The Muscular Sytem

Question 1

Discuss muscle fiber orientation.

Answer 1

• Parallel muscle fibers - long, have a great ROM
  4 Types
  
  1. Strap - ie. SCM, Rectus abdominis
  2. Fusiform - ie. biceps brachii
  3. Rhomboidal - ie. rhomboids
  4. Triangular - pectorals major, temporalis
• Oblique muscle fibers - shorter, numerous, great strength potential, shorter ROM
  3 Types
  
  1. Unipennate - ie. tibialis posterior
  2. Bipennate - ie. rectus femoris
  3. Multipennate - ie. deltoid

Question 2

Discuss active insufficiency.

Answer 2

• When a 2 joint muscle reaches the point where it cannot shorten any farther
• a 2 joint muscle is not able to contract over both joints at the same time throughout all available motion
• always agonist
• ie. hamstrings are less effective at hip extension when knee is bent

Question 3

Discuss passive insufficiency.

Answer 3

• Occurs when a 2 joint muscle cannot be elongated any farther without damage
• a 2 joint muscle will reach its max point of elongation prior to reaching the full ROM available at that joint
• always antagonist
• ie. hamstrings: knee extension is limited with full hop flexion

Question 4

Discuss tenodesis.

Answer 4

• opening and closing of the hand using passive insufficiency
• finger flexors and extensors are multipoint muscles
• this becomes critical to some quadriplegic patients

Question 5

Discuss types of muscle contraction.

Answer 5

Isometric contraction: force is produced, length of muscle does not change
- very safe; usually done after surgery

Isotonic contraction: (2 types)

1. Concentric Contraction
   - muscle shortens (attachments move closer together)
   - movement against gravity
   - acceleration activity
2. Eccentric Contraction
   - muscle lengtens (attachments move further apart)
   - movement with gravity
   - deceleration activity
   - tend to have more injuries associated with them

Question 6

Discuss the roles of muscles. 
Agonist
Antagonist
Co-contraction
Stabilizer

Answer 6

Agonist - causes motion, prime mover
Antagonist - performs opposite motion as agonist
Co-contraction - both contact at the same time
Stabilizer - muscle or group of muscles that work to support agonist to make it work more efficiently

Question 7

Discuss kinetic chains.

Answer 7

Closed kinetic chain (CKC)

• proximal segment moves
• distal segment fixed/stationary
• ie: squats

Open kinetic chain (OKC)

• proximal segment fixed/stationary
• distal segment moves
• ie: bicep curl, bench press