i well give you my lecture and then transcript and i want you to tell me if the transcript cover my lecture .
my lecture :


---

### Motor System  
**Nervous System Block**  
**Faculty of Applied Medical Sciences**

#### Learning Objectives:
- **Discuss the concept of upper motor neurons.**
- **Differentiate between medial and lateral motor system.**
- **List the names of descending motor tracts and their effect on muscle tone.**
- **Describe the descending motor tracts (corticospinal, rubrospinal, reticulospinal, vestibulospinal, tectospinal) and discuss their possible functions.**
- **Compare and contrast UMNL and LMNL.**

---

#### Upper Motor Neurons  
(Referencing Brodmann’s cortical areas 4, 5, 6, and 7.)

**Function of Corticospinal (Pyramidal) Tract**  
- Initiates fine, discrete, skilled voluntary movements.
- **Lateral corticospinal tract**: Controls distal limbs (e.g., fingers for skilled movement).
- **Anterior corticospinal tract**: Controls posture, axial, and proximal muscle for limbs.
- **Effect on stretch reflex**: Facilitates muscle tone through gamma motor neurons.

---

#### Corticobulbar Tract
- Terminates on **lower motor neurons** (LMNs, cranial nerve motor nuclei of the opposite side).
- Decussates (crosses) just before reaching target nuclei.
- **Function**: Controls face and neck muscles, facilitates muscle tone, and is involved in facial movements, mastication, and swallowing.

---

#### Motor Cortex: Motor Homunculus  
Visual representation of motor function in the cortex for body parts.

---

#### Extrapyramidal Tract
- **Rubrospinal tract**: Accessory route for transmitting relatively discrete signals from the motor cortex to the spinal cord (lateral).
- **Vestibulospinal tract**: Controls postural and righting reflexes.
- **Reticulospinal tract**: Influences motor functions as voluntary and reflex movements, excitatory or inhibitory to muscle tone.
- **Tectospinal tract**: Mediates turning of the head in response to visual or auditory stimuli.
- **Olivospinal tract**

---

#### Red Nucleus
- Serves as an alternative pathway for transmitting cortical signals to the spinal cord.

---

#### Excitatory-Inhibitory Antagonism Between Pontine and Medullary Reticular Nuclei
- **Pontine reticular system**: Causes powerful excitation of antigravity muscles when unopposed by the medullary reticular system, allowing some animals to maintain a standing position.

---

#### Functions of the Extrapyramidal Tract
- Sets the postural background needed for skilled movements.
- Controls subconscious gross movements.

---

#### Comparison Between Upper and Lower Motor Neuron Lesions
**LMNL** (Lower Motor Neuron Lesions):
- Partial damage causes paresis (weakness).
- Paralysis: Loss of movement in affected muscles.
- **Areflexia**: Absence of spinal reflexes.
- Flaccid and soft muscles, no tone or resting tension.
- No trophic influence on muscle fibers, leading to atrophy over time.

**UMNL** (Upper Motor Neuron Lesions):
- **Spinal Shock**: Initial phase of reduced muscle tone (hypotonia), areflexia, and paralysis.
- Reflexive functions later reappear, resulting in **spasticity** (increased muscle tone and reflexes).

---

#### Pyramidal System Overview
- Originates in the **cerebral cortex** and coordinates voluntary muscle movement via the **motor cortex, basal ganglia, cerebellum, and brainstem centers**.
- Involves **descending pathways** for posture and precise control.

---

transcript :
In order for a skeletal muscle to contract, your brain sends a signal, in the form of an action potential in an upper motor neuron.

The upper motor neuron is part of the cerebral cortex, and it activates a lower motor neuron, which is located in the anterior horn of the spinal cord.

From here, the action potential is sent through an axon down to its ending branches, called axon terminals, to muscle fibers which they innervate.

The place where an axon terminal meets the muscle fiber is the neuromuscular junction.

The neuromuscular junction has three main parts: a presynaptic membrane, which is the membrane of an axon terminal; a postsynaptic membrane, which is the membrane of a skeletal muscle fiber and is also called a motor end-plate; and a synaptic cleft, which is the gap between the presynaptic and postsynaptic membrane.

When an action potential reaches the axon terminal, it stimulates voltage-gated calcium channels in the membrane to open and extracellular calcium ions flow into the lower motor neuron.

Inside the axon terminal are synaptic vesicles that contain neurotransmitters called acetylcholine.

The calcium that enters the axon terminal binds to the vesicles, which allows them to fuse with the cell membrane of the axon terminal, releasing the acetylcholine into the synaptic cleft.

The acetylcholine then diffuses over to the motor end plate on the muscle fiber - and because it’s a short distance, that diffusion happens really quickly.

Here, two acetylcholine molecules will bind to one ligand-gated ion channel, also called nicotinic receptor.

When that happens, these ligand-gated ion channels, which are selective for positively charged ions, open up.

When they open, lots of sodium ions rush into the skeletal muscle fiber, and a few potassium ions leak out of the cell.

But overall there’s an increase in positive charge on the inside of the muscle fiber and therefore on the inside of the membrane, relative to the outside of the membrane - and this is called depolarization.

This local depolarization on the postsynaptic membrane is called an end-plate potential and it makes the resting potential of the cell membrane which is usually around -100mV, more positive, or in this case, less negative.

The local depolarization causes the cell membrane’s resting potential to rise up to about -60mV, and that’s the threshold for voltage gated sodium ion channels.

So when the threshold potential is reached, lots of voltage gated sodium ion channels open up, and there’s a huge influx of sodium ions into the muscle fiber.

This leads to a generation of an action potential which rapidly spreads along the entire membrane and that gets the entire muscle fiber to contract.

When the signal sent from the lower motor neuron stops, voltage-gated calcium channels on the presynaptic membrane close and influx of calcium ions stops.

This causes synaptic vesicles full of acetylcholine to stop fusing with the membrane and instead they remain within the cytoplasm of the axon terminal.

Molecules of acetylcholine that are left behind within the synaptic cleft, are degraded by an enzyme called acetylcholinesterase into choline and acetate.

The acetate diffuses out from the synaptic cleft, while choline is taken back into the axon terminal where it’s reused by the enzyme acetylcholine transferase to make new acetylcholine molecules.

Now, each skeletal muscle fiber has only one neuromuscular junction, so that means that each muscle cell is controlled by one lower motor neuron.

However, the axon of a lower motor neuron splits into many branches and each of these branches can innervate multiple adjacent muscle fibers.

This lower motor neuron and all the muscle fibers it innervates form a single “motor unit,” and on average, one motor neuron innervates 150 skeletal muscle fibers.

The number of skeletal muscle fibers that are innervated by one motor neuron depends on the precision of the muscle they control.

For example, muscles that control precise eye movements, consist of many relatively small motor units, where every lower motor neuron innervates only 10 to 15 muscle fibers.

On the other hand, large muscles like the biceps brachii muscle found in your upper arm, can have up to 2000 muscle fibers within a single motor unit.

Summary
Alright, as a quick recap. The neuromuscular junction is a site where a motor neuron meets a skeletal muscle fiber.

When a lower motor neuron is activated, there’s an influx of calcium ions into a presynaptic membrane, followed by release of acetylcholine into the synaptic cleft.

Acetylcholine binds to nicotinic receptors, and that leads to generation of an action potential and eventual muscle contraction.