Skeletal, Muscles, and Systems of Speech Flashcards
Muscles
Striated muscles or skeletal muscles: move the bones at the joints when contracted (voluntary)
Smooth muscles: move blood in vessels and material down the digestive tract (involuntary)
Cardiac muscles: muscles of the
heart
Muscle can only do one thing: contract
Contraction brings two points closer together, Longer muscles can contract farther than short muscles, Muscles with more fibers can exert more force of contraction
Fast Twitch muscle fibers
Contract quickly
Are for fine movement
Fatigue easily
Slow twitch muscle fibers
Are for larger movements
Exert greater force
Move more slowly
Have greater endurance
Antigravity muscles of trunk
Striated Muscle Composition: Hierarchy
Muscle is made up of muscle fibers Muscle fibers are made up of made up of myofibrils, Myofibrils are made up of myofilaments
-Thick myofilaments
-Thin myofilaments
Muscles Contract
-Muscles shorten in length (to approx. 1/3 of original length)
-Muscles can only pull structures
-Muscle requires neural connection if it is going to contract
-That activation occurs as a result of the central nervous system command reaching the peripheral cranial (or spinal) nerves
-The end product is movement!
-Impulse to activate muscle arises at the motor strip of the cerebral cortex
-Head and face region for muscles of speech
-More dorsal regions for trunk, arms, leg muscles
Neuron Terms
Neurons
-Dendrite
-Soma
-Axon
Glial cells
Responsible for waste removal, blood brain barrier and much more
Nuclei: aggregate of cell bodies in the central nervous system having functional unity
Ganglia: aggregate of cell bodies in the PNS having functional unity
e.g., spiral ganglion of the auditory system
Basic Function of the Neuron
A neuron’s function is to communicate by generation of an action potential
Synapse
Synapse is the space between two neurons where communication occurs:
between axon of one neuron and dendrite of another neuron
Speech Mechanism
Impulse passes through corticobulbar tract to terminate on a nucleus in brainstem
e.g., motor nucleus of V trigeminal to activate muscles of mastication
The nucleus activates the V trigeminal nerve
The V trigeminal nerve
-Synapses with muscle fiber
-Activation of the nerve causes the muscle to twitch
-Many muscle fibers activated causes a muscle to contract!
The motor unit
A motor unit is a motor neuron and all of the muscle fibers it innervates.
Skeletal Muscles
Muscles attach to structures:
Origin = attachment point of muscle that has limited movement
Anatomically this is the more proximal attachment
Insertion = attachment point that has more movement
Anatomically this is the more distal attachment
We will look at functional origin/insertion related
to the speech system, not classical anatomical
Tendons attach:
muscle to bone
muscle to cartilage
muscle to muscle
Muscles often work together with other muscles
Agonists are responsible for the movement
Antagonists perform movements opposite of the agonist
Synergists/Fixators stabilize structures
Muscle Movements
Isometric Contraction
Muscle action where its points of attachment do not move relative to each other (like flexing)
Concentric Contraction
Muscle is active and its attachments are drawn closer together
E.g., a flexor muscle is active and flexion occurs
Eccentric Contraction
Muscle is active and its attachments are drawn further apart
E.g., a flexor muscle is active and extension occurs when something is so heavy
(a muscle lengthens under load)
Flexion = bending at a joint bringing surfaces / ends closer together
Extension = bring surfaces / ends apart (straightening)
Adduction = bring tissues to midline
Abduction = bring tissues away from midline
Speech
Is extraordinarily complex process used to convert your inner thoughts into a chain of speech sounds (linguistic encoding), generated through the activation of multiple systems
Systems involved in speech
Respiratory System
Phonatory System
Articulatory/ Resonatory System
