Muscular System Basics

Muscular System
The muscular system consists of all the muscles of the body, approximately 42% of your total body weight.

Muscles cause movement, maintain posture, and produce heat.
There are 3 types, classified according to function and appearance: cardiac, skeletal, and smooth.

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3 types of Muscle

All muscle fibers are elongated

The myocardium, or cardiac muscle, is striated (horizontal markings). They are striated and interconnected through branches. They are stimulated to contract by electrical impulses sent out from small clumps of specialized tissue in the heart - the sinoatrial (SA) and atrioventricular (AV) nodes.
Contractions are rhythmic (60-100 bpm) and involuntary, all-or-nothing contractions.
The heart pumps blood to the lungs and to the body.

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Cardiac Muscle

Smooth muscle tissue is involuntary and lacks striation. There are two types of smooth muscle: multi-nucleate and visceral.
Multi-unit smooth muscle has a rapid and vigorous contraction. It is found in the irises of the eye and blood arteries. Visceral tissue creates slow and sustained contractions most often in a wave-like motion called peristalsis. These repeated contractions are usually rhythmic and help to push things through pathways of hollow organs.

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Smooth Muscle

Skeletal muscle fibers are striated and multinucleated. Muscles are under voluntary control and contract rapidly. Skeletal muscles are responsible for whole-body movement as well as overall posture maintenance, joint stability, and the production of body heat. Functionally, skeletal muscles are capable of responding to stimuli (excitability), shortening their length (contractility), stretching/extending (extensibility), and the ability to return to their normal shape (elasticity).​

Skeletal Muscle

Multiple Choice

What type of muscle lines the inside of the stomach?

• cardiac

• skeletal

• smooth

Multiple Choice

What type of muscle is/are voluntary?

• smooth and cardiac

• smooth

• skeletal and smooth

• skeletal

Multiple Choice

What type of muscle(s) is involuntary?

• skeletal and smooth

• cardiac and skeletal

• smooth and cardiac

• skeletal

Multiple Choice

What type of muscle is not banded or striated?

• cardiac

• skeletal

• smooth

• Circumferential

Multiple Choice

What type of muscle makes up your heart?

• Cardiac

• Skeletal

• Smooth

• Canulary

Multiple Choice

Which muscle tissue has muscle cells that are highly branched and interconnected?

• Cardiac

• Smooth

• Skeletal

• Visceral

Multiple Choice

Which muscle tissue is located inside blood vessels?

• Cardiac

• Smooth

• Skeletal

• Vestibular

Multiple Choice

Which muscle tissue would be responsible for chewing food?

• Smooth

• Skeletal

• Cardiac

• Vestibular

Multiple Choice

What type of muscle tissue is this?

• cardiac

• skeletal

• smooth

Each skeletal muscle is an organ made up of thousands of muscle fibers, connective tissue coverings, blood vessels, and nerve fibers.

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Skeletal Muscle Anatomy

Multiple Choice

A bundle of muscle fibers is a

• muscle

• fascicle

• myofibril

• sarcomere

Each muscle fiber (elongated cell) is wrapped in a thin, delicate layer of connective tissue (CT) called endomysium. Many muscle fibers are bundled together into groups called fascicles. Each fascicle is wrapped in a second layer of CT made of collagen called perimysium. Then, each skeletal muscle is covered in a third layer of dense, fibrous CT called the epimysium. Finally, individual muscles are then covered in a fourth, very tough, layer of CT called the deep fascia. Deep fascia may extend past the length of the muscle and attach to bone.
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Connective Tissue Wrappings

Multiple Choice

The connective tissue that surrounds each fascicle is called?

• Fascia
• Epimysium
• Perimysium
• Endomysium

Multiple Choice

The connective tissue that is found on the outer covering of the muscle is called?

• Fascicle

• Epimysium

• Perimysium

• Endomysium

When the epimysium of a muscle is fused to the periosteum of a bone or perochondrium of cartilage it is a direct (fleshy) attachment. When the muscle fascia extends beyond the length of the muscle as a rope-like tendon or a sheet-like aponeurosis, it is an indirect attachment. Indirect attachments anchor the muscle to the CT covering of a bone, cartilage, or another muscle.
The origin of a muscle is its immovable end. The insertion of a muscle is its movable end. When a muscle moves, its insertion end is pulled toward its origin.

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Skeletal Muscle Attachments

Multiple Choice

Muscle to bones are known as

• Tendon

• Ligament

• Aponeurosis

• Muscle Fibers

Multiple Choice

Attachment of skeletal Muscles to Other skeletal Muscles

• Tendon

• Ligament

• Aponeurosis

• Muscle Fiber

Multiple Choice

From smallest to largest, which list of muscle components is in the correct order?

• Myofilaments

  Muscle FIber

  Fascicle

  Muscle Tissue

• Muscle Fiber

  Myofilaments

  Fascicle

  Muscle Tissue

• Myofilaments

  Fascicle

  Muscle Fiber

  Muscle Tissue

• Muscle FIber

  Fascicle

  Myofilaments

  Muscle Tissue