hbs lesson 1.2

Skeletal Muscle

A type of muscle tissue that is under voluntary control and is responsible for the movement of bones.

Has striations

Peripherally located nuclei

Smooth Muscle

Involuntary muscle found in the walls of internal organs and structures, such as the intestines and blood vessels.

No striations

Centrally located nucleus

Cardiac Muscle

Involuntary muscle found only in the heart, responsible for pumping blood throughout the body.

Has striations

Centrally located nucleus

Sarcomere

The basic contractile unit of muscle fiber, composed of actin and myosin filaments.

Smallest unit where contraction occurs.

Actin

thin myofilament

Myosin

thick myofilament

Myofilament

A filament that constitutes myofibrils, including actin and myosin.

Myofibril

A long, thread-like structure in muscle cells made up of sarcomeres, responsible for muscle contraction.

Muscle fiber / Muscle cell

A single muscle cell that can contract and is surrounded by a plasma membrane.

Fascicle

A bundle of muscle fibers surrounded by perimysium.

Muscle

A tissue composed of fibers that contract to produce movement.

Tendon

A fibrous connective tissue that attaches muscle to bone.

Endomysium

The connective tissue that surrounds individual muscle fibers.

Epimysium

The outer layer of connective tissue that surrounds an entire muscle.

Perimysium

The connective tissue that surrounds fascicles within a muscle.

Troponin

A protein complex involved in muscle contraction that binds calcium ions.

Tropomyosin

A protein that blocks the binding sites on actin filaments, preventing muscle contraction in a relaxed state.

Cross-Bridge Cycle

The process by which myosin heads attach to actin filaments and pull them to produce muscle contraction.

Origin

The fixed attachment point of a muscle that does not move during contraction.

Insertion

The movable attachment point of a muscle that is pulled toward the origin during contraction.

Agonist

A muscle that is primarily responsible for producing a specific movement.

Antagonist

A muscle that opposes the action of another muscle.

Flexor

A muscle that decreases the angle between two body parts.

Extensor

A muscle that increases the angle between two body parts.

Fibrous Joint

A type of joint where bones are connected by dense connective tissue, allowing little to no movement.

Cartilaginous Joint

A joint where bones are connected by cartilage, allowing limited movement.

Synovial Joint

A joint characterized by a fluid-filled cavity that allows for a wide range of motion.

Ball and Socket Joint

A type of synovial joint that allows for rotational movement in multiple directions.

Hinge Joint

A type of synovial joint that allows for movement in one plane, similar to a door hinge.

Pivot Joint

A joint that allows for rotational movement around a single axis.

Condyloid Joint

A joint that allows for movement in two planes, such as flexion, extension, and circular motion.

Plane Joint

A joint that allows for sliding or gliding movements between flat surfaces.

Saddle Joint

A joint that allows for movement in two planes and is shaped like a saddle.

Rotation

The movement of a body part around its own axis.

Lateral Rotation

Rotation of a body part away from the midline.

Medial Rotation

Rotation of a body part toward the midline.

Circumduction

A circular movement of a limb that involves flexion, extension, abduction, and adduction.

Abduction

Movement of a limb away from the midline of the body.

Adduction

Movement of a limb toward the midline of the body.

Depression

The movement of a body part downward.

Elevation

The movement of a body part upward.

Flexion

A bending movement that decreases the angle between two body parts.

Extension

A straightening movement that increases the angle between two body parts.

Hyperextension

Extension of a joint beyond its normal range of motion.

Plantar Flexion

The movement of the foot that points the toes downward.

Dorsiflexion

The movement of the foot that points the toes upward.

Supination

The rotation of the forearm that turns the palm upward.

Pronation

The rotation of the forearm that turns the palm downward.

Eversion

The movement of the foot that turns the sole outward.

Inversion

The movement of the foot that turns the sole inward.

Protraction

The movement of a body part forward.

Retraction

The movement of a body part backward.

Hyaline (articular) cartilage

A smooth, glassy type of cartilage that covers the ends of bones in synovial joints.

Elastic cartilage

A type of cartilage that is flexible and resilient, found in structures like the ear.

Fibrocartilage

A tough type of cartilage that provides support and absorbs shock, found in intervertebral discs.

ACL (Anterior Cruciate Ligament)

A ligament in the knee that helps stabilize the joint by preventing forward movement of the tibia.

PCL (Posterior Cruciate Ligament)

A ligament in the knee that prevents backward movement of the tibia.

MCL (Medial Collateral Ligament)

A ligament on the inner side of the knee that provides stability to the joint.

LCL (Lateral Collateral Ligament)

A ligament on the outer side of the knee that provides stability to the joint.

Anterior Drawer Test

A clinical test used to assess the integrity of the ACL.

Posterior Drawer Test

A clinical test used to assess the integrity of the PCL.

Valgus Stress Test

A test used to assess the integrity of the MCL by applying a lateral force to the knee.

Varus Stress Test

A test used to assess the integrity of the LCL by applying a medial force to the knee.

Goniometer

An instrument used to measure the range of motion of joints.

Kinesiology Tape

A therapeutic tape used to support muscles and joints without restricting movement.