HEAD AND NECK

Skull, Scalp, Superficial Face

>Before studying the detailed anatomy of the Head and Neck, examine the following bones of the skull:

Major Bones of the Skull

	Frontal Bone (1)
	Parietal bone (2)
	Occipital bone (1)
	Temporal bone (2)
	Sphenoid bone (1)
	Ethmoid bone (not seen in these views (1)
	Inferior nasal concha (2)
	Lacrimal bone (2)
	Vomer (1)
	Nasal bone (2)
	Maxilla (2)
	Palatine bone (2)
	Zygomatic bone (2)
	Mandible (1)

Lateral aspect of the mandible:

	body
	ramus
	inferior border
	posterior border
	coronoid process
	head of condyle
	neck of condyle
	mandibular notch

Other items of lateral skull:

	temporomandibular joint
	external auditory meatus
	zygomatic arch coronal suture

Air Sinuses of the Skull

Several of the bones of the skull have developed air spaces that are lined with mucous membrane. It is this mucous membrane that becomes infected in sever cases of sinusitis. It is also irritation of the mucous membrane that results in excessive fluid production that can fill the air spaces and give you a stuffed nose feeling. Since these sinuses are embedded in bone, they cannot be seen easily on regular skull preparations and usually require sawing into the bone to see them. Some believe that the function of the sinuses are twofold: 1) makes the skull lighter to carry around and 2) serve as resonating chambers during speech. The figures below were taken from a specially prepared skull.

Air Sinuses
Frontal
Maxillary
Sphenoid
Ethmoid
Mastoid

Once you have learned some of the bones of the skull, you should then try to visualize some areas as they project to the skin. In the following diagrams, you can see some areas of the skull as they project onto the skin of the face.

FACIAL SKULL

The sensory nerves of the face enter the face through a series of foramina:

	1 supraorbital (supraorbital nerve & vessels) Deep to frontalis m.
	2 infraorbital (infraorbital nerve & vessels) Deep to levator labii superioris m.
	3 mental (mental nerve & vessels) deep to the platysma m.
	4 zygomaticofacial (zygomaticofacial nerve)

Identify the following on the anterior skull and face

	glabella
	superciliary arch
	canine fossa
	alveolar processes
	anterior nasal spin

In cadaver dissections, the skin is removed carefully and the muscles of facial expression are identified. This is no easy task since the skin is very thin and with very little fatty tissue beneath it. The motor nerves to the muscles of facial expression and the muscles themselves are just beneath the skin. Up until now you have studied muscles that have had 2 bony attachments. The muscles of the face may have a bony attachment but the insertion is into the skin. This is how we can make facial expressions of happiness, sadness, anger or disapproving. Most of us understand these expressions well.

Once the skin is removed and the muscles cleaned, you can start to name them. In the following images, the muscles are identified.

MUSCLES OF THE FACE

Muscles of facial expression (image 1):

frontalis
orbicularis oculi

	orbital portion
	palpebral portion

zygomaticus major
levator labii superioris alequae nasii
levator anguli oris
orbicularis oris
risorius
depressor anguli oris
depressor labii inferioris
mentalis
platysma

Image 2 displays the buccinator and the masseter muscles. The masseter is a muscle of mastication, not facial expression but it is superficial in the face.

You might notice that the muscles of facial expression are arranged around the orifices of the face: orbit, nasal cavity, mouth and ear (although you wont examine these).

Muscles around the mouth include:

	zygomaticus major (3)
	levator labii superior alequae nasii (4)
	levator anguli oris (5)
	orbicularis oris (6)
	risorius (7)
	depressor anguli oris (8)
	depressor labii inferioris (9)
	buccinator

Muscles around the orbit are:

	frontalis (1)
	orbicularis oculi (2)

MOTOR INNERVATION
TO THE FACE

The motor innervation to the muscles of facial expression is Cranial Nerve VII (Facial) (yellow in the diagram)
It leaves the skull through the stylomastoid foramen on the base of the skull and immediately turns forward to enter the substance of the parotid gland (pink in the image). While within the gland, it divides into 5 major divisions:

	T -- temporal
	Z -- zygomatic
	B -- buccal
	M -- mandibular
	C -- cervical

Another nerve enters deep in the buccal area where the buccal branches of the facial nerve are found but it is a purely sensory branch of the mandibular branch of Cranial Nerve V (Trigeminal). It supplies the mucous membrane inside the cheek and to the skin in this area. The parotid duct (white) can be seen crossing the masseter muscle on it way to penetrate the buccinator muscle. It opens into the mouth opposite the upper 2nd molar tooth. It forms a small swelling (papilla) inside the oral cavity that can be easily seen. The partotid gland is one of three salivary glands in the head and neck.

The transverse facial artery (red) runs just above the parotid duct and is a branch of the superficial temporal artery.

The arterial and venous supply to the face is seen in the diagram. They are the:

Facial artery

	inferior labial
	superior labial
	angular

Facial vein

Superficial temporal artery

Superficial temporal vein

The facial vein is important clinically because it has a direct connection to the ophthalmic vein and then to a deep venous sinus within the cranial cavity, the cavernous sinus. Bacteria can enter the facial vein and gain access to internal cranial structures resulting in infection there. This is probably the reason our mothers always said not to squeeze our pimples.

FEATURES OF THE ORBITAL REGION

Inspect and palpate the living eye. To the right are a few items that can easily be seen:

	palpebral commissures
	medial & lateral angles (7,8)
	cornea
	sclera (3)
	iris (2)
	pupil (1)
	lacrimal caruncle (4)
	lacrimal punctum (5)
	openings of tarsal glands (6)
	eyelashes
	eyebrows

Under the lacrimal caruncle (4) is located the medial palpebral ligament to which the orbicularis oculi muscle attaches and beneath which is the lacrimal sac (7) which empties into the lacrimal duct (8) that enters the nose.

Tarsal cartilages are found in each eye lid and add rigidity to the lids. These can be seen if the eyelid is inverted so that the conjuntival side is exposed.

Structures of the External Ear

On yourself or a lab partner, identify the following parts of the external ear:

	1 concha
	2 crus of helix
	3 helix
	4 scaphoid fossa
	5 antihelix
	6 antitragus
	7 tragus

Sensory Nerves of the Face

The sensory nerves of the face are terminal branches of the three divisions of the trigeminal nerve (cranial nerve V)

Opthalmic division (V1)

	lacrimal
	supraorbital
	supratrochlear
	infratrochlear
	external nasal

Maxillary division (V2)

	infraorbital
	zygomaticofacial

Mandibular division (V3)

	buccal
	mental

The Scalp

The skin of the scalp continues from t he front and lateral side of the face into the occipital region of the skull posteriorly. The makeup of the scalp is important clinically because trauma to the scalp is frequent and it is up to the clinician to determine by palpation and observation just how serious the trauma is.

The scalp is made of 5 layers and they spell scalp:

	S -- skin
	C -- dense Connective tissue
	A -- aponeurosis
	L -- loose connective tissue
	P -- periosteum

The blood vessels travel through the dense connective. The connective tissue has a special relationship with the arteries in this area. When an artery is severed, the connective tissue fibers around the vessel contract and pull the artery open. This results is more hemorrhage than in other places. With scalp hemorrhage, compression must be used to stop the bleeding. Blood vessels and nerves come into the scalp from three different regions: 1) anterior (supraorbital), 2) lateral (superficial temporal), 3) posterior (occipital). There is free anastomoses from side to side. With all of this blood supply, lacerations of the scalp are usually profuse and because of the nerve supply, very sensitive.
The loose connective layer of the scalp will allow bacteria or fluid to pass freely from the posterior aspect of the scalp into the eyelids in front. Trauma in the back of the head can result in blood showing up in the eyelids and should make you suspect something going on in the back of the head.

Major Sutures and Anthropological Landmarks of the Skull

The major sutures to identify are the:

	coronal
	lambdoid
	sagittal

Major anthropological points:

	bregma
	lambda

Finally, take a look at some of the skull structures you have identified thus far but through a radiographic image.

coronal suture
frontal sinus
orbit
ethmoid sinus
nasal cavity
inferior concha
maxillary sinus
ramus of mandible
body of mandible
nasal septum
mastoid air cells
sphenoid sinus
hypophyseal fossa

Summary of items in this lesson

Bones

Frontal Bone (1)

Parietal bone (2)

Occipital bone (1)

Temporal bone (2)

Sphenoid bone (1)

Ethmoid gone (1)

Inferior nasal concha (2)

Lacrimal bone (2)

Vomer (1)

Nasal bone (2)

Maxilla (2)

Palatine bone (2)

Zygomatic bone (2)

Mandible (1)

body
ramus
inferior border
posterior border
coronoid process
head of condyle
neck of condyle
mandibular notch

temporomandibular joint
external auditory meatus
zygomatic arch
coronal suture
anterior nasal spin

Foramina

supraorbital

infraorbital

mental

zygomaticofacial

glabella

superciliary arch

canine fossa

alveolar processes

Sutures and anthropological landmarks

Sutures

coronal

lambdoid

sagittal Anthropological landmarks

bregma

lambda

Muscles

zygomaticus major

levator labii superioris alequae
nasii

levator anguli oris

orbicularis oris

risorius

depressor anguli oris

depressor labii inferioris

buccinator

frontalis

orbicularis oculi

orbital portion

palpebral portion

Nerves

Facial

T -- temporal

Z -- zygomatic

B -- buccal

M -- mandibular

C -- cervical

Trigeminal

Opthalmic division (V1)

lacrimal
supraorbital
supratrochlear
infratrochlear
external nasal

Maxillary division (V2)

infraorbital
zygomaticofacial

Mandibular division (V3)

buccal
mental

Arteries

Facial

inferior labial
superior labial
angular

External carotid

Superficial temporal
artery

Veins

Facial vein

Superficial temporal
vein

Eye features

palpebral
commissures
medial lateral angles
cornea
sclera
iris
pupil
lacrimal caruncle
lacrimal punctum
openings of tarsal
glands
eyelashes
eyebrows

External ear features

concha
crus of helix
helix
scaphoid fossa
antihelix
antitragus
tragus

Scalp

S -- skin

C -- dense Connective tissue

A -- aponeurosis

L -- loose connective tissue

P -- periosteum

Air sinuses

frontal

maxillary

ethmoid

sphenoid

Radiographs

coronal suture
frontal sinus
ethmoid sinus
maxillary sinus
sphenoid sinus
nasal septum
inferior concha
body of mandible
ramus of mandible
mastoid sinus
hypophyseal fossa

AFGALALY محمد عبد الفتاح جلال