Anatomy · MU Sofia

Bones and Muscles · 32. Structure of muscles (body). Structure of fasciae, tendons, sesamoid bones, synovial sheaths and

Covers the three muscle types (skeletal, cardiac and smooth) and the sarcomere as the functional unit, then lists the auxiliary structures: tendons, aponeuroses, fasciae, bursae and ligaments. Describes tendon structure and ends with a step-by-step sequence of muscle contraction and relaxation, from the nerve signal through calcium release to the sliding of actin filaments.

Inside: 4 sections · 3 labelled pictures · 11 flashcards · 1 min

Topic 32 of 264 in the MU Sofia syllabus for Anatomy (Dental Medicine, Year 2). The free AceMed note covers it in 4 sections, about 202 words (1 min of reading), with 11 flashcards.

In this note

  1. MUSCLES & TENDONS
  2. Structure:
  3. Auxiliary structures:
  4. Tendons structure:

MUSCLES & TENDONS

  • Muscles can be categorised into 3 types: Skeletal, cardiac and smooth

Structure:

Sarcomere "the functional unit"

Auxiliary structures:

Auxiliary structures of muscles are the supportive tissues & organs that assist in the function and movement of muscles.

  1. 1. Tendons
  2. 2. Aponeuroses: Flat tendons that attach muscles to other muscles or to bones.
  3. 3. Fascia: Connective tissue that surrounds muscles blood vessels & nerves.
  4. 4. Bursae: Small fluid-filled sacs located between tendons and bone or between muscles and skin.
  5. 5. Ligaments: connect bone to bone.

Tendons structure:

Tendons are dense connective tissue that attach muscles to bones, providing stability and transmitting the force generated by muscle contraction to produce movement.

  • Muscle contraction is initiated by the signal from CNS
  • Release of acetylcholine at the neuromuscular junction
  • Causes action potential in muscle fibre
  • Triggers the release of calcium ions from sarcoplasmic reticulum
  • Calcium ions combine with troponin and tropomyosin uncovers the binding sites on actin and initiates contraction
  • Myosin binding sites on actin exposed. Myosin head binds to actin
  • Myosin head executes power stroke
  • Actin filament slides towards the centre of sarcomere (contraction)
  • Signal from CNS stops; calcium ions are pumped back into the sarcoplasmic reticulum
  • Tropomyosin masks the binding sites. Filaments pulled back to the original position (relaxation)

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