Anatomy: Skeletal Muscles (Locations & Functions)

Question 1

Sarcolemma

Answer 1

Function: Encloses the muscle fiber and conducts action potentials.
Origin: Derived from the plasma membrane of muscle cells.
Location: Surrounds each muscle fiber (cell).

Question 2

Sarcoplasm

Answer 2

Function: Site of metabolic processes and contains organelles and myofibrils.
Origin: The cytoplasm of muscle cells.
Location: Inside the muscle fiber.

Question 3

Mitochondrion

Answer 3

Function: Produces ATP through aerobic respiration.
Origin: Organelle found in eukaryotic cells.
Location: Scattered throughout the sarcoplasm of muscle fibers.

Question 4

Sarcoplasmic Reticulum

Answer 4

Function: Stores and releases calcium ions (Ca²⁺) during muscle contraction.
Origin: Specialized form of endoplasmic reticulum in muscle cells.
Location: Surrounds myofibrils within the muscle fiber.

Question 5

Myofibril

Answer 5

Function: Contains the contractile elements (sarcomeres) responsible for muscle contraction.
Origin: Composed of myofilaments (actin and myosin).
Location: Runs parallel within the muscle fiber.

Question 6

Nucleus

Answer 6

Function: Contains genetic material and regulates cellular activities, including protein synthesis.
Origin: Found in all eukaryotic cells.
Location: Typically located at the periphery of the muscle fiber.

Question 7

Striation

Answer 7

Function: Indicates the organized arrangement of muscle fibers and contractile proteins.
Origin: Result of alternating thick (myosin) and thin (actin) filaments.
Location: Visible across myofibrils and muscle fibers under a microscope.

Question 8

Triad

Answer 8

Function: Facilitates rapid transmission of action potentials and calcium release.
Origin: Formed by two terminal cisternae and one transverse tubule.
Location: At the junction of the A and I bands in the myofibrils.

Question 9

Terminal Cisternae

Answer 9

Function: Stores calcium ions and releases them during muscle contraction.
Origin: Extensions of the sarcoplasmic reticulum.
Location: Flank the T-tubules in the triad structure.

Question 10

Transverse Tubule (T-tubule)

Answer 10

Function: Transmits action potentials deep into the muscle fiber.
Origin: Extensions of the sarcolemma.
Location: Penetrates into the muscle fiber at the junction of the A and I bands.

Question 11

Endomysium

Answer 11

Function: Surrounds and supports individual muscle fibers.
Origin: Layer of connective tissue.
Location: Within a muscle, surrounding each muscle fiber.

Question 12

Perimysium

Answer 12

Function: Surrounds and organizes bundles of muscle fibers (fascicles).
Origin: Connective tissue layer.
Location: Between individual fascicles within a muscle.

Question 13

Epimysium

Answer 13

Function: Surrounds the entire muscle, providing support and protection.
Origin: Outer layer of connective tissue.
Location: Envelops the entire muscle.

Question 14

Fascicle

Answer 14

Function: A bundle of muscle fibers that allows for organized structure and efficient force generation.
Origin: Group of muscle fibers surrounded by perimysium.
Location: Found within a muscle, grouped together to form the muscle.