Part 6/14:
Skeletal muscle contractions are neurogenic, meaning they require neural input via somatic motor neurons. These neurons originate in the motor cortex, brainstem, or spinal cord and project their axons to muscle fibers. When a motor neuron fires, it releases neurotransmitters at the neuromuscular junction, initiating an action potential that propagates along the muscle fiber, leading to contraction.
In contrast, smooth and cardiac muscles are myogenic, capable of initiating contractions independently of neural input:
Smooth muscle: Found in blood vessels and internal organs; involuntary, non-striated.
Cardiac muscle: Forms the heart; involuntary, striated, with rhythmic contractions.