Soleus vs EDL Muscle Fatigue

• The soleus tetanus peaks are fused because they do not completely relax before peaking again.
• Fused tetanus peaks are caused by calcium ions remaining inside the fibers of the soleus.
• The EDL (Extensor Digitorum Longus) is faster at getting rid of the calcium ions, preventing tetanus at low stimulation frequencies.

Reason for EDL fatigue

• The EDL fatigues more quickly than the soleus.
• Reason: The EDL uses mostly anaerobic metabolism, while the soleus uses mostly aerobic metabolism.
• The EDL uses anaerobic metabolism to achieve faster speeds.

Characteristics of Skeletal Muscle Cells

• Skeletal muscle cells are attached to bones and are responsible for voluntary movement.
• Skeletal muscles facilitate rapid and strong contractions.
• Contractions are controlled by somatic nervous system

Muscle Origin Point

• The origin point of a muscle is usually located at the immovable or less movable bone or tissue.
• Origin is the muscle's anchor.
• When the muscle contracts, it pulls the insertion point on the movable bone closer to the origin point.

Muscle Movement

• Skeletal muscles cause movement through contraction.
• Through contraction, skeletal muscles pull bones and soft tissues closer together or further away.
• Muscles attach to different locations and work together to create complex movements.

Muscle Insertion Points

• Skeletal muscles can have more than one insertion point.
• Additional insertion points enhance the muscle's force or cause movement in multiple bones or tissues.

Activities Using Skeletal Muscles

• Skeletal muscles are used during sports, singing, and even sleeping on surfaces that do not support the spine, like wet sand.

Synergist Muscles

• Synergist muscles stabilize the action of the prime mover by preventing shifts at intermediate joints.
• Specialized synergists that stabilize the origin are called fixators.

Elbow Flexion Fixator

• The deltoid muscle involved in elbow flexion acts as a fixator.
• The deltoid stabilizes the origin of the biceps brachii, allowing for stable flexion movement.