Lect 10 - Musculoskeletal System; Form And Action At Joints

Flashcards covering key concepts of the musculoskeletal system, including lever systems, muscle actions, and specific muscle functions.

In anatomical levers, what body part acts as the lever?

Bone

In anatomical levers, what acts as the pivot or fulcrum?

Joint

In anatomical levers, what provides the applied force or pull?

Muscle contraction

In anatomical levers, what creates the load?

Weight of what is being moved (external or internal)

What is the arrangement of a First-class lever?

Load → fulcrum → applied force.

What type of movement is exemplified by the neck extension at the atlanto-occipital joint, in terms of lever class?

First-class lever

What is the arrangement of a Second-class lever?

Fulcrum → load → applied force

What type of movement is exemplified by the plantar flexion at the ankle joint, in terms of lever class?

Second-class lever

What is the arrangement of a Third-class lever?

Fulcrum → applied force → load

What type of movement is exemplified by flexion at the elbow joint, in terms of lever class?

Third-class lever

How much can muscle fibers shorten relative to their resting length?

Up to 50%

What is tension proportional to in a muscle?

Cross-sectional area (CSA)

Describe the fibre arrangement in parallel muscles as well as features?

Fibers arranged vertically between muscle tendons/attachments.

smaller CSA —> less tension —> shorten more —> large ROM

Describe the fibre arrangement in pennate muscles as well as features?

Fibers arranged obliquely between muscle tendons/attachments.

greater CSA —> more tension —> shortens less —> small ROM

In what type of muscle action does the muscle shorten?

Concentric

In what type of muscle action does the muscle elongate?

Eccentric

In what type of muscle action does the muscle length remain the same?

Isometric

What role does an agonist muscle play?

Acts concentrically to create a movement at a joint

What role does an antagonist muscle play?

Acts eccentrically to oppose and control the movement

What role do stabilizer muscles play?

Holds a joint still to prevent movement

What role do neutralizer muscles play?

Eliminates an unwanted movement caused by another muscle

What type of movement do concentric action of muscles ANTERIOR to a joint facilitate?

FLEXION

What type of movement do concentric action of muscles POSTERIOR to a joint facilitate?

EXTENSION

What type of movement do concentric action of muscles MEDIAL to a joint facilitate?

ADDUCTION

What type of movement do concentric action of muscles LATERAL to a joint facilitate?

ABDUCTION

Biceps brachii: origin, insertion, movement?

• origin

  • scapula

• insertion

  • radial tuberosity

• movement

  • shoulder: flexion

  • elbow: flexion

  • radioulnar joints: supination

Triceps brachii: origin, insertion, movement?

• origin

  • scapula & humerus

• insertion

  • olecranon process of ulna

• movement

  • shoulder: extension

  • elbow: extension

Deltoid: origin, insertion, movement?

• origin

  • scapula & clavicle

• insertion

  • deltoid tuberosity

• movement

  • shoulder: extension

  • elbow: extension

Iliopsoas: origin, insertion, movement?

• origin

  • iliacus: iliac fossa

  • psoas major: lumbar vertebrae

• insertion

  • femur

• movement

  • hip: flexion

Gluteus maximus: origin, insertion, movement?

• origin

  • ilium & sacrum

• insertion

  • femur

• movement

  • hip: extension

Hamstrings: origin, insertion, movement?

• origin

  • ischium (+ femur for biceps femoris)

• insertion

  • tibia (semimembranosus and semitendinosus)

  • fibula (biceps femoris)

• movement

  • hip: extension

  • knee: flexion + rotation when knee is flexed

Quadriceps femoris: origin, insertion, movement?

• origin

  • rectus femoris: ilium

  • vastus medialis, intermedius, lateralis: femur

• insertion

  • tibial tuberosity

• movement

  • hip: flexion (rectus femoris only)

  • knee: extension

Tibialis anterior: origin, insertion, movement?

• origin

  • tibia

• insertion

  • tarsals

• movement

  • ankle: dorsiflexion

Triceps surae: origin, insertion, movement?

• origin

  • gastrocnemius: condyles of femur

  • soleus: tibia & fibula

• insertion

  • calcaneus via. calcaneal/Achilles tendon

• movement

  • knee: flexion (gastrocnemius only)

  • ankle: plantarflexion

Features of concentric muscle action?

muscle is active —> burns energy —> develops tension

tension > load

change in joint position

Features of eccentric muscle action?

muscle is active —> burns energy —> develops tension

tension < load

change in joint position

Features of isometric muscle action?

muscle is active —> burns energy —> develops tension

tension = load

no change in joint position