Recap on Bony Orbit, Eye Movement & Visual Pathways Lecture 9 Quiz

29 Questions

Which of the following is NOT a key function of the facial muscles?

Allowing for voluntary control of facial expressions

Which of the following facial muscles is responsible for drawing the eyebrows inferiorly and medially, leading to a 'worried' or 'concerned' expression?

Corrugator Supercillii

What is the clinical relevance of the facial nerve (CN VII) in relation to facial expression?

It provides voluntary control of the facial muscles

Which muscle is responsible for closing the eyelids?

Orbicularis Oculi

Which of the following is NOT a common embryological origin of the facial muscles?

Skin

Which facial muscle group is responsible for controlling the movements of the nose?

Nasal

Which cranial nerve is responsible for incyclotorsion of the eye?

CN IV

Which cranial nerve is associated with the abductor function of the eye?

CN VI

What is the primary function of CN III in relation to the eye?

Medial rotation

Which cranial nerve is related to supplying extraocular muscles of the eye?

CN III

Which cranial nerve is known for its special interest in providing visual input to the brain?

CN II

What is the role of the chorda tympani nerve branch in taste sensation?

Bringing taste sensation to the anterior 2/3 of the tongue

Which nerve supplies the submandibular and sublingual glands to produce saliva?

Facial nerve

What muscle is innervated by branches of the facial nerve proper?

Muscles of facial expression

What facial feature may sag and be drawn to the opposite side when smiling due to facial nerve dysfunction?

Cheek

Which clinical feature indicates dysfunction of orbital muscles due to facial nerve issues?

Inability to close eyelid causing cornea to dry out

What is a common examination technique for assessing facial nerve (Bell's) palsy?

Raising eyebrows and closing eyelids

Which facial muscle is responsible for flaring the nostrils and wrinkles skin over the dorsum of the nose in expressions of anger or exertion?

Nasalis

In atypical parkinsonism, vertical wrinkling on the forehead is known as the 'Procerus sign,' which muscle is involved in this phenomenon?

Corrugator Supercillii

Which facial muscle works with risorius to depress the corners of the mouth, associated with expressions of sadness or frown?

Depressor Anguli Oris

Which cranial nerve supplies motor innervation to facial muscles?

CN VII (Facial)

Which segment of CN VII is responsible for innervating the lacrimal gland?

Intracranial (Cisternal) Segment

Which part of CN VII is defined by its long course and is split into parts, with one branch being the Chorda Tympani branch?

Intratemporal Segment

Which cranial nerve is responsible for motor innervation to the muscles of facial expression?

CN VII

Which branch of CN VII is responsible for visceromotor function to the lacrimal gland and mucous glands of the nasal cavity and palate?

Greater petrosal nerve

Which segment of the facial nerve is responsible for motor innervation to the muscles of facial expression?

Intratemporal segment

Which nerve provides special sensation (taste) to the anterior two-thirds of the tongue?

Chorda tympani nerve

What is the main consequence of damage to the greater petrosal nerve branch of CN VII?

Loss of tears

Through which foramen does the extracranial segment of CN VII leave the facial canal in the petrous part of the temporal bone?

Stylomastoid foramen

Study Notes

Facial Muscles

Located in subcutaneous tissue, originating from bone or fascia and inserting onto skin
When contracting, they pull on skin and exert their effects
Only muscle group to insert onto skin
Arranged into groups acting on:
Orbital (eyelids)
Nasal (nose)
Oral (mouth and lips)

Key Facial Muscles

Occipital and frontal bellies: common tendon raises eyebrows, furrows skin (Botox target), works together with orbital muscles
Corrugator supercillii: draws eyebrows inferiorly and medially (worry/concern), "elevenses wrinkles" (Botox target)
Orbicularis oculi: closes eyelids
Procerus: depresses medial end of eyebrow
Nasalis: flares nostrils (anger/exertion), wrinkles skin over dorsum of nose (disdain/dislike)
Buccinator: attaches laterally to alveolar process of maxillae and alveolar part of mandible
Levator anguli oris: dilator of the mouth, active in smiling, keeps cheeks taut, widens oral fissure (grinning or grimacing)
Depressor anguli oris: dilator of the mouth, works with risorius to depress corners of mouth (sadness/frown)
Risorius: dilator of the mouth, draws the angle of the mouth backwards

Cranial Nerve (CN) VII (Facial Nerve)

Course:
- Arises from pons
- Courses through cranium via internal acoustic meatus
- Exits skull at stylomastoid foramen
- Pierces through parotid gland (does not innervate it)
- Gives rise to 5 branches supplying the face
Supplies:
- Muscles of facial expression
- Stapedius muscle
- Lacrimal gland
- Submandibular and sublingual salivary glands
Clinical relevance:
- With facial nerve dysfunction, patients may present with:
  - Paralysis of oral muscles: difficulty eating, food collecting between teeth and cheeks, sagging tissue around mouth, cheek sagging, and drawn to opposite side when smiling
  - Paralysis of orbital muscles: inability to close eyelid, cornea dryness, drooping lower eyelid, lacrimal fluid pooling, and failure to remove debris, leading to corneal ulceration

Branches of CN VII

Greater petrosal nerve:
- Visceromotor to lacrimal gland and mucous glands/membranes of nasal cavity and palate
- Loss of tears, dry nasal cavity
Chorda tympani nerve:
- Visceromotor to submandibular and sublingual salivary glands
- Special sensation (taste) to anterior 2/3 tongue
- Reduction of salivation, loss of taste
Facial nerve proper:
- Motor to muscles of facial expression
- Facial palsy

Test your knowledge on the bony orbit, eye movement, and visual pathways discussed in Lecture 9 of ANAT20010 Clinical Human Anatomy 3 by Dr. Laura Gorman. Topics include the contents of the orbit, bony framework, orbital foramina, extraocular and intraocular muscles of the eye, and their respective nerve supplies.

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