2. muscular system Flashcards
muscular system
- refers to skeletal muscle system
- primarily attached to bone
- produce movement by contracting - byproduct = heat
skeletal muscle
- cells called fibres
- fascicle = group fibres
- whole muscle = group of fascicles
CT components of skeletal muscle
- fascia = CT
- tendons and aponeuroses
fascia = CT
epimysium - surrounds entire muscle
perimysium - surrounds fascicles
endomysium - surrounds each muscle fiber
tendons and aponeuroses
- extensions of epi, peri, and endomysium
- anchors to bone (periosteum), cartilage, skin, or fascia
- tendon=rope-like
eg. achilles tendon - aponeurosis=sheet like
eg. galea aponeurotica-epicranial aponeurosis
skeletal muscle fiber structure
large multinucleate cells parts: sarcolemma sarcoplasm myofibrils T-tubules sarcoplasmic reticulum
sarcolemma
cell membrane
sarcoplasm
cytoplasm
myofibrils
(intracellular structures)
- within each fibre there are several hundreds to thousands
- composed of sarcomeres
sarcomere structure
composed of proteins
-made of 2 types of myofilaments:
thin and thick
thin filaments
composed of:
- actin-functions in contraction
- tropomyosin
- troponin- regulate contraction (regulatory proteins)
thick filaments
composed of:
-myosin-functions in contraction
attached to Z discs by titin
has rod-like tail with 2 globular heads
*head extends toward actin and attaches to it -forming a cross bridge
*the myofilaments create dark and light bands (striations) of the sarcomere
*sarcomeres join end to end (at Z discs) to form myofibrils
thick filaments banding pattern:
A band H zone I band Z discs M line
A band
dark=length of thick filament - myosin and actin (with troponin and tropomyosin)
H zone
lighter band at centre of A band- myosin only
I band
light-actin (with troponin and tropomyosin) and titin
Z discs
in center of I band
- actin and titin attach
- connect sarcomeres: between 2 z-discs = 1 sarcomere
M line
where myosin tails (thick myofilaments) attach to each other (center of sarcomere)
T-tubules
- continuations of sarcolemma that extend deep into fibre (cell)
- directly encircle myofilaments of myofibrils at junction of A and I bands (2/sarcomere)
sarcoplasmic reticulum
smooth ER
-triad - 2 enlarged areas of SR (terminal cisternae) and T-tubule
how muscles produce movement
- pulling on bones when they contract
- using group action
- lever systems
pulling on bones when they contract
- origin=attachment of tendon to stationary bone
- insertion=attachment of tendon to movable bone
using group action
- agonist=major muscle producing the movement
- synergists=help the agonist action and prevent undesirable motions caused by the agonist
- antagonist=produces opposite action of agonist (contraction inhibited when agonist contracts)
lever systems
-bone/muscle interaction at a joint
*parts:
-levers=bone
-fulcrum=joint
*effort must be great than resistance to get movement
page 3 has examples
naming of skeletal muscles
- action they perform (in anatomical position)
- shape of muscle
- origin and insertion
- location
- relative-size
- direction of fibres
- number of origins
action they perform (in anatomical position)
a. flexors
- decrease angle b/w 2 bones
eg. biceps brachii
b. extensors
- increase angle (back to anatomical position after flexion)
eg. triceps brachii
c. abductors
- move limb away from midline
d. adductors
- move limb toward midline
shape of muscle
eg. deltoid
- triangular shape
eg. trapezius
- trapezoid shape (no two sides parallel)
origin and insertion
eg. sternocleidomastoid
* origin
- sterno=sternum
- cleido=clavicle
* insertion
- mastoid=mastoid process of temporal bone
location
eg. tibialis anterior
relative size
eg. gluteus
* maximus
* medius
* minimus
direction of fibers
eg1. rectus abdominis
* rectus=straight ll
eg2. external obliques \ //
number of origins
eg1. biceps brachii
* 2 origins on scapula
eg2. triceps brachii
* 2 origins on scapula and humerus
eg3. quadricips femoris
* 4 origins os coxa and femur
