The orbital region pdf - Head and Neck

Basic Anatomy

The orbits are a pair of bony cavities that contain the

549

The Orbital Region

eyeballs; their associated muscles, nerves, vessels, and fat;

the eye is closed.

nea when the eye is open and rises only slightly when

gin of the cornea. The lower lid lies just below the cor

straight ahead, the upper lid just covers the upper mar

cornea of the eye. When the eye is open and looking

the eye is closed, the upper eyelid completely covers the

lids and is the entrance into the conjunctival sac. When

is the elliptical opening between the eye

bral fissure

palpe

The

lateral angles.

medial

each other at the

larger and more mobile than the lower, and they meet

light by their closure (Fig. 11.16). The upper eyelid is

The eyelids protect the eye from injury and excessive

guarded by two thin, movable folds, the eyelids.

and most of the lacrimal apparatus. The orbital opening is

Eyelids

and

-
-

lacrimal papilla and punctum

orifices of tarsal glands

caruncula lacrimalis

plica semilunaris

iris

pupil

cornea

inferior meatus of nose

lacrimal duct in
nasolacrimal
canal

tarsal plates

lateral palpebral

ligament

medial palpebral

ligament

levator palpebrae

superioris

lacrimal gland

lacrimal sac

orbital septum

supraorbital nerve

supratrochlear nerve

infratrochlear nerve

frontal bone

orbicularis oculi

orbital septum

superior tarsal plate

tarsal gland

eyelash

sebaceous gland

subtarsal

sulcus

iris

cornea

conjunctiva

superior fornix of conjunctiva

smooth muscle

levator palpebrae superioris

conjunctiva covering sclera

FIGURE 11.16

in the levator palpebrae superioris.

Sagittal section through the upper eyelid, and the superior fornix of the conjunctiva. Note the presence of smooth muscle

yellow

duct. Note that a small window has been cut in the orbital septum to show the underlying lacrimal gland and fat (

Left eye, showing the superior and inferior tarsal plates and the lacrimal gland, sac, and

lacrimalis, and puncta lacrimalis.

Right eye, with the eyelids separated to show the openings of the tarsal glands, plica semilunaris, caruncula

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CHAPTER 11

are summarized in Table 11.2.

The origins and insertions of the muscles of the eyelids

attached to the sclera and the lower lid.

lid is pulled downward slightly by the conjunctiva, which is

tinues to cover the upper part of the cornea, and the lower

On looking downward, both lids move, the upper lid con

rioris contracts, and the upper lid moves with the eyeball.

upper lid. On looking upward, the levator palpebrae supe

eye is opened by the levator palpebrae superioris raising the

relaxation of the levator palpebrae superioris muscles. The

closed by the contraction of the orbicularis oculi and the

and the position of the eyeball. The eyelids are

ris muscles

levator palpebrae superio

orbicularis oculi

The position of the eyelids at rest depends on the tone of

Movements of the Eyelids

tarsal plate and the skin (Fig. 11.16).

orbital septum to reach the anterior surface of the superior

pierces the

levator palpebrae superioris muscle

tion of the

(Table 11.16). The aponeurosis of inser

ris oculi muscle

orbicula

septum are covered by the palpebral fibers of the

The superficial surface of the tarsal plates and the orbital

the tarsal plates.

The tarsal glands are embedded in the posterior surface of

to the crest of the lacrimal bone (Fig. 11.16).

bral ligament,

medial palpe

ends of the plates are attached by a band, the

a bony tubercle just within the orbital margin. The medial

lateral palpebral ligament,

are attached by a band, the

The lateral ends of the plates

tarsal plates.

rior and inferior

is thickened at the margins of the lids to form the supe

the periosteum at the orbital margins. The orbital septum

(Fig. 11.16). This is attached to

orbital septum

sheet, the

The framework of the eyelids is formed by a fibrous

and is thus clinically important.

small foreign particles introduced into the conjunctival sac

the margin of the lid (Fig. 11.16). The sulcus tends to trap

which runs close to and parallel with

subtarsal sulcus,

Beneath the eyelid is a groove,

palpebral fissure.

open at the

which is

conjunctival sac,

thus forms a potential space, the

ducts of the lacrimal gland (see below). The conjunctiva

upper lateral part of the superior fornix is pierced by the

Its epithelium is continuous with that of the cornea. The

onto the anterior surface of the eyeball (Fig. 11.16).

nices

inferior for

the superior

the eyelids and is reflected at

is a thin mucous membrane that lines

conjunctiva

The

canaliculus carry tears down into the nose (see page 551).

lacrimalis projects into the lacus, and the punctum and

(Figs. 11.16 and 11.17). The papilla

canaliculus lacrimalis

which leads into the

punctum lacrimale,

is a small hole, the

is present. On the summit of the papilla

papilla lacrimalis,

Near the medial angle of the eye a small elevation, the

the caruncle.

lies on the lateral side of

plica semilunaris,

fold, called the

(Figs. 11.16 and 11.17). A reddish semilunar

lacrimalis

caruncula

of which is a small, reddish yellow elevation, the

in the center

lacus lacrimalis,

eyeball by a small space, the

The more rounded medial angle is separated from the

flow of tears and helps make the closed eyelids airtight.

eyelashes (Fig. 11.16). This oily material prevents the over

onto the margin of the lid; their openings lie behind the

modified sebaceous glands that pour their oily secretion

are long,

tarsal glands

rately between adjacent lashes. The

(glands of Moll) are modified sweat glands that open sepa

ciliary glands

open directly into the eyelash follicles. The

taneous junction. The sebaceous glands (glands of Zeis)

They are arranged in double or triple rows at the mucocu

hairs on the free edges of the eyelids (Figs. 11.16 and 11.17).

are short, curved

eyelashes

The

conjunctiva.

called the

and the deep surface is covered by a mucous membrane

The superficial surface of the eyelids is covered by skin,

The Head and Neck

and

the

-
-

the

and the

pupil

sclera

lateral angle of eye

cornea
iris

superficial

conjunctival

plexus of arteries

posterior margin
of eyelid
anterior margin
of eyelid

inferior fornix of conjunctiva

punctum lacrimalis

papilla
lacrimalis

caruncula lacrimalis

site for palpation

of medial

palpebral ligament

lacus lacrimalis

plica semilunaris

superior palpebral sulcus

orbital margin

left eyebrow

FIGURE 11.17

Left eye of a 29-year-old woman.

The lower eyelid pulled downward and slightly everted to reveal the

view of the medial angle between the eyelids.

An enlarged

The names of structures seen in the examination of the eye.

punctum lacrimale.

Basic Anatomy

551

Muscles of the Eyeball and Eyelids

T A B L E 1 1 . 2

the zygomatic nerve, the zygomaticotemporal nerve, and

nerve, the nerve of the pterygoid canal, the maxillary nerve,

the internal carotid plexus and travels in the deep petrosal

is from

sympathetic postganglionic nerve supply

The

lacrimal gland within the lacrimal nerve.

branch and the zygomaticotemporal nerve. They reach the

join the maxillary nerve. They then pass into its zygomatic

canal. The postganglionic fibers leave the ganglion and

its great petrosal branch and via the nerve of the pterygoid

(sphenopalatine ganglion) via the nervus intermedius and

preganglionic fibers reach the pterygopalatine ganglion

of the facial nerve. The

lacrimal nucleus

derived from the

parasympathetic secretomotor nerve supply

The

the superior fornix of the conjunctiva by 12 ducts.

septum (Fig. 11.16). The gland opens into the lateral part of

anterior and upper part of the orbit posterior to the orbital

palpebrae superioris. It is situated above the eyeball in the

around the lateral edge of the aponeurosis of the levator

which are continuous with each other

palpebral part,

small

orbital part

The lacrimal gland consists of a large

Lacrimal Gland

(see Table 11.4)

Trochlear nerve

Tendinous ring on

Muscle

Origin

Insertion

Nerve Supply

Action

Extrinsic Muscles of Eyeball (Striated Skeletal Muscle)
Superior rectus

posterior wall of

orbital cavity

Superior surface of

eyeball just posterior to

corneoscleral junction

Oculomotor nerve

(3rd cranial nerve)

Raises cornea upward and

medially

Inferior rectus

posterior wall of

orbital cavity

Inferior surface of eyeball just

posterior to corneoscleral

junction

Oculomotor nerve

(3rd cranial nerve)

Depresses cornea

downward and medially

Medial rectus

posterior wall of

orbital cavity

Medial surface of eyeball just

posterior to corneoscleral

junction

Oculomotor nerve

(3rd cranial nerve)

Rotates eyeball so that

cornea looks medially

Lateral rectus

posterior wall of

orbital cavity

Lateral surface of eyeball just

posterior to corneoscleral

junction

Abducent nerve (6th

cranial nerve)

Rotates eyeball so that

cornea looks laterally

Superior oblique

Posterior wall of

orbital cavity

Passes through pulley and

is attached to superior

surface of eyeball beneath

superior rectus

(4th cranial nerve)

Rotates eyeball so that

cornea looks downward

and laterally

Inferior oblique

Floor of orbital cavity

Lateral surface of eyeball

deep to lateral rectus

Oculomotor nerve

(3rd cranial nerve)

Rotates eyeball so that

cornea looks upward and

laterally

Intrinsic Muscles of Eyeball (Smooth Muscle)
Sphincter pupillae

of iris

Parasympathetic via

oculomotor nerve

Constricts pupil

Dilator pupillae

of iris

Sympathetic

Dilates pupil

Ciliary muscle

Parasympathetic via

oculomotor nerve

Controls shape of lens; in

accommodation, makes

lens more globular

Muscles of Eyelids
Orbicularis oculi

Levator palpebrae

superioris

Back of orbital cavity

Anterior surface and upper

margin of superior tarsal

plate

Striated muscle

oculomotor nerve,

smooth muscle

sympathetic

Raises upper lid

Lacrimal Apparatus

and a

lacrimal sac

lacrimales pass medially and open into the

The canaliculi

puncta lacrimalis.

through the

lacrimales

From here, the tears enter the

lacus lacrimalis.

The tears circulate across the cornea and accumulate in the

Lacrimal Ducts

finally the lacrimal nerve.

canaliculi

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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.