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There are also skeletal muscles that do not pull against the skeleton for movements. For example, there are the muscles that produce facial expressions. The insertions and origins of facial muscles are in the skin, so that certain individual muscles contract to form a smile or frown, form sounds or words, and raise the eyebrows. There also are skeletal muscles in the tongue, and the external urinary and anal sphincters that allow for voluntary regulation of urination and defecation, respectively. In addition, the diaphragm contracts and relaxes to change the volume of the pleural cavities but it does not move the skeleton to do this.

Everyday connections

Exercise and stretching

When exercising, it is important to first warm up the muscles. Stretching pulls on the muscle fibers and it also results in an increased blood flow to the muscles being worked. Without a proper warm-up, it is possible that you may either damage some of the muscle fibers or pull a tendon. A pulled tendon, regardless of location, results in pain, swelling, and diminished function; if it is moderate to severe, the injury could immobilize you for an extended period.

Recall the discussion about muscles crossing joints to create movement. Most of the joints you use during exercise are synovial joints, which have synovial fluid in the joint space between two bones. Exercise and stretching may also have a beneficial effect on synovial joints. Synovial fluid is a thin, but viscous film with the consistency of egg whites. When you first get up and start moving, your joints feel stiff for a number of reasons. After proper stretching and warm-up, the synovial fluid may become less viscous, allowing for better joint function.

Patterns of fascicle organization

Skeletal muscle is enclosed in connective tissue scaffolding at three levels. Each muscle fiber (cell) is covered by endomysium and the entire muscle is covered by epimysium. When a group of muscle fibers is “bundled” as a unit within the whole muscle by an additional covering of a connective tissue called perimysium, that bundled group of muscle fibers is called a fascicle    . Fascicle arrangement by perimysia is correlated to the force generated by a muscle; it also affects the range of motion of the muscle. Based on the patterns of fascicle arrangement, skeletal muscles can be classified in several ways. What follows are the most common fascicle arrangements.

Parallel muscles have fascicles that are arranged in the same direction as the long axis of the muscle ( [link] ). The majority of skeletal muscles in the body have this type of organization. Some parallel muscles are flat sheets that expand at the ends to make broad attachments. Other parallel muscles are rotund with tendons at one or both ends. Muscles that seem to be plump have a large mass of tissue located in the middle of the muscle, between the insertion and the origin, which is known as the central body. A more common name for this muscle is belly    . When a muscle contracts, the contractile fibers shorten it to an even larger bulge. For example, extend and then flex your biceps brachii muscle; the large, middle section is the belly ( [link] ). When a parallel muscle has a central, large belly that is spindle-shaped, meaning it tapers as it extends to its origin and insertion, it sometimes is called fusiform    .

Questions & Answers

what are the musles which are found at the forearm
Magembe Reply
Brachioradialis,Flexo capi radialis,Flexor digitorum profundus,Flexor pollicis longus, Extensor digitorum,,Extensor capiradialis longus and brevis.
Titus
where are skeletal muscle located?
Gildas Reply
Are attached at the bone via tendons
Fatuma
what are the bone found into the ear and their function
Justinian Reply
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Nadine Reply
what is anatomy
ORIATO Reply
How can one understands muscles
ORIATO
Human Anatomy:is the study structure of the body
Abba
WHO Discovered Anatomy
Abba Reply
Vesalius
Shikha
what causes the breathing in of air?
Phoka Reply
what is synergist
Flora Reply
hello
Kawsar
working together
Gerhaldish
means connective
Happy
embryonic development of the heart
wamaitha Reply
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Nadine
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Nadine
w͚h͚a͚t͚ a͚n͚ a͚n͚a͚t͚o͚m͚y͚
Nadine
pharmacology what is it?
Symon
The study of drugs, their chemical and physical properties, their biological and therapeutic effect on the body and also their metabolism within the body and finally how the drug gets excreted from the body.
dr
Study of substances that interact with living systems through chemical processes especially by binding to regulatory molecules and activating or inhibiting body processes
Victor
Roles of cytokines in regulating immune system in the body
Gift Reply
define pharmarcology
HAUWA Reply
pharmacology can be defined as science of drugs and their uses
Lawal
structural mechanism of muscle contraction
warda Reply
descrete body system
Ujunwa Reply
I am paramedic student
Abid
I want to be a doctor but due to poverty I could afforded fees
Abid
there how many systems of the body.?
Phabian Reply
11
Orsine
a͚m͚ a͚ m͚e͚d͚i͚c͚a͚l͚ nurse
Nadine
11
Nadine
what's is reganal anatomy
Sose Reply
it is the study of interrelationships between different organs in a certain region of the body e.g abdomen
Taurai
this helps understand how these different organs work together to serve a particular body region
Taurai

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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