Muscle Tissue and Organization Flashcards
Why are muscles considered organs?
they are composed of muscle, epithelial, connective, and nervous tissue
What do muscles convert?
chemical energy into physical energy
Types of muscle tissue
skeletal, smooth, and cardiac
typically voluntary muscle tissue
skeletal
typically involuntary muscle tissue
smooth and cardiac
Is essential for propelling materials through our internal tubes (i.e. peristalsis)
smooth muscle
is essential for the pumping of blood (found only in the walls of the heart)
cardiac muscle
specific characteristics ALL muscle cells exhibits
Excitability, Contractility, Elasticity, and Extensibility
another name for muscle cells
muscle fibers
muscle fiber property which means it responds to electrical stimuli
Excitability
muscle fiber property which means it contracts to move bones or propel materials inside the body
Contractility
muscle fiber property which means the muscle cell will recoil to its resting length when the applied tension is removed
Elasticity
muscle fiber property which means a muscle cell is capable of extending in length in response to the contraction of opposing muscle cells
Extensibility
length of a single muscle fiber
as long as the muscle itself
hypertrophy
increase in muscle fiber size (not number)
often follows regular exercise
hypertrophy
Functions of skeletal muscle tissue
- Body Movement (using bones as levers)
- Maintenance of Posture (stabilize joints for upright position)
- Temperature Regulation
- Storage and Movement of Materials (sphincters vs. orifices)
- Support by Stabilizing the Body Walls (prevent displacement of internal structures)
When a student falls asleep in lecture hall, muscular control of the bones and joints is lost, allowing the head to droop forward and the temporomandibular joint to become depressed. Which function of skeletal muscle tissue is absent in this situation?
Maintenance of Posture
Gross anatomy of skeletal muscle includes:
muscle attachments, blood vessels, and nerves
At the ends of a muscle the connective tissue layers merge to form a fibrous cordlike ______, which typically attaches to bone.
tendon
Sometimes the tendon forms a thin, flattened sheet, called an _______. (Greek for “from sinew”)
aponeurosis
which characteristic does a tendon share with a muscle cell?
tendons have some elasticity
the less moveable attachment of a muscle. where does it typically lie?
the origin, which typically lies proximal to the insertion
the more moveable attachment of a muscle. where does it typically lie?
the insertion, which typically lies distal to its origin
Why are skeletal muscles classified as voluntary?
they are controlled by the Somatic (voluntary) Nervous System
the neurons (nerve fibers) that stimulate muscle contraction and innervate muscle fibers within the muscle
motor neurons
neurons that travel away from the center of activity (which is the CNS). another term for motor neurons
efferent neurons
muscle fibers will do this if they are not periodically stimulated to contract by motor neurons
atrophy (waste away)
atrophy
to waste away muscle fibers
the long extension of each motor neuron that transmits a nerve impulse to a muscle fiber
axon
where does the axon travel through?
the fibrous coverings of the muscle
sends impulses to the brain and spinal cord about the activity of the muscles
sensory neurons
neurons that travel towards the CNS. another term for sensory neurons
afferent neurons
bundles of muscle fibers lie parallel to each other within each muscle and are termed _____.
fascicles
The organization of fascicles in different muscles varies in these four different patterns.
- Circular muscles
- Parallel muscles
- Convergent muscles
- Pennate muscles
pattern where fascicles are are concentrically arranged around an opening or recess
Circular muscles
Why is a circular muscle also called a sphincter?
because the contraction of the muscle closes off an opening (orifice)
another name for circular muscles
sphincters
an example of a sphincter that is found within the lips and surrounds the opening of the mouth. Why is this so special?
the orbicularis oris muscle, which is the first sphincter of the digestive tract
pattern where fascicles run parallel to its long axis.
parallel muscles
the central body of a parallel muscle
a “belly”
what happens to the body (belly) of parallel muscle when it shortens (contracts)?
it increases in diameter (bulges)
2 examples of parallel muscles that bulge when they contract
biceps brachii and the rectus abdominis (which forms the “six-pack”)
pattern of widespread fascicles (bundle of muscle fibers) that converge on a common attachment site. these are often triangular shaped, resembling a broad fan with a tendon at the tip. (ex. Deltoid)
Convergent muscles
a convergent muscle on the anterior of the chest that inserts onto the proximal end of the humerus
pectoralis major
have one or more tendons extending through their body, and the fascicles are arranged at an oblique angle to the tendon. Latin for “looks like a feather”
Pennate muscles
unipennate muscle
all muscle fibers are on the SAME SIDE of the tendon
bipennate muscle
most common arrangement. muscle fibers are on BOTH SIDES of the tendon
multipennate muscle
tendon branches within the muscle. example: deltoid muscle
biomechanics
the practice of applying mechanical principles to biology.
when analyzing muscle contraction, an anatomist often uses this practice to compare it to a lever
biomechanics
A “__1__” is an elongated, rigid object that rotates around a fixed point called the “__2___”.
1: lever
2: fulcrum
The part of a lever from the fulcrum to the point of effort.
the “effort arm”
The part of a lever from the fulcrum to the point of resistance.
the “resistance arm”
In the body, what acts as the lever that moves the resistance (R)? the fulcrum (F)? generates the effort (E)?
a long bone acts as the lever that move the R, a joint serves as the F, and a muscle attached to the bone generates the E.
When thinking about a muscle providing the effort (E), what must you realize?
That the effort is NOT where the body of the muscle is located, but rather where the muscle attaches (inserts) to the bone.
Types of Lever Systems
"F R E 1 2 3" first class (1)=fulcrum (F) in middle second class (2)=resistance (R) in middle third class (3)=effort (E) in middle
A lever system similar to a seesaw, in which the fulcrum (F) is between the effort (E) and the resistance (R).
First Class Lever System
One example of a first class lever is the ______ joint of the neck, where the muscle on the posterior side of the neck pull inferiorly on the nuchal lines of the occipital bone and oppose the tendency of the head to tip anteriorly.
atlanto-occipital
One example of a first class lever is the pulling of the _______ muscle on the ______ to extend the elbow. (In this instance, the effort arm is very short and the resistance arm is very long.)
pulling of the “triceps brachii muscle” on the “olecranon process”
A lever system similar to lifting the handles of wheelbarrow, in which the resistance (R) is between the fulcrum (F) and the effort (E).
Second Class Lever System
Contracting the calf muscle to elevate the body onto the distal ends of metatarsals (ball of foot) is an example of what type of lever?
Second Class Lever
A lever system similar to a drawbridge, in which the effort (E) is between the resistance (R) and the fulcrum (F).
Third Class Lever System
The most common type of lever system in the body
Third Class Levers
The flexion of the elbow and elevation of the mandible to bite off a piece of food is demonstrating what types of levers?
both are Third Class Levers
What is important to remember about the actions of skeletal muscles?
they do NOT work in isolation; rather they work together to produce movements
Muscles are grouped according to their primary actions into these 3 types.
Agonist, Antagonist, and Synergist
An “____” (also called a “____”) is a muscle that contracts to produce a particular movement, such as the triceps brachii muscle causing extension of the forearm.
agonist (also called a prime mover)
An “_____” is a muscle whose actions oppose those of the agonist, such as the biceps brachii muscle causing flexion of the forearm.
antagonist
The opposing force of an antagonist muscle enables us to do what?
control the speed of the agonist to allow smooth movements
A “____” is a muscle that assists the prime mover in performing its action, such as the teres major muscle assisting the latissimus dorsi in moving the arm.
synergist
Skeletal muscles are named according to what 7 criteria?
- Muscle action
- Specific body regions
- Muscle attachments
- Orientation of muscle fibers
- Muscle shape and size
- Muscle heads/tendons of origin
- Relative position
adductor, flexor, extensor, pronator, and levator (lifter) are examples of which criteria used in naming skeletal muscles?
muscle action
pectoralis, intercostal, and brachii are examples of which criteria used in naming skeletal muscles? What do each of those mean?
Specific body regions
Pectoralis=the chest, or “pectus”
Intercostal=between the ribs
Brachii=on upper arm
zygomaticus and sternocleidomastoid are examples of which criteria used in naming skeletal muscles? What do each of those mean?
Muscle attachments
Zygomaticus=zygomatic bone
Sternocleidomastoid=sternum, clavicle, and mastoid process of skull
rectus, transverse, and oblique are examples of which criteria used in naming skeletal muscles? What do each of those mean?
Orientation of muscle fibers
Rectus=straight
Transverse=across
Oblique=at an angle
deltoid, trapezius, longus, brevis, teres, maximus, and minimus are examples of which criteria used in naming skeletal muscles? What do each of those mean?
Muscle shape and size Deltoid=shaped like triangle Trapezius=shaped like trapezoid Longus=long Brevis=short Teres=both long and round Maximus=large Minimus=small
biceps, triceps, and quadriceps are examples of which criteria used in naming skeletal muscles? What do each of those mean?
Muscle heads/tendons of origin
Biceps=2 heads/tendons of origin
Triceps=3 heads/tendons of origin
Quadriceps=4 heads/tendons of origin
This begins as a direct result of increasing inactivity, typically in a person’s mid-30s.
a slow progressive loss of skeletal muscle mass
What components of all muscle tissues decreases with inactivity? What often replaces the lost muscle mass?
size and power decreases. mass replaced by adipose tissue or fibrous connective tissue.
Aging affects the muscular system by decreasing the number of contractile filaments within muscle cells, which then causes what?
muscle cells (muscle fibers) to diminish in size (atrophy)
Overall, as an individual ages, what muscle functions are impaired that result in a tendency to fatigue easily?
muscle strength and endurance
This often accompanies aging, and leads to poorer delivery of oxygen and nutrients to muscle cells.
decreased cardiovascular performance
Tolerance for this decreases with age and rapid fatigue occurs
exercise
This has a reduced capacity to recover from disease or injury with age.
muscle tissue
As a person ages, increasing amounts of dense regular connective tissue causes a decrease in muscle elasticity. What process does this describe?
fibrosis
How can the adverse affects aging has on the muscular system be delayed?
Through regular, moderate exercise coupled with good nutrition
What is the common name and scientific name for a “bifid Zygomaticus Major” muscle deformity? What medical condition (much more serious) is this similar to?
dimple, or gelasin. This is similar to an inward hernia
inflammation of either a tendon or a synovial sheath surround the tendon. typically from overuse. may be caused by absent “glide-path”
tendonitis
syndrome of chronic severe pain involving both muscles and skeleton. most commonly affects neck or lower back. treated through self-care measures, and NSAIDS
fibromyalgia
collective terms for several hereditary diseases where skeletal muscle degenerates
muscular dystophy
most common neuromuscular disease. expression of sex-linked recessive allele. exclusively affects males. posture abnormalties (scoliosis). rarely live past 30 and die of resp or heart complications. possible treatment by altered virus carring gene for dystrophin (essential protein for muscle function missing in these patients)
Duchenne muscular dystrophy DMD
common disorder associated with excessive use of postural muscles. “trigger point” stimulation of pain. bands of muscle fibers tighten and twitch after skin is toughed. can also produce autonomic nervous system changes (flushed skin, sweating, goose bumps)
myofascial pain syndrome MPS
unilateral paralysis of muscles of facial expression. nerve is inflamed and compressed within narrow stylomastoid foramen. may use prednisone to reduce inflammation and swelling of nerve, or acyclovir (antiviral) if herpes simplex is suspected.
facial nerve (CN VII) paralysis, Bell Palsy
eyes are improperly aligned, not working synchronously to transmit stereoscopic view. brain ignores eye and becomes lazy eye. 2 types, external vs. internal that are caused by oculomotor cranial nerve (CN III) or abducens cranial nerve (CN VI)
strabismus
when lazy eye loses visual acuity
strabismic amblyopia
toxin prevents release of ACh at NMJ and leads to muscular paralysis. commonly caused my improperly canned foods, and infants ingesting unpasteurized honey.
Botulism
known as wryneck, shortened and tightened sternocleidomastoid muscle.hematoma and fibrosing of muscle tissue. extended periods of time in infant seats. plagiocephaly (flattening of head) often accompanies. treatment with botox, stretching, surgery.
congenital muscular torticollis CMT
extracapsular femur fracture, typically from trauma
intertrochanteric fracture
intracapsular femoral fracture. often in those with osteoporosis. results in tearing of retinacular fibers and retinacular arteris. head and neck of femur lose blood supply causing death of bone tissue due to lack of blood (avascular necrosis)
subcapital fractures
