Exploring the Labyrinth 1772 – The Ear's Complex Maze

Anatomist David Bainbridge: "The first person to find his way through this labyrinth was an Italian named Antonio Scarpa—an arrogant, sarcastic, domineering, rude, vengeful artist, anatomist, and genius."

The Italian anatomist qualified as a physician at just 18 and later headed the anatomy department at the University of Pavia for more than 50 years. Today, he is best remembered for his 1772 publication describing detailed dissections of the labyrinth-like structure of the inner ear. The fluid within this intricate maze of the ear is known in his honor as "Scarpa's fluid".

After Scarpa's death, his assistant severed his skull and put it on display. Scarpa's skull is still exhibited in the university museum today.

The ear can be divided into three parts: the outer ear, middle ear, and inner ear. The outer ear includes the pinna and earlobe. The middle ear is air-filled and consists of the eardrum (tympanum) and three small bones called ossicles: the hammer, anvil, and stirrup. The inner ear contains the organs needed for balance and hearing. It includes a series of fluid-filled bony and membranous tubes. This complex bony labyrinth has three parts:

1. the spiral cochlea, which contains hair cells that vibrate and transmit sounds to the auditory nerve;
2. the semicircular canals, which help with balance; and 
3. the vestibule, which connects the cochlea and semicircular canals and contains additional structures that help with balance.

The term vestibular system includes the semicircular canals and the vestibule. Movement of the fluid in the three semicircular canals in each ear corresponds to movements of the head, and hair cells convert this movement into nerve signals.

The otolithic organs in the vestibule help detect acceleration during body movements. As the body moves, calcium carbonate crystals in these organs deflect in response to acceleration, moving hair cells and generating sensory signals. In a normal cochlea, high frequencies cause vibrations near the beginning of the spiral coil, while low frequencies stimulate the far end of the cochlea. Labyrinthitis (inflammation of the labyrinth) can cause dizziness and nausea.

Description of the Article Image: A section of the inner ear, consisting of the spiral cochlea, semicircular canals, and interconnected tubes forming three loops.

Historical Figures Mentioned in This Article: Antonio Scarpa (1752–1832)

• Previous topic: Cerebrospinal Fluid 1764 – A Clear, Colorless Fluid
• Next topic: Hunter's Anatomy of the Pregnant Uterus 1774