The structures involved in equilibrium are located in the inner ear. There are two types of equilibrium - static and dynamic. Static equilibrium occurs when the body is motionless or moving in a straight line, and involves the utricle, saccule, and otolith membranes. Dynamic equilibrium occurs during rotational movement and involves the three semicircular canals and their associated ampullae and cupulae. Both static and dynamic equilibrium allow the detection of head position and movement via hair cells that detect fluid motion and send nerve impulses.

1. Sense of Equilibrium (pg 8)

2. Sense of Equilibrium (pg 8)
• Allows you to balance

3. Sense of Equilibrium (pg 8)
• Allows you to balance
• Structures involved in equilibrium are located
in the inner ear

4. Sense of Equilibrium (pg 8)
• Allows you to balance
• Structures involved in equilibrium are located
in the inner ear
• 2 types: Dynamic and static

5. Static equilibrium
• Occurs when body is motionless or moving in
a straight line

6. Static equilibrium
• Occurs when body is motionless or moving in
a straight line
• The vestibule contains two saclike structures,
the utricle and the saccule. Each contains a
small structure called a macula

7. Static equilibrium
• Occurs when body is motionless or moving in
a straight line
• The vestibule contains two saclike structures,
the utricle and the saccule. Each contains a
small structure called a macula
• The macula contains hair cells that protrude
into the jelly-like otolithic membrane. A dense
layer of calcium carbonite crystals, called
otoliths, cover the surface of the membrane

8. Static equilibrium
• Occurs when body is motionless or moving in
a straight line
• The vestibule contains two saclike structures,
the utricle and the saccule. Each contains a
small structure called a macula
• The macula contains hair cells that protrude
into the jelly-like otolithic membrane. A dense
layer of calcium carbonite crystals, called
otoliths, cover the surface of the membrane
• When you tilt your head forward, gravity pulls
the otoliths and membrane down, which bend
the hair cells and stimulates nerve impulses

9. Dynamic equilibrium
• Occurs when the body is moving in a
rotational or angular direction

10. Dynamic equilibrium
• Occurs when the body is moving in a
rotational or angular direction
• 3 Semicircular canals, each at right angles to
each other. Contain fluid called endolymph

11. Dynamic equilibrium
• Occurs when the body is moving in a
rotational or angular direction
• 3 Semicircular canals, each at right angles to
each other. Contain fluid called endolymph
• At the base of each canal is swelling called an
ampulla

12. Dynamic equilibrium
• Occurs when the body is moving in a
rotational or angular direction
• 3 Semicircular canals, each at right angles to
each other. Contain fluid called endolymph
• At the base of each canal is swelling called an
ampulla
• Ampulla contains the cristaampullaris, which
consists of hair cells covered by a dome-
shaped gelatinous mass called the cupula

13. Dynamic equilibrium
• Occurs when the body is moving in a rotational or
angular direction
• 3 Semicircular canals, each at right angles to each
other. Contain fluid called endolymph
• At the base of each canal is swelling called an
ampulla
• Ampulla contains the cristaampullaris, which
consists of hair cells covered by a dome-shaped
gelatinous mass called the cupula
• When the head turns, the semicircular canals
move with it, but the endolymph lags behind due
to inertia. The fluid pushes against the cupula and
tilts it to one side. This causes the hairs to
bend, sending nerve impulses