Chapter 10 Exam Review Questions

Define lever, effort, load and fulcrum in relation to muscle mechanics.

*Lever*: rigid bar (bone) that moves on a fixed point called *fulcrum* (joint). *Effort*: force (supplied by muscle contraction) applied to lever to move resistance (load) *Load*: resistance (bone+tissues+any added weight) moved by the effort

Define origin, insertion and belly of a muscle.

*Origin*- bony attachment at stationary end of muscle *Belly*- thicker, middle region of muscle between origin and insertion *Insertion*- bony attachment to mobile end of muscle

Name the common patterns of muscle fascicle arrangement and give an example of each.

1. *Circular muscles*: Ex: orbicularis oculi, urethral and anal sphincters 2. *Convergent muscles*: fan-shaped, broad at origin and tapering to a narrower insertion. Ex: pectoralis major, temporalis 3. *Parallel Muscles*: can span longer distances that other shapes. Ex: rectus abdominis, zygomaticus major 4. *Fusiform muscles*: thick in middle and tapered at ends Ex: biceps brachii, gastronemius 5. *Pennate muscles*- short facicles attach obliquely to central tendon running length of muscle. Ex: unipennate: (palmar interosseus, extensor digitorum longus) bipennate: (rectus femoris) multipennate: (deltoid)

List the criteria used in naming muscles. Provide an example to illustrate the use of each criterion.

1. *Muscle Location*: bone or bony region associated with the muscle. Ex: temporalis (over temporal bone) 2. *Muscle Shape*: Ex: deltoid muscle (triangle) 3. *Muscle Size*: Ex: maximus (largest), minimus (smallest), longus (long) 4. *Direction of Muscle fibers or fascicles*: Ex: rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis) 5. *Number of origins*: Ex: biceps (2 origins), and triceps (3 origins) 6. *Location of attachments*: Ex: Named according to point of origin or insertion 7. *Muscle action*: named for action they produce. Ex: flexor or extensor 8. *Several criteria can be combined*: Ex: extensor carpi radialis longus

Describe the function of prime movers, antagonists, synergists, and fixators.

1. Prime Movers- major responsibility for producing specific movement 2. Antagonist- opposes or reverses particular movement. 3. Synergist- helps prime movers, adds extra force to same movement 4. Fixators- synergist that immobilizes bone or muscle's origin- gives prime mover stable base on which to act *Examples*- 1. prime mover- brachialis 2. synergist- biceps brachii 3. antagonist- triceps brachii 4. fixator- rhomboids