Topic 2: External Ear Anatomy, Vascularization, Innervation, Embryology, and Malformations

Comprehensive vocabulary flashcards reviewing the anatomical structures, dimensions, vascularization, innervation, embryology, and malformations of the external ear based on the lecture notes.

Anatomy of the Ear (Oído)

The organ responsible for perceiving sound volume, pitch, timbre, and direction, structurally divided into the external ear (oído externo), middle ear (oído medio), and inner ear (oído interno).

Pabellón auricular

The visible part of the external ear measuring approximately $5-8\,cm$ high and $4-6\,cm$ wide, composed mainly of elastic cartilage covered by skin, which acts as an antenna to collect, amplify, and direct sound toward the middle ear.

Hélix

The outer border of the ear, whose root attaches the pabellón auricular to the skull.

Antihélix

A curved prominence situated in front of the hélix with two branches that delimit the fosa triangular.

Concha

The central depression of the pabellón auricular that leads directly into the conducto auditivo externo (CAE).

Trago

A cartilaginous projection situated in front of the entrance to the conducto auditivo externo (CAE).

Antitrago

A cartilaginous projection situated opposite the trago.

Lóbulo

The inferior, soft portion of the pabellón auricular that lacks cartilage.

Conducto auditivo externo (CAE)

An S-shaped canal measuring approximately $25-30\,mm$ in length and $7\,mm^2$ in diameter that carries sound to the tympanic membrane, providing an auditory gain of $15-20\,dB$ between $3000$ and $4000\,Hz$.

Istmo

The junction between the outer cartilaginous two-thirds and the inner bony one-third of the conducto auditivo externo.

Cartilaginous Portion of the CAE

The outer two-thirds of the conducto auditivo externo, containing hairs as well as ceruminous and sebaceous glands that produce cerumen to protect against dirt and infections.

Bony Portion of the CAE

The inner one-third of the conducto auditivo externo, formed by the tympanic bone and spanning an extension of $8\,mm$.

Anatomical Relations of the CAE Walls

The spatial relationships surrounding the conducto auditivo externo: superiorly to the endocranium (fosa craneal media), inferiorly to the parotid gland (parótida), anteriorly to the temporomandibular joint (ATM), posteriorly to the mastoid process (mastoides), and medially (interno) to the tympanic membrane.

Arteria auricular anterior y posterior

Branches of the external carotid artery that irrigate the fibrocartilaginous system of the pabellón auricular and the conducto auditivo externo.

Arteria timpánica anterior

A branch of the internal maxillary artery that irrigates the bony portion of the external ear.

Arteria auricular profunda

A branch of the internal maxillary artery that irrigates the skin of the conducto auditivo externo, the tympanic membrane, and the temporomandibular joint (ATM).

Lymphatic System of the External Ear

Lymphatic network comprising preauricular nodes, subauricular/intraparotid nodes (subauricular, anterior border of sternocleidomastoid, intraparotid), and posterior nodes (outer face of the mastoid).

Sensory Innervation of the CAE

Provided by the auriculotemporal nerve (V) for the anterior wall and tympanic membrane, the auricular branch of the vagus nerve (X) for the posterior and superior walls, and the facial nerve (VII) for the posterior and inferior walls and tympanic membrane.

Motor Innervation of the External Ear

Supplied primarily by the facial nerve (VII), which serves as the main motor nerve related to the external ear.

Embryological Development of the External Ear

Development occurring mainly during the first trimester: 1st branchial arch forms trago and root of hélix (fuses with 2nd arch at 3rd month); 2nd branchial arch forms superior/inferior hélix, antitrago, and concha (from week 3); 1st branchial cleft forms CAE (from week 4); 1st pharyngeal pouch forms Eustachian tube, tympanic cavity, attic, antrum, and mastoid cells (starts week 4 to 7th fetal month).

Oreja en asa

A malformation caused by the absence of the antihelical fold or excessive cartilage, causing the ear to protrude farther from the head; treated with otoplasty starting at $6-7$ years of age.

Macrotia

A malformation characterized by an excessively large pabellón auricular.

Microtia

A malformation characterized by an abnormally small pabellón auricular, classified into grades I through IV.

Anotia

The complete absence of the external ear and the conducto auditivo externo (CAE).

Poliotia

A malformation characterized by the presence of additional auricular appendages.

Tubérculo de Darwin

A congenital thickening located on the hélix of the ear.

Oreja de fauno

A malformation characterized by an elongated and pointed pabellón auricular.

Oreja de Wildermuth

An ear malformation involving an alteration in the relationship between the antihélix and the hélix.