Summary Of Head and Neck

HEAD AND NECK

Skull,

Examine the following bones of the skull before studying the detailed anatomy of the Head and Neck:

Major Bones of the Skull

• Frontal Bone

• Parietal bone

• Occipital bone

• Temporal bone

• Mastoidprocess

• Sphenoid bone

• Ethmoid bone

• Inferior nasal concha

• Lacrimal bone

• Vomer

• Nasal bone

• Maxilla

• Palatine bone

• Zygomatic bone

• Mandible

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

 Some 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 severe 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.

Some of the skull structures you have identified thus far but through a radiographic image. 

1.coronal suture

2.frontal sinus

3.orbit

4.ethmoid sinus

5.nasal cavity

6..inferior concha

7.maxillary sinus

8.ramus of mandible

9.body of mandible

10.nasal septum

11.mastoid air cells

12.sphenoid sinus

13.hypophyseal fossa

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.

The major sutures to identify are the:

coronal

lambdoid

sagittal

Major anthropological points:

bregma

lambda

FACIAL SKULL

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

1 supraorbital (supraorbital nerve & vessels) Deep to frontalis muscle.

2 infraorbital (infraorbital nerve & vessels) Deep to levator labii superioris muscel

3 mental (mental nerve & vessels) deep to the platysma mucle.

4 zygomaticofacial (zygomaticofacial nerve)

The anterior skull and face are:

glabella

superciliary arch

canine fossa

alveolar processes

anterior nasal spine

                   

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:

1)frontalis

2)orbicularis oculi

-orbital portion

-palpebral portion

3)zygomaticus major

4)levator labii superioris alequae nasii

5)levator anguli oris

6)orbicularis oris

7)risorius

8)depressor anguli oris

9)depressor labii inferioris

10)mentalis

11)platysma

The second image below 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 and 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. 

External Ear

 Following parts of the external ear:

1 concha

2 crus of helix

3 helix

4 scaphoid fossa

5 antihelix

6 antitragus

7 tragus