Lecture 10 Flashcards
What is the difference between the extrafusal muscle fibers and intrafusal muscle fibers and what neurons contract them?
- Extrasusal muscle fibers are for moving the muscles and they are activated by Alpha Motor Neurons
- Intrafusal Muscle fibers are for detecting muscle length and are contracted by the Gamma Neurons to adjust sensitivity for precise movements.
What are intrafusal muscle fibers (together with the sensory neurons) also called and what two types are there?
- They are also called muscle spindles because the sensory neurons wrap around the muscle fibers
- MS1 is for detecting muscle length
- MS2 is for detecting changes is muscle length
What two kinds of sensory neurons are there on the muscle fibers.
- Golgi Tendon organs are on the extrafusal muscle fiber for detecting the force/stretch they give.
- Sensory afferent neurons are wrapped around the intrafusal muscles to detect muscle length
What is proprioception?
It is the sense of information about the location of your body parts
Where is the neuromuscular junction located. What neurotransmitter is involved
It is the synapse between motor neurons and muscle fibers.
Acetylcholine is involved
What are myofibril and what two parts are there to it?
- Myofibril are segments that make up the muscle fiber.
- They consist of Actin and Myosin
In what steps does actin and myosin create muscle movement and with what neurotransmitter.
- Acetylcholine activates the process
1. Myosin (arm) attaches to Actin (wall)
2. Myosin then falls foreward
3. Then Myosin lets loose and is in rest condition at a further point along the actin
4. Then they attach again.
How does reflexive muscle contraction happen when a weight is dropped in your hand or when you are balancing? (3 steps)
- Muscle spindles detect increased muscle length
- They give this information via the dorsal rout ganglions at the spinal cord
- Alpha Motor Neurons receive this information monosynaptically and contract the muscle
How does the Golgi tendon organ protect you from damaging the muscle? (2 steps)
- The Golgi Tendon organs perceives too much stress on the muscle
- It then inhibits the motor neurons from firing so no contraction happens
What are the three parts of the motor cortex? And what is the motor homunculus
- Primary motor cortex,
- The motor homunculus shows the representation of each body part in the primary motor cortex.
Association cortex:
- Premotor cortex
- Supplementary Motor Area (SMA)
What are the two groups of cortical spinal tracts and what is their function
- The lateral group is for independent movements of individual (asymmetrical) limbs.
- The Ventromedial groups is for body posture
- Both have several tracts
What are the 2/4 functions of the cerebellum in movement
- Orientation
- Body posture
- Timing
- Balance
What is the Lateral system of the cerebellum for and in what two steps does it do this? What is the ventromedial system important for
- Lateral system is important for controlling independent movements to make them smoother
1. The cerebellum receives a planned movement from the primary motor cortex through the pontine nucleus
2. It then decides what muscles to use and for how long and sends the information back via the thalamus to the primary motor cortex and red nucleus - Ventromedial system is important for orientation and body posture.
What are agonist and antagonist muscles? And what happens when there is damage to cerebellum?
- Agonist muscles are for moving your limb to an intended location
- Antagonist muscles are for the opposite action to stop at the right place and time. (so you don’t overshoot.
- Damage to the cerebellum leads to overshooting and then overcompensating.
What is the SMA supplementary Motor Area important for? What do individual neurons do and when are they active?
- It is important for planning sequences of movements like when you push and then pull a lever
- Individual neurons plan for a specific sequence. It is active BEFORE the action
