Muscular System – SPO #1 Using specimens, models, and/or diagrams, describe and identify the following components of skeletal muscle: Muscle belly Epimysium Perimysium Fascicle Endomysium Muscle Fiber/cell Tendon

Skeletal Muscle Organization & Structure Skeletal muscle is a bundle of skeletal muscle fibers wrapped in connective tissue layers: Epimysium Dense layer of collagen fibers surrounding entire muscle Perimysium Fibrous layer dividing skeletal muscle into bundles of fibers called muscle fascicles Endomysium Delicate connective tissue surrounding individual muscle fibers/cells

Organization of skeletal muscle

Organization of skeletal muscle

Skeletal Muscle Fiber Structure Contain hundreds of nuclei Filled with cylindrical structures called myofibrils: Packed with myofilaments: Thin filaments composed mostly of actin Thick filaments composed primarily of myosin Banded appearance of myofibrils gives entire fiber a striated look

Striations of skeletal muscle

Structure of a skeletal muscle fiber Nuclei Myofibrils Sarcoplasm Mitochondria Sarcolemma Skeletal muscle fiber Myofibril Sarcoplasmic reticulum Thick filament Thin filament A skeletal muscle contains skeletal muscle tissue,connective tissues, blood vessels, and nerves

Attachment of Skeletal Muscle - Tendons Collagen fibers of connective tissue layers in skeletal muscle extend beyond muscle at end Bundle of fibers is tendon Tendon attaches muscle to bone Sheet of fibers is aponeurosis Aponeurosis attaches muscle to broader area Collagen fibers extend into bone matrix

Muscle fibers are attached to tendons Epimysium Myofibrils Endomysium The sliding filament theory explains the physical changes that occur during a contraction Muscle fiber Tendon Perimysium

Tension Transmitted to Bone Myofilaments attached to end of muscle fiber Muscle fibers attached to tendons attached to bone Sarcomere contraction reflected out to entire skeletal muscle Result is movement of bone

Skeletal Muscle and Tendon

Muscular System – SPO #2 Define the following terms and use them appropriately as they apply to the parts of muscles and the roles that muscles play during a body movement: Origin Insertion Prime mover/Agonist Antagonist Synergist Fixator

Skeletal Muscle Functional Terms Origin: Where fixed end of skeletal muscle attaches Insertion: Where movable end of skeletal muscle attaches Action: Specific movement of a skeletal muscle

Origin and insertion of skeletal muscles Origins of biceps brachii muscle Action Insertion of biceps The names of muscles provide clues to their appearance and/or function

Functional Description of Skeletal Muscles Prime mover or Agonist Responsible for producing particular movement Example: biceps brachii in bending elbow Antagonist: Opposes action of agonist Example: triceps brachii in bending elbow Synergist: Helps agonist work efficiently by providing additional pull or stability Example: brachioradialis in bending elbow Fixator: Acts to stabilize the origin of the agonist (and the joint it moves over) in order to help the agonist function more effectively Example: trapezius and rhomboids during flexion of biceps brachii

Skeletal muscles may be described by their functions Agonist, or prime mover, in bending the elbow Synergist helps the agonist and stabilizes the elbow joint Insertion of brachioradialis muscle Antagonist in bending the elbow Origin of The names of muscles provide clues to their appearance and/or function

Biceps brachii

During Flexion of Biceps brachii – Trapezius & Rhomboid major act as FIXATORS

Muscular System – SPO #3 Describe the following muscle actions: - Flexion - Extension - Abduction - Adduction - Rotation - Circumduction - Pronation - Supination - Inversion - Eversion - Dorsiflexion - Plantar flexion - Protraction - Retraction - Hyperextension - Elevation - Depression * Refer to APR video for additional examples

Specific Flexion Terms Lateral flexion: When vertebral column bends to side Dorsiflexion: Flexion at ankle joint involving elevation of sole of foot (toes pointing upwards) Plantar flexion: Extension at ankle joint (toes pointing downward)

Lateral flexion of the head Broad descriptive terms are used to describe movements with reference to the anatomical position

Dorsiflexion and plantar flexion flexion (ankle extension) Dorsiflexion (ankle flexion) Broad descriptive terms are used to describe movements with reference to the anatomical position

Abduction and Adduction Refers to movement of appendicular skeleton: Abduction: Movement away from longitudinal axis Spreading fingers or toes (moving away from midline) Adduction Movement toward longitudinal axis Bringing fingers or toes together (moving toward midline)

Abuction and adduction Abduction Broad descriptive terms are used to describe movements with reference to the anatomical position

Circumduction Tracing large circle with hand while keeping arm straight Movement occurring at shoulder called circumduction

Circumduction Broad descriptive terms are used to describe movements with reference to the anatomical position

Rotation Rotation can be of trunk or limbs: Trunk directional terms with reference to anatomical position Left rotation (looking to left) Right rotation (looking to right) Limbs Medial rotation or internal or inward rotation Anterior surface of limb turned toward trunk Lateral rotation or external or outward rotation Opposite movement

Rotational movements in the body Right rotation Left Lateral (external) Medial (internal) Terms of more limited application describe rotational movements and special movements

Movement at Proximal Radio-Ulnar Joint Rotation of radial head causing rolling of distal epiphysis of radius across anterior surface of ulna: Pronation Turning wrist and hand from palm facing front to palm facing back Supination Turning wrist and hand from palm facing back to palm facing front

Supination and pronation of the arm Terms of more limited application describe rotational movements and special movements

Special Movements Opposition: Movement of thumb toward palm or pads of other fingers Inversion and eversion involve twisting motion of foot: Inversion turning sole inward; eversion turning sole outward

Special Movements Protraction and retraction: Protraction moving body part anteriorly in horizontal plane Retraction moving body part posteriorly in horizontal plane Depression and elevation: Depression moving in inferior direction; elevation moving in superior direction

Special movements Opposition Retraction Protraction Eversion Inversion Terms of more limited application describe rotational movements and special movements Depression Elevation

Muscular System – SPO #4 Identify the following reasons for naming muscles and site at least one example for each. Location Shape Size of muscle Direction of muscle fiber Number of heads Location of origin and/or insertion Action

The names of muscles provide clues to their appearance and/or function

Naming Muscles Skeletal muscles named according to: Region of body (femoris = thigh) Position (posterior = back) Nature of origin (biceps = two heads) Shape (deltoid = triangle) Size (maximus = largest) Action (flexor = bending movement)

Muscular System – SPO #5 Using microscope images, models, and/or illustrations, identify and describe the structure of the following types of muscle tissue and the listed components: Smooth Cardiac Skeletal Striations Intercalated disc

Muscle Tissue One of the four primary tissue types Specialized for contraction Three types: Skeletal muscle tissue Cardiac muscle tissue Smooth muscle tissue

Types of muscle tissue Skeletal Muscle Tissue Cardiac Muscle Tissue Smooth Muscle Tissue Functional Anatomy of Skeletal Muscle Tissue

What Type of Muscle Tissue Is It?

What Type of Muscle Tissue Is It?

What Type of Muscle Tissue Is It?

What Type of Muscle Tissue Is It?

Muscle Tissue Types Skeletal muscle: Cardiac muscle: Smooth muscle: Moves the body by pulling on bones of skeleton Cardiac muscle: Found only in the heart Propels blood Smooth muscle: Moves fluid and solids along digestive tract Regulates diameter of small arteries