Draw a well labelled diagram of the membranous labyrinth found in the inner ear.
Topic: Membranous labyrinth — diagram
Answer
Your diagram must show: • the COCHLEA — the coiled, snail-shaped structure • THREE SEMICIRCULAR CANALS, drawn in three planes at right angles, each with a swollen AMPULLA at its base • the UTRICULUS and SACCULUS — the two sacs of the vestibule, between the canals and the cochlea • the OVAL WINDOW and ROUND WINDOW • the AUDITORY NERVE leaving from the cochlea
Labels required: cochlea, semicircular canals, ampulla, utriculus, sacculus, oval window, round window, auditory nerve.
THE THREE SEMICIRCULAR CANALS MUST BE DRAWN IN THREE DIFFERENT PLANES, at right angles to one another. That is not decoration — it is precisely what allows them to detect movement in ALL THREE DIMENSIONS. Drawing them side by side in one plane misses the point of the structure.
THE DIVISION OF LABOUR the diagram shows: COCHLEA — HEARING (it contains the organ of Corti) SEMICIRCULAR CANALS — DYNAMIC balance, the body in motion UTRICULUS and SACCULUS — STATIC balance, the body at rest
So the inner ear does TWO unrelated jobs, and the diagram makes that visible.
The whole membranous labyrinth is filled with ENDOLYMPH and surrounded by PERILYMPH — endo meaning within, peri meaning around.