1.1 General Organisation of the Head and Neck Flashcards
What two parts make up the cranium?
Neurocranium- surrounds and protects brain
Viscerocranium- forms the face
What are the joints between bones in the skull called?
Sutures- specialised fibrous joints
What are the two main nerves of the face?
Facial Nerve
Trigeminal Nerve
What does the facial nerve supply?
Supplies muscles of facial expression
What does the trigeminal nerve supply?
Sensory innervation to face and motor to muscles of mastication
What are the blood vessels supplying the face?
Facial artery
Facial vein
What types of muscles are muscles of facial expression?
Dilators/ sphincters
Attach to bone, skin/fascia of the face and other muscles
Supplied by Facial nerve CNVII
What do muscles of mastication act on?
Act on the temporomandibular joint
Open or close the jaw, bone-to-bone attachments
Supplied by the trigeminal nerve, mandibular branch
What bones do muscles of facial expression attach to?
Frontal bone
Zygoma/Zygomatic arch
Maxilla
Mandible
Label the image
What is the structure of occipitofrontalis?
Two muscle bellies, frontal and occipital, joined by broad flat connective tissue sheet epicranial aponeurosis
What is the function of the occipitofrontalis muscle?
Raises the eyesbrows and wrinkles skin of forehead
Can test facial nerve by testing this movement
What is the structure of orbicularis oculi?
One muscle circling around each eye orbit
Flat, constrictor muscle
What are the two parts of the orbicularis oculi?
Orbital
-squeezes eyelids together tightly
Palpebral
-gently closes eyelid (involuntary blinking)
What is the critical role of the orbicularis oculi?
Protects the eye
Keeps front of eye moist (tear film)
What is the function of orbicularis oris?
Purses lip together- contributes to facial expressions and speech
Seals mouth closed- helps keep food/fluid inside oral cavity
Describe the structure of the orbicularis oris
One muscle surrounding orifice of mouth
Flat, constrictor muscle & forms majority of lips
Arises from maxilla and mandible, inserts into skin and membrane of lips
What is the function of the buccinator?
Holds cheek taut to prevent food from collecting between teeth and cheek
Contract buccinator to expel air against pursed lips, playing trumpet
What is the structure of the buccinator?
Flat, thin muscle forming wall of cheek
What are the dilators of the mouth?
Risorius
Zygomaticus major (teeth smile)
Draw angles of the mouth superiorly and posteriorly to smile
What is the platysma?
Muscle of facial expression, runs very superficially in neck, immediately beneath the skin
What is the structure of the platysma?
Thin-sheet like muscle
Arises from fascia overlying anterior chest
Inserts onto mandible
Tenses the skin, makes you grimace
Aids in depression if the mandible
What innervates muscles of facial expression?
Extracranial branches of facial nerve
Label the image
To Zanzibar By Motor Car
How are branches of the facial nerve named?
In accordance with region going to supply
Close relationship to parotid gland (not supplied by facial, glossopharyngeal, facial does all other salivary glands)
What is the route of the facial nerve?
- Pons
- Enters petrous bone via internal accoustic meatus
- Exits skull by Stylomastoid foramen
- Runs through Parotid gland
- Branches into facial expression muscles
What can cause damage to the facial nerve?
Parotid gland pathology
-Malignancy
-Surgery
Can cause ipsilateral paralysis of facial muscles
What is the commonest cause of Facial nerve lesions?
Bell’s palsy
Rule everything else out first, idiopathic but presumed to be infective aetiology
What is Bell’s palsy?
Most common non-traumatic cause of ipsilateral facial paralysis
Due to inflammation of the facial nerve, inflammation causes oedema and compression of the nerve as it leaves the skull
How do facial nerve lesions present?
Ipsilateral facial muscle weakness or paralysis
How does parotid cancer present?
- Weakness of facial muscles on one side with ipsilateral enlargement of the parotid gland.
- Weakness due to infiltration of cancer into parotid gland
- Benign parotid pathology (e.g mumps) usually has no facial weakness as nerve not involved
What scale can be used to indicate facial nerve palsy severity?
House-Brackmann Scale
What are the different branches of the trigeminal nerve?
Va- Opthalmic
Vb- Maxillary
Vc- Mandibular
What branch of the trigeminal nerve also has motor function?
Vc- Mandibular branch
What are the muscles of mastication?
Temporalis
Masseter
Medial and Lateral Pterygoids
What is the function of the temporalis?
Elevates and posterior fibres retract mandible
Close mouth and pull back
What is the function of the masseter?
Strong elevator and protacts mandible
What is the function of the medial pterygoid?
Elevates the mandible, act together with lateral pterygoid to move jaw side to side
Close the mouth
What is the function of the lateral pterygoid?
Depresses mandible opens jaw
Acts with medial pterygoid to move jaw side to side
think laaaaaaaaaaaaaaaaaaaaaaa
