Muscular System Overview
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Module: Support and Movement
Activity: Anatomy Overviews
Title: Muscular System: Overview
1. Click the Skeletal Muscle Cross Section and identify each of
the following. Consult your textbook for a description of
each.
Epimysium
the connective tissue that surrounds the entire muscle at the
outermost layer of the muscle.
Deep Fascia
connective tissue with dense irregular tissue that lines the body
wall and limbs.
Muscle Cell
muscle fibers that are elongated and striated and
multinucleated. A skeletal muscle fiber is actually embryonic
cells that have fused together to form one large cell with multiple
nuclei.
Perimysium
dense regular connective that surrounds the fascicles.
Myofibril
a threadlike structure, extending longitudinally inside a muscle fiber or cell consisting mainly of thick
filaments (myosin) and thin filaments (actin, troponin, and tropomyosin).
Filament small structures within the myofibril.
It contains thin and thick filaments.
Sarcolemma
the cell membrane of a muscle fiber(cell), especially of a skeletal muscle fiber.
Endomysium
Loose connective tissue that separates each individual muscle fiber within a muscle bundle.
Fascicle
a small bundle or cluster, especially of nerve or muscle fiber (cell). Also called fasciculus.
Tendon
a white fibrous cord of dense regular connective tissue that attaches muscle to bone.
Bone (radius)
a bone of upper limb distal to the humerus.
Periosteum
the membrane that covers the outer layers of the bone. This consists of connective tissue, osteogenic
cells, osteoblast. These are essential for bone growth, repair and nutrition.
2. Using your textbook, define an aponeurosis.
A sheet- like tendon joining one muscle with another or with bone.
3. Identify each of the following:
Biceps brachii
Tendon
Radius
Describe arm movement (flexion) when filaments are contracted.
When the filaments of biceps brachii muscle contract, the radius bone moves
and serves as a lever. The elbow joints serves as the fulcrum for the lever.
When the filaments contract, the skeletal muscle shortens because thick
and thin filament slide past one another. This process is called the
SLIDING FILAMENT
MECHANISM.
Click on the Skeletal Muscle Cell.
Muscle fibers contain bundles of myofibrils. Myofibrils are composed of smaller filaments.
Identify each of these structures in the diagram.
Actin Filaments
Myosin Filaments
Titan Filaments
Terminal cisterns of SR
Mitochondria
Sarcoplasmic Reticulum ()
Muscle fiber
Sarcolemma
Myofibrils
Sarcomere
Sarcoplasm
T (transverse) tubules
Describe what happens when a sarcomere shortens.
The shortening of a sarcomere causes the shortening of the whole muscle fiber, which in turn leads
to shortening of the entire muscle.
Identify each of the following:
Origins of triceps brachii
Belly of triceps brachii
Insertion of triceps brachii
humerus
4. Identify each of the following:
Origins of biceps brachii
Tendons
Belly of biceps brachii
Elbow joints
Radius
Ulna

Describe the following muscle functions
o
Movement producing body
producing body movements such as exercising and simple facial expressions are the result
of the functional work of bone, joints and skeletal muscle.
o Stabilization
the skeletal muscle contractions stabilize joints and help maintain body positions such as
standing and sitting. Postural muscles contract continuously to help stabilized our body.
o Heat production
Muscle contractions can maintain body temperature through the production of heat in a
process called thermogenesis. This is evident during shivering when skeletal muscles contract
involuntarily to generate heat.