Flashcards in Muscle Mechanics and Control Deck (88):
Outermost tissue of skeletal muscle, forms the overcoat of the muscle and helps to separate it from other muscles
Continues past the fleshy part of muscle to help form its attachment to the bone
Within each skeletal muscle, surrounds a group of muscle fibers or muscles cells which are held together.
Each group of muscle fibers or cells that is wrapped by the perimysium
Within each fascicle are
Connective tissue which surrounds muscle fibers and goes between each one within fascicles
Connective tissue sheets also provide entry and exit routes for blood vessels and nerve fibers that serve the muscle, these bloods vessels and fibers are called
Important for the activity of skeletal muscle because skeletal muscle is completely dependent upon the nerves, aka innervation
Neurovascular Bundle (Nerve Supply)
Normally a muscle is supplied by one nerve, which may supply only one, two, or several muscles?
T/F: Skeletal muscle tissues is striated
Endomysium, Perimysium, and Epimysium form these 4 types of muscle attachments
Extensions of connective tissue sheaths, forming a cord like attachment to outer covering of bone, periostium
Tendons are usually marked by what structure on bone?
Type of attachment that is a broad sheet of connective tissue for the attachment of a muscle
Attaches and forms a ridge like or line on skeletal structure it attaches to, but may also attach do dermis of skin
Muscle fibers continue almost to the bone, there is very little connective tissue.
Fleshy attachments occur where bone is like this, because the forces are widely distributed along attachment site, rather than one location
Muscle fibers attach to the connective tissue of the dermis of the skin (like muscles of facial expression)
Gives the shape to muscles
The strength of muscle and direction in which the pulled are determined by the orientation of...
A feather shaped type of muscle fibers
All muscles attach from one side
All muscles attach from two sides
Shaped like a bunch of feathers converged on a single point
Arranged diagonally causes slight reduction of force, but more fibers meaning more cross sectional area and overall greater strength
Fan shaped fibers, broad origin and narrow insertion. Strong because fascicles exert tension on relatively small insertion
Sphincter forming rings around body openings
Thick in the middle and taper on both ends, forming a belly in the middle. Contractions are moderately strong.
Long straplike muscles of uniform width and parallel fasicles. Small cross section. Spread over long distances and shorten more, but small cross section.
What gives muscles their strength
Cross sectional area
Longer muscles can shorten more, and more parallel.
Ok, but they're not very powerful
Origins and insertions of muscles
Proximal attachment, usually the less moveable attachment. Tendons are usually longer.
Distal attachment, usually the more freely moveable attachment. Tendons usually shorter.
Muscles pull on both ends, bringing both ends of muscle towards the proximal end
Muscles must do what to cause an action?
Cross a joint
The movement of a muscle can depend upon these two things
1) The axis of the joint crossed
2) The side that the muscle crosses
Describes the bone-muscle relationships
Component of lever system, the elongated rigid object that rotates around a fixed point
Component of lever system which is the fixed point around which the levers will rotate (axis)
Component of lever system which is the effort applied at one end of the lever to overcome the weight or load
The weight or resistance at some point of the lever that will be overcome by the force
What are the levers in the human body
What are the axis/fulcrum or pivot points
Joints, most commonly diarthrodial
Force/effort of the human body
The resistance/load of lever system in human body
Gravity, or other externally applied resistance
Class of lever where the fulcrum is between the force and the load
The effort is applied at one end of the lever, the fulcrum is at the other, and the load is at the middle.
The effort is applied between the fulcrum and the load, the most common in the human body
It is important to notice that the effort is the point where the muscle attaches to the bone, not the muscle belly
The neck muscles are an example of
1st class lever
Lifting body weight up onto toes is an example of
2nd class lever
Doing bicep curls is an example of
3rd class lever
These type of levers are designed to increase speed and range of motion of the distal end of the lever
3rd Class Lever
These type of levers achieve the goal of human motion which is to move through space better than 1st or 2nd class levers
3rd Class Lever
Most effective interaction of skeletal muscle to produce an action causing the movement.
Prime Mover or Agonist
Opposite of the agonist, contraction causes joint action which reverses the movement
Helps prime mover and reduces undersireable movement that may occur as prime mover contracts
Ex: muscles crossing two joints
Anchors, steadies or supports a bone or body part so that an active muscle has a firm base on which to pull
Fixators or stabilizers
Many synergists and stablizers are involved in what type of muscles?
Muscles may act as prime mover in one movement, antagonist in another, synergist or fixator in a third
What are the two rhomboids of the scapula?
Major and Minor
These muscles retract the scapula as agonists or prime movers
There are antagonists to the serratus anterior muscle which protracts the scapula
These are stabilizers of the scapula to allow the levator scapula to extend the neck
These are synergistic to retraction of the scapula with the middle fibers of the trapezius
The control of the somatic motor system by the nervous system
Brain sends messages through a group of tracks that will synapse on motor cells in the brain stem and the spinal cord which will ultimately send info to cranial nerves and spinal nerves of head neck and body
What aspect of frontal lobe of the brain directs all intentional/volitional movements?
Primary Motor Cortex (in precentral gyrus)
As an action potential develops it send messages to cells in cranial nerve nuclei and spinal chord, they are sent down the
Motor neurons located in both the spinal cord and cranial nerve nuclei which receive messages from brain after the pyramidal tract
Alpha motor neurons
These send messages via cranial or spinal nerves to the muscles of the head neck and body
Alpha motor neurons
Alpha motor neurons send what type of information to the cranial and spinal nerves? Also known as motor information which causes muscles to contract
These nerves go to the head and neck
These nerves go to muscles within the body
Where cranial and spinal nerves exit alpha motor neurons they terminate on muscle fibers
An alpha motor neuron and all the muscle fibers it innervates on these
Small ratio of nerves to muscle fibers gives
Fine control (like eye muscles)
Large ratio of nerves to muscle gives
Gross control (postural muscles)
Review segment at 26:30 for description
The nerve ending and the muscle fiber
What type of connection is made at neuromuscular junction?
Folded part of muscle cell membrane that forms synapse with motor nerve
Motor End Plate
The sense of knowing where our body is in space, involves sensory feedback to the brain from the muscles
This occurs via muscle spindles and golgi tendon organs
Stretch receptors within muscle that tell the state of contraction/tension of the muscle, especially abundant in muscles that require fine control
Located in tendons of muscles, monitor the pull or contraction on a tendon and send it to the brain
Information coming from brain that is motor information