The scalp pdf - Head and Neck

574

CHAPTER 11

The Head and Neck

Muscles of the Head (continued )

T A B L E 1 1 . 4

Laterally:

parotid gland

tory meatus (Fig. 11.33) and the glenoid process of the

The tympanic plate of the external audi

Posteriorly:

Tuberosity of maxilla and

Temporalis

Muscle

Origin

Insertion

Nerve
Supply

Action

Muscles of Mastication
Masseter

Zygomatic arch

Lateral surface

ramus of mandible

Mandibular

division of

trigeminal

nerve

Elevates mandible to occlude teeth

Floor of temporal fossa

Coronoid process of

mandible

Mandibular

division of

trigeminal

nerve

Anterior and superior fibers

elevate mandible; posterior

fibers retract mandible

Lateral pterygoid (two

heads)

Greater wing of sphenoid

and lateral pterygoid

plate

Neck of mandible and

articular disc

Mandibular

division of

trigeminal

nerve

Pulls neck of mandible forward

Medial pterygoid (two

heads)

lateral pterygoid plate

Medial surface of angle

of mandible

Mandibular

division of

trigeminal

nerve

Elevates mandible

■

The parotid gland, fascia, and skin (see Fig. 11.85)

lotemporal nerve

The maxillary artery and vein and the auricu

Medially:

■

Clinical Significance of the Temporomandibular

of the temporomandibular joint may

articular disc

Joint

The temporomandibular joint lies immediately in front of the

external auditory meatus. The great strength of the lateral

temporomandibular ligament prevents the head of the mandi-

ble from passing backward and fracturing the tympanic plate

when a severe blow falls on the chin.

The

become partially detached from the capsule, and this results

in its movement becoming noisy and producing an audible

click during movements at the joint.

Dislocation of the Temporomandibular Joint

Dislocation sometimes occurs when the mandible is

depressed. In this movement, the head of the mandible and

the articular disc both move forward until they reach the sum-

mit of the articular tubercle. In this position, the joint is unsta-

ble, and a minor blow on the chin or a sudden contraction of

the lateral pterygoid muscles, as in yawning, may be sufficient

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

(continued)

to pull the disc forward beyond the summit. In bilateral cases,

lateral margins of the aponeurosis are attached to

occipitofrontalis muscle (Figs. 11.37 and 11.38). The

sheet that unites the occipital and frontal bellies of the

poneurosis (epicranial), which is a thin, tendinous

arteries, and a free anastomosis takes place between them.

arteries are branches of the external and internal carotid

Numerous arteries and veins are found in this layer. The

aponeurosis of the occipitofrontalis muscle (Fig. 11.37).

the fibrous septa uniting the skin to the underlying

onnective tissue beneath the skin, which is fibrofatty,

numerous sebaceous glands

kin, which is thick and hair bearing and contains

layer of the scalp.

to denote the

the scalp, use each letter of the word

To assist one in memorizing the names of the five layers of

intimately bound together and move as a unit (Fig. 11.37).

The scalp consists of five layers, the first three of which are

dislocation is easily achieved by pressing the gloved thumbs

the mouth is fixed in an open position, and both heads of the

mandible lie in front of the articular tubercles. Reduction of the

downward on the lower molar teeth and pushing the jaw back-

ward. The downward pressure overcomes the tension of the

temporalis and masseter muscles, and the backward pressure

overcomes the spasm of the lateral pterygoid muscles.

The Scalp

Structure

SCALP

■

Basic Anatomy

575

the temporal fascia. The subaponeurotic space is the

The origin, insertion, nerve supply, and action of this

Occipitofrontalis

the skull bones (Fig. 11.37).

continuous with the periosteum on the inner surface of

periosteum on the outer surface of the bones becomes

that at the sutures between individual skull bones, the

surface of the skull bones. It is important to remember

ericranium, which is the periosteum covering the outer

and with the intracranial venous sinuses (Fig. 11.37).

veins of the scalp with the diploic veins of the skull bones

emissary veins are valveless and connect the superficial

but it also contains some important emissary veins. The

nium). The areolar tissue contains a few small arteries,

aponeurosis to the periosteum of the skull (the pericra

space (Fig. 11.37) and loosely connects the epicranial

oose areolar tissue, which occupies the subaponeurotic

attachment of the aponeurosis to the temporal fascia.

itofrontalis muscle, and it extends laterally as far as the

limited in front and behind by the origins of the occip

potential space beneath the epicranial aponeurosis. It is

■

Muscles of the Scalp

muscle are described in Table 11.4.

superficial temporal artery

auriculotemporal nerve

temporalis

temporomandibular joint

nerve to masseter

maxillary artery

deep temporal nerves

maxillary nerve

lateral pterygoid

posterior superior

alveolar nerve

buccal nerve

lingual

nerve

mylohyoid

anterior belly

of digastric

nerve to the mylohyoid and

anterior belly of digastric

submandibular duct

hyoid bone

hyoglossus

hypoglossal nerve

submandibular ganglion

lingual nerve

styloglossus

lingual artery

stylopharyngeus

nerve to mylohyoid

inferior alveolar nerve

internal jugular vein

spinal part of

accessory nerve

sphenomandibular ligament

stylohyoid ligament

chorda

tympani

nerve

FIGURE 11.36

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

mandible have been removed to display deeper structures.

576

CHAPTER 11

The Head and Neck

diploe¨

supratrochlear nerve

supraorbital nerve

zygomaticotemporal nerve

auriculotemporal nerve

lesser occipital nerve

greater occipital nerve

occipital artery

posterior auricular artery

superficial temporal artery

zygomaticotemporal artery

supraorbital artery

supratrochlear artery

skin

connective tissue

aponeurosis

loose connective

tissue

pericranium

(periosteum)

outer table of

parietal bone

inner table of

parietal bone

cerebral vein in

subarachnoid space

inferior sagittal sinus

falx cerebri

cerebral cortex

pia mater

cerebral artery in
subarachnoid space

arachnoid

meningeal layer

of dura mater

endosteal layer

of dura mater

arachnoid granulation

superior sagittal sinus

diploic vein

emissary vein

superficial vein of scalp

sagittal suture

FIGURE 11.37

Sensory nerve supply and arterial supply to the scalp.

relation of cerebral blood vessels to the subarachnoid space.

the falx cerebri, the superior and inferior sagittal venous sinuses, the arachnoid granulations, the emissary veins, and the

Coronal section of the upper part of the head showing the layers of the scalp, the sagittal suture of the skull,

Basic Anatomy

577

auricularis superior

epicranial aponeurosis

frontal belly of occipitofrontalis

auricularis anterior

orbicularis oculi

procerus

compressor naris

dilatator naris

buccinator

orbicularis oris

mentalis

depressor labii inferioris

depressor anguli oris

platysma

zygomaticus major

zygomaticus minor

levator labii superioris

levator labii superioris alaeque nasi

auricularis posterior

occipital belly of occipitofrontalis

risorius

FIGURE 11.38

Muscles of facial expression.

nerves (Fig. 11.37).

company with the supratrochlear and supraorbital

of the ophthalmic artery, ascend over the forehead in

branches

supraorbital arteries,

supratrochlear

The

the midline anteriorly, the following arteries are present:

The arteries lie in the superficial fascia. Moving laterally from

licles, and, for this reason, the smallest cut bleeds profusely.

The scalp has a rich supply of blood to nourish the hair fol

vertex of the skull (Fig. 11.37).

of the scalp and supplies the skin as far forward as the

ramus of the 2nd cervical nerve, ascends over the back

a branch of the posterior

greater occipital nerve,

The

face of the auricle.

ital region (Fig. 11.37) and the skin over the medial sur

(C2), supplies the scalp over the lateral part of the occip

a branch of the cervical plexus

lesser occipital nerve,

The

region.

terminal branches supply the skin over the temporal

of the head from in front of the auricle (Fig. 11.37). Its

division of the trigeminal nerve, ascends over the side

a branch of the mandibular

auriculotemporal nerve,

The

the temple (Fig. 11.37).

division of the trigeminal nerve, supplies the scalp over

a branch of the maxillary

zygomaticotemporal nerve,

The

11.37). It supplies the scalp as far backward as the vertex.

rior orbital margin and ascends over the forehead (Fig.

sion of the trigeminal nerve, winds around the supe

a branch of the ophthalmic divi

supraorbital nerve,

The

nearly as far as the vertex of the skull.

passes backward close to the median plane and reaches

rior orbital margin and supplies the scalp (Fig. 11.37). It

division of the trigeminal nerve, winds around the supe

a branch of the ophthalmic

supratrochlear nerve,

The

lowing nerves are present:

fascia. Moving laterally from the midline anteriorly, the fol

The main trunks of the sensory nerves lie in the superficial

surprise or horror.

occipitofrontalis can raise the eyebrows in expressions of

rosis to move on the pericranium. The frontal bellies of the

tissue of the fourth layer of the scalp allowing the aponeu

ers of the scalp move forward or backward, the loose areolar

Note that when this muscle contracts, the first three lay-

Sensory Nerve Supply of the Scalp

-
-

Arterial Supply of the Scalp

and the

578

CHAPTER 11

back of the scalp drain into the occipital nodes.

behind the ear drain into the mastoid nodes. Vessels in the

nodes; lymph vessels in the part of the scalp above and

above the ear is into the superficial parotid (preauricular)

(Fig. 11.40). Drainage from the lateral part of the scalp

forehead drain into the submandibular lymph nodes

Lymph vessels in the anterior part of the scalp and

Lymph Drainage of the Scalp

(Fig. 11.37).

emissary veins

bones and the intracranial venous sinuses by the valveless

another and are connected to the diploic veins of the skull

The veins of the scalp freely anastomose with one

bral veins or the internal jugular vein.

posterior triangle; the plexus in turn drains into the verte

plexus, which lies beneath the floor of the upper part of the

drains into the suboccipital venous

occipital vein

The

gland, to form the external jugular vein (Fig. 11.39).

division of the retromandibular vein, just below the parotid

unites with the posterior

posterior auricular vein

The

romandibular vein (Fig. 11.39).

vein in the substance of the parotid gland to form the ret

unites with the maxillary

superficial temporal vein

The

medial margin of the orbit to form the facial vein.

unite at the

supraorbital veins

supratrochlear

The

Venous Drainage of the Scalp

high as the vertex of the skull.

plies the skin over the back of the scalp and reaches as

pany with the greater occipital nerve (Fig. 11.37). It sup

ascends from the apex of the posterior triangle, in com

a branch of the external carotid artery,

occipital artery,

The

scalp above and behind the auricle (Fig. 11.37).

carotid artery, ascends behind the auricle to supply the

a branch of the external

posterior auricular artery,

The

temporal regions.

branches, which supply the skin over the frontal and

nerve (Fig. 11.37). It divides into anterior and posterior

of the auricle in company with the auriculotemporal

branch of the external carotid artery, ascends in front

the smaller terminal

superficial temporal artery,

The

The Head and Neck

-
-

and

Clinical Significance of the Scalp Structure

because of the attachment of the periosteum to the sutural

other hand, subperiosteal blood or pus is limited to one bone

the nuchal lines, and laterally by the temporal lines. On the

skull, being limited in front by the orbital margin, behind by

the epicranial aponeurosis. It tends to spread over the

Blood or pus may collect in the potential space beneath

Occasionally, an infection of the scalp spreads by the emis

and the neck. Thus, in an emergency situation, encircle the head

the superficial arteries supplying the scalp ascend from the face

Anatomically, it is useful to remember in an emergency that all

through the windshield. Because of the profuse blood supply,

Even a small laceration of the scalp can cause severe blood loss.

the ducts of which are prone to infection and damage by combs.

It is important to realize that the skin, the subcutaneous tissue,

and the epicranial aponeurosis are closely united to one another

and are separated from the periosteum by loose areolar tissue.

The skin of the scalp possesses numerous sebaceous glands,

For this reason, sebaceous cysts of the scalp are common.

Lacerations of the Scalp

The scalp has a profuse blood supply to nourish the hair follicles.

It is often difficult to stop the bleeding of a scalp wound because

the arterial walls are attached to fibrous septa in the subcutane-

ous tissue and are unable to contract or retract to allow blood

clotting to take place. Local pressure applied to the scalp is the

only satisfactory method of stopping the bleeding (see below).

In automobile accidents, it is common for large areas of the

scalp to be cut off the head as a person is projected forward

it is often possible to replace large areas of scalp that are only

hanging to the skull by a narrow pedicle. Suture them in place,

and necrosis will not occur.

The tension of the epicranial aponeurosis, produced by the

tone of the occipitofrontalis muscles, is important in all deep

wounds of the scalp. If the aponeurosis has been divided, the

wound will gape open. For satisfactory healing to take place, the

opening in the aponeurosis must be closed with sutures.

Often, a wound caused by a blunt object such as a base-

ball bat closely resembles an incised wound. This is because

the scalp is split against the unyielding skull, and the pull of the

occipitofrontalis muscles causes a gaping wound. This anatomic

fact may be of considerable forensic importance.

Life-Threatening Scalp Hemorrhage

just above the ears and eyebrows with a tie, shoelaces, or even

a piece of string and tie it tight. Then, insert a pen, pencil, or stick

into the loop and rotate it so that the tourniquet exerts pressure

on the arteries.

Scalp Infections

Infections of the scalp tend to remain localized and are usually

painful because of the abundant fibrous tissue in the subcutane-

ous layer.

sary veins, which are valveless, to the skull bones, causing

osteomyelitis. Infected blood in the diploic veins may travel by

the emissary veins farther into the venous sinuses and produce

venous sinus thrombosis.

ligaments.

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

Basic Anatomy

579

posterior
auricular vein

vertebral vein

internal jugular
vein

external
jugular
vein

right
brachiocephalic
vein

anterior jugular vein

facial vein

maxillary
vein

superficial
temporal
vein

subclavian
vein

retromandibular
vein

FIGURE 11.39

Main veins of the head and neck.

retroauricular
(mastoid nodes)

occipital
nodes

superficial
cervical
nodes

deep cervical nodes

jugular trunk

tracheal nodes

laryngeal nodes

anterior cervical
nodes

submandibular
nodes

submental nodes

buccal
nodes

parotid nodes

FIGURE 11.40

Lymph drainage of the head and neck.

area over the angle of the mandible and the parotid gland

divisions of the trigeminal nerve, except for the small

The skin of the face is supplied by branches of the three

they follow the wrinkle lines.

elasticity. Surgical scars of the face are less conspicuous if

contracting muscles, coupled with the loss of youthful skin

of the skin perpendicular to the long axis of the underlying

Wrinkle lines of the face result from the repeated folding

No deep fascia is present in the face.

of facial expression.

loose connective tissue, in which are embedded the muscles

ceous glands. It is connected to the underlying bones by

The skin of the face possesses numerous sweat and seba

The Face

Skin of the Face

Sensory Nerves of the Face

(Fig. 11.41), which is supplied by the great auricular nerve

process; the maxillary nerve serves the region developed

nerve supplies the region developed from the frontonasal

of dermatomes of the trunk and limbs. The ophthalmic

inal nerve is slight compared with the considerable overlap

(C2 and 3). The overlap of the three divisions of the trigem-

supratrochlear nerve

infratrochlear nerve

supraorbital

nerve

lacrimal nerve

zygomaticotemporal

nerve

auriculotemporal

nerve

infraorbital nerve

external nasal nerve

buccal nerve

great auricular nerve

mental nerve

cervical branch

mandibular
branch

buccal
branch

zygomatic
branch

temporal
branch

supratrochlear artery

supraorbital artery

zygomaticotemporal

artery

superficial temporal artery

lacrimal artery

zygomaticofacial artery

infraorbital artery

transverse facial artery

external nasal artery

facial artery

mental artery

external carotid artery

internal jugular vein

mental vein

facial vein

transverse facial
vein

infraorbital vein

zygomaticofacial
vein

supraorbital vein

supratrochlear vein

zygomaticofacial

nerve

lacrimal vein

superficial temporal
vein

zygomaticotemporal
vein

FIGURE 11.41

Venous drainage of the face.

Arterial supply of the face.

expression.

Branches of the 7th cranial nerve to muscles of facial

Sensory nerve supply to the skin of the face. B.

The scalp

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