Organ of Corti – Anatomy, Structure and Clinical Relevance

Organ of Corti – Anatomy, Structure and Clinical Relevance

In this post, we’ll explore the Organ of Corti, the sensory organ of hearing.

📍 Location and General Structure

• The Organ of Corti is located on top of the basilar membrane within the scala media of the cochlea.
• The basilar membrane forms the floor of the scala media and separates it from the scala tympani.
• The basilar membrane and Organ of Corti increase in width and thickness from the base to the apex of the cochlea.

🧱 1. Basilar Membrane

• It is a sheet of extracellular matrix composed of:

  • Collagen (type IV – α1 to α5 chains)
  • Fibronectin
  • Laminin type 11

• Underside of the basilar membrane faces the perilymph of scala tympani and is lined by tympanic border cells.

🧱 2. Tectorial Membrane

• Overlies the Organ of Corti.

• Attached medially to the interdental cells of the spiral limbus.

• Not attached laterally to the organ of Corti.

• Composed of:

  • Collagen types II, V, and IX
  • Autogelin, α and β tectorin
  • CEACAM16

• Contains:

  • Henson’s stripe on its underside
  • Covenant fiber network on its upper surface

• Formed only during cochlear development and cannot regenerate – damage leads to permanent hearing loss.

🎧 3. Cochlear Hair Cells

• Convert sound energy into electrical impulses.
• Two types:
  • Inner Hair Cells (IHC) – ~3,500 cells in 1 row
  • Outer Hair Cells (OHC) – ~12,000 cells in 3–4 rows

What are the Differences Between Inner and Outer Hair Cells?

• Afferent fibers mostly innervate inner hair cells (95%).
• Efferent fibers originate from the olivocochlear bundle in the superior olivary complex.

🧱 4. Supporting Cells

🔹 Deiters’ Cells

• Intercalated between outer hair cells.

• Provide mechanical support and rest on the basilar membrane.

🔹 Pillar Cells

• Inner and outer pillar cells separate IHCs and OHCs.

• Form the tunnel of Corti, filled with cortilymph.

🔹 Hensen’s Cells

• Located lateral to Deiters’ cells.

• Contain lipid droplets, may add mass.

🔹 Claudius and Boettcher Cells

• Located on the outer skirt of the Organ of Corti.

• Functions:

  • Mechanical support
  • Add mass
  • Cochlear homeostasis – remove extracellular K⁺ via gap junctions

What is Stria Vascularis?

📌 Summary

• The Organ of Corti is essential for hearing and consists of basilar and tectorial membranes, inner and outer hair cells, and supporting cells.
• Inner hair cells are crucial for sound transmission, while outer hair cells help in modulating the function of IHCs.
• Tectorial membrane damage causes irreversible hearing loss.
• Supporting cells play both structural and metabolic roles in cochlear function.