The Auricle

An organ situated bilaterally on the Human Cranium, at the same level as the Nose, bordering the Face and the Head. It is the motherboard for Somatic Balance and Hearing and consists of the Outer, Middle and Inner Ear. Innervated by the Vestibulocochlear Nerve, number eight of the twelve Cranial Nerves, as well as smaller branches from other Nerves, this mixture of Bones, Nerves, Vessels, Membranes, Skin and Muscles is essential for the everyday function of one of the five Human Senses.

The Outer Ear

A Cartilaginous structure that is covered with Skin and lightly vascularized. It consists of the following convexities, concavities and folds (in a clockwise direction):

  • Tragus
  • Intertragic Notch
  • Antitragus
  • Auricular Lobule
  • Auricular Concha
  • Antihelix
  • Auricular Tubercle
  • Antihelical Crura
  • Scaphoid Fossa
  • Helix
  • Triangular Fossa
  • Helical Crux

Within these structures lies the orifice known as the External Acoustic Meatus. This is the entrance to the Middle and Inner Ear.

The Middle Ear

The Tympanic membrane is the border between the External Acoustic meatus of the Outer Ear and the Middle Ear. Just behind it sit the three Auricular Bones known as the Incus, Malleus and Stapes. They articulate upon each other and the Malleus balances upon the tympanic membrane, transmitting sound vibration from the Outer to the Inner Ear. The membrane is thin and when looking at it directly the Malleus and the articulating Incus can be seen. The Incus connects the Malleus and the Stapes, which articulates directly with the Fossa Ovale or the Vestibular Window as it is known. This is the doorway to the Inner Ear.

The Inner Ear

In the most Inner cavity of the Auricle, runs the Facial and Vestibulocochlear Nerves, Cranial Nerves VII and VIII respectively. Just below these Nervous structures lies the Auricular Vestibule made up of the Semicircular Canals and the Cochlea, which consists of the Scala Tympani, the Cochlear Duct and the Scala Vestibuli. It is here that the fibers of the Vestibulocochlear nerve separate, to innervate both the Auricular Vestibule and the Cochlear individually.

Within the Cochlea are tiny hollow canals which are split into three parts, as mentioned above. Within the Cochlear Duct is an arrangement of Hair cells, that vibrate in correlation to sound and transmit the information to the following Tract:

  • Hair Cells of the Cochlear Duct in the Cochlea of the Inner Ear
  • Nerve Terminals of the Cochlear Part of the Vestibulocochlear Nerve (CN VIII)
  • Spiral Ganglia
  • Ventral and Dorsal Cochlear Nuclei in the Spinal Cord
  • Lateral Lemniscus
  • Nucleus of the Lateral Lemniscus
  • Inferior Colliculus
  • Medial Geniculate Body
  • Auditory Radiations in the Temporal Lobe
  • Acoustic Area of the Cortex - Auditory Cortex

Studying the Ear can be a challenge, but nowadays the many creative ideas and techniques that are accessible at our fingertips, allow the anatomy student to find the perfect method that will provide knowledge and understanding for him or her.

Amplifon provides an interactive anatomical illustration of the Auricle with information bubbles and a comprehensive guide of the mechanism and path of sound through the apparatus.

In conjunction with kenHub, this makes learning Anatomy in it’s entirety become easy!

Reference: Frank H. Netter, Atlas of Human Anatomy, 4th Edition, Saunders, Chapter 1, Plates 92-98

Author: Dr. Alexandra Sieroslawska

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