Skeletal and smooth muscle
Why this matters
Every restoration you place is loaded by muscle. The masseter drives 400–900 N onto a molar, a sleeping bruxer can exceed his own waking maximum, and the commonest sign of temporomandibular disorder is muscle pain, not joint pain. The same calcium machinery explains malignant hyperthermia after suxamethonium and why the vasoconstrictor in a cartridge works. Muscle physiology is chairside physiology for a dentist.
The big picture
Muscle is one machine tuned three ways. Actin and myosin slide past each other on ATP; the only question is what lets them. Skeletal muscle unblocks the thin filament with troponin under voltage control, and grades force by recruiting motor units and raising their firing rate. Smooth muscle phosphorylates myosin itself, then latches, holding tone for a fraction of the energy.
Nothing shortens — the filaments slide; skeletal calcium unblocks the track, smooth-muscle calcium switches on the motor.
The 15 cards in this lesson
- 01Nothing shortens: the filaments slide
- 02The sarcomere, labelled
- 03The cross-bridge cycle and where ATP acts
- 04From nerve impulse to calcium: the triad
- 05Calcium in, calcium out: RyR1 and SERCA
- 06The motor unit and the size principle
- 07Twitch, summation and tetanus
- 08Length, velocity and the force a muscle makes
- 09Fibre types I, IIa and IIx
- 10What actually causes fatigue
- 11Skeletal versus smooth muscle
- 12Calmodulin, MLCK and the latch state
- 13The muscles of mastication and bite force
- 14Clinical alert — in the lesson
- 15Clinical alert — in the lesson
You have got it when
You can say what does and does not shorten in a contracting sarcomere, name the protein each calcium ion binds in skeletal and in smooth muscle, and explain why a low-force clench held for an hour hurts more the next day than a maximal one. You can quote a bite-force number together with the method that produced it.
40 references, graded by tier: 21 tier-1 · 18 tier-2 · 1 tier-3 · sources last checked 2026-08-10
The full lesson entry includes
- All 15 teaching cards, each opening at Quick and expanding into Learn and Deep
- 5 final-challenge questions with worked rationales, and a micro-check on every card
- The 10-prompt recall deck, scheduled today, +1, +3, +7 and +21 days
- The misconceptions students actually hold, each with its correction
- All 40 references, tiered and annotated
More preclinical curriculum
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