General Organisation Of The Head And Neck Flashcards
What are the two parts of the cranium
Neurocranium + viserocranium
What are the two groups of face muscles?
- muscles of facial expression
- muscles of mastication
Outline the muscles of facial expression
- mainly dilators or sphincters expect buccinators
- attach to bone
- insert into skin/fascia of face
- suppled by extracranial branches of the facial nerve
Outline the muscles of mastication
- move the mandible at the temporomandibular joint
- allow for opening + closing of jaw
- supplied by mandibular division of trigeminal nerve
Innervation of the muscles of facial expression
Extracranial branches of the facial nerve
Innervation of the muscles of mastication
Mandibular division of trigeminal nerve
What are the muscles of facial expression?
- occipitofrontalis
- orbicularis oculi
- orbicularis oris
- buccinator
- risorius
- zygomatic major
- platysma
Main sensory supply of face and scalp
Via the three divisions of trigeminal nerve
- ophthalmic (Va)
- maxillary (Vb)
- mandibular (Vc)
How many muscles of mastication are there?
Name them
4
- lateral pterygoid
- medial pterygoid
- temporalis
- masseter
What do the muscles of facial expression act as?
What is the exception?
- sphincters or dilators
- except buccinator (cheek muscle) > keep cheek taut + help keep food in oral cavity when chewing
What are the branches of the facial nerve?
TZBMC
- temporal
- zygomatic
- buccle
- marginal mandibular
- cervical
Route of the facial nerve
Pons > internal acoustic meatus > exits base of skull > runs through parotid gland > branches to muscles of facial expression
Most common cause of facial nerve lesion
Bell’s palsy
What scale is used to indicate the severity of facial nerve lesions?
House-Brackmann scale
What is it important to assess in cases of facial nerve lesion?
eye occlusion
eye can dry out + potential blindness if eyelids can’t close
Action of pterygoids
Together - move mandible side to side
Lateral - depresses mandible ‘laaaaa’
Medial- elevates mandible + protrudes
Outline temporalis:
- location
- action
- innervation
- what is used to test it?
- Location: above ear
- Action - elevates + retracts mandible
- Innervation - mandibular division of the trigeminal nerve
- Test: clench jaw
Outline the masseter:
- location
- innervation
- action
- Location: zygomatic arch to mandible
- Innervation: mandibular division of trigeminal nerve
- Action: elevates + protracts mandible
Branches of the trigeminal nerve
Va - ophthalmic
Vb - maxillary
Vc - mandibular
Outline occipitofrontalis
- two muscle bellies (frontal + occipital) joined by epicardial aponeurosis
- frontalis inserts into skin of eyebrow > no bony attachment
- Innervation: facial nerve
- Test: ask patient to raise eyebrows
Outline orbicularis oculi:
- location
- role
- innervation
- action
- Two parts: orbital + palpebral
- Location: one circle around each eye socket
- Role: protects eyes + keeps moist
- Innervation: facial nerve
- Action of orbital part: squeezes eyelids together tightly
- Action of palpebral part: gently closes eyelids
Outline orbicularis oris:
- location
- origin
- insertion
- action
- innervation
- Location - one surrounding orifice of mouth
- Origin: maxilla + mandible
- Insertion: skin of lips
- Action - purses lips together (speech + facial expression) + seals mouth closed (keeps food in oral cavity)
- Innervation: facial nerve
Outline buccinator:
- describe
- action
- innervation
- flat, thin muscle forming wall of cheek
- Action: holds cheek inwards against teeth (prevents food from collecting between cheek and gum) + expel air against pursed lips (e.g. playing trumpet)
- Innervation: facial nerve
Outline the dilators of the mouth:
- action
- innervation
e.g. risorius + zygomatic major
- Action: draws angles of mouth superiorly + posteriorly > smile
- Innervation: facial nerve
Outline platysma
- insertion
- action
- mostly in neck
- Aries from fascia overlying anterior chest
- Insertion: lower mandible, subcutaneous tissue of skin of lower face
- Action: tenses skin of anterior neck +draws down inferior lips
What is Bell’s palsy?
Inflammation of the facial nerve
How can you differentiate between facial nerve weakness + stroke?
Forehead is spared in stroke
Forehead not spared in facial nerve palsy
Action of the supra hyoid muscles
Elevate hyoid
Depression mandible
Action infrahyoid muscles
Depression hyoid + help stabilise it
