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Questions and Answers
What is the primary role of the T tubules in muscle fibers?
What is the primary role of the T tubules in muscle fibers?
Which property of muscles refers to the ability to respond to a stimulus?
Which property of muscles refers to the ability to respond to a stimulus?
Which connective tissue layer surrounds an entire skeletal muscle?
Which connective tissue layer surrounds an entire skeletal muscle?
What are myofibrils primarily composed of?
What are myofibrils primarily composed of?
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Which of the following muscle types is associated with features such as striations and voluntary control?
Which of the following muscle types is associated with features such as striations and voluntary control?
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Which characteristic is unique to skeletal muscle compared to cardiac and smooth muscle?
Which characteristic is unique to skeletal muscle compared to cardiac and smooth muscle?
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What type of muscle is characterized by branching chains of cells and the presence of intercalated discs?
What type of muscle is characterized by branching chains of cells and the presence of intercalated discs?
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Which type of muscle is primarily found in the walls of hollow visceral organs?
Which type of muscle is primarily found in the walls of hollow visceral organs?
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How do skeletal muscles differ from cardiac muscles in terms of contraction regulation?
How do skeletal muscles differ from cardiac muscles in terms of contraction regulation?
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Which of the following statements about muscle contraction speed is accurate?
Which of the following statements about muscle contraction speed is accurate?
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Study Notes
Book Information
- Title: Seeley's Essentials of Anatomy & Physiology
- Edition: Tenth
- Authors: Cinnamon Vanputte, Jennifer Regan, Andrew Russo
- Publisher: McGraw-Hill Education
- Note on figures and tables: Separate PowerPoint slides are available for figures and tables, pre-inserted into PowerPoint without notes.
Types of Muscles
-
Skeletal:
- Attached to bones
- Striated
- Voluntarily controlled
-
Cardiac:
- Located in the heart
- Striated
- Involuntarily controlled
-
Smooth:
- Located in blood vessels and hollow organs
- Non-striated
- Involuntarily controlled
Comparison of Muscle Types
- Characteristics | Skeletal | Cardiac | Smooth
- --|---|---|---
- Body location | Attached to bones or facial muscles | Walls of the heart | Mostly in walls of hollow visceral organs
- Cell shape and appearance | Single, long, cylindrical, multinucleate, striations very obvious | Branching chains of cells, uninucleate, striations; intercalated discs | Single, fusiform, uninucleate, no striations
- Connective tissue components | Epimysium, perimysium, and endomysium | Endomysium, attached to fibrous skeleton of the heart | Endomysium
- Regulation of contraction | Voluntary, via nervous system control | Involuntary; heart has pacemaker, nervous system control, hormones | Involuntary; nervous system controls, hormones, chemicals
- Speed of Contraction | Slow to fast | Slow | Very slow
- Rhythmic contraction | No | Yes | Yes, in some
Properties of Muscles
- Contractility: The ability of muscle to shorten forcefully or contract.
- Excitability: The capacity of muscle to respond to a stimulus.
- Extensibility: The ability to be stretched beyond resting length and still contract.
- Elasticity: The ability of the muscle to recoil to its original resting length after being stretched.
Skeletal Muscle Structure
- Skeletal muscle (or striated muscle) composes approximately 40% of body weight.
- It's attached to the skeletal system.
- Some attach to skin or connective tissue sheets.
- Called "striated" muscle due to transverse bands (striations).
Connective Tissue Coverings
- Epimysium: Connective tissue sheath surrounding each skeletal muscle.
- Perimysium: Surrounds fascicles (groups of muscle cells).
- Endomysium: Surrounds each skeletal muscle cell (fiber).
Muscle Fiber Structure
- Single cylindrical cells with multiple nuclei located at the periphery.
- Length ranges from 1 cm to 30 cm and are generally 0.15 mm in diameter.
- Nuclei located at the fiber's periphery.
- Sarcolemma (cell membrane) has many tube-like inward folds (transverse tubules or T tubules).
- T tubules occur at regular intervals and extend into the fiber's center.
- Associated with enlarged portions of the smooth endoplasmic reticulum (sarcoplasmic reticulum).
- Enlarged portions are called terminal cisternae.
- T tubules connect the sarcolemma to terminal cisternae to form muscle triads.
- Sarcoplasm - cytoplasm of a muscle fiber containing bundles of protein filaments.
- Myofibrils are protein filament bundles.
- Myofibrils consist of myofilaments (actin and myosin).
Muscles of the Head and Neck
- Facial muscles
- Mastication (chewing) muscles
- Swallowing muscles
- Eye muscles
- Head and neck muscles
Specific Muscles or Groups
(Examples, see the original texts for complete lists)
- Buccinator (cheek muscle)
- Masseter (chewing)
- Temporalis (chewing)
- Pterygoid (chewing)
- Various eye, swallowing, and facial muscles
- Sternocleidomastoid (neck)
- Platysma (neck)
- Trapezius (neck and shoulders)
- Muscles of the tongue and swallowing
- Neck flexors and extensors
- Deep back muscles
Trunk Muscles
- Vertebral column
- Thorax
- Abdominal wall
- Pelvic floor
- Erector spinae (extends vertebral column)
- Iliocostalis, longissimus, spinalis (components of erector spinae)
Thoracic Muscles
- Scalenes (elevates ribs)
- External intercostals (elevate ribs)
- Internal intercostals (depress ribs)
- Diaphragm (quiet breathing)
Abdominal Wall Muscles
- Rectus abdominis
- External abdominal oblique
- Internal abdominal oblique
- Transverse abdominis (all compress the abdomen)
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Description
Test your knowledge of the three types of muscles: skeletal, cardiac, and smooth, as described in Seeley's Essentials of Anatomy & Physiology. This quiz covers their characteristics, locations, and control mechanisms, guiding you through essential concepts in human anatomy.
