Muscles & Levers Flashcards
What are the seven shapes of skeletal muscles?
- Circular
- Convergent
- Parallel
- Fusiform
- Pennate
- Unipennate
- Multipennate
Examples include:
- Circular: Orbicularis oris
- Convergent: Pectoralis major
- Parallel: Sartorius
- Fusiform: Biceps brachii
- Pennate: Deltoid
- Unipennate: Extensor digitorum
- Multipennate: Rectus femoris
Define muscle compartment.
A muscle compartment is a group of muscles surrounded by fascia that share a common function.
Muscle compartments help organize muscles in the limbs.
Define fascia.
Fascia is a connective tissue that surrounds muscles, groups of muscles, and organs.
It provides support and structure.
Define intermuscular septum.
An intermuscular septum is a fibrous connective tissue that separates different muscle compartments.
It helps to compartmentalize muscles.
What is the difference between direct and indirect muscle attachments?
Direct attachment: Muscle fibers attach directly to the bone.
Indirect attachment: Muscle fibers connect to a tendon that attaches to the bone.
Examples:
- Direct: Brachialis
- Indirect: Biceps brachii
Define aponeurosis.
Aponeurosis is a flat, sheet-like tendon that connects muscles to the parts they move.
Example: The abdominal aponeurosis.
Define retinaculum.
Retinaculum is a band of tissue that holds tendons in place at the wrist or ankle.
Example: Flexor retinaculum.
Define prime mover (agonist).
The prime mover (agonist) is the muscle that provides the primary force for a specific movement.
Example: The biceps brachii during elbow flexion.
Define synergist.
A synergist is a muscle that assists the prime mover in performing a movement.
Example: Brachialis during elbow flexion.
Define antagonist.
An antagonist is a muscle that opposes the action of the prime mover.
Example: Triceps brachii during elbow flexion.
How are skeletal muscles named?
Skeletal muscles are named based on factors such as location, size, shape, direction of fibers, number of origins, and action.
Examples:
- Location: Rectus femoris
- Size: Gluteus maximus
- Shape: Deltoid
- Direction: Transversus abdominis.
How do muscles and bones connect to form lever systems?
Muscles attach to bones via tendons, and when muscles contract, they pull on the bones, creating movement around a joint.
This system allows for various types of movements.
What is the difference between speed levers and power levers?
Speed levers allow for greater speed of movement; power levers allow for greater force.
Most skeletal muscles are part of speed lever systems because they prioritize quick movements.
Example of speed lever: Bicep curl; example of power lever: Heavy lifting.
Explain the difference between 1st, 2nd, and 3rd degree levers.
1st degree: Fulcrum in the middle (e.g., neck extension).
2nd degree: Load in the middle (e.g., standing on tiptoes).
3rd degree: Effort in the middle (e.g., bicep curl).
3rd degree levers are most common in the human body due to the arrangement of muscles and joints.
This commonality allows for a wide range of motion.
