Ear - Johnson

Auricle (Pinna) parts

Helix Antihelix Tragus Antitragus Lobule

Direction to pull ear for irrigation

Superiorly (upward)

Innervation of the external ear (Posterior)

Lesser Occipital nerve (C2) and Great Auricular nerve (C2 C3)

Innervation of the external ear (Anterior/Tragus)

Auriculotemporal nerve (branch of CN V3)

Reflex caused by stimulating the ear canal (e.g. Q-tip)

Cough or bradycardia (due to Vagus nerve CN X)

Clinical sign of Herpes Zoster Oticus

Blisters on the eardrum/ear canal (involvement of CN VII)

Umbo

Center of the tympanic membrane where the malleus attaches

Cone of Light location

Anterior-inferior quadrant of the tympanic membrane

Roof of Middle Ear (Tegmental Wall)

Formed by Tegmen Tympani; erosion leads to Middle Cranial Fossa (meningitis/brain abscess)

Floor of Middle Ear (Jugular Wall)

Related to Internal Jugular Vein; erosion risks jugular thrombosis and damage to CN IX X XI

Anterior Wall of Middle Ear (Carotid Wall)

Related to Internal Carotid Artery and opening of Pharyngotympanic tube

Posterior Wall of Middle Ear (Mastoid Wall)

Connects to Mastoid Air Cells via Aditus to Mastoid Antrum; related to Facial Nerve and Sigmoid Sinus

Medial Wall of Middle Ear (Labyrinthine Wall)

Separates middle ear from inner ear; features Promontory Oval Window Round Window

Structure causing Mastoiditis

Infection spreading from middle ear into Mastoid Air Cells via the Aditus

Clinical sign of Mastoiditis

Postauricular tenderness and protrusion of the auricle

Order of Ossicles (Lateral to Medial)

Malleus (Hammer) -> Incus (Anvil) -> Stapes (Stirrup)

Otosclerosis

Calcification of the Annular Ligament at the Oval Window

Tensor Tympani insertion and action

Attaches to Malleus; tenses TM to dampen noise

Tensor Tympani innervation

CN V3 (Trigeminal)

Stapedius insertion and action

Attaches to Stapes; dampens vibration of stapes

Stapedius innervation

CN VII (Facial Nerve)

Hyperacusis

Abnormally loud hearing due to paralysis of Stapedius or Tensor Tympani

Chorda Tympani pathway

Branches from CN VII passes between Malleus and Incus (medial to TM)

Chorda Tympani function

Taste to anterior 2/3 tongue + Parasympathetic to Submandibular/Sublingual glands

Greater Petrosal Nerve function

Parasympathetic to Lacrimal Gland (tears)

Nerve providing sensory innervation to Middle Ear mucosa

Glossopharyngeal Nerve (CN IX) via the Tympanic Plexus

Lesser Petrosal Nerve origin and target

Originates from Tympanic Plexus (CN IX); targets Otic Ganglion (Parotid Gland)

Referred ear pain (Oropharynx/Tonsils)

Mediated by CN IX (Glossopharyngeal)

Referred ear pain (Teeth)

Mediated by CN V (Trigeminal)

Pharyngotympanic Tube function

Equalizes pressure between Middle Ear and Nasopharynx

Muscles opening the Pharyngotympanic Tube

Tensor Veli Palatini Levator Veli Palatini Salpingopharyngeus

Reason for pediatric Otitis Media

Tube is shorter and more horizontal in children impairing drainage

Cholesteatoma

Overgrowth of epithelial tissue in middle ear often due to chronic infection

Pars Tensa vs Pars Flaccida

Pars Tensa is the tense vibrating part of TM, Pars flaccida is the upper slack part

Arterial supply to the external ear

Posterior auricular artery (posterior) and Superficial temporal artery (anterior)

Promontory of the middle ear

A bulge on the medial wall produced by the basal turn of the cochlea

Prominence of the facial canal

A ridge on the medial wall where the facial nerve runs, erosion here causes facial palsy

Aditus to Mastoid Antrum

The specific opening connecting the middle ear to the mastoid air cells