Cranial nerves and main nerves of the neck and Brachial plexus pdf - Head and Neck

Basic Anatomy

605

Clinical Significance of the Cervical Lymph Nodes

the pharynx, the cervical part of the esophagus, and the external

ined, including the face, scalp, tongue, mouth, tonsil, and

cally the various areas known to drain into a node to discover

or the tongue. An infected tooth of the upper or lower jaw may

pathologic condition in the scalp, the face, the maxillary sinus,

example, an enlarged submandibular node can be caused by a

of the body that drains its lymph into a particular node. For

determine the cause and be knowledgeable about the area

an enlarged lymph node. It is the physician’s responsibility to

great clinical importance. Examination of a patient may reveal

Knowledge of the lymph drainage of an organ or region is of

be responsible. Often, a physician has to search systemati-

the cause.

Examination of the Deep Cervical Lymph Nodes

Lymph nodes in the neck should be examined from behind the

patient. The examination is made easier by asking the patient to

flex the neck slightly to reduce the tension of the muscles. The

groups of nodes should be examined in a definite order to avoid

omitting any.

After the identification of enlarged lymph nodes, pos-

sible sites of infection or neoplastic growth should be exam-

pharynx.

Carcinoma Metastases in the Deep Cervical Lymph

Node

In the head and neck, all the lymph ultimately drains into the

deep cervical group of nodes. Secondary carcinomatous depos-

its in these nodes are common. The primary growth may be easy

to find. On the other hand, at certain anatomic sites, the primary

growth may be small and overlooked, for example, in the larynx,

auditory meatus. The bronchi, breast, and stomach are some-

times the site of the primary tumor. In these cases, the second-

ary growth has spread far beyond the local lymph nodes.

When cervical metastases occur, the surgeon usually

decides to perform a block dissection of the cervical nodes. This

procedure involves the removal en bloc of the internal jugular

vein, the fascia, the lymph nodes, and the submandibular sali-

vary gland. The aim of the operation is removal of all the lymph

tissues on the affected side of the neck. The carotid arteries

and the vagus nerve are carefully preserved. It is often neces-

sary to sacrifice the hypoglossal and vagus nerves, which may

be involved in the cancerous deposits. In patients with bilateral

spread, a bilateral block dissection may be necessary. An inter-

val of 3 to 4 weeks is necessary before removing the second

internal jugular vein.

C L I N I C A L N O T E S

Cranial Nerves

The cranial nerves are named as follows:

Organization of the Cranial Nerves

I. Olfactory

II. Optic

III. Oculomotor

IV. Trochlear

V. Trigeminal

VI. Abducent

VII. Facial
VIII. Vestibulocochlear

IX.

yngeal

Glossophar

X. Vagus

XI. Accessory

XII. Hypoglossal

olfactory bulb

enter the

openings of the cribriform plate of the ethmoid bone to

Bundles of these olfactory nerve fibers pass through the

cavity above the level of the superior concha (Fig. 11.63).

mucous membrane is situated in the upper part of the nasal

in the olfactory mucous membrane. The olfactory

cells

olfactory receptor nerve

The olfactory nerves arise from

Olfactory Nerves

are summarized in Table 11.6.

the skull through which the nerves leave the cranial cavity

of the cranial nerves, their functions, and the openings in

the remaining nerves are mixed. The different components

accessory, and hypoglossal nerves are entirely motor; and

entirely sensory; the oculomotor, trochlear, abducent,

The olfactory, optic, and vestibulocochlear nerves are

in the cranial cavity. The

olfacto

bulb is connected to the olfactory area of the cerebral

cort

the back of the eyeball and leaves the orbital cavity through

of the retina. The optic nerve emerges from

ganglionic layer

The optic nerve is composed of the axons of the cells of the

Optic Nerve

olfactory tract

by the

the optic canal to enter the cranial cavity (Fig. 11.11). The

the midbrain (Fig. 11.64). It passes forward between the pos

The oculomotor nerve emerges on the anterior surface of

Oculomotor Nerve

of the cerebral hemisphere (Fig. 11.63).

visual cortex

and terminate

optic radiation

body pass posteriorly as the

The axons of the nerve cells of the lateral geniculate

superior colliculus and are concerned with light reflexes.

11.63). A few fibers pass to the pretectal nucleus and the

(Fig.

lateral geniculate body

apsing with nerve cells in the

side. Most of the fibers of the optic tract terminate by syn

each retina pass posteriorly in the optic tract of the same

opposite side, whereas the fibers from the lateral half of

of the

optic tract

retina cross the midline and enter the

In the chiasma, the fibers from the medial half of each

side to form the optic chiasma (Fig. 11.63).

optic nerve then unites with the optic nerve of the opposite

in the

terior cerebral and superior cerebellar arteries (Fig. 11.11).
It then continues into the middle cranial fossa in the lateral
wall of the cavernous sinus. Here, it divides into a superior

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CHAPTER 11

The Head and Neck

Cranial Nerves

T A B L E 1 1 . 6

V. Trigeminal

IV. Trochlear

Vision

Nerve

Components

Function

Opening in Skull

I. Olfactory

Sensory

Smell

Openings in cribriform plate of

ethmoid

II. Optic

Sensory

Optic canal

III. Oculomotor

Motor

Lifts upper eyelid, turns eyeball upward,

downward, and medially; constricts pupil;

accommodates eye

Superior orbital fissure

Motor

Assists in turning eyeball downward and

laterally

Superior orbital fissure

Ophthalmic division

Sensory

Cornea, skin of forehead, scalp, eyelids, and

nose; also mucous membrane of paranasal

sinuses and nasal cavity

Superior orbital

fissure

Maxillary

division

Sensory

Skin of face over maxilla and the upper lip;

teeth of upper jaw; mucous membrane of

nose, the maxillary air sinus, and palate

Foramen rotundum

Mandibular

division

VIII. Vestibulocochlear

Taste from anterior two thirds of tongue, floor

Motor

Muscles of mastication, mylohyoid, anterior

belly of digastric, tensor veli palatini, and

tensor tympani

Foramen ovale

Sensory

Skin of cheek, skin over mandible, lower lip,

and side of head; teeth of lower jaw and

temporomandibular joint; mucous mem-

brane of mouth and anterior two thirds of

tongue

VI. Abducent

Motor

Lateral rectus muscle: turns eyeball laterally

Superior orbital fissure

VII. Facial

Motor

Muscles of face, cheek, and scalp; stapedius

muscle of middle ear; stylohyoid; and poste-

rior belly of digastric

Internal acoustic meatus, facial

canal, stylomastoid foramen

Sensory

of mouth, and palate

Secretomotor

parasympathetic

Submandibular and sublingual salivary glands,

lacrimal gland, and glands of nose and

palate

Vestibular

Sensory

Position and movement of head

Internal acoustic meatus

Cochlear

Sensory

Hearing

IX. Glossopharyngeal

Motor

Stylopharyngeus muscle: assists swallowing

Secretomotor

parasympathetic

Parotid salivary gland

Jugular foramen

Sensory

General sensation and taste from posterior

third of tongue and pharynx; carotid sinus

and carotid body

Basic Anatomy

607

Cranial Nerves (continued )

T A B L E 1 1 . 6

olfactory bulb

olfactory tract

olfactory nerves

nasal septum

olfactory bulb

olfactory tract

olfactory nerves

inferior
concha

right eyeball
and retina

optic nerve

optic chiasma

visual
cortex

optic
radiation

lateral geniculate
body

FIGURE 11.63

which enter the orbital cavity

inferior ramus,

nerve and its connections.

The optic

nasal septum and the lateral wall of the nose.

Distribution of the olfactory nerves on the

and an
through the superior orbital fissure (Fig. 11.18).

The superior oblique muscle of the eyeball (extrinsic

The trochlear nerve supplies:

through the superior orbital fissure (Figs. 11.11 and 11.18).

the lateral wall of the cavernous sinus and enters the orbit

It then passes forward through the middle cranial fossa in

leaves the posterior surface of the midbrain (Fig. 11.64).

nerves. Having crossed the nerve of the opposite side, it

The trochlear nerve is the most slender of the cranial

Trochlear Nerve

and accommodation of the eye.

upward, downward, and medially; constricting the pupil;

responsible for lifting the upper eyelid; turning the eye

The oculomotor nerve, therefore, is entirely motor. It is

(Fig. 11.19).

short ciliary nerves

the eyeball in the

and reach

ciliary ganglion

These fibers synapse in the

parasympathetic component of the oculomotor nerve.

lae of the iris and the ciliary muscles are supplied by the

The constrictor pupil

The intrinsic muscles of the eye:

tus, and inferior oblique (Fig. 11.64; see also Figs. 11.18

superioris, superior rectus, medial rectus, inferior rec

the levator palpebrae

The extrinsic muscles of the eye:

The oculomotor nerve supplies the following:

■

and 11.19)

■

muscle) (Fig. 11.20)

Trigeminal Nerve

the eye downward and laterally.

The trochlear nerve is entirely motor and assists in turning

The trigeminal nerve is the largest cranial nerve (Fig. 11.65).

trigeminal

the large sensory root expands to form the

part of the temporal bone in the middle cranial fossa. Here,

the posterior cranial fossa, to reach the apex of the petrous

and it passes forward, out of

sensory root,

and a large

root

motor

It leaves the anterior aspect of the pons as a small

Taste from epiglottis and vallecula and afferent

X. Vagus

Nerve

Components

Function

Opening in Skull

Motor

Constrictor muscles of pharynx and intrinsic

muscles of larynx; involuntary muscle of

trachea and bronchi, heart, alimentary tract

from pharynx to splenic flexure of colon;

liver and pancreas

Jugular foramen

Sensory

fibers from structures named above

XI. Accessory

Cranial root

Motor

Muscles of soft palate, pharynx, and larynx

Jugular foramen

Spinal root

Motor

Sternocleidomastoid and trapezius muscles

XII. Hypoglossal

Motor

Muscles of tongue controlling its shape and

movement (except palatoglossus )

Hypoglossal canal

608

CHAPTER 11

The Head and Neck

midbrain

oculomotor nerve

superior ramus

superior rectus

levator palpebrae superioris

medial rectus

inferior oblique

short ciliary nerve

ciliary ganglion

inferior rectus

inferior ramus

pons

midbrain

trochlear nerve

superior oblique

pons

FIGURE 11.64

Origin and distribution of the trochlear nerve.

Origin and distribution of the oculomotor nerve. B.

ganglion

of the face and the side of the nose.

the infraorbital foramen. It gives sensory fibers to the skin

the infraorbital groove, and it emerges on the face through

(Fig. 11.19). It then continues as the infraorbital nerve in

fossa to enter the orbit through the inferior orbital fissure

men rotundum (Fig. 11.11) and crosses the pterygopalatine

of the cavernous sinus and leaves the skull through the fora

the middle cranial fossa. It passes forward in the lateral wall

The maxillary nerve arises from the trigeminal ganglion in

Maxillary Nerve (V2)

ethmoid and sphenoid sinuses

that is sensory to the

Posterior ethmoidal nerve

that supplies the skin of the eyelids

Infratrochlear nerve

nea (Fig. 11.20)

the dilator pupillae muscle and sensory fibers to the cor

that contain sympathetic fibers to

Long ciliary nerves

to the ciliary ganglion (Fig. 11.20)

Sensory fibers

the following:

Its branches include

external nasal nerve.

the nose with the

and it then supplies the skin of the tip of

nasal branches

internal

crista galli to enter the nasal cavity. It gives off two

nial cavity. It then descends through a slit at the side of the

through the anterior ethmoidal foramen to enter the cra

anterior ethmoid nerve

(Fig. 11.20), and continues as the

forward on the upper border of the medial rectus muscle

crosses the optic nerve, runs

nasociliary nerve

The

air sinus and the skin of the forehead and the scalp.

These nerves leave the orbital cavity and supply the frontal

(Fig. 11.20).

supratrochlear nerves

and

supraorbital

the levator palpebrae superioris muscle and divides into

runs forward on the upper surface of

frontal nerve

The

the upper eyelid.

gland and gives branches to the conjunctiva and the skin of

lacrimal gland. The lacrimal nerve then enters the lacrimal

contains the parasympathetic secretomotor fibers to the

zygomaticotemporal branch of the maxillary nerve, which

the lateral rectus muscle (Fig. 11.18). It is joined by the

runs forward on the upper border of

lacrimal nerve

The

Branches

enter the orbital cavity through the superior orbital fissure.

branches, the lacrimal, frontal, and nasociliary nerves, which

ous sinus in the middle cranial fossa and divides into three

11.50). It runs forward in the lateral wall of the cavern

The ophthalmic nerve is purely sensory (Figs. 11.65 and

Ophthalmic Nerve (V1)

(Figs. 11.11 and 11.65).

(V3) nerves arise from the anterior border of the ganglion

it. The ophthalmic (V1), maxillary (V2), and mandibular

below the sensory ganglion and is completely separate from

The motor root of the trigeminal nerve is situated

cave.

trigeminal

lies within a pouch of dura mater called the

(Figs. 11.11 and 11.65). The trigeminal ganglion

the

■

Basic Anatomy

609

medulla oblongata

trigeminal ner

auriculotemporal

mandibular

inferior alveolar

alveolar

superior

lacrimal ner

trigeminal ganglion

ophthalmic division

frontal nerve

nasociliary nerve

maxillary nerve

infraorbital nerve

nerves

lingual nerve

nerve

mylohyoid nerve

lingual nerve

nerve

division

nerve

pons

abducent nerve

lateral rectus (cut)

FIGURE 11.65

Origin and distribution of the abducent nerve.

Distribution of the trigeminal nerve.

610

CHAPTER 11

to the temporalis muscle

Deep temporal nerves

to the masseter muscle (Fig. 11.36)

Masseteric nerve

Branches from the Anterior Division of the

palatini muscle.

not only the medial pterygoid, but also the tensor veli

which supplies

Nerve to the medial pterygoid muscle,

Meningeal branch

Branches from the Main Trunk of the Mandibular

rior and a large posterior division (Fig. 11.66).

the mandibular nerve, and then divides into a small ante

men ovale and joins the sensory root to form the trunk of

the trigeminal nerve also leaves the skull through the fora

ovale to enter the infratemporal fossa. The motor root of

ganglion and passes out of the skull through the foramen

11.11 and 11.65). The sensory root leaves the trigeminal

The mandibular nerve is both motor and sensory (Figs.

Mandibular Nerve (V3)

nasopharynx

which supplies the roof of the

Pharyngeal branch,

supply the palate, the tonsil, and the nasal cavity

(Fig. 11.19), which

Greater and lesser palatine nerves

inferior orbital fissure

which enter the orbit through the

Orbital branches,

Branches

lacrimal and nasal glands (see page 551).

pterygopalatine fossa (Fig. 11.19). It is secretomotor to the

glion, which is suspended from the maxillary nerve in the

The pterygopalatine ganglion is a parasympathetic gan

Pterygopalatine Ganglion

and the incisor teeth

supplies the maxillary sinus as well as the upper canine

(Fig. 11.19), which

Anterior superior alveolar nerve

teeth, the gums, and the cheek

plies the maxillary sinus as well as the upper premolar

(Fig. 11.19), which sup

Middle superior alveolar nerve

teeth and adjoining parts of the gum and the cheek

supplies the maxillary sinus as well as the upper molar

(Fig. 11.19), which

Posterior superior alveolar nerve

rimal gland.

glionic parasympathetic fibers that are going to the lac

the palate, and the pharynx. They also contain postgan

that have passed through the ganglion from the nose,

palatine fossa (Fig. 11.19). They contain sensory fibers

suspend the pterygopalatine ganglion in the pterygo

which are two short nerves that

Ganglionic branches,

the lacrimal gland via the lacrimal nerve.

ral branch gives parasympathetic secretomotor fibers to

that supply the skin of the face. The zygomaticotempo

zygomaticotemporal and the zygomaticofacial nerves

(Fig. 11.19), which divides into the

Zygomatic branch

Meningeal branches

Branches

The Head and Neck

■

-
-

■

Nerve

■

Mandibular Nerve

■

(Fig. 11.36)

nerve are sensory (except the nerve to the mylohyoid muscle).

The branches of the posterior division of the mandibular

the inferior alveolar nerve to the lingual nerve

which frequently runs from

Communicating branch,

muscle.

hyoid muscle and the anterior belly of the digastric

(Fig. 11.36), which supplies the mylo

hyoid nerve

mylo

11.50). Before entering the canal, it gives off the

(mental nerve) to supply the skin of the chin (Fig.

lower jaw and emerges through the mental foramen

enters the mandibular canal to supply the teeth of the

(Figs. 11.36 and 11.66), which

Inferior alveolar nerve

to the submandibular ganglion.

secretomotor fibers

preganglionic parasympathetic

mouth. It also gives off

anterior two thirds of the tongue and the floor of the

11.66), and it supplies the mucous membrane of the

(Figs. 11.36 and

chorda tympani nerve

joined by the

and crosses the submandibular duct. In its course, it is

11.66). It then runs forward on the side of the tongue

alveolar nerve and enters the mouth (Figs. 11.36 and

which descends in front of the inferior

Lingual nerve,

gland.

tor fibers from the otic ganglion to the parotid salivary

conveys postganglionic parasympathetic secretomo

temporomandibular joint, and the scalp. This nerve also

auricle (Fig. 11.66), the external auditory meatus, the

which supplies the skin of the

Auriculotemporal nerve,

Branches from the Posterior Division of the

division of the mandibular nerve.

of the anterior

only sensory branch

nerve), and it is the

(which is supplied by the facial

the buccinator muscle

does not supply

the cheek (Fig. 11.36). The buccal nerve

to the skin and the mucous membrane of

Buccal nerve

Nerve to the lateral pterygoid muscle

■

Mandibular Nerve

■

-
-

■

to the posterior border of the mylohyoid line on the mandible.

region from the infratemporal fossa by running beneath the

Injury to the Lingual Nerve

The lingual nerve passes forward into the submandibular

origin of the superior constrictor muscle, which is attached

Here, it is closely related to the last molar tooth and is liable

to be damaged in cases of clumsy extraction of an impacted

third molar.

C L I N I C A L N O T E S

Otic Ganglion

auriculotemporal nerve.

secretomotor fibers reach the parotid salivary gland via the

lesser petrosal nerve (see page 614). The postganglionic

sopharyngeal nerve, and they reach the ganglion via the

goid muscle. The preganglionic fibers originate in the glos

skull, and it is adherent to the nerve to the medial ptery

located medial to the mandibular nerve just below the

The otic ganglion is a parasympathetic ganglion that is

-
-

Basic Anatomy

611

mandibular nerve

middle meningeal artery

auriculotemporal nerve

styloid process

inferior alveolar nerve

stylopharyngeus

glossopharyngeal nerve

superior constrictor

middle constrictor

styloglossus

inferior alveolar nerve

nerve to mylohyoid

stylohyoid ligament

deep part of submandibular gland

submandibular ganglion

lingual nerve

hypoglossal nerve

sublingual gland

genioglossus

opening of

submandibular duct

mylohyoid

anterior belly

of digastric

geniohyoid

hypoglossus

buccinator

medial pterygoid

chorda tympani

lingual nerve

nerve to

medial pterygoid

tensor veli palatini

FIGURE 11.66

Infratemporal and submandibular regions. Parts of the zygomatic arch, the ramus, and the body of the mandi

(Figs. 11.11 and 11.65). It passes forward with the internal

hindbrain between the pons and the medulla oblongata

This small nerve emerges from the anterior surface of the

Abducent Nerve

tenses the soft palate and the tympanic membrane.

the head and innervates the muscles of mastication. It also

The trigeminal nerve is thus the main sensory nerve of

salivary glands.

motor fibers pass to the submandibular and the sublingual

tympani and the lingual nerves. Postganglionic secreto

reach the ganglion from the facial nerve via the chorda

11.36 and 11.66). Preganglionic parasympathetic fibers

and is attached to the lingual nerve by small nerves (Figs.

glion that lies deep to the submandibular salivary gland

The submandibular ganglion is a parasympathetic gan

outline of the sublingual gland is shown as a solid black wavy line.

ble have been removed. Mylohyoid and lateral pterygoid muscles have also been removed to display deeper structures. The

Submandibular Ganglion

carotid artery through the cavernous sinus in the middle

612

CHAPTER 11

stylomastoid foramen. The facial nerve now passes forward

mid and it emerges from the temporal bone through the

pages 567 and 568). The nerve descends behind the pyra

on the medial side of the aditus of the mastoid antrum (see

tory and, at the posterior wall of the middle ear, bends down

The nerve then bends sharply backward above the promon

(Fig. 11.67; see also Figs. 11.29 and 11.30).

late ganglion

genicu

panic cavity), the nerve swells to form the sensory

ear. On reaching the medial wall of the middle ear (tym

enters the facial canal that runs laterally through the inner

bone (Fig. 11.28). At the bottom of the meatus, the nerve

internal acoustic meatus in the petrous part of the temporal

cranial fossa with the vestibulocochlear nerve and enter the

medulla oblongata. The roots pass laterally in the posterior

anterior surface of the hindbrain between the pons and the

(Fig. 11.67). The nerve emerges on the

vus intermedius)

(ner

The facial nerve has a motor root and a sensory root

Facial Nerve

ble for turning the eye laterally.

lateral rectus muscle (Fig. 11.65) and is therefore responsi

orbital fissure (Fig. 11.18). The abducent nerve supplies the

cranial fossa and enters the orbit through the superior

The Head and Neck

through the parotid gland to its

tion (Fig.

distribu

11.67).

temporal branch

facial nerve

zygomatic branch

upper buccal branch

lower buccal branch

marginal mandibular branch

cervical branch

to platysma

nerve to posterior

belly of digastric

nerve to stylohyoid

posterior

auricular

branch

motor root

sensory root

geniculate

ganglion

greater

petrosal

nerve

nerve of

pterygoid canal

deep petrosal

nerve

sympathetic

plexus around

internal

carotid artery

nerve to medial

pterygoid muscle

lingual nerve

tympanic branch

glossopharyngeal

nerve

chorda tympani

facial canal

facial nerve

tympanic plexus

nerve to

stapedius

lesser

petrosal nerve

sympathetic nerve

otic

ganglion

FIGURE 11.67

the taste fibers are shown in black. The glossopharyngeal nerve is also shown.

Branches of the facial nerve within the petrous part of the temporal bone;

Distribution of the facial nerve. B.

Basic Anatomy

from the stylomastoid foramen.

lar branches given off by the facial nerve as it emerges

muscu

tric, and the stylohyoid nerves (Fig. 11.67) are

the posterior belly of the digas

Posterior auricular,

floor of the mouth.

fibers from the anterior two thirds of the tongue and

and the sublingual salivary glands. It also contains taste

sympathetic secretomotor fibers to the submandibular

nerve. The chorda tympani contains preganglionic para

entering the infratemporal fossa and joining the lingual

thus

petrotympanic fissure,

middle ear through the

of the tympanic membrane (Fig. 11.29) and leaves the

It runs forward over the medial surface of the upper part

canal in the posterior wall of the middle ear (Fig. 11.67).

arises from the facial nerve in the facial

Chorda tympani

middle ear (Fig. 11.67).

supplies the stapedius muscle in the

Nerve to stapedius

tains taste fibers from the palate.

nose and the palate. The greater petrosal nerve also con

secretomotor to the lacrimal gland and the glands of the

gopalatine ganglion. The postganglionic fibers are

onic parasympathetic fibers that synapse in the ptery

geniculate ganglion (Fig. 11.67). It contains pregangli

arises from the nerve at the

Greater petrosal nerve

Important Branches of the Facial Nerve

613

■

-
-

■

Five terminal branches to the muscles of facial expression.

the facial nerve (Fig. 11.28).

cranial fossa and enter the internal acoustic meatus with

medulla oblongata (Fig. 11.68). They cross the posterior

the anterior surface of the brain between the pons and the

They leave

cochlear.

vestibular

of two sets of fibers:

The vestibulocochlear nerve is a sensory nerve that consists

Vestibulocochlear Nerve

and from the palate.

from the anterior part of the tongue and floor of the mouth

tion, and lacrimation and is a pathway for taste sensation

The facial nerve thus controls facial expression, saliva

anguli oris muscles.

vical branch supplies the platysma and the depressor

cal branch supplies the buccinator muscle, and the cer

The buc

and pass to the muscles of the face and the scalp.

branches that emerge from the anterior border of the gland

the gland (see page 630). Here, it gives off the terminal

it is located between the superficial and the deep parts of

(Fig. 11.85B) after leaving the stylomastoid foramen, and

The facial nerve lies within the parotid salivary gland

(Fig. 11.67).

cervical branches

mandibular,

the

buccal,

zygomatic,

temporal,

These are the

the

and the

and

pons

cochlear nerve

vestibular ganglion

utricle

ampulla of superior
semicircular duct

ampulla of lateral semicircular duct

ampulla of posterior semicircular duct

cochlear duct

spiral ganglion

vestibular nerve

medulla oblongata of cochlea

tympanic plexus

lesser petrosal
nerve

rootlets of glossopharyngeal nerve

superior and inferior sensory ganglia

internal carotid artery

stylopharyngeus

soft palate

tonsillar branches

lingual branches to posterior third of tongue

pharyngeal branch

common carotid artery

carotid body

carotid sinus nerve

carotid sinus

otic
ganglion

parotid
salivary
gland

external carotid artery

tympanic
branch

FIGURE 11.68

Distribution of the glossopharyngeal nerve.

Origin and distribution of the vestibulocochlear nerve. B.

614

CHAPTER 11

clavian artery

first part of the sub

side, the nerve hooks around the

(Fig. 11.69). On the right

Recurrent laryngeal nerve

the cricothyroid muscle.

is located close to the superior thyroid artery; it supplies

is motor and

external laryngeal nerve

vocal cords. The

of the piriform fossa and the larynx down as far as the

is sensory to the mucous membrane

laryngeal nerve

internal

internal and the external laryngeal nerves. The

(Fig. 11.69) divides into the

Superior laryngeal nerve

palate (except the tensor veli palatini).

pharynx (except the stylopharyngeus) and of the soft

pharyngeal plexus and supplies all the muscles of the

nial part of the accessory nerve. This branch joins the

contains nerve fibers from the cra

Pharyngeal branch

Meningeal and auricular branches

Important Branches of the Vagus Nerve in the Neck

opening in the diaphragm.

the lung, and enters the abdomen through the esophageal

num of the thorax (Fig. 11.69), passing behind the root of

carotid sheath (Fig. 11.49). It passes through the mediasti

the carotid arteries and internal jugular vein within the

The vagus nerve descends through the neck alongside

laryngeal branches.

and is distributed mainly in its pharyngeal and recurrent

joins the vagus nerve

cranial root of the accessory nerve

Below the inferior ganglion, the

inferior sensory ganglia.

superior and

jugular foramen. The vagus nerve has both

the posterior cranial fossa and leaves the skull through the

cerebellar peduncle. The nerve passes laterally through

the medulla oblongata between the olive and the inferior

ers (Fig. 11.69). It emerges from the anterior surface of

The vagus nerve is composed of motor and sensory fib

Vagus Nerve

from the carotid sinus and carotid body.

which influence the arterial blood pressure and respiration,

pharynx and the back of the tongue and carries impulses,

promotes salivation. It also conducts sensation from the

The glossopharyngeal nerve thus assists swallowing and

vallate papillae).

brane of the posterior third of the tongue (including the

(Fig. 11.68) passes to the mucous mem

Lingual branch

nerve and the sympathetic trunk.

and also receive branches from the vagus

geal plexus

pharyn

(Fig. 11.68) run to the

Pharyngeal branches

Nerve to the stylopharyngeus muscle

tion) (Fig. 11.68).

mechanism for the regulation of heart rate and respira

blood pressure and the carotid body and chemoreceptor

sinus (pressoreceptor mechanism for the regulation of

contains sensory fibers from the carotid

Carotid branch

ganglion.

and they synapse in the otic

lesser petrosal nerve,

fibers for the parotid salivary gland now leave the plexus

middle ear (Fig. 11.68). Preganglionic parasympathetic

passes to the tympanic plexus in the

Tympanic branch

Important Branches of the Glossopharyngeal

part of the neck to the back of the tongue (Fig. 11.68).

glossopharyngeal nerve then descends through the upper

located on the nerve as it passes through the foramen. The

are

inferior sensory ganglia

superior

foramen. The

fossa and leaves the skull by passing through the jugular

ebellar peduncle. It passes laterally in the posterior cranial

medulla oblongata between the olive and the inferior cer

(Fig. 11.68). It emerges from the anterior surface of the

The glossopharyngeal nerve is a motor and sensory nerve

Glossopharyngeal Nerve

are therefore concerned with hearing.

spiral organ of Corti

cochlear fibers originate in the

(Fig. 11.68). The

spiral ganglion of the cochlea

cells of the

The cochlear fibers are the central processes of the nerve

Cochlear Fibers

movement of the head.

they are concerned with the sense of position and with

from the vestibule and the semicircular canals; therefore,

acoustic meatus (Fig. 11.68). The vestibular fibers originate

cells of the vestibular ganglion situated in the internal

The vestibular fibers are the central processes of the nerve

Vestibular Fibers

The Head and Neck

and

Nerve

■

as the

■

men magnum. It then turns laterally to join the cranial root.

side the spinal cord and enters the skull through the fora

part of the spinal cord (Fig. 11.70). The nerve ascends along

column (horn) of the upper five segments of the cervical

The spinal root arises from nerve cells in the anterior gray

Spinal Root

posterior cranial fossa and joins the spinal root.

ebellar peduncle (Fig. 11.70). The nerve runs laterally in the

medulla oblongata between the olive and the inferior cer

The cranial root emerges from the anterior surface of the

Cranial Root

root (part) and a spinal root (part) (Fig. 11.70).

The accessory nerve is a motor nerve. It consists of a cranial

Accessory Nerve

structures with afferent and efferent fibers.

of all the cranial nerves and supplies the aforementioned

The vagus nerve has the most extensive distribution

pancreas.

associated with the alimentary tract, such as the liver and

to the splenic flexure of the colon. It also supplies glands

lungs; and much of the alimentary tract from the pharynx

sels within the thorax; the larynx, trachea, bronchi, and

The vagus nerve thus innervates the heart and great ves

(Fig. 11.69).

descend into the thorax, and end in the cardiac plexus

(two or three) arise in the neck,

Cardiac branches

of the upper part of the trachea.

ynx below the vocal cords, and the mucous membrane

cricothyroid muscle, the mucous membrane of the lar

and it supplies all the muscles of the larynx, except the

The nerve is closely related to the inferior thyroid artery,

into the neck between the trachea and the esophagus.

and then ascends

arch of the aorta

hooks around the

the trachea and the esophagus. On the left side, the nerve

and then ascends in the groove between

■

-
-

Basic Anatomy

615

superior laryngeal nerve

left vagus nerve

internal laryngeal nerve

external laryngeal nerve

left recurrent
laryngeal nerve

left recurrent laryngeal nerve

cardiac branches

cardiac plexus

left vagus nerve

celiac plexus

aorta

liver

heart

right recurrent

laryngeal nerve

right vagus nerve (cut)

right lung

celiac branch of

right vagus nerve

spleen

kidney

anterior pulmonary
plexus

pharyngeal branch

superior and inferior
sensory ganglia of vagus
nerve

esophageal plexus

FIGURE 11.69

Distribution of the vagus nerve.

hypoglossal nerve

hypoglossus muscle

genioglossus
muscle

nerve to geniohyoid
muscle

lingual nerve

styloglossus muscle

descending

cervical

nerve

nerve to thyrohyoid

muscle

ansa cervicalis

descending branch

of hypoglossal nerve

medulla
oblongata

spinal cord

nerves to trapezius

muscle

nerves to

sternocleidomastoid

muscle

spinal root (part)

of accessory nerve

vagus nerve

cranial root of accessory nerve

FIGURE 11.70

Distribution of the hypoglossal nerve.

Origin and distribution of the accessory nerve. B.

616

CHAPTER 11

two large muscles in the neck.

ments of the sternocleidomastoid and trapezius muscles,

the soft palate, pharynx, and larynx and controls the move

The accessory nerve thus brings about movements of

cle (Fig. 11.55).

posterior triangle of the neck to supply the trapezius mus

mastoid muscle, which it supplies, and then crosses the

laterally and enters the deep surface of the sternocleido

cricothyroid muscle). The spinal root runs downward and

yngeal plexus) and to the muscles of the larynx (except the

the muscles of the soft palate and pharynx (via the phar

joins the vagus nerves and is distributed in its branches to

jugular foramen. The roots then separate: The cranial root

The two roots unite and leave the skull through the

The Head and Neck

into action. Then, the patient is asked to shrug the shoulders,

causing the sternocleidomastoid of the opposite side to come

will drop. The patient will experience difficulty in elevating the

is paralyzed, the muscle will show wasting, and the shoulder

triangle in a relatively superficial position. It can be injured at

Injury to the Spinal Part of the Accessory Nerve

The spinal part of the accessory nerve crosses the posterior

operation or from penetrating wounds. The trapezius muscle

arm above the head, having abducted it to a right angle by

using the deltoid muscle.

Clinical examination of this nerve involves asking the

patient to rotate the head to one side against resistance,

causing the trapezius muscles to come into action.

C L I N I C A L N O T E S

Hypoglossal Nerve

the omohyoid, the sternohyoid, and the sternothyroid

Branches from this loop supply

ansa cervicalis.

(C2 and 3) to form

descending cervical nerve

joins the

(C1 fibers) passes downward and

Descending branch

Meningeal branch

Important Branches of the Hypoglossal Nerve

joined by C1 fibers from the cervical plexus.

the tongue (Fig. 11.70). In the upper part of its course, it is

crosses the internal and external carotid arteries to reach

nerve then passes downward and forward in the neck and

and leaves the skull through the hypoglossal canal. The

pyramid and the olive, crosses the posterior cranial fossa,

anterior surface of the medulla oblongata between the

The hypoglossal nerve is a motor nerve. It emerges on the

■

the

muscles.

of the levator scapulae and the scalenus medius muscles

branches, which form loops that lie in front of the origins

first four cervical nerves. The rami are joined by connecting

The cervical plexus is formed by the anterior rami of the

movements of the tongue.

the palatoglossus) and therefore controls the shape and

nerve thus innervates the muscles of the tongue (except

The hypoglossal

Nerve to the geniohyoid muscle (C1).

except the palatoglossus (pharyngeal plexus)

Muscular branches to all the muscles of the tongue

Nerve to the thyrohyoid muscle (C1)

■

Main Nerves of the Neck

Cervical Plexus

(Fig.

xus is covered in front by the pre

11.57). The ple

internal jugular vein within the carotid sheath. The cervical

vertebral layer of deep cervical fascia and is related to the

Clinical Testing of the Cranial Nerves

retinal veins, edema of the retina, and bulging of the optic disc

vein as it crosses the space, resulting in congestion of the

arachnoid space will compress the thin walls of the retinal

arachnoid space of the nerve sheath a short distance behind

forward around the optic nerve to the back of the eyeball. The

remembered that the intracranial subarachnoid space extends

ophthalmoscope. When examining the optic disc, it should be

The retinas and optic discs should then be examined with an

is then tested by using charts with lines of print of varying size.

any changes in eyesight have been noted. The acuity of vision

The optic nerve is evaluated by first asking the patient whether

tumors of the frontal lobes may produce lesions of the olfactory

that food flavors depend on the sense of smell and not on the

part of the examination of every neurologic patient. It may reveal

Systematic examination of the 12 cranial nerves is an important

a lesion of a cranial nerve nucleus or its central connections, or

it may show an interruption of the lower motor neurons.

Testing the Integrity of the Olfactory Nerve

The olfactory nerve can be tested by applying substances with

different odors to each nostril in turn. It should be remembered

sense of taste. Fractures of the anterior cranial fossa or cerebral

nerves, with consequent loss of the sense of smell (anosmia).

Testing the Integrity of the Optic Nerve

retinal artery and vein run in the optic nerve and cross the sub-

the eyeball. A rise in cerebrospinal fluid pressure in the sub-

(papilledema).

The visual fields should then be tested. The patient is asked

to gaze straight ahead at a fixed object with the eye under test,

the opposite eye being covered. A small object is then moved in

an arc around the periphery of the field of vision, and the patient

is asked whether he or she can see the object. It is important not

C L I N I C A L N O T E S

(continued)

618

CHAPTER 11

The Head and Neck

All the muscles of the larynx are supplied by the recurrent

plexus and their distribution.

Table 11.7 summarizes the branches of the cervical

central part of the diaphragm.

peritoneum covering the upper and lower surfaces of the

dium, the mediastinal parietal pleura, and the pleura and

diaphragm. It also sends sensory branches to the pericar

The phrenic nerve is the only motor nerve supply to the

described on page 99.

of the subclavian artery. Its further course in the thorax is

cle (Fig. 11.57) and enters the thorax by passing in front

downward across the front of the scalenus anterior mus

5th cervical nerves of the cervical plexus. It runs vertically

The phrenic nerve arises in the neck from the 3rd, 4th, and

Phrenic Nerve

Phrenic nerve

Muscular branch to the diaphragm.

the nerve to the thyrohyoid and geniohyoid.

Other C1 fibers within the hypoglossal nerve leave it as

the omohyoid, sternohyoid, and sternothyroid muscles.

cervical nerve fibers within the ansa cervicalis supply

(Fig. 11.60). The first, second, and third

ansa cervicalis

(C2 and 3), to form the

descending cervical nerve

hypoglossal as the descending branch, which unites with

glossal nerve. Some of these C1 fibers later leave the

ceptive, C3 and 4). A branch from C1 joins the hypo

3), levator scapulae (C3 and 4), and trapezius (proprio

muscles, sternocleidomastoid (proprioceptive, C2 and

Prevertebral

Muscular branches to the neck muscles.

from the phrenic nerve (gallbladder disease).

clinically, because pain may be referred along them

over the shoulder region. These nerves are important

intermediate, and lateral branches supply the skin

(C3 and 4). The medial, and

supraclavicular nerves

The

plies the skin over the front of the neck

(C2 and 3), which sup

transverse cervical nerve

The

the skin over the angle of the mandible

(C2 and 3), which supplies

greater auricular nerve

The

of the scalp and the auricle

(C2), which supplies the back

lesser occipital nerve

The

Cutaneous branches

Branches

neck, and the shoulders.

plexus supplies the skin and the muscles of the head, the

the muscles on the affected side are wasted, and the tongue

the paralyzed side. In patients with long-standing paralysis,

tionary. The result is the tip of the tongue’s deviation toward

tongue forward, leaving the paralyzed side of the tongue sta

normal genioglossus muscle pulls the unaffected side of the

tongue forward, is paralyzed on the affected side. The other,

as follows. One of the genioglossus muscles, which pull the

toward the paralyzed side (Fig. 11.78). This can be explained

the nerve is present, it will be noted that the tongue deviates

The patient is asked to put out the tongue, and if a lesion of

The hypoglossal nerve supplies the muscles of the tongue.

action. Then, the patient should be asked to shrug the shoulders,

laryngeal branch of the vagus, except the cricothyroid muscle,

which is supplied by the external laryngeal branch of the supe-

rior laryngeal branch of the vagus. Hoarseness or absence of the

voice may occur. Laryngoscopic examination may reveal abduc-

tor paralysis (see page 650).

Testing the Integrity of the Accessory Nerve

The accessory nerve supplies the sternocleidomastoid and the

trapezius muscles by means of its spinal part. The patient should

be asked to rotate the head to one side against resistance, caus-

ing the sternocleidomastoid of the opposite side to come into

causing the trapezius muscles to come into action.

Testing the Integrity of the Hypoglossal Nerve

is wrinkled on that side.

■

-
-

the

■

abdominal pressure. Consequently, the lower lobe of the lung

Phrenic Nerve Injury and Paralysis of the

Diaphragm

The phrenic nerve, which arises from the anterior rami of

the third, fourth, and fifth cervical nerves, is of considerable

clinical importance because it is the sole nerve supply to the

muscle of the diaphragm. Each phrenic nerve supplies the

corresponding half of the diaphragm.

The phrenic nerve can be injured by penetrating wounds

in the neck. If that occurs, the paralyzed half of the diaphragm

relaxes and is pushed up into the thorax by the positive

on that side may collapse.

About one third of persons have an accessory phrenic

nerve. The root from the fifth cervical nerve may be incor-

porated in the nerve to the subclavius and may join the main

phrenic nerve trunk in the thorax.

C L I N I C A L N O T E S

Brachial Plexus

become arranged around the axillary artery in the axilla

cross the posterior triangle of the neck, and the cords

medius muscles (Fig. 11.57). The trunks and divisions

neck between the scalenus anterior and the scalenus

The roots of the brachial plexus enter the base of the

terior cord.

pos

posterior divisions of all three trunks join to form the

medial cord,

of the lower trunk continues as the

the anterior division

lateral cord,

trunks unite to form the

The anterior divisions of the upper and middle

divisions.

posterior

anterior

Each trunk then divides into

trunk.

lower

and the roots of C8 and T1 unite to form the

trunk,

middle

the root of C7 continues as the

upper trunk,

The roots of C5 and 6 unite to form

cords.

divisions,

roots, trunks,

(Fig. 11.71). This plexus is divided into

7th, and 8th cervical and the first thoracic spinal nerves

the neck by the union of the anterior rami of the 5th, 6th,

The brachial plexus is formed in the posterior triangle of

and

the

and

and the

Basic Anatomy

619

Summary of the Branches

of the Cervical Plexus

and Their Distribution

T A B L E 1 1 . 7

Branches

Distribution

Cutaneous
Lesser occipital

Skin of scalp behind ear

Greater auricular

Skin over parotid salivary gland,

auricle, and angle of jaw

Transverse

cutaneous

Skin over side and front of neck

Supraclavicular

Skin over upper part of chest and

shoulder

Muscular
Segmental

Prevertebral muscles, levator scapulae

Ansa cervicalis

(C1, 2, 3)

Omohyoid, sternohyoid, sternothyroid

C1 fibers via

hypoglossal nerve

Thyrohyoid, geniohyoid

Phrenic nerve

(C3, 4, 5)

Diaphragm (most important muscle of

respiration)

Sensory

Phrenic nerve

(C3, 4, 5)

are summarized in Table 9.4.

The branches of the brachial plexus and their distribution

Branches

axillary sheath.

artery and vein are enclosed in the

(see Fig. 9.20). Here, the brachial plexus and the axillary

Pericardium, mediastinal parietal

pleura, and pleura and peritoneum

covering central diaphragm

Injury to the Brachial Plexus

ing a local anesthetic. The anesthetic solution is massaged

The roots and trunks of the brachial plexus occupy the antero-

inferior angle of the posterior triangle of the neck. Incomplete

lesions can result from stab or bullet wounds, traction, or

pressure injuries. The clinical findings in Erb-Duchenne and

Klumpke’s lesions are fully described on page 429.

Brachial Plexus Nerve Block

It will be remembered that the axillary sheath, formed from the

prevertebral layer of deep cervical fascia, encloses the bra-

chial plexus and the axillary artery. A brachial plexus nerve

block can easily be obtained by closing the distal part of the

sheath in the axilla with finger pressure, inserting a syringe

needle into the proximal part of the sheath, and then inject-

along the sheath, producing a nerve block. The syringe needle

C L I N I C A L N O T E S

(continued)

may be inserted into the axillary sheath in the lower part of the

posterior triangle of the neck or in the axilla.

page 89)

neck and ends in the cardiac plexus in the thorax (see

which descends in the

superior cardiac branch,

The

form the pharyngeal plexus

branches of the glossopharyngeal and vagus nerves to

which unite with the pharyngeal

Pharyngeal branches,

12th cranial nerves

which join the 9th, 10th, and

Cranial nerve branches,

carotid artery.

ies and are distributed along the branches of the external

arteries. These branches form a plexus around the arter

to the common and external carotid

Arterial branches

rami of the cervical nerves

to the upper four anterior

Gray rami communicantes

plexus.

branches around the artery to form the internal carotid

the carotid canal in the temporal bone. It divides into

onic fibers, accompanies the internal carotid artery into

consisting of postgangli

internal carotid nerve,

The

Branches

skull (Fig. 11.60).

The superior cervical ganglion lies immediately below the

rior, middle, and inferior cervical ganglia.

The sympathetic trunk possesses three ganglia: the supe

the prevertebral layer of deep fascia (Fig. 11.49).

embedded in deep fascia between the carotid sheath and

common carotid arteries (i.e., medial to the vagus) and is

sympathetic trunk. It lies directly behind the internal and

where it becomes continuous with the thoracic part of the

to the base of the skull and below to the neck of the 1st rib,

The cervical part of the sympathetic trunk extends upward

Cervical Part of the Sympathetic Trunk

exercise. Rarely, pressure on the first thoracic nerve causes

At the root of the neck, the brachial plexus and the subclavian

Compression of the Brachial Plexus and the

Subclavian Artery

artery enter the posterior triangle through a narrow muscu-

lar–bony triangle. The boundaries of the narrow triangle are

formed in front by the scalenus anterior, behind by the sca-

lenus medius, and below by the 1st rib. In the presence of a

cervical rib (see page XXX), the 1st thoracic nerve and the

subclavian artery are raised and angulated as they pass over

the rib. Partial or complete occlusion of the artery causes

ischemic muscle pain in the arm, which is worsened by

symptoms of pain in the forearm and hand and wasting of the

small muscles of the hand.

The Autonomic Nervous System in

the Head and Neck

Sympathetic Part

Superior Cervical Ganglion

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