I need help understanding muscle insertions and originates. I know originate mee

Question

I need help understanding muscle insertions and originates. I know originate meens muscle doesnt move and insertion does move, but i cannot quite connect the dots

in example:

Sartorius muscle of the thigh/pelvis

1) originates: on and below anterior superior spine of ilium. - what does this actually meen?

2) inserts: on the medial aspect of tibial tuberosity. - what does this actually meen?

3) innervated: by femoral nerve - what does this actually meen? (something to do with the nervous system and or pre/post ganglion fibers or something?

4) not anatomy related - I have 20 questions per month. if i post a question that contains 5 questions, does that count as 5 questions or 1?

Explanation / Answer

1) The origin of muscle means the attachment site that doesn't move during contraction, while insertion of muscle is the attachment site that does move during the muscle contract.

Innervation: Each skeletal muscle fibre is stimulated to contract by chemical (acetylcholine) released by certain nerve terminal (motor neuron- carry impulses from central nervous system to effector tissue "muscle"). The supply of muscle by this neuron to stimulate is innervation.

The example given by you:

Sartorius muscle

Origin: Anterior superior iliac spine on lateral edge of hip bone

Insertion: medial aspect of tibial tuberosity

Action: at the knee joint sartorius helps to flex the leg. It flex, abduct, and lateral rotation of thigh with assistance of other muscles. Sartorius pulls foot and angle towards knee of opposit leg.

By this action we can see the hip bone (origin) is stable while thigh and lower leg (insertion) is moving by the action of muscle.

Femoral nerve stimulate the muscle to contract and relax.

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