidal

posterior ethmoidal nerve

The

choroid to reach the iris.

ball. They continue forward between the sclera and the

the short ciliary nerves and pierce the sclera of the eye

dilator pupillae muscle. The nerves pass forward with

(Fig. 11.20). They contain sympathetic fibers for the

from the nasociliary nerve as it crosses the optic nerve

two or three in number, arise

long ciliary nerves,

The

ing branch.

join the nasociliary nerve by means of the communicat

through the ganglion without interruption, and then

to the ciliary ganglion via the short ciliary nerves, pass

sensory nerve. The sensory fibers from the eyeball pass

communicating branch to the ciliary ganglion

The

Branches of the Nasociliary Nerve

(Fig. 11.20).

infratrochlear nerves

anterior ethmoidal

of the medial rectus muscle, and ends by dividing into the

above the optic nerve, runs forward along the upper margin

part of the superior orbital fissure (Fig. 11.18). It crosses

of the trigeminal nerve. It enters the orbit through the lower

The nasociliary nerve arises from the ophthalmic division

Nasociliary Nerve

(see below).

thetic fibers to the sphincter pupillae and the ciliary muscle

that passes to the ciliary ganglion and carries parasympa

nerve to the inferior oblique gives off a branch (Fig. 11.19)

the medial rectus, and the inferior oblique muscles. The

orbit in a similar manner and supplies the inferior rectus,

of the oculomotor nerve enters the

inferior ramus

The

muscle (Fig. 11.18).

pierces it, and supplies the levator palpebrae superioris

(Fig. 11.18). It supplies the superior rectus muscle, then

orbit through the lower part of the superior orbital fissure

of the oculomotor nerve enters the

superior ramus

The

Oculomotor Nerve

and supplies the superior oblique muscle (Fig. 11.20).

of the superior orbital fissure (Fig. 11.18). It runs forward

The trochlear nerve enters the orbit through the upper part

Trochlear Nerve

the mucous membrane of the frontal air sinus.

skin of the forehead; the supraorbital nerve also supplies

around the upper margin of the orbital cavity to supply the

that wind

supraorbital nerves

and

supratrochlear

into the

rioris beneath the roof of the orbit (Fig. 11.20). It divides

forward on the upper surface of the levator palpebrae supe

part of the superior orbital fissure (Fig. 11.18) and passes

the trigeminal nerve. It enters the orbit through the upper

The frontal nerve arises from the ophthalmic division of

Frontal Nerve

ends by supplying the skin of the lateral part of the upper lid.

(parasympathetic secretomotor fibers). The lacrimal nerve

555

and

■

is a

■

as the

Ciliary Ganglion

in the

Orbit

communicates through the inferior orbital fissure with the

inferior ophthalmic vein

the facial vein (Fig. 11.9). The

communicates in front with

superior ophthalmic vein

The

Ophthalmic Veins

tributed to the skin of the forehead (see page 581).

are dis

supraorbital arteries

supratrochlear

The

to the lacrimal gland

lacrimal artery

The

near the optic nerve.

near the corneoscleral junction; the latter group enters

posterior groups. The former group enters the eyeball

can be divided into anterior and

ciliary arteries

The

muscular branches

The

ophthalmoscope. The branches are end arteries.

branches, which may be studied in a patient through an

Here, it divides into

optic disc.

ball at the center of the

in the substance of the optic nerve and enters the eye

entrance to the nerve (Figs. 11.25 and 11.26). It runs

pierces the meningeal sheaths of the optic nerve to gain

is a small branch that

central artery of the retina

The

Branches of the Ophthalmic Artery

orbital cavity.

■

and

556

CHAPTER 11

The Head and Neck

pterygoid venous plexus. Both veins pass

ough

backward thr

the superior orbital fissure and drain into the

nous sinus.

caver

(Fig. 11.21). For the superior

rotate it medially

but also

they not only raise and depress the cornea, respectively,

on the medial side of the vertical axis of the eyeball,

Because the superior and the inferior recti are inserted

oblique muscles.

inferior

superior

lateral rectus,

rectus,

medial

inferior rectus,

superior rectus,

are the

wall of the orbital cavity to the eyeball (Fig. 11.18). These

There are six voluntary muscles that run from the posterior

Eye

Extrinsic Muscles Producing Movement of the

marker. The eye rotates either medially or laterally.

the eyeball use the upper rim of the cornea (or pupil) as the

is the rotation of the eye medially. Rotatory movements of

adduction

is the rotation of the eye laterally, and

abduction

is the rotation of the eye downward,

depression

upward,

is the rotation of the eye

Elevation

becomes as follows:

(horizontal, vertical, and sagittal). The terminology then

of the anterior pole as it rotates on any one of the three axes

of the eye are then related to the direction of the movement

as the anatomic “anterior pole” of the eye. All movements

The center of the cornea or the center of the pupil is used

Terms Used in Describing Eye Movements

or nodes are present in the orbital cavity.

No lymph vessels

Lymph Vessels

The Eye

Movements of the Eyeball

the

and the

and

rectus muscle to raise the cornea directly upward, the
inferior oblique muscle must assist; for the inferior

rect

carefully Figure 11.24.

muscles of the eyeball are summarized in Table 11.2. Study

The origins, insertions, nerve supply, and actions of the

rectus muscle.

erally and is inserted into the sclera beneath the superior

the frontal bone. The tendon now turns backward and lat

through a fibrocartilaginous pulley (trochlea) attached to

that the tendon of the superior oblique muscle passes

oblique muscle must assist (Figs. 11.21 and 11.22). Note

to depress the cornea directly downward, the superior

vertical axis

superior
rectus

transverse axis

medial
rectus

inferior
rectus

lateral
rectus

superior rectus

transverse axis

inferior rectus

sagittal axis

transverse axis

lateral rectus

superior
rectus

medial

recti

inferior rectus

lateral rectus

vertical axis

FIGURE 11.21

The actions of the four recti muscles in producing movements of the eyeball.