Skeletal Muscles

Skeletal muscle fibers

are innervated by large, myelinated nerve fibers that originate from large motoneurons in the anterior horns of the spinal cord.

Anterior horns of the spinal cord

Skeletal muscle fibers are innervated by large, myelinated nerve fibers that originate from large motoneurons

Neuromuscular junction

The chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction

Motor End Plate

neuromuscular junction from a large, myelinated nerve fiber to a skeletal muscle fiber. Covered by Schwann cells

Synaptic Gutter

invaginated membrane between a single axon terminal and the muscle fiber membrane

Synaptic space/Synaptic Cleft

space between the terminal and the fiber membrane

Subneural Cleft

bottom of the gutter are numerous smaller folds of the muscle membrane

Subneural cleft

greatly increase the surface area at which the synaptic transmitter can act.

Synaptic Vesicles

Contains the Ach

Acetylcholine

neurotransmitter that excites the muscle membrane

Acetylcholinesterase

enzyme that breaks down Ach found in the synaptic cleft

Acetylcholine

The short time that the acetylcholine remains in the synaptic space—a few milliseconds at most— normally is sufficient to excite the muscle fiber. Then the rapid removal of the acetylcholine prevents continued muscle re-excitation after the muscle fiber has recovered from its initial action potential.

Cholinomimetic

Stimulate the Muscle Fiber by Acetylcholine-Like Action.

Curariform

A group of drugs can prevent passage of impulses from the nerve ending into the muscle

Curare

a drug that blocks the gating action of acetylcholine on the acetylcholine channels by competing for the acetylcholine receptor sites.

Botulinum

a bacterial poison that decreases the quantity of acetylcholine release by the nerve terminals.