Blake_Anatomy_12_Biomechanics Flashcards
(22 cards)
Fascicles
Bundles of Myofibers (Muscle cells)
Myofibers
- Muscle cells containing bundles of myofibrils (end-to-end sarcomeres.)
- Enclosed by a sarcolema with superficial nuclei
Tendons
- Attach muscle to bone, skin or another muscle
- Thick, cordlike structure
- Forms a thin, flattened sheet, termed an aponeurosis
Aponeurosis
Tendons which form a thin, flattened sheet
Ligaments
bind bone to bone
Origin of a muscle
- the less movable attachement of a muscle - attached to more “fixed bone”
- Insertion is pulled toward the origin
- Typically lies proximal to the insertion
Insertion of a Muscle
- the more movable attachement of a muscle - attached to the bone that moves in response to contraction
- Insertion is pulled toward the origin
- Typically lies distally to the origin
Four types of organizational patterns in fascicles:
- Circular - also called a sphincter
- Convegent - triangular
- Parallel - parrallel to the long axis (ave a central body called the “belly” or “gaster”
- Pennate - One or more tendons extending through their body, and the fascicles are arranged at an oblique angle to the tendon
Example of Parallel, strap-like muscle
Sternocleidomastoid
Example of Parallel, fusiform muscle
Biceps brachi
Example of convergent muscle
pectoralis major
Example of Unipennate muscle
Flexor pollicis longus (anteriomedial wrist)
Example of Bipennate muscle
Rectus femoris
Example of multipennate muscle
Deltoid
Example of circular muscle
orbicularis oris
Effort in a lever system
Load or moment arm = work required
load in a lever system
load or resistance arm = what is being resisted or being moved
Fulcrum in a lever system
the point of movement
Formula for a lever system
F*FA=R*RA
3 Classes of levers
- 1st Class - fulcrum between force and resistance
- 2nd Class - resistance between force and fulcrum
- 3rd Class - force is between resistance and the fulcrum
3 types of actions of skeletal muscles
- Agonsits: prime mover, contracts to produce a movement
- Antagonists: oppose the actions of the agonist
-
Synergists:
- Assist the prime mover
- creates tension exerted close to insertion or stabilizes the point of origin
- called “fixators”
Describe the differences between male and female pelvis and it’s effect on femoral angle.
What biomechanical effect does this angle have?
The transverse diameter of the pelvic inlet is larger on women resulting in a greater femoral angle.
Women have a mechanical disadvantage in stabilizing the body during walking -> increase injury to the gluteus medius at the point of insertion.
