Sensory Systems: Vestibular System

There are 6 SSC (both ears combined). There are 3 functional units (pairs)

The SSCs (semicircular canals) in the vestibular system are most sensitive to angular acceleration and rotation. These structures are responsible for detecting changes in head position and movement, particularly rotational movements. They contain fluid-filled canals that are oriented in different planes, allowing them to detect movement in different directions. When the head rotates or experiences angular acceleration, the fluid in the canals moves, stimulating hair cells that transmit signals to the brain, enabling us to perceive and maintain balance.

-bend TOWARD kinocilium = depol
-bend AWAY FROM kinocilium= hyperpol

The vestibular system is responsible for detecting various aspects related to balance and orientation. It detects static equilibrium, which refers to the ability to maintain balance while stationary. It also detects upright posture, helping us maintain an upright position against gravity. Additionally, the vestibular system detects linear acceleration, allowing us to perceive changes in speed and direction. Therefore, the correct answer is "All of the above" as the vestibular system detects static equilibrium, upright posture, and linear acceleration.

The main purpose of the vestibular system is to provide input for body orientation and movement. This system is responsible for detecting changes in head position and movement, which helps in maintaining balance and coordinating movements of the body. It also plays a crucial role in spatial awareness and helps in adjusting body position to maintain stability.

If there is damage to the vestibulo-cerebellar reflex tract that controls eye movements, nystagmus will occur. Nystagmus is an involuntary, rhythmic oscillation of the eyes. It can manifest as repetitive horizontal, vertical, or rotary movements. Damage to the vestibulo-cerebellar reflex tract disrupts the normal coordination of eye movements, leading to the characteristic jerking or shaking of the eyes seen in nystagmus.

-tectorial membrane--> cochlea/sound
-otolithic membrane --> utricle/saccule (vestib system)
(see table pt. 109)

The statement is true because the Right Lateral SCC (semicircular canal) and the Left Lateral SCC work together to detect rotational movements of the head. These two structures are part of the vestibular system in the inner ear and are responsible for maintaining balance and equilibrium. When the head rotates, the fluid inside these canals moves, stimulating hair cells that send signals to the brain about the direction and speed of the rotation. Therefore, the Right Lateral SCC and the Left Lateral SCC function as a unit to provide accurate information about head movements.

Right Anterior and Left Posterior make one functional unit

During the beginning of a rotation, the endolymph in the SSC moves in the opposite direction as the rotation, causing excitation of the hair cells. This is because the movement of the endolymph stimulates the hair cells, leading to the transmission of signals to the brain, which is perceived as a sense of rotation or movement.

The Lateral Vestibulospinal Tract is responsible for controlling postural control. This means that it helps maintain balance and stability of the body during various movements and positions. It receives input from the vestibular system, which is involved in sensing the body's position and movement in space. By sending signals to the muscles involved in maintaining posture, the Lateral Vestibulospinal Tract helps ensure that the body stays upright and balanced.

The vestibulo-ocular reflex is responsible for producing smooth, horizontal, conjugate eye movements. These eye movements help to stabilize the visual field during head movements. The reflex utilizes the Medial Longitudinal Fasciculus (MLF), which is a pathway that connects the vestibular nuclei in the brainstem to the oculomotor nuclei. The MLF coordinates the movement of the extraocular muscles to ensure that the eyes move in a coordinated manner.

superior, lateral, inferior, medial

cupula--> angular acceleration (SSCs)
otolithic membrane --> linear acecleration (utricle/saccule)

The utricle and saccule are sensory organs in the inner ear responsible for detecting changes in head position and linear acceleration. They contain hair cells that are sensitive to the movement of otoliths, small calcium carbonate crystals. These hair cells can detect very small movements, and studies have shown that they are capable of detecting head tilts as small as 0.5 degrees. This sensitivity allows the utricle and saccule to contribute to our sense of balance and spatial orientation.

Vestibular sensation information goes to Brodmann's areas 3, 1, and 2 of the postcentral gyrus. These areas are part of the somatosensory cortex and are responsible for processing sensory information from the body, including touch, proprioception, and vestibular sensation. Vestibular sensation refers to the sense of balance and spatial orientation, which is crucial for maintaining equilibrium and coordinating movement. By sending information to these specific areas, the brain can accurately interpret and respond to vestibular input, allowing for proper balance and coordination.

The utricle is a part of the inner ear that helps detect changes in head position and movement. When the head is perfectly upright, the utricle is also perfectly upright. This means that it is aligned with the vertical axis of the body, allowing it to accurately sense changes in head position and provide the brain with information about the body's orientation in space.

Utricle and saccule have a gelatinous substance that contains CALCIUM CARBONATE CRYSTALS which adds to the weight of the subtance

The correct answer is Medial Vestibulospinal Tract. When you start dozing off in class and your head bobs down and then jerks back up, it is due to the activation of the Medial Vestibulospinal Tract. This reflex is responsible for maintaining balance and posture by controlling the muscles of the neck and trunk in response to changes in head position or movement. When you start falling asleep and your head begins to droop, the change in head position triggers the Medial Vestibulospinal Tract to activate and jerk your head back up, helping you maintain an upright posture.

Vestibular sensation is transmitted to the VPL (ventral posterior lateral) nucleus of the thalamus. The VPL nucleus is responsible for relaying sensory information from the body to the somatosensory cortex. In the case of vestibular sensation, the VPL nucleus receives signals from the vestibular nuclear complex, which is responsible for processing and integrating information related to balance and spatial orientation. From the VPL nucleus, the information is further transmitted to the somatosensory cortex, where it is perceived and interpreted.