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Long bones

Bones greater in length than width, found in limbs, serving as levers for movement.

Examples of long bones

Femur, humerus, ulna, radius, tibia, fibula.

Short bones

Bones that are nearly equal in length and width, very strong with less movement, mainly found in the wrists and ankles.

Examples of short bones

Carpals (wrist bones) and tarsals (ankle bones).

Flat bones

Thin bones providing protection and a large area for muscle attachment, consisting of two layers of compact bone surrounding a thin layer of spongy bone.

Irregular bones

Bones that provide protection and support, such as the vertebrae and pubis.

Sesamoid bones

Small bones developed in tendons around some joints, an example is the patella (kneecap).

Vertebral column

A column of vertebrae that supports the head and body, with hollow centers for the spinal cord.

Joints

Connective tissues responsible for connecting bones, allowing movement and preventing damage.

Types of connective tissue in joints

Tendons, ligaments, and cartilage.

Cartilage in joints

Smooth, slightly elastic tissue that provides shock absorption, especially in synovial joints.

Function of tendons

Attach muscles to bones, allowing movement by pulling across the joints.

Function of ligaments

Join bone to bone across joints, providing stability and preventing dislocation.

Fixed joints

Immovable joints, like those found in the skull.

Cartilaginous joints

Slightly movable joints, allowing small restricted movements, such as those between vertebrae.

Synovial joints

Freely movable joints that allow movement in one or more directions.

Ball and socket joint

Allows circular movement, found in the shoulder and hip.

Hinge joint

Permits back and forth motion, found in the knee, elbow, and phalanges.

Pivot joint

Allows rotation of one bone around another, found in the elbow.

Gliding joint

Permits sliding motion of one bone over another, found between wrist and ankle bones.

Saddle joint

Allows movement in two directions, found at the base of the thumb.

Condyloid joint

Allows movement in two planes, characterized by an oval-shaped head of one bone fitting into a shallow cavity in another.

Functions of muscles

To create movement, maintain adequate posture, and maintain essential bodily functions.

Types of muscle

Skeletal, smooth, and cardiac muscles.

Skeletal muscle

Often called striated muscle, responsible for voluntary movements and maintaining posture.

Smooth muscles

Involuntary muscles found in vital organs such as the bladder, digestive system, and blood vessels.

Cardiac muscle

The muscle of the heart, which is involuntary and has a similar appearance to skeletal muscle.

Reciprocal inhibition

A coordination mechanism where one muscle contracts (agonist) while the opposing muscle relaxes (antagonist).

Agonist

The muscle causing major action by shortening (concentric contraction); e.g., bicep in the upward phase of a bicep curl.

Antagonist

The muscle that must relax and lengthen (eccentric contraction) to allow movement; e.g., bicep curl where the tricep is the antagonist.

Synergist

A muscle that assists the agonist to produce the required movement; e.g., tricep during a bench press.

Stabilizer

Muscles that ensure joint stability; e.g., gluteus maximus during seated hamstring curls.

Skeletal muscle fiber arrangement

The arrangement of muscle fibers affects force production and contraction speed, consisting of several types including fusiform, pennate, and radiate.

Fusiform

Muscle fibers that run parallel to the tendon; designed for mobility with a wide range of motion, but produce low force. Examples include the Sartorius and biceps.

Pennate muscles

Muscle fibers arranged at an angle to the tendon; designed for strength and power. Includes unipennate, bipennate, and multipennate arrangements.

Unipennate

Muscle fibers located on one side of a central tendon; an example is the tibialis anterior.

Bipennate

Muscle fibers located on both sides of a central tendon; an example is the rectus femoris.

Multipennate

Muscle fibers branching out from multiple tendons; produces the greatest force; an example is the deltoid.

Radiate muscles

Muscle fibers radiate from a central tendon, allowing for strength and mobility; an example is the pectoralis major.

Type 1 fibers

Slow-twitch oxidative fibers that are red in color, larger in size, low in force production, slow in contraction, and have high fatigue resistance.

Type 2A fibers

Fast-twitch oxidative fibers that are pinkish, medium in size, have medium force production and contraction speed, and medium fatigue resistance.

Type 2B fibers

Fast-twitch glycolytic fibers that are white, smaller in size, high in force production, very fast in contraction speed, and have low fatigue resistance.

Motor unit

A motor unit consists of a motor neuron and the muscle fibers it innervates, which work together to produce muscle contraction.

Motor neuron function

A motor neuron transmits impulses from the spinal cord to the muscle fibers, enabling movement.

Dendrites

Dendrites act as receptors that receive impulses from the spinal cord and deliver them to the motor neuron cell body.

Cell body of motor neuron

The cell body of a motor neuron directs the response to impulses received from its dendrites.

Role of the spinal cord in movement

The spinal cord serves as the communication pathway between the brain and the muscles, transmitting action potentials.

Motor nerves

Motor nerves carry the action potential from the spinal cord to the motor neurons, facilitating muscle movement.

process of movement

brain to spinal cord to motor nerves then motor neurons

Strength of muscular contraction

The intensity of muscle contraction influenced by the all-or-nothing principle.

All-or-nothing principle

A principle stating that once a nerve impulse reaches a threshold, all muscle fibers in the motor unit contract maximally.

Threshold in muscle contraction

The minimum nerve impulse required to trigger a muscle contraction; below this threshold, no contraction occurs.

Isokentic contraction

A type of muscle contraction where the muscle changes length while maintaining constant tension.

Isometric contraction

Muscle contraction where the muscle applies force without changing length; no movement occurs.

Isokinetic contraction

A muscle contraction that occurs against a variable load, allowing resistance changes during the muscle's range of motion.

Concentric contraction

A type of isotonic contraction where the muscle shortens as it contracts, e.g., lifting the bicep during a curl.

Eccentric contraction

A type of isotonic contraction where the muscle lengthens while contracting, e.g., lowering the bicep during a curl.