proprioception

What is proprioception?

Proprioception is the perception of body positions and movement, essential for coordinating movement.

What are proprioceptive receptors?

Proprioceptive receptors are specialized sensory receptors that work to control pairs of muscles. The two main types are Golgi tendon organs and muscle spindles.

What is the primary function of Golgi Tendon Organs?

Golgi Tendon Organs monitor muscle tension and force. They have a relaxing effect on muscles.

What is the primary function of Muscle Spindles?

Muscle spindles respond to and monitor muscle stretch and length. They cause muscles to flex.

How do primary and secondary fibers from proprioceptors transmit information?

Primary and secondary fibers travel via the dorsal root and can form synapses at the spinal cord, taking proprioceptive information to the Central Nervous System.

Describe the Golgi Tendon Reflex.

The Golgi Tendon Reflex senses excessive tension in a muscle. It sends a signal to the CNS via afferent neurons to the spinal cord, causing the muscle to relax through an inhibitory signal, thereby preventing muscle damage.

What is the Muscle Spindle - Stretch Reflex Circuit?

The Muscle Spindle - Stretch Reflex Circuit is a reflex that causes muscle contraction in response to the muscle being stretched.

Outline the steps of the Muscle Spindle - Stretch Reflex Circuit when a muscle is stretched (e.g., weight on hand).

1. Muscle perceives stretch.

2. An A fiber attached to the muscle spindle is activated, which then activates a monopolar sensory neuron.

3. The sensory neuron projects to the spinal cord at the dorsal root.

4. At the dorsal horn, the sensory neuron synapses with an alpha motor neuron, which innervates the stretched muscle (excitatory response).

5. There is also a synapse with an inhibitory interneuron that sends a signal to inhibit the antagonist muscle (e.g., triceps).

6. The signal travels down the motor neuron, releasing ACh at the bicep muscle's NMJ, leading to contraction (excitatory signal), while the tricep muscle receives an inhibitory signal suppressing its contraction.

Which cranial nerves control bilateral movement?

Oculomotor, Trochlear, Abducens (for eye movement), those for jaw muscles, throat muscles, Vagus nerve, and Spinal accessory (for neck muscles).

Which cranial nerves control contralateral movement?

Cranial nerves controlling facial muscles and the Hypoglossal nerve (for tongue movement).

What are the functions of the ventral and dorsal roots of spinal nerves?

Ventral roots are motor, and dorsal roots are sensory.

Where do synapses occur in spinal nerve pathways?

Synapses happen in the grey matter of the spinal cord.

What is the Pyramidal System responsible for?

The Pyramidal System is responsible for the voluntary control of muscles in the body and face.

Describe the pathway of fibers in the Pyramidal System.

Fibers originate in the cerebral cortex, travel down the pyramids of the medulla, and cross the midline in the lower medulla. For example, the pyramidal tract from the right hemisphere crosses to innervate the left spinal cord.

What is the consequence of damage to the primary motor cortex (M1)?

Damage to the M1 causes partial paralysis to the contralateral side of the body.

Where do axons of the pyramidal tract originate?

Axons of the pyramidal tract originate from neurons in the primary motor cortex (M1).

What anatomical structure is associated with the primary motor cortex (M1)?

M1 consists of the precentral gyrus, located anterior to the central sulcus.

What is the function of the Supplementary Motor Area (SMA)?

The Supplementary Motor Area is involved in planning internally generated movements and the mental rehearsal of complex movement sequences.

What is the function of the Premotor Cortex?

The Premotor Cortex directs movement in response to external cues.

What are the two tracts making up the Pyramidal System and what do they control?

1. Corticospinal tract: Controls body movement.

2. Corticobulbar tract: Controls head and neck movement.