Chapter 6: Getting in Gear: The Muscles Summary

Myology is the study of muscles.

Muscles are the fleshy parts of the skeleton.

Muscle cells referred to as fibers are the longest cells in the body.

Fibers are connected by the connective tissue and covered by the sheath.

Function of muscles

1. Movement: skeletal muscles produce mechanical work from chemical energy. The muscles contract to produce movement which ranges from tapping of a finger to kicking of a ball. The most powerful movements require many muscles to work together.
2. Antigravity:  Muscles allow movement and standing against gravity.
3. Vital functions: muscles carry out involuntary body functions like heartbeats, constriction of blood vessels, and peristalsis.
4. Generation of heat: Te chemical reactions in muscles release heat which regulates the body temperature. 
5. Keeping the body together: Muscle structures bind one body part to another.

Muscle development processes

Myogenesis is the process through which muscle tissues are generated.

Morphogenesis is the formation of muscles in internal organs.

Classification of muscles

1. Smooth muscle: This muscle tissue forms sheets that line the surfaces of hollow organs. The muscle lacks cross -striations. It produces low involuntary movements and extended contractions.
2. Cardiac muscle: it is located in the heart walls.  Cardiac muscle fibers are cross striated branched and move involuntarily.
3. Skeletal muscle: It is the muscle tissue that moves voluntarily through the central nervous system coordination. It contains long cylindrical striated fibers that contract easily but tire faster also. The muscle contains 25%  protein, 5% inorganic and organic material, and 75% water.

Muscle contraction

The muscle contraction sliding theory shows that myosin from thick filaments attaches to actin from thin filaments to form actomyosin.

 This makes filaments to slide past each other.

In this process, H-zone reduces, Z-lines are pulled near each other, and I-bands are reduced.

Contraction finally takes place.

Muscle organ

• It consists of two parts:
  • The belly which contains muscle fibers.
  • Tendons which have fibrous regular connective tissue.
• Endomysium is the areolar connective tissue that surrounds every muscle fiber outside the sarcolemma.
• Fasciculi are bundles formed by binding fibers together using endomysium.
• The belly is formed by a group of fasciculi.
• Epimysium is the areolar connective tissue that surrounds the belly.
• Trabecular is the connective tissue through which lymph vessels and blood vessels pass into the fasciculus.

How muscle contraction relate to tone

• Isometric: It happens when a contracting muscle cannot move any mass or luggage.
  • It maintains its initial length but induces tension.
  •  There is no mechanical work and the produced energy is released as heat.
• Isotonic: It takes place when the load faces resistance. Very little tension is produced.

Directions for muscle movement

• Longitudinal: This is where muscle fibers move parallel to one another or longitudinal to the muscle length.
• Pennate: this happens when muscles bind to the tendon sides and extend the muscle length. It has the following subcategories:
  • Unipennate: fibers bind to a single side of a tendon.
  • Bipennate: two sides of the tendon has fibers bound.
  • Multipennate: Many sides of the tendons has fibers bound.
• Radiate: fibers converge at a central point from a broad area.
• Sphincter: It contains fibers arranged around an opening in a circle.

Types of fasciae

• Superficial fisciae
• Deep fasciae
• Subserous fasciae

Revision

Trapezius
a pair of large triangular muscles extending over the back of the neck and shoulders and moving the head and shoulder blade.

deltoid
each of the three parts of a deltoid muscle, attached at the front, side, and rear of the shoulder.

wrist extensors
extends and abducts the wrist towards the ulna.

wrist flexors
six muscles in the anterior compartment of the forearm that act on the wrist and finger joints. As a group, the primary action of the wrist flexors is flexion

gluteus maximus
any of three muscles in each buttock that move the thigh, the largest of which is the gluteus maximus.

latissimus dorsi
either of a pair of large, roughly triangular muscles covering the lower part of the back, extending from the sacral lumbar, and lower thoracic vertebrae to the armpits.

erector spinae
a large muscle that originates near the sacrum and extends vertically up the length of the back. It lies on each side of the vertebral column and extends alongside the lumbar, thoracic and cervical sections of the spine.

adductors
a muscle whose contraction moves a limb or other part of the body toward the midline of the body or toward another part.

semimembranosus
a large muscle of the inner part and back of the thigh that arises by a thick tendon from the back part of the tuberosity of the ischium, is inserted into the medial condyle of the tibia, and acts to flex the leg and rotate it medially and to extend the thigh.

gastrocnemius
he chief muscle of the calf of the leg, which flexes the knee and foot. It runs to the Achilles tendon from two heads attached to the femur.

biceps femoris
the muscle in the back of the thigh that helps to flex the leg.

semitendinosus
muscle of the posterior and inner part of the thigh that arises from the ischial tuberosity along with the biceps femoris, that is inserted by a long round tendon which forms part of the inner hamstring into the inner surface of the upper part of the shaft of the tibia, and that acts to flex the leg

teres major
either of two muscles passing below the shoulder joint from the scapula to the upper part of the humerus, one (teres major) drawing the arm toward the body and rotating it inward, the other (teres minor) rotating it outward.

infraspinatus
a muscle that occupies the chief part of the infraspinous fossa of the scapula, is inserted into the greater tubercle of the humerus, and rotates the arm laterally.

triceps brachii
ny of several muscles having three points of attachment at one end, particularly also triceps brachii, the large muscle at the back of the upper arm.

pectoralis major
hick, fan-shaped muscle, situated at the chest (anterior) of the human body. It makes up the bulk of the chest muscles in the male and lies under the breast in the female.

biceps brachii
the large muscle in the upper arm that turns the hand to face palm uppermost and flexes the arm and forearm.

sartorius
a long, narrow muscle running obliquely across the front of each thigh from the hipbone to the inside of the leg below the knee.

rectus abdominis
each of a pair of long flat muscles at the front of the abdomen, joining the sternum to the pubis and acting to bend the whole body forward or sideways.

external oblique
the largest and the most superficial (outermost) of the three flat muscles of the lateral anterior abdomen.

vastus lateralis
the largest and the most superficial (outermost) of the three flat muscles of the lateral anterior abdomen.

vastus medialus
a muscle present in the anterior compartment of thigh, and is one of the four muscles that make up the quadriceps muscle.

soleus
a broad muscle in the lower calf, below the gastrocnemius, that flexes the foot to point the toes downward.

tibialis anterior
is a muscle that originates in the upper two-thirds of the lateral (outside) surface of the tibia and inserts into the medial cuneiform and first metatarsal bones of the foot.

tensor facia latae
a muscle that arises especially from the anterior part of the iliac crest and from the anterior superior iliac spine, is inserted into the iliotibial band of the fascia lata about one third of the way down the thigh, and acts to flex and abduct the thigh.

serratus anterior
is a muscle that originates on the surface of the 1st to 8th ribs at the side of the chest and inserts along the entire anterior length of the medial border of the scapula.

A movement which brings a limb – arm or leg – away from the body is ________.
Abduction

This means that the muscle can function under your control of it.
Voluntary

The russian twist exercise or side planks helps to strengthen which muscle?
External Obliques

What is an area of discolored skin that appears after an injury causing blood vessels to rupture beneath the skin and leak?
Bruise

The tough tissue that attaches a muscle to bone is a ____________.
Tendon

The muscle that raises your eyebrows is the _________.
Frontalis

A hereditary disorder in which muscle fibers are progressively destroyed and has no cure is __.
Muscular Dystrophy

The muscle that opens and closes the jaw is the __________.
Masseter

A muscle that flexes the forearm or elbow joint is a ________
Biceps

The action of closing or shortening muscle fibers at a joint is ___________.
Contraction

The natural tension in the fibers of a muscle is ___________.
Muscle Tone

The muscle that is strengthened through the exercise of sit-ups is called the ____.
Rectus Abdominis

The muscle type that attaches to bone and provides body movement is the __________ muscle.
Skeletal

The muscle that rotates the head and neck is the ___________.
Sternocleidomastoid

What is the muscle type that lines the walls of your blood vessels?
Smooth

When an organ or tissue protrudes through an area of weak muscle is a _______.
Hernia

This is the result of when a muscle pulled because it is stretched or partially torn due to overexertion.
Muscle Strain

The action of opening or lengthening muscle fibers at a joint is _________.
Extension

The best treatment for a cramp is to massage the muscle, stretch, and increase levels of what mineral?
Potassium

What are the 3 main functions of the Muscular System?
Maintenance of Posture, Movement, Production of Body Heat

What type of exercise gets your heart rate up?
Aerobic Exercise

What is the muscle that is being strengthened through the exercise “calf raises?”
Gastrocnemius

A movement which brings a limb – arm or leg – closer towards the body is __________.
Adduction

The bench press exercise helps to strengthen the ________ muscle best.
Pectoralis Major

The ________ muscle is the only type of muscle that is voluntary.
Skeletal

When your muscles become weaker and decrease in size and strength due to the lack of use over a period of time they begin to ____________.
Atrophy

The muscle type that allows your heart to contract and beat is the _____ muscle.
Cardiac

The muscle that extends the forearm is the ___________ muscle.
Triceps

The exercise “curls” is an example of an exercise that strengthens which muscle?
Biceps

Inflammation of a tendon is ______________.
Tendonitis

The type of muscle that is found in the esophagus is the ________ muscle.
Smooth