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9: Skeletal Muscle Organization, Musculature and Physiology

Integrated Human Anatomy and Physiology Lab Manual I: Fundamentals of Structure and Movement · LibreTexts

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    From LibreTexts, under CC BY-NC 4.0, as the source states it; its equations are written in TeX, which the PDF shows typeset. This page at LibreTexts.

    Introduction

    When most people think of muscles, they think of the muscles that are visible just under the skin, particularly of the limbs. These are skeletal muscles, so-named because most of them move the skeleton. In humans, skeletal muscle comprises approximately 40% of total body weight and contains 50-75% of all body proteins. In this lab, we will focus on the various domains of muscle structure and function including properties, cytoskeletal architecture, excitation-contraction coupling, and force and power generation. In addition, study gross anatomy of a skeletal muscle, including origin, insertion, and action.

    Learning Objectives
    • Identify the key structural components of skeletal muscle tissue under a microscope, including muscle fibers, nuclei, sarcomeres, and the connective tissue layers (epimysium, perimysium, endomysium).
    • Explain the sliding filament theory of muscle contraction and its relationship to the structure of the sarcomere.
    • Describe the different muscle fiber types (fast twitch, slow twitch) and their functional implications.
    • Identify the muscles of the body on a model or image using anatomical terms/vocabulary.
    • Analyze the gross anatomy of a skeletal muscle, including its origin, insertion, and action.

    • 9.1: Background Information
      This page provides a comprehensive overview of skeletal muscles, detailing their roles in movement, posture, and homeostasis, including muscle fiber organization and motor neuron activation at the neuromuscular junction.
    • 9.2: Activity 1
      This page focuses on identifying skeletal muscle structures including epimysium, endomysium, perimysium, and fascicles, along with their labels in an accompanying figure. It highlights the importance of connective tissue sheaths in muscle organization and notes that a printed lab version is required for full participation, as some elements aren't available digitally.
    • 9.3: Activity 2
      This page details the structures of skeletal muscle associated with the elbow joint, including a matching table for terms like origin and insertion. It features a diagram illustrating key musculoskeletal components, highlighting how flexor muscles (e.g., biceps brachii) facilitate arm bending, while extensor muscles (e.g., triceps brachii) enable arm straightening, with arrows indicating movement directions during elbow flexion and extension.
    • 9.4: Activity 3
      This page outlines an interactive role-playing activity that teaches the sliding filament theory of muscle contraction. Students assume roles like actin, myosin, calcium ions, and ATP, utilizing props to illustrate their functions and dynamics. The exercise emphasizes the activation of myosin by calcium ions and the role of ATP in providing energy for contraction. It concludes with a recap of the essential concepts learned during the activity.
    • 9.5: Activity 4
      This page covers the identification and understanding of skeletal muscles in the human body through various educational methods. Students will engage in labeling muscles related to head, arm, and lower limb functions and document their findings. It details key muscles of the upper limb and lower limb, highlighting their origins, insertions, and actions, such as the deltoid and gluteus maximus.
    • 9.6: Activity 5
      This page outlines a lab activity where students examine how temperature impacts handwriting as a fine motor skill. They hypothesize that higher temperatures will improve writing speed and clarity. Participants will engage in writing tasks under different temperature conditions (cold, room, warm) to measure performance. Emphasis is placed on muscle function and coordination, fostering a collaborative and supportive environment for learning.
    • 9.7: Activity 6
      This page explores the impact of muscle fatigue on fine motor skills by analyzing the number of beans moved by participants with their dominant hand before and after inducing fatigue through a fist-holding task. Data from three trials assess performance changes, fostering reflections on how muscle fatigue influences fine motor skills and the types of muscle fibers involved.
    • 9.8: Glossary
      This page provides an overview of critical terms and concepts regarding skeletal muscle structure and function. It defines sarcomeres, myofilaments (myosin and actin), and connective tissues (endomysium, perimysium, epimysium) that support muscle fibers. The page also covers excitation-contraction coupling, the role of acetylcholine at the neuromuscular junction, and the mechanisms of depolarization and action potentials in muscle fibers, essential for understanding muscle contraction.

    Thumbnail: Anatomical illustration of the human muscular system highlighting different muscle fiber arrangements—circular (orbicularis oris), multipennate (deltoid), convergent (pectoralis major), parallel-fusiform (biceps brachii), unipennate (extensor digitorum), bipennate (rectus femoris), and parallel (sartorius)—with labeled locations and directional arrows for reference

    . (CC BY-NC-SA 4.0 ; Rosanna Hartline via LibreTexts).

    This page titled 9: Skeletal Muscle Organization, Musculature and Physiology was last modified on Tue, 01 Sep 2026 01:45:29 GMT and is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Lakshmikanta Sengupta and Susmita Sengupta.