Muscles 1 Flashcards
What are the 3 different types of muscles?
Smooth
Cardiac
Skeletal
What is the sarcolemma?
Cell membrane of a muscle cell
What 8s the sarcoplasmic reticulum?
Endoplasmic reticulum of muscle cells
What is epimysium?
Outermost covering (also referred to as deep fascia )
What is perimysium?
Intermediate covering
What is endonysium?
Innermost covering (single cell)
The structure of each muscle type is different based on its function with the body :
- produce movement
- maintain pressure
- generates heat
- stores minerals
- provide protection
- produces peristalsis
- constrict blood vessels
Describe smooth muscle
- spindle shaped cells (thick middle with tapered edges)
- thin diameter (3-8um)
- variable intermediate length
- single, centrally placed nucleus
- Only endomysium
- One cell= one fiber
- gap junctions are found in some areas
- has capacity to regenerate
- slow contraction
- involuntary
Where is smooth muscle found?
Found in walls of vessels and found in some organs
Describe cardiac muscle
- branched cylindrical shaped cells
- large diameter (10-20um)
- long length
- single, centrally placed nucleus
- endomysium and perimysium
- one cell= one fiber
- attached to each other by intercalated discs
- Gap junctions and desmosomes
- has limited capacity to regenerate
- slow contraction
- involuntary
Describe skeletal muscle
- elongated cylindrical cells
- large diameter (10-100um)
- long length
- multiple, peripheral nuclei
- endomysium, perimysium and epimysium
- one fiber consist of one fused elongated multinucleated cell
- no junctions
- has limited capacity to regenerate
- fast contractions
- different types of fibers
-voluntary
What types of nerves innervate skeletal muscles? Why?
Sensory and motor neurons
motor nerves cause them to contract
-Sensory nerves give information of what position the muscle is in (proprioception)
Describe neuromuscular junctions
The nerve fiber branches and attaches to muscle fibers at the neuromuscular junction
1 fiber= 1 neuromuscular
1 nerve may serve up to 100 fibers
- The lower the ratio of muscle fibers to nerve fibers the higher the specificity of movement
- E.g. muscles of the hand few muscle fibers to a nerve therefore very intricate movements possible
Explain muscle contraction
- Myosin heads break down ATP and become reoriented and energized
- Myosin heads bind to actin, forming cross-bridges
- Myosin cross-bridges rotate toward center of the sacromere (power strike)
- As myosin heads bind ATP, the cross-bridges detach from actin
What is hypertrophy?
Increase in the size of existing muscle cells as a response to stress
What is hyperplasia?
Increase in the number of muscle cells
What is atrophy?
Decrease in both size and number of cells
How are muscles grouped?
Skeletal muscles are broadly grouped as muscles that move the limbs (appendicular) and muscles that move the face, back and trunk (axial)
Within these smaller groups based on their major function is made
These groups are called compartments
-In the limbs often separated by thick fascia sheaths
Each compartment share a common:
- Action
- Innervation
- Attachment(general)
- Embryologic origin
Compartments mar by named for their location or the shared action
What are appendicular muscles?
- Upper and lower limbs share a common arrangement
- But their actions are opposite due to limb rotation during embryologic development
What are the patterns and layers of appendicular muscles?
The patterns and layers are generally comparable
Quick hints
The extensors are where the nails are
Special actions
Forearm- supination/pronation
Ankle= inversion and Eversion
Explain the axial muscles
Face
- muscles of facial expression
- muscles of mastication
Anterior neck
-Strap muscles responsible for moving the larynx and pharynx for swallowing
-muscles responsible for bending
Posterior neck and back
Mostly postural except for the neck
Trunk
Accessory respiration and bending
What are the associated names with muscles?
Shape- deltoid
Size- magnus
Attachment- carpi
Movement- flexor
Length- breves
Depth- superficialis
Number of bellies -triceps
