Muscles Flashcards
What are the three types of muscle tissues?
Skeletal, cardiac, and smooth
How do the three muscle groups differ?
Cell structure, body location, how they are stimulated to contract
All muscles are…
elongated
What are the muscle cells called?
Muscle fibers
How many muscles are there in the body?
600
What do the muscle fibers do?
Have the ability to shorten or contract
What is in the muscle fibers to make them contract?
Two types of myofilaments
What does myo mean?
Muscle
What are the muscle filaments equivalent to?
The microfilaments of the cytoskeleton
What does sarco mean and what does it refer to?
Flesh, the muscle
What is the cytoplasm of a muscle cell called?
Sarcoplasm
Where are the skeletal muscles attached to?
The body’s skeleton
What do the skeletal muscles do to the look of the body?
Give it a smoother contour
What do muscle fibers look like?
Shaped like cigars, multinucleated cells, the largest type of the muscle fiber type
What are skeletal muscles also called and why?
Striated muscles, its fibers appear to be striped
What is the sarcolemma and what can be seen just beneath it?
Plasma membrane in muscle cells, many oval nuclei
What are the myofibrils?
The nuclei are pushed aside by these long ribbon-like organelles
What do the myofibrils do?
Give the muscle cell its striped appearance
What are the two types of thread? What colors are they?
Myosin (dark)
Actin (light)
What is myosin?
The protein that makes up the thick myosin filaments
What does myosin have?
ATP enzymes
WHat does ATP do?
Generates the power for muscle contraction
WHat does calcium do?
Provides the final “go” signal for contraction
What are the important key words for describing cardiac muscle?
Cardiac, striated, involuntary
How are cardiac fibers arranged?
Cushioned by small amounts of connective tissue arranged in spiral or figure 8 shaped bundles
Where is the frontalis and what does it do?
Covers the frontal bone and allows for the raising of the brows
What are the orbicularis oculi and what do they do?
Fibers that run in circles around the eyes. Closing of the eyes, squinting, blinking, winking
What is the buccinator and what does it do?
A fleshy muscle that runs horizontally across the cheek and inserts into the orbicularis oris. It flattens the cheek (as in whistling)
What does the buccinator also do?
It is also a chewing muscle because it compresses the cheek to hold the food between the teeth during chewing
What is the orbicularis oris and what does it do?
The circular muscles of the lips, this is often called the “kissing muscle” because it closes the mouth and protrudes the lips
What is the zygomaticus and what does it do?
Extends from the corner of the mouth to the cheek bone, referred to as the “smiling muscle”, it raises the corners of the mouth upward
What is the masseter and what does it do?
Covers the angle of the lower jaw as it runs from the zygomatic process of the temporal bone to the mandible, this muscle closes the jaw by elevating the mandible, masticating (chewing) muscle
What is the temporalis and what does it do?
A fan shaped muscle overlying the temporal bone. It insterts into the mandible and acts as a synergist (enhances the effectiveness) of the masseter in closing the jaw
What is the platysma and what does it do?
A single sheet like muscle that covers the anterior lateral neck. It originates from the connective tissue covering of the chest and inserts into the area around the mouth. Its action is to pull the corners of the mouth inferiorly, producing a downward sag of the mouth
How does the sternocleidomastoid muscle work and what does it do?
When they contract, they flex your neck. This allows for the bowing of the head, sometimes called “prayer” muscles
What is the pectoralis major?
A large fan shaped muscle covering the upper part of the chest, its origin is from the shoulder girdle and the first six ribs
How does exhalation work?
The internal intercostal muscles, which lie deep to the external intercostals, depress the rib cage
What are the 4 muscles of the abdominal girdle?
Rectus abdominus, external oblique, internal oblique, transverses abdominis
Where are the trapezius muscles and what do they do?
They extend the head (the opposite of the sternocleidomastoids). They can also elevatem depress, adduct, and stabilize the scapula
What are the latissimus dorsi and what do they do?
Large flat muscles that cover the lower back, extends and adducts the humerus
Why are the latissimus dorsi important?
Are important when the arms must be brought down, like when swimming or sledge hammering
What are the deltoid muscles?
Fleshy, triangle-shaped muscles that form the rounded shape of your shoulders, the origin winds across the shoulder girdle from the spine of the scapula to the clavicle, it inserts into the proximal humerus
What is important about the deltoid muscles?
Because of the bulk sizem they are a favorite location for the injection of small amounts of medications (less than 5ml)
What do the deltoids do?
Prime movers of arm abduction
