Muscle Types from Seeley's Anatomy 10th Edition

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)