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Chapter 10: The Muscular System Overview

  • Human Anatomy and Physiology Eleventh Edition

  • PowerPoint® Lectures prepared by Karen Dunbar, Ivy Tech Community College

  • Copyright © 2019, 2016, 2013 Pearson Education, Inc.

Skeletal Muscles: Functional Groups

  • Prime Movers:

    • Major force for a specific movement.

  • Antagonists:

    • Oppose or reverse particular movements.

  • Synergists:

    • Add force to a movement and reduce undesirable movements.

  • Fixators:

    • Immobilize bone or muscle’s origin.

Naming Skeletal Muscles

  • Location: Associated bone/body region.

  • Shape: e.g. Deltoid is triangular.

  • Relative Size: e.g. Maximus (largest), Minimimus (smallest), Longus (long).

  • Fiber Direction: e.g. Rectus (straight), Transversus, Oblique.

  • Number of Origins: e.g. Biceps (2), Triceps (3).

  • Attachments: Named by point of origin/insertion.

  • Action: e.g. Flexors contract or extensors stretch.

Muscle Mechanics: Arrangement of Fascicles

  • Circular: Concentric rings (e.g. Orbicularis Oris).

  • Convergent: Converge toward a single tendon (e.g. Pectoralis Major).

  • Parallel: Parallel to muscle's long axis (e.g. Sartorius).

  • Fusiform: Spindle-shaped with parallel fibers (e.g. Biceps Brachii).

  • Pennate: Short fascicles attach obliquely to a central tendon (e.g. Rectus Femoris).

Lever Systems

  • Components:

    • Lever: Rigid bar (bone) moving on a fulcrum (joint).

    • Effort: Force applied by muscle contraction.

    • Load: Resistance moved by effort.

  • Mechanical Advantage: Power lever allows heavy load movement with less effort.

  • Classes of Levers:

    • First Class: Fulcrum between load and effort (e.g. head lifting).

    • Second Class: Load between fulcrum and effort (e.g. toe standing).

    • Third Class: Effort between fulcrum and load (e.g. flexing forearm by biceps).

Major Skeletal Muscles

  • Grouped by function/location with details:

    • Names, origin/insertion, actions, and innervation.

Muscles of the Head

  • Facial Expression: Insert into skin; innervated by cranial nerve VII (facial nerve).

  • Muscles of Mastication: Involved in jaw closure; innervated by cranial nerve V (trigeminal nerve).

Muscles of Anterior Neck and Throat

  • Two groups involved in swallowing:

    • Suprahyoid: Move hyoid/larynx, form oral cavity floor.

    • Infrahyoid: Depress hyoid/larynx during talking/swallowing.

Muscles of the Neck and Vertebral Column

  • Functional groups:

    • Head Movement: Sternocleidomastoid, suprahyoid, infrahyoid, scalene muscles.

    • Trunk Extension: Erector spinae group (Iliocostalis, Longissimus, Spinalis).

  • Maintains posture and extends the trunk.