BGZ2025 Use It or Lose It summary case 1 up to and including case 6
Extensive summary of case 1 up to and including case 6 with additional
comments from the tutor included. The original document was too large to
upload on Stuvia, so this is part 1 of BGZ2025 from the cases
PROBLEM 1: AT THE FITNESS CENTRE
Anatomy of the muscles type of muscle + function
The movement (vertical, horizontal)
Connection between muscles
Which movement, which muscle can train
Muscles, bones, joints
Skeletal muscle tissue different types + functions
Leg extension machine: al ows certain movement, extensor movement.
Movement goes around an axis and plane
Hip abductor pushing something from the body; turning your hip, training abdominal
Muscle shapes: triangular, fusiform, digastric
Bicep curl, involved muscles: biceps, triceps
Sit-up, involved muscles: rectus abdominis, external obliques
Shoulder girdle: around the shoulder, joint is different in shoulder compared to the knee
Scapular muscles: ‘shoulder blade of the scapular’
What is the structure of the musculoskeletal system? Learning goals:
1. What is the anatomy of the muscles + bones?
2. What are muscles for? (support the bones, allowing movement)
3. What are the different types of bones?
4. What are the roles of the skeleton?
5. Which muscles are involved in the exercises mentioned in the task?
6. What is the axis and what is the plane of certain movement mentioned in the task?
7. What is a joint, which type of joints are there + function? (shoulder, ankle, elbow)
8. Do all the muscles contract in the same way? (flexion; isometric, concentric, eccentric)
Books of anatomy & physiology
1. What is the anatomy of the muscles + bones musculoskeletal system?
Centrum + periphery
Muscle is the dominant tissue in the heart and in the wal s of other hol ow organs. In al
its forms, muscle tissue makes up nearly half the body’s mass. Muscles are distinguished
by their ability to transform chemical energy (ATP) into directed mechanical energy. In
so doing, they become capable of exerting force.
3 types of muscle tissue:
1) Skeletal muscle (muscles attached to bones)
Skeletal muscle tissue is packaged by connective tissue sheets into organs cal ed
skeletal muscles that are attached to the bones of the skeleton. These muscles
form the flesh of the body, and as they contract they pul on bones or skin,
causing body movements. Skeletal muscle cells, also cal ed muscle fibers, are
long, cylindrical cells that contain many peripheral y located nuclei. Their
obvious banded, or striated, appearance reflects the precise alignment of their
Most of them are attached to the bones of the skeleton, enabling these muscles
to control body movement.
The fibers are large, multinucleate cells that appear striped or striated under the
Often described as voluntary muscles can contract without conscious
Unique in that they contract only in response to a signal from a somatic motor
neuron. They cannot initiate their own contraction and their contraction is not
influenced directly by hormones.
Skeletal muscles make up the bulk of muscle in the body and constitute about
40% of total body weight. They position and move the skeleton.
Skeletal muscles are usual y attached to bones by tendons made of col agen.
The origin of a muscle is the end of the muscle that is attached closest to the
trunk or to the more stationary bone. The insertion of the muscle is the more distal
or more mobile attachment.
When the bones attached to a muscle are connected by a flexible joint,
contraction of the muscle moves the skeleton.
o Flexor: the centers of the connected bones are brought closer together
when the muscle contracts, and the movement is cal ed flexion.
o Extensor: the bones move away from each other when the muscle
contracts, and the movement is cal ed extension.
Most joints in the body have both flexor and extensor muscles, because a
contracting muscle can pul a bone in one direction but cannot push it
back. Flexor-extensor pairs are cal ed antagonistic muscle groups because
they exert opposite effects. In each case, when one muscle contracts and
shortens, the antagonistic muscle must relax and lengthen.
Skeletal muscles are composed of muscle fibers
o Muscles function together as a unit. A skeletal muscle is a col ection of
muscle cells or muscle fibers. Each skeletal muscle fiber is a long, cylindrical
cell with up to several hundred nuclei near the surface of the fiber.
o Skeletal muscle fibers are the largest cells in the body, created by the fusion
of many individual embryonic muscle cells. Committed stem cells cal ed
satellite cells lie just outside the muscle fiber membrane. Satellite cells
become active and differentiate into muscle when needed for muscle
growth and repair.
o The fibers in a given muscle are arranged with their long axes in paral el.
Each skeletal muscle fiber is sheathed in connective tissue, with groups of
adjacent muscle fibers bundled together into units cal ed fascicles.
Col agen, elastic fibers, nerves, and blood vessels are found between the
fascicles. The entire muscle is enclosed in a connective tissue sheath that is
continuous with the connective tissue around the muscle fibers and fascicles
and with the tendons holding the muscle to underlying bones.
o The cell membrane of a muscle fiber is cal ed the sarcolemma, and the
cytoplasm is cal ed the sarcoplasm. The main intracellular structures in
striated muscles are myofibrils, highly organized bundles of contractile and
elastic proteins that carry out the work of contraction. Skeletal muscle fibers
also contain extensive sarcoplasmic reticulum (SR), a form of modified
endoplasmic reticulum that wraps around each myofibril like a piece of
lace. The sarcoplasmic reticulum consists of longitudinal tubules with
enlarged end regions cal ed the terminal cisternae. The sarcoplasmic
reticulum concentrates and sequesters Ca2+ with the help of a Ca2+-
ATPase in the SR membrane. Calcium release from the SR creates calcium
signals that play a key role in contraction in al types of muscle. The terminal
cisternae are adjacent to and closely associated with a branching network
of transverse tubules, also known as t-tubules. One t-tubule and its two
flanking terminal cisternae are cal ed a triad. The membranes of t-tubules
are a continuation of the muscle fiber membrane, which makes the lumen
of t-tubules continuous with the extracellular fluid.
Criteria of naming muscles:
-Muscle location: Some muscle names indicate the bone or body region with
which the muscle is associated. Examples: The temporalis muscle overlies the
temporal bone, and intercostal muscles run between the ribs.
-Muscle shape: Some muscles are named for their distinctive shapes. Examples:
The deltoid muscle is roughly triangular, and together the right and left trapezius
muscles form a trapezoid.
-Muscle size: Terms such as maximus (largest), minimus (smal est), longus (long),
and brevis (short) are often used in muscle names. Examples: The gluteus
maximus and gluteus minimus are the large and smal gluteus muscles,
-Direction of muscle fibers: The names of some muscles reveal the direction in
which their fibers (and fascicles) run in reference to some imaginary line, usual y
the midline of the body or the longitudinal axis of a limb bone. In muscles with
the term rectus (straight) in their names, the fibers run paral el to that imaginary
line (axis). Transversus indicates that the muscle fibers run at right angles to that
line, and oblique indicates that the fibers run obliquely to it. Examples: The rectus
femoris (straight muscle of the thigh, or femur) and transversus abdominis
(transverse muscle of the abdomen).
-Number of origins: When biceps, triceps, or quadriceps forms part of a muscle’s
name, you can assume that the muscle has two, three, or four origins,
o Biceps Brachii
1.1 The biceps brachii is a two-headed muscle group that is made up of an inner short head and an outer long head, both of which are located at the front of the arm. The short head originates at the corocoid process of the scapula, or shoulder blade. ...