A6 - the face Flashcards
how may bones make up the viscerocranium?
14
what is the common embryonic origin of the muscles of facial expression?
2nd pharyngeal arch
all the muscles of facial expressions are innervates by what?
facial nerve
where do the muscles of facial expression insert?
dermis of the skin
what is the muscle of the scalp?
occipitofrontalis
describe the occipitofrontalis
- consists of 2 bellies (frontal and occipital), joined in the middle by an aponeurosis
- the muscle moves the scalp on the skull, wrinkles the skin on the forehead and elevates the eyebrows
what are the 2 muscles of the eyelids?
orbicularis oculi and corrugator supercilii
what are the 2 parts of orbicularis oculi?
orbital and palpebral
what do the 2 different parts of orbicularis oculi do?
- orbital — wrinkles the eyelids and closes them tightly
- palpebral — closes the eyelids gently
what does corrugator supercilii do?
draws the eyelids medially forming wrinkles in the forehead
what are the 3 muscles of the nostrils?
nasalis, depressor septi nasi and procerus
label the 3 muscles of the nose
label the muscles that act on the lips
what is the muscle of the cheek and its function?
buccinator — required for blowing and sucking and is also used to keep the bolus of the food between the teeth when chewing
what is the muscle of the neck and its function?
= platysma
- depresses the mandible and the angle of the mouth and tenses the skin over the inferior face and neck
what innervates all the muscles of mastication?
the mandibular branch of the trigeminal nerve (V3)
what nerves exit at where the arrows are pointing? where do the nerves arise?
describe infraorbital and mental nerves
a - infraorbital nerve = terminal branch of the maxillary division of CN V
d - mental nerve = branch of inferior alveolar nerve which arises from the mandibular division of CN V
label the muscles A-H
what are the 5 layers of the scalp?
S — skin
C — connective tissue — a fibrofatty layer that attaches the skin to the underlying aponeurosis.
many arteries and vins form an anastomosing network in this layer
A — aponeurosis (of occipitofrontalis)
L — loose areolar connective tissue — connects the aponeurosis to the periosteum of the skull. it
contains important emissary veins that connect the superficial veins of the scalp with the
diploic veins of the skull with the dural venous sinuses
P — pericranium — the periosteum covering the bones of the skull
what are the muscles of mastication?
- masseter
- temporalis
- medial pterygoid
- lateral pterygoid
all the muscles of mastication insert into the ____ and act on the _____
- mandible
- temporomandibular joint
origin, insertion and action of temporalis
- O = temporal fossa
- I = coronoid process of mandible
- A = elevation and retraction of mandible
origin, insertion and action of masseter
- O = zygomatic arch
- I = lateral surface of ramus and angle of mandible
- A = elevation of mandible
origin, insertion and action of medial pterygoid
- O :
head 1 = medial aspect of lateral pterygoid plate
head 2 = tuberosity of maxilla - I = medial surface of ramus and angle of mandible
- A = laterally moves and protracts mandible
origin, insertion and action of lateral pterygoid
- O :
head 1 = infratemporal surface and crest of greater wing of sphenoid
head 2 = lateral surface of lateral pterygoid plate - I = neck of mandible
- A = laterally moves and protracts mandible
(protrusion of mandible if both sides contracting, lateral deviation of mandible if only one side contracting)
what other muscles assist in mastication in depressing the jaw?
digastric, geniohyoid and mylohyoid
describe the parotid gland
- a bilateral salivary gland
- the largest of 3 salivary glands
where is the parotid gland?
wedged between the ramus of the mandible anteriorly and the mastoid process and sternocleidomastoid posteriorly
what does the parotid gland extend superficially over?
the masseter muscle
what encapsulates the parotid gland?
parotid sheath
why is there fatty tissue between the lobes of the parotid gland?
to allow the gland to be flexible to accommodate the motion of the mandible
what type of salvia does the parotid gland produce?
serous
what are the boundaries of the parotid region?
> superiorly — zygomatic arch
inferiorly — inferior border of mandible
anteriorly — masseter muscle
posteriorly — external ear and sternocleidomastoid
the secretions of the parotid gland are transported to the oral cavity by what?
the Stensen duct
describe the course of the stensen duct
- arises from the anterior surface of the gland
- transverse the masseter muscle
- it then pierces the buccinator, moving medially
- opens into the oral cavity near the 2nd upper molar
what happens to CN VII in the parotid gland?
it divides into 5 (or more) branches which leaver the gland on the anteromedial surface to innervate the muscles of facial expression — none of these nerves innervate the parotid gland itself
what types of innervation does the parotid gland receive?
sensory and autonomic
what supplies sensory innervation to the parotid gland?
auriculotemporal and greater auricular nerves
what supplies paraysympathetic innervation to the parotid gland?
auriculotemporal nerve
(glossopharyngeal nerve IX synapses with the otic ganglion, the auriculotemporal nerve then carries PS fibres from the otic ganglion to the parotid gland)
effects of parasympathetic vs sympathetic stimulation of parotid gland
PS - increase in saliva production, thin watery saliva
S - reduce in secretion of saliva, thicken saliva