musculo-skeletal anatomy making the body move!. goals important muscle groups to know review muscle...
TRANSCRIPT
Musculo-Skeletal Anatomy
Making the body move!
Goals
• Important muscle groups to know
• Review muscle functions, types, and general anatomy
• In-depth look at skeletal muscle:– Connective tissue covering– Skeletal muscle fibers– Neuromuscular junction
Three types of muscle
1. Skeletal
2. Cardiac
3. Smooth
The Anterior
(see handout)
Anterior = “Front”
The Posterior (See handout)
Posterior = “back”
Functions of Muscle
• Producing movement.
• Maintaining posture.
• Stabilizing joints.
• Generating heat.
Characteristics of Muscles (some review, some *new*!)
• Muscle cells are elongated (*muscle cell = muscle fiber)
• *Contraction of muscles is due to the movement of microfilaments
• *All muscles share some terminology– Prefix myo refers to muscle– Prefix mys refers to muscle– Prefix sarco refers to flesh
Skeletal Muscle Characteristics
• *Most are attached by tendons to bones
• Cells have many nuclei
• Striated – have visible banding
• Voluntary – subject to conscious control
• *Cells are surrounded by and bundled by connective tissue
Skeletal Muscle
• Striated, long, cylindrical, multi-nucleated.
• Attached to bones• Voluntarily controlled• * Range of contractile
speed
Cardiac Muscle
• Striated, one nucleus, branching chains of cells, intercalated discs (= dark bands)
• Found only in the heart.• Involuntary contraction.• *Slow speed of
contraction.• *Rhythmic contraction.
Smooth Muscle
• One nucleus, no striations.
• *Found along the walls of blood vessels and digestive canals.
• Involuntary contraction.
• *Very slow contraction.
Skeletal Muscle Attachments
• What structures do muscles attach to?– Bones– Cartilages– **extensions of connective tissue coverings
Connective tissue coverings• Layers of connective tissue enclose and
separate all parts of a skeletal muscle
1.Fascia
2.Epimysium
3.Perimysium
4.Endomysium
FriendsEnjoyProtectingEach other
Fascia
• layers of connective tissue that separate individual skeletal muscles from each other– hold muscles in position– May extend beyond muscle to form:
• Tendon – cord-like structure• Aponeuroses – sheet-like structure
Connective Tissue Wrappings of Skeletal Muscle
• Fascia – on the outside of the epimysium
• Epimysium – covers the entire skeletal muscle
Figure 6.1
Connective Tissue Wrappings of Skeletal Muscle
• Perimysium – around a fascicle (bundle) of fibers
• Endomysium – around single muscle fiber
Figure 6.1
How does the structure of the coverings arrangement allow the muscles to function?
• Structure: layers of connective tissue enclose and separate all parts of a skeletal muscle
• Function: – allows parts to move somewhat independently– Blood vessels and nerves pass through the
layers allows for blood/nutrient supply and stimulation
Review
• Produce movement
• Maintain posture
• Stabilize joints
• Generate heat
• Connective tissue coverings ?
Overall structure of muscle• Muscle
• Fascicles (bundles)
• Muscle fibers (cells)
• Myofibrils
• Thick and thin filaments
Muscle fibers• Definition: single cell that contracts in
response to stimulation, relaxes when stimulation ends
• Thin, elongated cylinder that could extend full length of muscle
Muscle fibers• Cells are multinucleate
• Nuclei are just beneath the sarcolemma
Microscopic Anatomy of Skeletal Muscle
• Sarcolemma – specialized plasma membrane
• Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum
Figure 6.3a
Figure 6.3b
Microscopic Anatomy of Skeletal Muscle
• Myofibril– Bundles of myofilaments– Myofibrils are aligned to give distinct bands
• I band =
light band• A band =
dark band
• Bands make muscle look STRIATED
Microscopic Anatomy of Skeletal Muscle
• Sarcomere– Contractile unit of a muscle fiber– From Z disc to Z disc
Figure 6.3b
Microscopic Anatomy of Skeletal Muscle• sarcomere organization (Section of
myofibrils)– Thick filaments = myosin filaments = dark
band• Composed of the protein myosin• Has ATPase enzymes (for contraction)
Figure 6.3c
Microscopic Anatomy of Skeletal Muscle
• Organization of the sarcomere– Thin filaments = actin filaments = light band
• Composed of the protein actin
Figure 6.3c
Microscopic Anatomy of Skeletal Muscle
• Myosin filaments have heads (extensions, or cross bridges)
• Myosin and actin overlap somewhat
Figure 6.3d
Microscopic Anatomy of Skeletal Muscle
• At rest, there is a bare zone that lacks actin filaments
• Sarcoplasmic reticulum (SR) – for storage of calcium
Figure 6.3d
Modeling activity• In pairs, using the available materials, create a
model of a myofibril segment between 2 M lines.• Include/indicate sarcomere, actin, myosin, 2 M
lines, I band, and A band