Superficial Face and Parotid Region

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Superficial Face and Parotid Region
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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)

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Lateral aspect of the mandible

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

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• Other items of lateral skull
• temporomandibular joint
• external auditory meatus
• zygomatic arch coronal suture

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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.

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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.

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FACIAL SKULL

• The sensory nerves of the face enter the face
  through a series of foramina
• supraorbital (supraorbital nerve vessels) Deep
  to frontalis m.
• 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
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• 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.

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MUSCLES OF THE FACE

• Muscles of facial expression
• 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).

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• 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)

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MOTOR INNERVATIONTO 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

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• 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.

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• 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.

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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

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• 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.

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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

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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

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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.

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• 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.

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Major Sutures and Anthropological Landmarks of
the Skull

• The major sutures to identify are the
• coronal
• lambdoid
• sagittal
• Major anthropological points
• bregma
• lambda

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• 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

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The Parotid Region of the Face

• The parotid region is actually part of the neck
  but it extends into the facial region as well. It
  also must be studied before the infratemporal
  region can be examined. We will examine the
  parotid region from superficial to deep pointing
  out the gland itself and the structures running
  through it.

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• The parotid gland is a superficial structure
  located in the upper neck above the posterior
  belly of the digastric muscle. It is a salivary
  gland that has a large duct  (pd) which crosses
  the masseter muscle to pierce the buccinator
  muscle opposite the upper 2nd molar tooth. The
  duct can frequently be rolled between the finger
  and the masseter muscle. The skin overlying the
  lower pole of the gland is supplied by the
  greater auricular nerve (ga), a branch of the
  cervical plexus. You have already identified the
  branches of the facial nerve appearing at the
  upper and anterior edges of the gland (yellow).

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• If the parotid gland is carefully removed, you
  can identify the structures located within it.
  The first plane is the venous plane and consists
  of the retromandibular vein (rm) and its
  tributaries and branches
• st--superficial temporal
• rm--retromandibular vein
• m--maxillary vein
• ad--anterior division
• f--facial
• cf--common facial
• pd--posterior division
• pa--posterior auricular
• ej--external jugular
• The common facial vein empties into the internal
  jugular vein and the external jugular into the
  subclavian vein near its junction with the
  internal jugular.

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• When the venous plane is removed we reach the
  important nervous plane. The importance of this
  plane is the presence of the facial (VII) nerve.
  The facial nerve leaves the skull through the
  stylomastoid foramen and immediately enters the
  deep part of the parotid gland where it gives off
  its branches
• posterior auricular (pa)
• motor branch to posterior belly of digastric (db)
  
• temporal branch (t)
• zygomatic branch (z)
• buccal branches (b)
• mandibular branch (m)
• cervical branch (c)

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• Deep to the nerves lies the arterial plane which
  includes terminal parts of  the external carotid
  artery and its branches
• external carotid artery (EC)
• occipital artery (oc)
• maxillary artery (m)
• transverse facial artery (tf)
• superficial temporal artery

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• The deepest part of the parotid region is the
  parotid bed and houses the deep part of the gland
  which fills the small space between the neck of
  the condyle of the mandible (nc) and the mastoid
  process (m). Other structures forming the floor
  of this space are the
• styloid process (sp)
• stylohyoid muscle (sh)
• stylopharyngeus muscle (sph)
• posterior belly of the digastric muscle (pbd)
• The gland becomes infected and swollen in mumps.
  If you have had the mumps, you will realize just
  how difficult it is to open your mouth. Now, you
  can see why this is so. When you open the mouth,
  you narrow the parotid bed space and compress the
  deep parotid gland between the neck of the
  condyle and the mastoid process.

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The Infratemporal Fossa and Muscles of Mastication

• The infratemporal fossa is a small space between
  the ramus of the mandible and the lateral
  pterygoid plate of the sphenoid. On a skull, it
  is big enough for maybe 1 1/2 fingers but it has
  many things in it. Following is a tabulation of
  the infratemporal fossa and all of its contents.

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• The lateral wall of the infratemporal fossa is
  noted in the 1st image and consists of the
• ramus (4)
• coronoid process (1)
• head of condyle (2)
• neck of condyle (3)
• body (5)
• angle (6)

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• Medial wall lateral pterygoid plate (1) Roof
  greater wing of sphenoid (3) includes foramen
  ovale foramen spinosum Posteriorly styloid
  process (4)

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• There are four muscles of mastication on each
  side that control the movement of the mandible
• masseter
• medial pterygoid
• lateral pterygoid
• temporalis
• The lateral pterygoid is the main muscle that
  opens the mouth. It is helped from gravity and a
  couple of neck muscles. It opens the jaw by
  pulling forward on the neck of the mandible and
  causing the jaw to drop.

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• The artery entering the infratemporal fossa is
  the maxillary branch of the external carotid
  artery. As can be seen, it has many branches (11
  in all). You will probably not be responsible for
  all of them but I have included them all for
  completeness.
• Maxillary artery
• deep auricular (da)
• anterior tympanic (at)
• middle meningeal (mm)
• accessory middle meningeal (amm)
• inferior alveolar (ia)
• buccal (b)
• deep temporal (dt)
• posterior superior alveolar (psa)
• descending palatine (dp)
• infraorbital (io)
• sphenopalatine (sp)
• External carotid artery (ec)
• occipital (oc)
• transverse facial (tf)
• superficial temporal (st)
• The sphenopalatine and descending palatine
  arteries pass through a small space between the
  pterygoid process of the sphenoid and the
  maxilla, the pterygomaxillary fissure.

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• The mandibular nerve (V3) is the nerve of the
  infratemporal fossa and is responsible for
  supplying the muscles of mastication plus two
  tensor muscles 1) tensor palati and 2) tensor
  tympani. The branches are as follows
• deep temporal (dt)
• auriculotemporal (at)
• inferior alveolar (ia)
• nerve to the mylohyoid (nmh)
• lingual (l)
• buccal (b)
• branches to lateral pterygoid (not labeled)
• Not shown
• meningeal branch
• nerve to masseter

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The Temporomandibular Joint (TMJ)

• The temporomandibular joint (tmj) is a synovial
  type joint separated by an interarticular disc.
  The disc splits the joint into two separate
  joints. The upper joint (ujc) is between the
  mandibular (articular) fossa of the temporal bone
  and the articular disk and provides a sliding
  motion when the lateral pterygoid contracts and
  pulls the condyle and disc forward. 
• The lower joint (ljc) is between the articular
  disc and the head of the condyle of the mandible.
  The action here is a hinge-like action, in which
  the mandible drops, thereby opening the mouth.
• When dentition or muscle action is not in proper
  alignment, the joint can be secondarily affected
  and pain can ensue. This is TMJ disease and
  requires dental specialists to correct the
  problem.

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Table of Muscles