MUSCLE NOTES IB SEHS

Smooth Muscle

Involuntary muscle that makes up hollow organs, has no striations, and typically contains 1 nucleus.

Cardiac Muscle

Involuntary, striated muscle that makes up the heart and may have 1-2 nuclei.

Skeletal Muscle

Voluntary, striated muscle attached to bones via tendons, responsible for movement, and contains multiple nuclei.

Contractibility

The ability of muscle tissue to shorten and generate force.

Extensibility

The ability of muscle tissue to lengthen beyond its normal resting length.

Elasticity

The ability of muscle tissue to return to its original length after being stretched.

Atrophy

Decrease in muscle size or number of myofibrils due to disuse, aging, or disease.

Hypertrophy

Increase in muscle size or number of myofibrils due to increased workload or stress.

Epimysium

The outer covering or layer of muscle tissue.

Perimysium

The outer layer surrounding a fascicle (group of muscle fibers).

Endomysium

The internal layer that surrounds each individual muscle fiber.

Myofibril

Elongated, contractile threads found in striated muscle, made up of actin and myosin.

Sarcomere

The smallest subunit of a muscle fiber where muscle contractions occur.

Fibrous Joint

A joint where two bones are joined by fibrous connective tissue, allowing little or no movement.

Cartilaginous Joint

A joint that unites two bones using cartilage, allowing limited movement.

Synovial Joint

Freely moving joints that have a synovial capsule around them.

Articular Capsule

The sleeve-like structure enclosing the cavity of a synovial joint.

Synovial Fluid

Fluid that lubricates the joint capsule in synovial joints.

Bursae

Small fluid-filled sacs that reduce friction between tendons and bones.

Meniscus

A disk of fibrocartilage that cushions the ends of bones in a joint.

Hinge Joint

A type of synovial joint that allows bending and straightening in one direction (e.g., elbow).

Ball and Socket Joint

A synovial joint that allows movement in all directions (e.g., shoulder).

Pivot Joint

A synovial joint that allows rotation of one bone around another (e.g., neck).

Saddle Joint

A synovial joint that allows side-to-side and up-and-down movement (e.g., thumb).

Condyloid Joint

A synovial joint that allows movement in two directions (e.g., wrist).

Gliding Joint

A synovial joint where bones glide against each other (e.g., carpal bones).

Tendons

Connective tissue that connects muscles to bones, transmitting muscular pull.

Ligaments

Connective tissue that connects bone to bone, providing joint stability.

Cartilage

A strong connective tissue that reduces friction in joints and supports soft tissues.

Hyaline Cartilage

A type of cartilage that reduces friction in joints, found at the ends of long bones.

Elastic Cartilage

A type of cartilage that maintains shape and flexibility, found in the external ear.

Fibrocartilage

A type of cartilage that provides support and acts as a shock absorber, found in intervertebral discs.

isokentic

• when a muscle contracts so that the body segment to which it is attached moves at a constant speed around the join

• Rare, does not usually happen w/o equipment