2 - face and skull Flashcards
sensory function of the trigeminal nerve
cutaneous sensation from the face and forehead
divisions of the trigeminal nerve
V1 - ophthalmic nerve
V2 - maxillary nerve
V3 - mandibular nerve
which nerve innervates facial sensataround the frontal bone
ophthalmic nerve
which nerve innervates facial sensation around the middle part of the face
maxillary nerve
which nerve innervates facial sensation around the chin and upwards
mandibular nerv
clinical examination of sensory innervation in the face
pinprick and light touch sensations over each region
3 groups of important muscles in the head
- muscles of facial expression
- muscles of mastication
- extra ocular muscles
where do muscles of facial expression insert
the skin
function of the frontal belly of occipitofrontalis
- pulls scalp anteriorly
- wrinkles forehead
- elevates eyebrows
function of occipital belly of occupitofrontalis
pulls scalp posteriorly
function of orbiculares oculi
closes eyelids
function of orbiculares oris
closes the mouth
function of buccinator
- keeps cheek taught
- resists distension when whistling, sucking and blowing
function of platysma
tenses the skin of the inferior face and neck
function of zygomaticus major
draws the corner of the mouth upwards and laterally
which nerve innervates the muscles of facial expression
facial nerve
sensory functions of facial nerve
- taste
- part of external acoustic meatus and deeper parts of auricle
autonomic functions of facial nerve
- secretomotor to all salivary glands except parotid
circular muscle acting as a splinter around the eye
orbicularis oculi
dilators of the eyelid
- levator palpebrae superiosis
- superior tarsal
what complication would arise due to paralysis of orbiculares oculi?
inability to close eyelids tightly
- lower eyelid droops away and sags outwards (ectropion)
- spillage of teards
- drying of conjunctiva
- ulcerations
- secondary infection
largest salivary gland
parotid gland
how does the parotid duct travel
transversely across the face
where does the parotid duct open into
oral cavity near the second upper molar tooth
posterior boundary of parotid gland
mastoid process
anterior boundary of parotid gland
rams of mandible
conditions which result in parotid glands swelling
mumps
parotid gland stones
why is parotid gland stones painful
intense pain when salivating
functions of the parotid duct
carries secretions from the parotid gland into the mouth
5 terminal branches of the facial nerve
temporal division zygomatic division buccal division marginal mandibular division cervical division
where does the facial nerve divide
the parotid gland
why is the facial nerve vulnerable to damage within the parotid gland
it lies superficially
why is surgical removal of the parotid gland difficult
the facial nerve and its branches lie superficial
when is the facial nerve at risk
surgery
blunt or penetrating trauma
temporal bone fractures
structures which lie within the substance of the parotid gland
- facial nerve and divisions
- retromandibular vein
- external carotid artery and divisions
terminal branches of the external carotid artery
maxillary artery
superficial temporal artery
branches of the external carotid artery (in order going up)
- superior thyroid artery
- lingual artery
- facial artery
- maxillary artery
- superficial temporal artery
important branch of the maxillary artery
middle meningeal artery
what does the middle meningeal artery supply
cranial dura mater
route of the middle meningeal artery
under the pterion of the skull
what is the pterion
where the frontal bone, temporal bone, parietal bone and sphenoid bone converge on the skull
where does the common carotid artery bifurcate
C3-4
why is the pterion weak
several bones converge here
what type of inter cranial bleeding may result from a fracture to the pterion?
extradural haematoma / extradural haemorrhage
how does a fracture to the pterion result in an extradural haemorrhage?
- middle meningeal artery can be damaged
- blood accumulation between the skull and dura matter (subarachnoid bleeding)
- extradural haemorrhage
where to palpate for the superficial temporal artery (temporal pulse)
- area anterior to the ear
- posterosuperior to the temporomandibular joint
where to palpate for the anterior branch of the superficial temporal artery (temporal pulse)
- posterior to the zygomatic process of the frontal bone
- the artery is passing laterally to the temporal fascia
where to palpate for the carotid pulse
- lateral to the thyroid cartilage
- medial to the sternocleidomastoid muscle
where to palpate for the facial pulse
adjacent to the anterior margin of the masseter muscle
which cranial nerve loops around the internal and external carotid arteries
hypoglossal nerve (CN7)
function of hypoglossal nerve
innervates motor functions of the tongue (apart from palatoglossus)
eye socket
the orbit
how many bones make up the orbit
7
main foramina in the orbit
- superior orbital fissure
- interior orbital fissure
- infraorbital foramen
- lacrimal groove
- optic canal
bones making up the orbit
- frontal bone
- ethmoid bone
- nasal bone
- maxilla
- zygomatic bone
- sphenoid bone
extra-ocular muscles
- superior rectus
- inferior rectus
- medial rectus
- lateral rectus
- superior oblique
- inferior oblique
- levator palpebrae superiosis
which nerve are most extraocular muscles innervated by
oculomotor (CN3)
which 2 extra-ocular muscles are not innervated by the oculomotor nerve
lateral rectus
superior oblique
what nerve innervates the lateral rectus muscle
abducens nerve (CN6)
what nerve innervates the superior oblique muscle
trochlear nerve (CN4)
superior rectus muscle
elevates eyeball
inferior rectus muscle
depresses eyeball
medial rectus muscle
adducts eyeball (pulls the eyeball medially to look towards the midline)
lateral rectus muscle
abducts the eyeball (pulls eyeball laterally to look away from the midline)
superior oblique muscle
inverts (medially rotates the eyeball)
inferior oblique muscle
everts (laterally rotates the eyeball)
levator palpebrae superiosis muscle
lifts the eyelids
which nerves travel through the orbital fissure
- oculomotor
- trochlear
- abducens
which is the only cranial nerve to emerge from the dorsal aspect of the brainstem
trochlear nerve
where does the trochlear nerve emerge
the dorsal aspect of the brainstem
what is diplopia
double vision
how do you examine a patient’s eye movements?
the H test
- have a patient track an object, without moving their head, and move it in the shape of an H
- start in the midline
how to measure the function of the oculomotor nerve
- ask the patient to look medially
- check the upper lid is fully retracted on upward gase
how to measure the function of the abducens nerve
ask the patient to look laterally
how to measure the function of the trochlear nerve
ask the patient to look medially then downwards
ptosis
dropping of upper eyelid / lazy eye
ptosis is the malfunction of which muscle?
complete: loss of oculomotor nerve function for levator palpebrae superiosis
partial: loss of sympathetic innervation to the superior tarsal muscle
Horner’s Syndrome
Any lesion which leads to a loss of sympathetic function in the head
clinical presentations of Horner’s syndrome
- pupillary constriction
- partial ptosis
- absence of sweating
intraocular muscles
- ciliary muscle
- sphincter pupillae muscle
- dilator pupillae muscle
which intraocular muscles are supplied by the oculomotor nerve
ciliary
splinter pupillae
ciliary muscle
accommodation of the lens of the eye for near vision
- constricts ciliary body
- relaxes tension on lens
- lens becomes more rounded
dilator pupillae muscle
dilates pupil
sphincter pupillae muscle
constricts pupil
which muscles dilate and constrict the pupil
dilate: dilator pupillae muscle
construct: sphincter pupillae muscle
which autonomic ganglion innervates the intraocular muscles
ciliary ganglion:
- ciliary muscle
- sphincter pupillae muscle
superior cervical ganglion:
- dilator pupillae muscle
which structures articulate in the temporomandibular joint?
- mandibular fossa of the temporal bone
- condylar process of the mandible
what does the temporomandibular joint permit?
gliding, rotation, elevation and depression of the mandible
how are the two articulating surfaces of the TMJ separates?
articular disc of the TMJ
- this creates the superior and inferior articular cavities
how is the temporomandibular joint strengthened
- ligaments
- articular tubercle
TMJ when the mouth opens
protrusion:
condylar process glides anteriorly to lie directly beneath the articular tubercle
how do grinding movements in the jaw occur
if protraction occurs unilaterally
- condylar process undergoes rotation on the inferior surface of the articular disc
muscles of mastication
temporalis
masseter
lateral pterygoid
medial pterygoid
superficial muscles of mastication
temporalis
masseter
deep muscles of mastication
medial and lateral pterygoid
origin of temporalis muscle
temporal fossa of the skull
insertion of temporalis muscle
coronoid process of the mandible
origin or the masseter
zygomatic process of the temporal bone
insertion of the masseter muscle
external aspect of the ramus and angle of the mandible
origin of the lateral pterygoid muscle
external / lateral aspect of the lateral pterygoid plate of the sphenoid bone
insertion of the lateral pterygoid muscle
condyloid process of the mandible
origin of the medial pterygoid muscle
internal / medial aspect of the lateral pterygoid plate
insertion of the medial pterygoid muscle
internal aspect of the ramus and angle of the mandible
which nerve innervates the muscles of mastication
mandibular branch of the trigeminal nerve
what happens when the medial and lateral pterygoid muscles contract
the mandible moves laterally
how does protrusion of the jaw occur
lateral pterydoid assisted by medial pterygoid
how does retraction of the jaw occur
- temporalis contracts
- masseter muscle contracts
- digastric muscles contract
how does elevation of the jaw occur
- temporalis contracts
- masseter contacts
- medial pterygoid contracts
how does depression of the jaw occur
- gravity
- digastric muscles
route of the mandibular branch of the trigeminal nerve
from the brainstem to the face through the foramen oval in the base of the skull
consequences of unilateral damage to the mandibular branch of the trigeminal nerve
the jaw will deviate to one side when opened against resistance (deviates towards the paralysed side)
which side will the jaw deviate to if there is a lesion on the left mandibular branch of the trigeminal nerve?
left
palpebral fissure
the gap between the eyelids
origin of platysma
inferior edge of mandible
attachments to orbicularis oris
near the midline to the mandible and maxilla
route or facial nerve from brainstem out of the skull
brainstem
internal acoustic canal
gives off branches
stylomastoid foramen
which structures does the facial artery supply
most superficial structures of the face
sensory supply to the face
divisions of the trigeminal nerve
dilators of the mouth group of muscles function
opens the mouth
why is swelling of the parotid gland painful
because of the toughness of the surrounding fascia and it’s position between the mandible and the temporal bone behind
which muscle of mastication is fan-shaped?
temporalis
