A link between the skeletal system and the muscular system are tendons, which connect bones to muscles.
A link between the skeletal system and the nervous system is how the vertebrae are linked to the nerves in the spinal cord.
A link between the muscular system and the nervous system is how muscles respond when nerves signal them to after responding to the stimulus and traveling to the brain and back.
It may be either Disagreements or Intractable Situations. I'm not completely sure, sorry. I'd wait for another to come answer your question just to be safe.
Under the foreskin of an uncircumcised penis.
