Muscles. function, actions and identification of major superficial muscles, some conditions and treatments. types of muscles. Three structurally and functionally distinct types of muscle are found in vertebrates: smooth muscle , skeletal muscle and cardiac muscle . .
function, actions and
major superficial muscles, some conditions and treatments
Three structurally and functionally distinct types of muscle are found in vertebrates:
Skeletal muscles are named according to structural and/or functional characteristics.
dorsiflexion– toe towards the knee usingtibialis anterior
plantar flexion–”point toes” usinggastrocnemius
elevation - Upward movement of the shoulder girdle.
depression - Downward movement of the shoulder girdle..Depression
protraction and retraction are all movements associated with the shoulder girdle.
1. Lateral rotation
2. medial rotation
myofibrils contract instantly if ATP and Ca2+ is added to them, meaning that it is these single myofibrils which are the force generators in muscle cells.
Striated sarcomeres are separated by Z-discs. Two Z-discs bound a sarcomere in the direction of stretching. Thin filaments made of Actin are attached to each of these discs and extend towards each other inside the sarcomere. They do not overlap in the sarcomere’s striated form. In this case there is a dark band visible between the Z-discs. This is made up of the thick Myosin filaments which overlap partially with the thin Actin filaments which extend into a light half of the I-Band region left and right of the dark A-band.
When Myofibrils contract the thin and thick filaments move past each other. Each sarcomere unit of the myofibrils shortens proportionally to the muscle contraction. Upon contraction, it is the light bands which shorten whereas the dark bands do not change in length. This is explained by the Actin filaments sliding into the dark region of Myosin filaments.
Actin - the thin filaments
Myosin - the thick filaments
During contraction, actin fibers are pulled inward
a) pulling is by "hooks" on myosin (myosin heads)
b) hooks bend, using energy of ATP
c) each hook pulls, releases, pulls again until muscle is contracted
d) calcium (Ca2+) ions signal this to start
-Ca2+ into muscle starts contraction
-during relaxation, Ca2+ is transported out
NOTE: These pictures are intended to provide a virtual tour of the lab models and specimens. They are not intended to substitute for classroom/lab learning. They are simply supplemental material for you to use as reminders of what you should study or have already studied.
Muscles which occupy the layer closest to the surface of the skin are called superficial muscles. These are easily displayed on a person who has developed their physique for show or physical performance.
Alevator labii superioris
B zygomaticus minor
C zygomaticus major
E depressor anguli oris
F labii inferioris,
G orbicularis oris
masseter and directions of the lower jawbone movement
sternocleidomastoid muscle is the main muscle on the side of the neck.
The trapezius muscle is the one that tenses up most often. When you see people reaching back to massage their shoulders, it is the trapezius muscle that they are trying to loosen.
The other two muscles that have a tendency to tighten up are the sternocleidomastoid (often called the sterno-mastoid) and the scalene muscles.
Keep it Moving! The neck is by far the most mobile portion of the spine. Its ROM is generally 70 to 90 degrees.
The bones of the neck are called the cervical vertebrae.
Every mammal on earth, even the giraffe, has 7 of them. In humans, the cervical vertebrae are obviously a lot smaller than those of giraffes. They are also a lot smaller than the vertebrae of the other areas of the human spine.
Our necks need to use their mobility in order to maintain it. They work best when they can consistently move into and out of their full range of motion in a gentle - that is, not a jarring - way.
We rotate our necks fully when we look over our shoulder and then back the car down the driveway. We extend our necks completely when we look up at the ceiling.
The fact that we do not do these things often is one of the major reasons why our necks cause us problems. On occasion, when it’s essential for the neck to move to an extreme range of motion, it can’t cope with the job. That’s when injuries occur.
The trapezius covers a large section of the upper back. It conceals the upper part of the shoulder blade.
4 muscles of the abdominal area
internal oblique NS
transversus abdominis NS
triceps brachii – extends the arm, straightening the elbow
The hamstring muscle group comprises three muscles –
The action of these muscles is to bend the knee and extend the hip.
adductor magnus, longus, brevis and the pectineus, make up the adductor group.
Groin pulls are a strain at the attachment of the adductors to the pubic bone.
gastrocnemius is the calf muscle which are each divided into two hemispheres.
This picture illustrates the relationship between the superficial gastrocnemius muscle, the deeper soleus muscle and the large Achilles tendon which is visible attaching to the heel.
Tetany-stimuli is so fast that muscle cannot relax - stays contracted
(tetanus - bacterial toxin interferes with motor neuron function, uncontrolled stimulation)
Wearing away and/or softening of the articular cartilage, tissue that covers and protects the underside of the patella, the bottom end of the femur, and top end of the tibia. It absorbs stress to the knee joint and allows the patella to track smoothly in its femoral groove.Causes: Typically, excessive running Symptoms: Pain around the patella (kneecap), usually occurring on the medial (inner) side and below (inferior aspect of the patella).
occurs when excessive or repetitive stress causes tearing of the muscle fibers in the hamstring.Causes: Tight hamstring muscles, muscle imbalance, sudden movement, and repetitive strain are all common types of hamstring injuries. Symptoms: A sharp pain may be felt in the hamstring when a serious strain or tear occurs. This often happens during such action as an explosive move in basketball or a quick sprint. If you feel a deep ache in the hamstring area it may be a less severe strain or minor tear.
intramuscular injection delivers medicine directly into the muscle
Intramuscular injections contraction are the deepest injection type, delivering the medication into the muscle tissue. Most vaccines are currently delivered to the intramuscular depth.
Subcutaneous injections are delivered to the adipose (fat) layer just below the skin. Many therapeutic proteins are delivered to the subcutaneous depth, such as human growth hormone.
Intradermal injections are very shallow injections that deposit the medication between the layers of the skin. Many new DNA-based vaccines are delivered to the intradermal layer.injections
Loss of muscle fibers
Linked to young males (ages 3-5)
Lacking certain protein thus allows too much Ca+ into cell this leads to cell death and replacement with scarring
Ca++ pumps run out of ATP
Ca++ cannot be removed
eventually tissues break down
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