The Muscular SystemPSE 4U
Mr. S. Kelly
North Grenville DHS
Muscle Basics in
Review
• Three main types of muscles
• Skeletal: voluntary and striated (striped appearance under a
microscope)
• Cardiac: of the heart, form the wall of the heart,
involuntary, striated, directed by autonomic nervous system
• Smooth: surround body’s internal organs, involuntary
The musculoskeletal
system
AKA the locomotor system
Allows us to create movement
Comprised of muscles, bones, connective tissues
(ligaments, tendons, joint capsules, cartilage)
Muscular system and skeletal system can be examined
independently but are rarely considered separately
when studying movement, health, and exercise
Naming Muscles
Muscles are named with the following influences:
Action: flexor digitorum, extensor carpi ulnaris
Direction of fibers: rectus abdominus
Location: tibialis anterior
Number of divisions or heads: biceps, triceps
Shape: deltoid, trapezius
Point of attachment: sternocleidomastoid
Muscle pairs
• Muscles are often arranged in pairs… WHY?
• When muscles contract, they PULL on bones to create movement… therefore movement in the OPPOSITE direction requires an OPPOSING muscle (or group of muscles)
• Muscles responsible for a given movement are called agonistor prime mover
• The counteracting muscle (lengthens while agonist contracts) is called the antagonist
• Any complex movements require both agonist, antagonist, and stabilizer muscles working in conjuction
Short List of
Examples
Agonist (prime mover) Antagonist
Biceps brachii Triceps brachii
Deltoids Latissimus Dorsi
Pectoralis major Trapezius / Rhomboids
Rectus Abdominus Erector Spinae
Quadriceps Hamstrings
Gastroc/soleus complex Tibialis Anterior
Muscle Attachments
• Muscles attach to bones directly with the outer muscle
membrane attaching to the outer skeletal membrane
(pretty rare)
• Common form of attachment is indirect, via tendons
• The origin of a muscle is its attachment on the LEAST
moveable of the attachment sites
• The insertion of a muscle is its attachment on the
MORE moveable of the attachment sites
A look at the Muscle
Muscle Anatomy and
Terms
• Muscle fiber: a basic unit of skeletal muscle
• Endomysium: sheath of tissue covering each muscle fiber
• Fascicle (fasciculus): bundle of skeletal muscle fibers
• Perimysium: sheath of tissue that groups muscle fibers into fascicles
• Epimysium: tissue that envelopes the entire muscle (changes properties, tensile strength as it transitions from muscle to tendon)
Levels of Skeletal
Muscle Anatomy
Muscle Fiber
anatomy and terms
• Sarcolemma: cell membrane directly beneath the endomysium, contains cell’s cytoplasm
• Sarcoplasm: skeletal muscle cell’s cytoplasm
• This differs from cytoplasm of other cells in that it contains higher conc. of stored glycogen, myoglobin, Ca, mitochondria
• Myofibrils: thread-like structures running the length of the muscle fibe
• Sarcomeres: repeating structural compartments along myofibril; contain myosin and actin
Levels of muscle
anatomy
Proteins and
filaments
• Myosin: looks a bit like a golf club, possesses a head
and a tail; head has a binding site for actin
• Actin: possesses binding site for myosin head, also has
two other proteins…
• Troponin: has a binding site for calcium
• Tropomyosin: cord-like structure, resembles a string,
covers binding site on actin filament
Next…
• Sliding Filament Theory
• Neuromuscular system
• Excitation-contraction coupling
• Muscular system lab… may be in conjunction with
energy systems…