Muscle Mechanics and Control Flashcards by michael perna

Outermost tissue of skeletal muscle, forms the overcoat of the muscle and helps to separate it from other muscles

Epimysium

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Continues past the fleshy part of muscle to help form its attachment to the bone

Epimysium

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Within each skeletal muscle, surrounds a group of muscle fibers or muscles cells which are held together.

Perimysium

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Each group of muscle fibers or cells that is wrapped by the perimysium

Fascicles

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Within each fascicle are

muscle cells/fibers

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Connective tissue which surrounds muscle fibers and goes between each one within fascicles

Endomysium

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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

Neurovascular bundle

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Important for the activity of skeletal muscle because skeletal muscle is completely dependent upon the nerves, aka innervation

Neurovascular Bundle (Nerve Supply)

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Normally a muscle is supplied by one nerve, which may supply only one, two, or several muscles?

Several muscles

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T/F: Skeletal muscle tissues is striated

True

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Endomysium, Perimysium, and Epimysium form these 4 types of muscle attachments

Tendons
Apopneurosis
Fleshy Attachments
Dermal Attachments

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Extensions of connective tissue sheaths, forming a cord like attachment to outer covering of bone, periostium

Tendons

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Tendons are usually marked by what structure on bone?

Tubercle

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Type of attachment that is a broad sheet of connective tissue for the attachment of a muscle

Apopneurosis

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Attaches and forms a ridge like or line on skeletal structure it attaches to, but may also attach do dermis of skin

Apopneurosis

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Muscle fibers continue almost to the bone, there is very little connective tissue.

Fleshy Attachments

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Fleshy attachments occur where bone is like this, because the forces are widely distributed along attachment site, rather than one location

Smooth

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Muscle fibers attach to the connective tissue of the dermis of the skin (like muscles of facial expression)

Dermal Attachments

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Gives the shape to muscles

Fascicle arrangement

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The strength of muscle and direction in which the pulled are determined by the orientation of…

The fascicles

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A feather shaped type of muscle fibers

Pennate

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All muscles attach from one side

Unipennate

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All muscles attach from two sides

Bipennate

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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

Multipennate

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Fan shaped fibers, broad origin and narrow insertion. Strong because fascicles exert tension on relatively small insertion

Convergent

Sphincter forming rings around body openings

Circular

Thick in the middle and taper on both ends, forming a belly in the middle. Contractions are moderately strong.

Fusiform

Long straplike muscles of uniform width and parallel fasicles. Small cross section. Spread over long distances and shorten more, but small cross section.

Parallel

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

Attachment points

Proximal attachment, usually the less moveable attachment. Tendons are usually longer.

Origin

Distal attachment, usually the more freely moveable attachment. Tendons usually shorter.

Insertion

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

Lever System

Component of lever system, the elongated rigid object that rotates around a fixed point

Lever

Component of lever system which is the fixed point around which the levers will rotate (axis)

Fulcrum

Component of lever system which is the effort applied at one end of the lever to overcome the weight or load

Force/Effort

The weight or resistance at some point of the lever that will be overcome by the force

Load

What are the levers in the human body

Rigid bones

What are the axis/fulcrum or pivot points

Joints, most commonly diarthrodial

Force/effort of the human body

Muscles

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

1st class

The effort is applied at one end of the lever, the fulcrum is at the other, and the load is at the middle.

2nd Class

The effort is applied between the fulcrum and the load, the most common in the human body

3rd Class

It is important to notice that the effort is the point where the muscle attaches to the bone, not the muscle belly

OKOK

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

Antagonist

Helps prime mover and reduces undersireable movement that may occur as prime mover contracts Ex: muscles crossing two joints

Synergist

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?

Posturizers

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

Rhomboids

There are antagonists to the serratus anterior muscle which protracts the scapula

Rhomboids

These are stabilizers of the scapula to allow the levator scapula to extend the neck

Rhomboids

These are synergistic to retraction of the scapula with the middle fibers of the trapezius

Rhomboids

The control of the somatic motor system by the nervous system

Neuromuscular control

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

Pyramidal Tract

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

Efferent information

These nerves go to the head and neck

Cranial nerves

These nerves go to muscles within the body

Spinal nerves

Where cranial and spinal nerves exit alpha motor neurons they terminate on muscle fibers

Muscle fibers

An alpha motor neuron and all the muscle fibers it innervates on these

Motor Unit

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

Neuromuscular junction

What type of connection is made at neuromuscular junction?

Synapse

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

Proprioception

This occurs via muscle spindles and golgi tendon organs

Proprioception

Stretch receptors within muscle that tell the state of contraction/tension of the muscle, especially abundant in muscles that require fine control

Muscle Spindles

Located in tendons of muscles, monitor the pull or contraction on a tendon and send it to the brain

Golgi Tendons

Information coming from brain that is motor information

Efferent Information

Information coming into the brain from the skeletal muscles

Afferent Information