Face, Scalp and Parotid Flashcards
What is the extent of the scalp?
From nuchal line to supraorbital margins
Laterally extends down to zygomatic arches
What does the nuchal line correspond to?
External posterior protuberance
What are the five layers of the scalp?
S - skin C - connective tissue (dense) A - aponeurosis L - loose connective tissue P - pericranium
What does the skin have associated with it?
Hair follicles
What is in the dense connective tissue layer?
Fat
Vessels
Nerves
What muscle is the aponeurosis of the scalp of?
Occipitofrontalis
What are the two bellies of the occipitofrontalis?
Anterior = frontalis Posterior = occipitalis
What does the occipitofrontalis do?
Moves scalp
Frowns forehead
Why does a scalp wound deep to the aponeurosis gape?
Opposing pull of two bellies of occipitofrontalis
Also contributes to heavy bleeding
Why can you move the upper part of the scalp?
Because of loose connective tissue layer
Which layers of the scalp are moved when you “move the scalp”?
Outer three layers that are fused together over bone
Why can infection localise in the loose connective tissue of the scalp?
Because of consistency
What is under the periosteum/pericranium?
Skull and meninges
Which layer of the scalp is the neurovascular layer?
Layer 2
Which arteries are in the scalp?
Branches of internal and external carotid arteries
Do the branches of the internal and external carotid arteries communicate in the scalp?
Yes, via free and rich anastomoses
Why do scalp wounds bleed so heavily?
Because of rich arterial supply
Why don’t scalp wounds clot easily, and therefore contribute to the heavy bleeding?
Connective tissue septa in layer 2 adhere to margins and hold open cut vessels
What is the best treatment to stop bleeding in a scalp wound?
Apply tourniquet around head near wound
What is the difference in the layered organisation between the face and scalp?
No layer 4
No aponeurosis - muscles of facial expression instead
What is the origin of the muscles of facial expression?
Bone or fascia
What is the attachment of the muscles of facial expression?
Skin of face
What are the muscles of facial expression arranged around?
Facial orifices
- Eye
- Nasal cavity
- Mouth
What is the arrangement of the muscles of facial expression around the orifices?
Surround orifice as sphincter - close
Radiate out linearly from orifice - open
What are pharyngeal arches?
Embryological structures each supplied by a cranial nerve
Where are the muscles of facial expression derived from?
Second pharyngeal arch
Which nerve supplies the muscles of facial expression?
CN VII - facial nerve
Which nerve/s supply the sensory information from the skin of the face and scalp anterior to the ears?
CN V - trigeminal nerve
What are the three divisions of the trigeminal nerve?
Ophthalmic
Maxillary
Mandibular
What region does the ophthalmic nerve innervate?
Eye region including forehead and top of nose
What region does the maxillary nerve innervate?
Cheek region
- Cheek
- Upper lip
What region does the mandibular region innervate?
Jaw region
- Lower lip
- Jaw
Where does mandibular innervation go laterally?
Turns up to go over ear
What is the cutaneous innervation to the skin behind the ear?
Articular branch of CN X - vagus nerve
What cutaneous innervation does the skin on the back of the head have?
Dorsal rami
What is the cutaneous innervation of the C1 dorsal ramus?
None
What is the cutaneous innervation of the C2 dorsal ramus?
Back of head
What is the cutaneous innervation of the C3 dorsal ramus?
Back of neck - where cervical collar worn
What kind of nerve is the mandibular nerve?
Mixed
What is the motor innervation of the mandibular nerve?
Muscles of mastication
What does the trigeminal ganglion divide into?
Ophthalmic nerve
Maxillary nerve
Mandibular nerve
Where is he trigeminal ganglion?
Apex of petrous part of temporal bone - in middle of middle cranial fossa
What is the route of the ophthalmic nerve?
Exits skull via superior orbital fissure
Enters orbit
Up forehead
What is the route of the maxillary nerve?
Exits skull via foramen rotundum
Onto cheek
What is the route of the mandibular nerve?
Exits skull via foramen ovale
Onto jaw
What area of the scalp does the ophthalmic branch of the internal carotid supply?
Central forehead via branches winding out of orbit
What are the two major branches of the internal carotid on the central forehead?
Medial = supratrochlear arteries Lateral = supraorbital arteries
What is the main artery of the face?
Facial artery
What artery is the facial artery a branch of?
External carotid artery
What is the route of the facial artery?
Winds around inferior border of mandible and onto face
Heads to inferior border of eye
Tortuous course across cheek to inner corner of eye
Branches to
- Lower lip
- Upper lip
- Cheek
- Nose
Anastomoses with internal carotid branches at eye
What is the route of the superficial temporal artery?
Passes up and over zygomatic arch
Supplies anterior and lateral part of scalp
What are the branches of the external carotid artery supplying the face and scalp?
Facial artery
Superficial temporal artery
External auricular artery
Occipital artery
What areas do the external auricular and occipital arteries supply?
Behind ear
Which branches of the external carotid artery are accompanied by veins?
All
What is the main venous drainage of the face?
Facial vein
Where is the facial vein, and what is its shape?
Behind facial artery
Straighter than facial artery
How do the tissues of the face drain into the cavernous sinus?
Via emissary veins
Directly through facial bones
Can infections from the face spread into the brain and meninges and cause encephalitis and meningitis?
Yes, because facial tissues drain into cavernous sinus
Which lymph nodes drain the face and scalp?
Those in ring around base of scalp - Submental anteriorly - Submandibular more posteriorly and laterally - Pre-auricular and parotid near ear - Mastoid - Occipital Move into deep cervical nodes
What is the parotid gland?
Salivary gland
Where is the parotid gland?
Below zygomatic arch Above angle of mandible In front of ear Behind massoter muscle Superficial to styloid process
What is the parotid gland wrapped in?
Parotid fascia
What happens when the parotid gland is infected, as happens on mumps, for example?
Gland swells
Fascia doesn’t
Causes intense pain
How does the parotid gland deliver saliva to the mouth?
Via duct
- Comes forward from anterior border of gland
- Across massoter muscle
- Reaches anterior border and pierces buccinator muscles
- Enters oral cavity near second molar
What are the structures inside the parotid gland, from superficial to deep?
Facial nerve
Retromandibular vein
External carotid artery
How does the facial nerve exit the skull?
Via stylomastoid foramen, in between styloid and mastoid processes at base of skull
Which motor nerve innervates the occipitalis bell of the occipitofrontalis muscle?
Facial nerve branch
What else does the facial nerve innervate, that isn’t a muscle of facial expression?
Posterior belly of digastric and stylohyoid muscles
Where does the facial nerve enter the parotid gland?
Posteromedial surface
What does the facial nerve do inside the parotid gland?
Creates plexus within substance of gland
What is the name of the plexiform arrangement of the facial nerve within the parotid gland?
Pes anserinus
What are the five branches of the facial nerve, from superior to inferior?
Tall - temporal Zulus - zygomatic Bear - buccal Many - mandibular Children - cervical
What do the branches of the facial nerve innervate?
Muscles of facial expression
Where does the retro mandibular vein run?
Behind mandible
What forms the retromandibular nerve?
Union of superficial temporal and maxillary veins
What does the external carotid artery divide into after entering the parotid gland?
Superficial temporal artery
Maxillary artery
Given off within substance of gland
What is a very important branch of the maxillary artery?
Medial meningeal artery
What is the risk of performing surgery near the parotid gland?
Damaging facial nerve
Damage supply of muscles of facial expression in that side
What is Bell’s palsy?
Affects branches of facial nerve Unknown aetiology - possible previous viral infection Happens overnight Characteristics - Drooping eyelid - Flattening of nasolabial fold - A little drooling Treatment - High dose steroids - Can recover in weeks-months-years, but sometimes never
