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Anatomy > Muscles of Facial Expression & Parotid Gland > Flashcards

Muscles of Facial Expression & Parotid Gland Flashcards

1
Q

What embryological arch do MOM come from?

A

First pharyngeal arch (mandibular)

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2
Q

What embryological arch do the muscles of facial expression come from?

A

Second pharyngeal arch (hyoid)

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3
Q

WITH NERVUS INTERMEDIUS

Where does the general visceral efferent response travel?

parasympathetic

A

Originate from the superior salivatory nucleus in the Pons and provide secretomotor innervation to:
Lacrimal gland (tear production)
Mucous membranes of the nasal and oral cavities
Submandibular and sublingual salivary glands

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4
Q

WITH NERVUS INTERMEDIUS

Where does the special visceral afferent response travel?

A

These fibers carry taste sensation from the anterior two-thirds of the tongue via the chorda tympani nerve to the solitary nucleus in the medulla

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5
Q

Where does the special visceral efferent response travel?

A

orginates from motor nucleus in pons
to muscles of facial expression
+
addition muscles - stylohyoid, stapedius, posterior belly of diagastric

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6
Q

Where is the motor root of CNVII?

what is this angle called?

A

emerges from the angle in between the lower pons and the cerebellum

cerebellopontine

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7
Q

Where does the motor root enter?

A

enters the internal acoustic meatus (a canal in the petrous part of the temporal bone), alongside the nervus intermedius (which carries sensory and parasympathetic fibers) and CN VIII (vestibulocochlear nerve) and the labyrinthine artery

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8
Q

What does injury at the internal acoustic meastus affect?

A

affects muscles of facial expression and stapedius

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9
Q

What condition may occur due to injury at internal acoustic meatus?

A

hyperacusis

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10
Q

What is the tiny sensorial component of CNVII

A

supplies parts of external acoustic meatus and deep auricle

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11
Q

Where are the cell bodies for taste fibres located?

A

geniculate gangelion

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12
Q

Explain the course and clinical significance of the greater petrosal nerve.

A

The greater petrosal nerve arises from CN VII in the facial canal, carries parasympathetic fibers to the pterygopalatine ganglion, and its damage can lead to reduced lacrimal secretion, causing dry eye (xerophthalmia).

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13
Q

What does the stapedius attach to and what is it’s action?

A

dampens the movement of the stapes in the middle ear

attached to stapes (one of ossicles)

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14
Q

Where does CNVII emerge to supply the muscles of facial expression?

A

leaves petrous temporal bone through stylomastiod foramen

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15
Q

What are the intial branches of CNVII after the stylomastiod foramen and what do they supply?

A

posterior auricle - occipital belly of the occipitofrontalis muscle and auricular muscles

diagastric - posterior belly of diagastric and stylohyoid muscle

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16
Q

What are the 5 branches of the muscles of facial expression?

A

temporal
zygomatic
buccal
marginal mandibular
cervical

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17
Q

What is the 5 branches plexus superficial to?

A

retromandibular vein
external carotid

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18
Q

What does each branch (5) provide innervation to?

A

Temporal - frontal belly of occipitofrontalis, orbicularis oculi

Zygomatic - orbicularis oculi, (upper lip muscles)

Buccal - buccinator, orbicularis oris

Marginal mandibular - orbiculairs oris

Cervical - platysma

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19
Q

What is the billateral cortical control of upper face?

why is this important?

A

The upper half of the face (e.g., forehead, upper eyelids) receives bilateral cortical input from both the left and right hemispheres of the brain.

This means that even if one side of the brain (e.g., after a stroke) is damaged, the other side can still provide input to the upper facial muscles, leading to upper facial sparing (no paralysis of the forehead).

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20
Q

What is contralateral cortical control of lower face?

A

The lower half of the face (e.g., mouth, lower eyelids) receives contralateral cortical input, meaning that the left hemisphere controls the muscles on the right side of the lower face and vice versa.
Damage to the cortex on one side (e.g., a stroke affecting the right side of the brain) will result in contralateral weakness or paralysis of the lower face (e.g., left-sided weakness).

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21
Q

What is upper facial sparing?

A

Upper facial sparing is a hallmark of central (upper motor neuron) lesions (like a stroke), where only the contralateral lower face is affected. The upper face is spared because it has bilateral cortical input.

22
Q

What effect do peripheral lesions have?

A

Peripheral lesions (e.g., damage to the facial nerve itself) will affect the entire ipsilateral side of the face (both upper and lower). This is seen in conditions like Bell’s palsy, where there is weakness or paralysis of the entire half of the face, including the forehead.

23
Q

How does the cortical control of facial nerve nuclei differ between the upper and lower face?

A

The upper face receives bilateral cortical input, leading to upper facial sparing in central lesions (e.g., strokes). In contrast, the lower face receives only contralateral cortical input, causing weakness or paralysis in central lesions.

24
Q

What branch of the 5 can be affected during surgery on submandibular gland?

What sign can this cause?

A

The marginal mandibular branch of CN VII dips inferior to the mandible overlying the submandibular gland & consequently it is at risk during surgery on this gland

The lower lip muscles may be paralysed causing saliva to dribble from the mouth

25
Q

How does the corneal reflex work, and which nerves are involved?

A

The corneal reflex involves CN V1 (ophthalmic division of the trigeminal nerve) sensing corneal irritation (afferent) and CN VII initiating the blink response via the orbicularis oculi (efferent).

Absence of this reflex indicates CN V or CN VII pathology.

26
Q

What are the muscles of facial expression?

A

Buccinator
Orbicularis oris
Orbicularis oculi
Occipitofrontalis
Platysma

27
Q

What is the function of the buccinator muscle, and what are its attachments?

A
  • Originates from posterior part of alveolar processes of maxilla/mandible & from pterygomandibular raphe
  • Fibres merge with orbicularis oris (insertion)
  • Its actions are to press the cheeks against the molar teeth & works with the tongue to keep food between occlusal surfaces of teeth & out of the oral vestibule
  • It also assists with smiling
28
Q

What is the route the parotid duct and where does it open?

A

lies on top of the masseter before reaching the buccinator & piercing it while en route to the oral cavity where it enters near the superior 2nd molar tooth

29
Q

What is the function of the buccal fat pad in infants?

A

Reinforces the cheeks and inhibits cheek collapse during feeding.

30
Q

What is the function of the orbicularis oris muscle, and what are its attachments?

A
  • Originates partially from buccinator/surrounding muscles & also from medial mandible/ maxilla
  • Inserts into mucous membrane of lips
  • Its actions are to close &/or protrude the lips
  • Together with the buccinator & tongue, keeps food between occlusal surfaces of teeth
  • Also assists in whistling
31
Q

What is the function of the platysma muscle, and what are its attachments?

A
  • Originates from subcutaneous tissue of the infra & supraclavicular regions
  • Inserts at base of mandible to merge with orbicularis oris, skin of cheek, lower lip & angle of mouth
  • Its actions are to tense the skin of inferior face/neck & depress the mandible
32
Q

What is the innervation of the occupitofrontalis?

A

Innervated by temporal branch (frontal belly)

posterior auricular branch (occipital belly) of CN VII

33
Q

What is the role of the epicranial aponeurosis in the movement of the scalp, and which muscles are involved?

A

The epicranial aponeurosis connects the frontal belly (frontalis) and occipital belly (occipitalis) of the occipitofrontalis muscle. These muscles work together to retract the scalp and wrinkle the forehead.

34
Q

What are the attachments and actions of the occiputofrontalis?

A
  • Frontal belly originates from epicranial aponeurosis & inserts into the skin/ subcutaneous tissue of eyebrows & forehead
  • Occipital belly originates from the lateral 2/3 of superior nuchal line & inserts into the epicranial aponeurosis
  • Its actions are to retract the scalp (occipital belly), wrinkle the forehead & elevate the eyebrows (frontal belly)
35
Q

What are the two parts of the orbicularis oculi?

A

palpebral
orbital

36
Q

What are the attachements for each part of the orbicularis oculi?

A
  • Palpebral originates from the medial palpebral ligament & inserts into the lateral palpebral raphe at the ligament
  • Orbital originates from the nasal part of the frontal bone, frontal process of maxilla & medial palpebral ligament & inserts into skin around margin of orbit
37
Q

What are the actions of the orbicularis oculi?

A

Its actions are to close the eyelids gently (involuntary or blinking reflex; palpebral part) or tightly (voluntary; orbital part)

38
Q

What dilator muscles insert into angle of mouth?

(modiolus)

A

zygomaticus major
risorius
depressor anguli oris
levator anguli oris

39
Q

What muscles help us smile?

A

Zygomaticus Major
Zygomaticus Minor
Risorius
Levator Labii Superioris

40
Q

What dilator muscles insert into upper or lower lips?

A

levator labii superiois
zygomaticus minor
depressor labii inferiois

41
Q

What muscle flares the nostrils?

A

levator labii superiois alaeque nasi

42
Q

What muscles wrinkle the skin over dorsum of nose?

A

procerus
transverse part of nasalis

43
Q

What structures are within the parotid gland?

A

CNVII
retromandibular vein
external carotid

44
Q

What is the cutaneous innervation of the parotid gland?

A

CNV3 - auriculotemporal
C2,3 - great auricular

45
Q

Explain the pathway of parasympathetic fibers to the parotid gland.

A

Preganglionic fibers from CN IX travel through the tympanic nerve and lesser petrosal nerve to the otic ganglion. Postganglionic fibers then reach the parotid gland via the auriculotemporal nerve (like a hitchhiker) (CN V3).

46
Q

Describe the sympathetic innervation to the parotid gland and its effect on salivary secretion.

A

Sympathetic fibers from the superior cervical ganglion reach the parotid gland via the external carotid artery nerve plexus, causing vasoconstriction and reduced saliva production, contributing to a dry mouth during stress.

47
Q

What structures pass through the parotid gland, and how is this clinically significant?

A

The facial nerve (CN VII), retromandibular vein, and external carotid artery pass through the parotid gland. Tumor excision within the gland poses a high risk of damaging the facial nerve.

48
Q

What is the most common salivary gland tumour?

A

pleomorphic adenoma

benign

49
Q

How can tumors of the parotid gland affect facial nerve function?

A

Tumors in the parotid gland may compress or infiltrate CN VII, causing facial weakness or paralysis. Resection of these tumors risks further nerve injury.

50
Q

What are the clinical features and etiology of Ramsay Hunt syndrome?

A

Ramsay Hunt syndrome presents with ipsilateral facial paralysis, ear pain, and a vesicular rash, caused by reactivation of the varicella-zoster virus (VZV) in the geniculate ganglion of CN VII.

51
Q

What are the additional signs of Ramsay Hunt syndrome - tinnitus, hearing loss, nausea, vomiting, vertigo, & nystagmus associated with?

A

Close proximity of geniculate ganglion to the CNVIII within the bony facial canal

52
Q

A typical arrangement for muscles of facial expression is that they arise from bone and insert into skin/ subcutaneous tissue. Why is that?

A

Their attachment to skin and subcutaneous tissue allows them to pull on the skin, creating expressions like smiling, frowning, or raising eyebrows.

Anatomy (13 decks)

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