Lecture 16 - Ear, Orbit, and Nasal Cavaties

Question 1

Outer Ear

Answer 1

Auricle: •Layer of skin over cartilage framework •Lobule = fibrous fatty tissue with no cartilage

Sensory innervation:
•Great auricular nerve
•Auriculotemporal nerve
•Lesser occipital nerve

External acoustic (auditory) meatus: 
•From auricle to tympanic membrane 
•2.5 cm in length 
•S-shaped 
•Lined by skin and ceruminous glands

Question 2

Middle Ear

Answer 2

Tympanic Membrane
Tympanic Cavity
Auditory Ossicles
Stapedius Muscle
Tensor Tympani Muscle
CN IX

Question 3

Tympanic membrane:

Answer 3

•Dense fibrous membrane •Covered by skin externally •Covered by mucosa internally

Question 4

Tympanic cavity:

Answer 4

•Air-filled cavity within petrous portion of temporal bone

• Round window:
• Enclosed by secondary tympanic membrane:
• Undergoes compensatory excursions with movement of stapes

•Oval window: •Closed by footplate of stapes

Question 5

Auditory ossicles

Answer 5

• Malleus: •Attached to tympanic membrane
• Incus
• Stapes: •Attached to oval window (fenestra vestibuli)

Question 6

Stapedius muscle

Answer 6

•Inserts onto neck of stapes •Contracts reflexively in response to loud sounds •Innervated by CN VII

Question 7

Tensor tympani muscle:

Answer 7

• Inserts onto malleus.
• Contracts reflexively to loud sounds.
• Innervated by CN V-3.

Question 8

CN IX

Answer 8

• Tympanic nerve: •GSA to mucosa of tympanic cavity, mastoid air cells, and auditory tube
• Lateral petrosal nerve: •Leaves tympanic cavity to floor of middle cranial fossa •Descends through foramen ovale to infratemporal fossa •Ends in otic ganglion

Question 9

Inner Ear

Answer 9

Lies within petrous part of temporal bone.

Consists of:
•Bony labyrinth: •Lined with periosteum
•Membranous labyrinth
•Supplied by: •Labyrinthine artery (from basilar artery): •(Basilar artery is formed by fusion of two vertebral arteries)

Cochlea:

Vestibule: •Contains: •Utricle •Saccule

Vestibulocochlear (auditory) nerve (CN VIII)

Semicircular Canals

Utricle/Saccule

Question 10

Semicircular canals

Answer 10

•Anterior, posterior, lateral •Arranged in three planes •Open into utricle •Dilated at one end to form ampulla: •With crista ampullaris •Senses rotational acceleration

Question 11

Utricle and Saccule

Answer 11

•With macula •Senses linear acceleration and pull of gravity

Question 12

Cochlea

Answer 12

•Resembles a snail shell •Three turns •Round window (fenestra cochlea)

Question 13

Roof (Bones of Orbit)

Answer 13

• Orbital plate of frontal bone (A)
• Lesser wings of sphenoid (B)
• Related to: •Frontal cerebral lobes
• Special features: •Fossa for lacrimal gland

Question 14

Floor (Bones of Orbit)

Answer 14

• Orbital plate of maxilla (A)
• Zygomatic (B)
• Orbital process of palatine
• Related to: •Maxillary sinus
• Special features: •Infraorbital groove and canal: •Infraorbital nerve: •Continuation of cranial nerve V2 •Infraorbital artery: •Branch of external carotid artery

Question 15

Medial wall (Bones of Orbit)

Answer 15

• Lacrimal (A)
• Frontal (B)
• Ethmoid (C)
• Related to: •Ethmoid air cells •Sphenoid sinus •Nasal cavity
• Special features: •Fossa for lacrimal sac •Opening for nasolacrimal canal

Question 16

Lateral Wall (bones of orbit)

Answer 16

• Zygomatic (A)
• Greater wing of sphenoid (B)
• Frontal

•Related to: •Temporal fossa containing temporalis muscle •Middle cranial fossa

Question 17

External Features of the Eye

Answer 17

• Conjunctiva

* Eyelids: •Tarsal plates •Tarsal glands

Question 18

Lacrimal apparatus

Answer 18

•Lacrimal papilla and puncta •Lacrimal canaliculi and sac •Nasolacrimal duct

Question 19

Superior orbital fissure

Answer 19

• III
• IV
• V-1 (ophthalmic branch): •Frontal •Lacrimal •Nasociliary
• VI
• Superior ophthalmic vein

Question 20

Optic canal

Answer 20

• Cranial nerve II

* Ophthalamic artery

Question 21

Anterior and posterior ethmoidal foramina

Answer 21

Exit for anterior and posterior ethmoidal nerves

Question 22

Inferior orbital fissure

Answer 22

Cranial nerves: •V2: •Infraorbital nerve •Zygomatic branch •Orbital branches

Question 23

Six Extrinsic Muscles of the Eye

Answer 23

Inferior Oblique
Superior Rectus
Medial Rectus
Inferior Rectus
Superior Oblique
Lateral Rectus
((Levator Palpebrae Superioris))

Question 24

Sensory Innervation of Orbit

Answer 24

Optic nerve
Ophthalmic nerve (V1):
•Lacrimal nerve •Nasociliary nerve: •Infratrochlear •Anterior and posterior ethmoidal nerves •Frontal nerve: •Supratrochlear •Supraorbital

Question 25

Hard Palate

Answer 25

* Anterior two-thirds of palate * Palatine folds of maxillae * Palatines

Question 26

Soft Palate

Answer 26

* Posterior third of palate | * Fibromuscular fold

Question 27

Teeth

Answer 27

* Maxillary | * Mandibular

Question 28

Vestibule/Mucous Membranes

Answer 28

* Between lips/cheeks and gums/teeth * Leads to: Oral cavity proper * Receives: Parotid duct: Opposite upper second molar

Question 29

Oral cavity/Mucous Membranes

Answer 29

* Bounded by: Teeth and gums, Hard/soft palates * Leads to: Pharynx (oropharynx) * Uvula

Question 30

Sensory Innervation of Mucous Membranes

Answer 30

CN V2: •Greater and lesser palatine nerves •Nasopalatine nerves ``` CN V3: •Lingual nerve: •Floor of mouth •Buccal nerve: •Vestibule and cheek ```

Question 31

Motor Innervation of Mucous Membranes

Answer 31

Sympathetics (see nasal cavity) ``` Sublingual and submandibular glands: •Parasympathetics from: •Superior salivatory nucleus via CN VII •To: •Submandibular/sublingual ganglia •To: •Submandibular and sublingual glands ``` Parotid glands: •Parasympathetics from: •Inferior salivatory nucleus via CN IX •To: •Otic ganglion •To: •Parotid gland

Question 32

Cranial Nerve VII

Answer 32

Facial Nerve

Question 33

Tongue

Answer 33

Mass of skeletal muscles covered by mucosa. •Location: •Anterior two-thirds in oral cavity proper •Posterior third in oropharynx •Sulcus terminalis •Foramen cecum •Frenulum •All intrinsic and extrinsic muscles of the tongue are innervated by CN XII

Question 34

Maxillary teeth:

Answer 34

Superior alveolar branches of CN V-2

Question 35

Mandibular teeth:

Answer 35

Inferior alveolar branches of CN V-3

Question 36

Tongue: general sensory:

Answer 36

* Anterior two-thirds: •CN V3 via lingual nerve | * Posterior one-third: •CN IX

Question 37

Tongue: taste:

Answer 37

* Anterior two-thirds: •CN VII via chorda tympani | * Posterior one-third: •CN IX