NB4-2 - Face and Scalp

Question 1

What are the two groups that all of the bones of the skull fit into?

Answer 1

1. Viscerocranium or Facial Skelton - the bones of the skull that do not make up the braincase
2. Neurocranium - the bones of the skull that make up the braincase

The Mandible is NOT considered to be part of the cranium

Question 2

What bones is the viscerocranium composed of? Describe their locations.

Answer 2

• 2 Nasal Bones - small bones that form the bridge of the nose and roof of nasal aperture
• 1 Vomer Bone - a thin bone that forms the inferior part of the nasal septum
• 2 Lacrimal Bones - pinky nail sized bone that forms the anterior medial wall of orbit
• 2 Zygomatic Bones - cheek bones, also form lateral inferior wall of orbit
• 1 Maxilla Bone - upper jaw, anterior 2/3 of hard palate, and most of the nasal aperture
• 2 Palatine Bones - floor of orbits, floor and later walls of nasal cavity, and posterior 1/3 of hard palate
• 2 inferior nasal conchae

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Question 3

List and describe the contents of the foramina of the viscerocranium.

Answer 3

• 2 Supraorbital foramina - above the orbit and just under the eyebrow. Contains the supraorbital nerve, artery, and vein
• 2 Infraorbital foramina - below the orbit and lateral to the nasal aperture. Contains the infraorbital nerve, artery, and vein
• 2 Mental foramina - anterolateral aspect of mandible. Contains the mental nerve, artery, and vein

Question 4

What does the term palpebral mean?

Answer 4

Of or relating to the eyelids

Question 5

List the facial muscles from the orbital group, say where they are located and what they do.

Answer 5

• 2 Orbicularis Oculi - completely surround each orbit
  
  • Palpebral part is in the eyelids and closes them gently
  • Orbital part encircles orbital opening and closes eyelids forcefully
• 2 Corrugator supercili - deep to the eyebrows, serves to draw them inferiomedially which wrinkles the skin above the nose

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Question 6

List the facial muscles of the nasal group, say where they are located and what they do.

Answer 6

• 2 Nasalis
  
  • Transverse part - located on lateral surface of nose and serves to compress the nares
  • Alar part - located on lateral surface of nose and behind nostril, serves to draw the alar cartilage down and lateral, flaring nares.
• 2 Procerus - spans from nasal bone to space between eyebrows, serves to draw the medial border of this regin downward, wrinking the skin
• 2 Depressor septi nasi - spans from maxilla to nasal septum, serves to widen the nares by pulling the nose inferiorly

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Question 7

List the facial muscles of the lower oral group, say where they are located and what they do.

Answer 7

• 2 Depressor anguli oris - from corner of mouth to body of mandible, serves to depress corners of mouth
• 2 Depressor labii inferioris - lateral lower lip to body of mandible, serves to depress lower lip laterally
• 2 Mentalis - medial lower lip to body of mandible, serves to position lip when drinking from a cup

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Question 8

List the facial muscles of the upper oral group, say where they are located and what they do.

Answer 8

• 2 Risorius - from corner of mouth to parotid gland, for grinning
• 2 Zygomaticus Major and Minor - lateral upper lip to zygomatic arch, used to smile
• 2 Levator labii superioris - side of nose to zygoma, serves to deepen furrow between nose and mouth
• 2 levator labii superioris alaeque nasi - maxilla to lateral nostril and upper lip, serves to flare nostrils
• 2 Levator anguli oris - lateral upper lip to zygoma, serves to elevate corners of mouth

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Question 9

List the facial muscles of the other oral group, say where they are located and what they do.

Answer 9

2 Buccinator Muscles

• Deep muscles of cheek
• Originates at the posterior maxilla and mandible opposite the molars and pterygomandibular raphe. Inserts into both the upper and lower portions of the orbicularis oris fibers
• Serves to press cheeks agains teeth and used during forceful expulsion of air from cheeks

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Question 10

List the facial muscles of the “other” group, say where they are located and what they do.

Answer 10

• 2 Platysma - overlaps the sternocleidomastoid (SCM), depresses jaw
• 6 Auricular Muslces - one superior, anterior, and posterior to auricles, mostly vestigial
• 2 Posterior bellies of digastric - from mastoid process to mandible, moves jaw and elevates hyoid
• Stylohyoid - from syloid process to hyoid bone, pulls hyoid backwards and elevates tongue
• Occipitofrontalis - consits of frontal and occipital belly connected by a long aponeurosis. Moves scalp, wrinkles forehead, and raises eyebrows

Refer to image

Question 11

Answer 11

A

Question 12

Describe the route the facial nerve and its branches take.

Answer 12

1. The Facial Nerve consists of the facial nerve proper and the nervus intermedius. Both exit the brainstem in the posterior cranial fossa at the pontomedullary junction and enter the internal acoustic meatus in the temporal bone.
2. Upon reaching the facial canal, the two nerves merge at the geniculate ganglion.
3. The facial nerve will then exit the skull via the stylomastoid foramen and enter the body of the parotid gland.
4. In the parotid gland, the facial nerve splits into 5 branches: temporal (to the orbits and forehead), zygomatic (across the zygoma to the lower orbit nose and upper lip), buccal (across the cheek to maxilla and upper mandible), marginal mandibular (along lower mandible), cervical (down into neck)

Question 13

Describe the type of innervation the Facial Nerve and its branches supply.

Answer 13

The facial nerve proper will supply motor innervation to the stapedius, stylohyoid, posterior belly of digastric, auricular muscles, occipitalis, and muscles of facial expresion (via its five branches)

The Nervus Intermedius will give of PSNS innervation to the pterygopalatine (PT) and submandibular ganglia. It will also carry somatosensory fibers from the small area of the auricle and taste sensation from the anterior 2/3 of the tongue.

Question 14

What mnemonic is used to remember the 5 motor branches of the facial nerve from superior to inferior?

Answer 14

Two Zebras Bit My Clavicle

1. Temporal
2. Zygomatic
3. Buccal
4. Marginal Mandibular
5. Cervical

Question 15

What structures pass through the parotid gland besides the facial nerve and its branches?

Answer 15

• The external carotid artery (ECA) and its branches: posterior auricular, transverse facial, maxillary, and superficial temporal
• The superficial temporal vein and maxillary vein which merge into the retromandibular within the parotid

Question 16

List the blood supply and innervation going to and from the parotid gland.

Answer 16

Blood supply and drainage - those vessels that pass through it

Sensory Innervation from auriculotemporal branch of the mandibular nerve (V3) from the CN5

Secretomotor innervation from the auriculotemporal branch which is carrying PSNS fibers from the otic ganglion from CN9

Question 17

Describe the path that the parotid duct takes.

Answer 17

Leaves anterior edge of gland midway between zygoma and mouth. It then crosses the masseter, penetrates the buccal fat pad and buccinator and opens into the oral cavity opposite the 2nd upper molar tooth

Question 18

List the major sensory divisions of the trigeminal nerve and the branches found within each division.

Answer 18

• Opthalmic Division - supraorbital, supratrochlear, infratrochlear, external nasal, and lacrimal
• Maxillary Division - zygomaticotemporal, zygomaticofacial, infraorbital
• Mandibular Division - auriculotemporal, buccal, and mental

Question 19

List the sensory trigeminal branches of the opthalmic division and say what they do.

Answer 19

1. Supratrochlear & Supraorbital innervate the upper eyelid, forehead, and scalp
2. Infratrochlear innervates the medial half of the upper eyelid, medial angle (where eyelids meet medially), and side of nose
3. External Nasal innervates the anterior nose
4. Lacrimal innervates the lateral half of upper eyelid and lateral angle

Question 20

List the sensory trigeminal branches of the maxillary division and say what they do.

Answer 20

1. Zygomaticotemporal innervates the anterior temple above the zygomatic arch
2. Zygomaticofacial innervates the small area over the zygomatic bone
3. Infraorbital innervates the lower eyelid, cheek, side of nose, and upper lip

Question 21

List the sensory trigeminal branches of the mandibular division and say what they do.

Answer 21

1. Auriculotemporal innervates over the temple
2. Buccal innervates the cheek area
3. Mental innervates over the chin

Question 22

Point out on your face where each sensory branch of CN5 innervates

Answer 22

Question 23

List and describe the location of the major arterial branches of the external carotid artery that supply the face.

Answer 23

• Facial Artery - branches off of ECA in the carotid triangle and travels under mandible before curving around onto the face and traveling up to the angle of the eye where it gives of the angular artery. Along its course it gives off the inferior and superior labial arteries
• Maxillary Artery - branches off of ECA within parotid gland and travels under the zygoma headed to the orbit. Along the way it gives off an inferior alveolar branch which turns into the mental artery that comes out onto the chin through the mental foramem. It also gives off the buccal and infra-orbital artery
• After giving off the maxillary artery, the ECA becomes the superficial temporal artery which supplies the areas superficial to the temples. It also gives off the transverse facial artery which supplies the areas over the zygomas

Question 24

List and describe the location of the major arterial branches of the internal carotid artery that supply the face.

Answer 24

Right after the ICA enters the braincase it gives off the opthalmic artery which branches into the zygomaticofacial, zygomaticotemporal, and dorsal nasal arteries.

Question 25

Why are facial injuries, even very minimal ones like pimple popping, potentially very dangerous?

Answer 25

Because emissary veins connect many facial veins to the cavernous sinus inside the braincase. This means that pathogens that enter the facial venous system have easy access into the braincase

Question 26

Describe the lymphatic drainage of the face.

Answer 26

• The medial part of the lower lip and chin drain to the submental nodes
• The medial corner of the orbit, external, medial cheek, upper lip, and lateral part of lower lip drain to the submandibular nodes
• The eyelids and lateral cheek drain to the preauricular and parotid nodes

Question 27

Describe the various layers of the scalp.

Answer 27

The first three layers of Skin, dense Connective tissue, and Aponeurosis are known as the scalp proper and are intimately attached. The next layer of Loose connective tissue facilitates movement of the scalp proper over the Pericranium (the periosteum of the calvaria (skullcap))

Question 28

What is considered to be the danger zone of the scalp and why?

Answer 28

The loose connective tissue layer because infections can easily spread through this layer to emissary veins that penetrate through the skull in drain into the sagittal sinuses.

Question 29

List and describe the locations of the sensory nerves that innervate the scalp.

Answer 29

• The areas of the scalp anterior to the ears and vertex (highest point) of the skull are innervated by the following branches of the trigeminal nerve: supratrochlear (V1), supraorbital (V1), Zygomaticotemporal (V2), and auriculotemporal (V3).
• The areas of the scalp posterior to the ears and vertex are innervated by the following branches from the C2 & C3 spinal nerves: great auricular, lesser occipital, greater occipital, and third occipital.

Question 30

List the arteries that supply the scalp.

Answer 30

• Posterior auricular, occipital, and superficial temporal which are all branches of the ECA
• Supratrochlear and supraorbital which are both branches of the opthalmic arteries which are branches of the ICA

Question 31

Describe how lymphatic drainage occurs form the scalp.

Answer 31

• Forehead drains to the submandibular nodes using lymph vessels that follow the facial artery
• Upper scalp anterior to vertex drinas to the preauricular and parotid nodes
• Upper scalp posterior to the vertex drains to the mastoid and upper deep cervical nodes
• Occipital region drains to the occipital and upper deep cervical nodes

Question 32

Answer 32

C