Week 2: Head and Neck 2: Face and Skull Flashcards
What are the 3 branches of the trigeminal nerve?
- ophthalmic
- mandibular
- maxillary
What are the 3 groups of muscles in the head?
- muscles of facial expression
- muscles of mastication
- extraocular muscles
What are the 6 muscles of facial expression?
- occipitofrontalis
- orbicularis oculi
- buccinator
- orbicularis oris
- dilators of the mouth
- platysma
Which nerve innervates the muscles of facial expression?
facial nerve (CN VII)
What is the action of occipitofrontalis?
- pulls the scalp anteriorly
- wrinkles the forehead
- elevates the eyebrows
- posterior part pulls scalp posteriorly
What is the function of orbicularis oculi?
closes the eyelids
What is the action of orbicularis oris?
sphincter of the mouth
What is the function of the dilators of the mouth?
control the aperture of mouth
What is the function of the buccinator muscles?
- keep the cheek taut
- resists distension when whistling, sucking and blowing
- to pull back the angle of the mouth and to flatten the cheek area, which aids in holding the cheek to the teeth during chewing
What is the action of platysma muscle?
tenses the skin of the inferior face and neck
What are the sensory functions of the facial nerve?
provides innervation to the external auditory meatus, the tympanic membrane and pinner of the ear.
Also provides taste sensation to the anterior 2/3rds of tongue
what is the tympanic membrane?
- a.k.a eardrum
- separates outer ear from middle ear
Which two muscles act as dilators of the eyelid?
- iris dilator muscle
2. pupillary dilator muscle
Paralysis of the orbicularis oculi can lead to what complications?
- failure of eyelid closure
- ectropion of the lower eye lid (sags outward)
- lead to corneal injury due to lack of protection, dryness
What is the function of the buccinator muscle in neonates?
suckling
Which salivary glands are the largest?
the parotid glands
Where is the parotid gland?
it occupies the interval between the mastoid process (origin of SCM) posteriorly, and the ramus of the mandible (covered by the masseter muscle), which it overlaps anteriorly
Where does the parotid duct penetrate the buccinator muscle?
opposite crown of the 2nd upper molar tooth
How do secretions from the parotid gland reach the mouth?
the parotid duct carries secretions - it travels over the masseter muscle to pierce the buccinator muscle and open (drain) into the mouth
What is the name of the duct that drains saliva from the parotid gland into the oral cavity, at area of upper cheeks?
stensen’s duct
where does the facial nerve divide into its 5 terminal branches?
in the parotid gland
the nerve lies superficially within the gland so is vulnerable to damage
What are the five branches of the facial nerve (CN VII)?
- temporal branch
- zygomatic branch
- buccal branch
- marginal mandibular branch
- cervical branch
What structures lie within the substance of the parotid gland?
- facial nerve
- the retromandibular vein
- external carotid artery
What is the retromandibular vein formed from?
the union of the superficial temporal vein and maxillary vein
what are the two terminal branches of the external carotid artery called?
maxillary artery and superficial temporal artery
What are the 7 anterior branches of the external carotid artery?
(Some Anatomists Like Freaking Out Poor Medical Students)
- superior thyroid artery
- ascending pharyngeal artery
- lingual artery
- facial artery
- occipital artery
- posterior auricular artery
- superficial temporal artery
The middle meningeal artery is a branch from which artery?
maxillary
What does the middle meningeal artery supply?
the dura mater and calvaria
Which bones converge at the pterion?
temporal
parietal
frontal
sphenoid
What type of intracranial bleeding might result from a fracture at the pterion?
extradural haematoma
What are the 4 pulses we can palpate in the face and which artery is being palpated in each case?
- Temporal pulse - superficial temporal artery
- Temporal pulse - anterior branch of superficial temporal artery
- Carotid pulse - common carotid
- Facial pulse - facial artery
Where do we palpate the facial pulse?
angle of mandible - aligns with corner of mouth
Where to we palpate temporal pulse?
either:
- area anterior to ear
- lateral to eyebrow at level of upper eyelid
Where do we palpate carotid pulse?
lateral to upper border of thyroid and medial to anterior border of sternocleidomastoid
What is the function of the hypoglossal nerve?
innervates tongue musculature
explain the course of the hypoglossal nerve
- loops around internal and external carotid arteries
- runs toward tongue
What are the orbits?
- eye sockets
- bilateral bone cavities in the facial skeleton, formed by 7 bones of the skull
What 4 foramina are located in the orbits?
- optic canal
- superior orbital fissure
- infra orbital groove
- infra orbital foramen
What are the 7 extraocular muscles?
- superior rectus muscle
- inferior rectus muscle
- medial rectus muscle
- lateral rectus muscle
- superior oblique muscle
- inferior oblique muscle
- levator palpebrae superioris
what is the function of the superior rectus muscle and which cranial nerve is it innervated by?
- elevates the eyeball
- supplied by CN III (Oculomotor nerve)
what is the function of the inferior rectus muscle and which cranial nerve is it innervated by?
- depresses the eyeball
- supplied by CN III (oculomotor)
what is the function of the medial rectus muscle and which cranial nerve is it innervated by?
- adducts the eyeball (looks towards nose)
- supplied by CN III (oculomotor)
what is the function of the lateral rectus muscle and which cranial nerve is it innervated by?
- abducts the eyeball (looks laterally)
- supplied by CN VI (abducens nerve)
what is the function of the superior oblique muscle and which cranial nerve is it innervated by?
- inverts (medially rotates) the eyeball
- supplied by CN IV (trochlear nerve)
what is the function of the inferior oblique muscle and which cranial nerve is it supplied by?
- everts (laterally rotates) the eyeball
- supplied by CN III (oculomotor)
what is the function of the levator palebrae superioris and which cranial nerve is it innervated by?
- muscle that lifts the eyelids
- supplied by CN III (oculomotor)
What is diplopia?
double vision - when you look at 1 object but see 2 images
Explain how you would examine the cranial nerves involved in eye movements
- oculomotor: ask patient to look medially. check that upper lid is fully retracted on upward gaze
- abducens: ask patient to look laterally
- trochlear: ask patient to look medially then look downwards
What is ptosis?
- drooping or falling of the upper eyelid
- results from malfunction of levator palpebrae superioris
What is horners syndrome?
characterised by miosis (constriction of pupil - resulting in decreased pupil size), ptosis and anhidrosis (absence of sweating of the face)
Why does mild ptosis occur in Horner’s syndrome?
damage to oculomotor nerve which innervates levator palpebrae superioris
What are the 3 intraocular muscles?
-sphincter pupillae
-dilator pupillae
-ciliary muscle
these muscles are WITHIN the eye
Which intraocular muscles are supplied by the oculomotor nerve?
ciliary and sphincter pupillae muscles
What is the function of the ciliary muscles?
changes the shape of the lens when your eyes focus on a near object
What is the function of the dilator pupillae muscle?
Dilate the pupil when available light decreases
What is the function of the sphincter pupillae muscle?
Constricts the pupil in bright light
Where is the temporomandibular joint?
the joint is formed by the articulation between the mandibular fossa of the temporal bone and the condylar process of the mandible
What is the function of the temporomandibular joint?
gliding, rotation, flexion (elevation) and extension (depression) of the mandible
Why is dislocation of the TMJ rare?
the articular tubercle acts with the ligaments to prevent dislocation
What is protrusion?
for the mouth to open the condylar process glides anteriorly to lie directly beneath the articular tubercle
What are the 4 muscles of mastication?
- temporalis
- masseter
- lateral pterygoid
- medial pterygoid
Where does the temporalis muscle originate and insert?
Origin: temporal fossa of the skull
Insertion: coronoid process of the mandible
Where does the masseter muscle originate and insert?
Origin: zygomatic process of the temporal bone
Insertion: lateral aspect of the ramus and angle of the mandible
Where does the lateral pterygoid originate and insert?
Origin: lateral aspect of the lateral pterygoid plate of the sphenoid bone
Insertion: condyloid process of the mandible
Where does the medial pterygoid originate and insert?
Origin: medial aspect of the lateral pterygoid plate
Insertion: medial aspect of the angle of mandible
How can the mandible move laterally?
due to contractions of the medial and lateral pterygoid muscles
What are the muscles of mastication supplied by?
the mandibular branch of the trigeminal nerve
Which muscles are involved in protrustion of mandible?
lateral pterygoid assisted by medial pterygoid
Which muscles are involved in retraction of mandible?
temporalis, masseter, geniohyoid and digastric
Which muscles are involved in elevation of mandible?
temporalis, masseter, medial pterygoid
Which muscles are involved in depression of mandible?
gravity, digastric, geniohyoid and mylohyoid muscles
