part 2 muscular system

• the four functions of muscle are:

  • produce movement
  • maintain posture
  • stabilize joints
  • generate heat
• muscles produce movement through contraction
• muscles maintain posture through being upright or seated
• muscles provide stabilization through tendons on muscles stabilizing bones at joints

  • also reduces wear and tear
• muscles generate heat through the use of ATP when moving muscles
• smooth muscle

  • involuntary
  • found in organ walls
  • lacks striations
  • single nucleus
  • tapered cells
• cardiac muscle

  • involuntary
  • found in the heart
  • striations
  • single nucleus
  • intercalated discs
• skeletal muscle

  • attached by tendons to periosteum
  • multinucleated
  • striations
  • voluntary
  • cells surrounded by connective tissue
• epimysium -> perimysium -> fascicle -> muscle fiber -> endomysium
• endomysium surrounds a single muscle fiber
• fascicle is around a bundle of fibers
• perimysium surrounds a fascicle
• epimysium covers the entire skeletal muscle
• fascia is on the outside of the epimysium
• origin: where the muscle is attached to stationary bone
• belly: central fleshy part of muscle
• insertion: where the muscle is attached to the bone that moves
• tendon: tissue that attaches muscle to bone
• ligaments: tissue connecting bone to bone, made of dense regular
• prime movers: muscle whose contraction (shortening) provides the desired movement
• synergists: muscle that aids the prime mover's motion + prevents rotation
• fixators: stabilizes the origin of a prime mover
• antagonist: muscle that opposes or reverses a prime mover when activated
• joints aka articulations describe the point at which bones connect with each other
• the two function of joints are to

  • hold the bones together
  • allow for mobility
• least to most moveable

  • synarthroses -> amphiarthroses -> diarthroses
• synarthroses aka fibrous joints
• amphiarthroses aka cartilaginous joints
• diarthroses aka synovial joints
• synarthroses

  • immoveable joints
  • untied by fibrous tissue (dense irregular)
  • skull sutures
• syndesmoses describes joints held together by ligaments

  • stabilizes distal end of tibia and fibular
  • stabilizes radius and ulna
• amphiarthroses

  • slightly moveable
  • connected by cartilage
  • ribcage, pubic symphysis, spinal column, vertebrae
• diarthroses

  • freely moveable
  • separated by joint cavity
  • shoulder, neck, knee, elbow, wrist, ankle, phalanges, hip sockets, C1, C2
• articular cartilage covers the ends of bones and helps reduce friction, made of hyaline cartilage
• fibrous capsule encloses joint surfaces
• joint cavity is the space between articulating bones filled with synovial fluid
• the synovial membrane lines the joint cavity and forms the synovial fluid
• bursa: tiny, slippery sac of fluid that cushions and reduces friction between bone and soft tissues
• the bursa is lined with synovial membranes
• tendon sheathe: elongated bursa that wraps around the tendon