MUSCLE NOTES IB SEHS

Different types of muscle
There are three different types of muscles: 

• Smooth muscle makes up hollowed tubed organs

  • blood vessels, stomach, small intestines, and esophagus

  • this muscle works involuntarily and has no striations

  • 1 nucleus

• Cardiac muscle is what makes up the heart

  • this muscle works involuntarily and is striated

  • may have 1-2 nuclei

• Skeletal muscle are those muscles that are attached to bones through tendons, its function is movement

  • this muscle works voluntarily and is striated/striped appearance

  • has multiple nuclei

Functions of Muscle

• movement of bones 

• movement of food and blood 

• keeps our posture

• generated 85% of body heat
  

Characteristics common to muscle tissue

• Contractibility - the ability to get shorter

• Extensibility - the ability to lengthen

• Elasticity - the ability to go back to resting length

• Atrophy - decrease in the number of myofibrils, or reduce the size of muscle due to age or lack of movement (trained muscle)

  • conditions that lead to atrophy - bed rest, lack of training/activity, space and flight, injury, body fat, off-season, disease, obesity

• Hypertrophy - increase in the number of myofibrils, or increase in the size of muscle (untrained muscle)

Structures of skeletal muscle

• epimysium - outer covering/layer of muscle (deep fascia)

• perimysium - outer layer of fascicle (group of muscle fibers)

• endomysium - internal layer that surrounds each muscle fiber

• muscle fibers - long, cylindrical cells that give the striated appearance and are the primary component responsible for movement

Structure of Skeletal Muscle

• myofibril - elongated, contractile threads found in the striated muscle

  • Made up of actin and myosin

• sarcomere - smallest subunit of a muscle fiber 

  • Where muscle contractions occur

  • space between dark and light bands

• actin - thin/light protein

• myosin - thick/dark protein

Joints

A joint is where two or more bones

meet (or articulate).

•Main functions are mobility, support

and strength

• Classified by movement and structure

FIBROUS JOINTS

• two bones joined by fibrous connective tissue

• allow little or no movement 

• Examples: skull sutures; radioulnar joint; tibiofibular joint
  
   CARTILAGINOUS JOINTS

  • unite two bones using cartilage

    • Fibrocartilage in your spine or hyaline cartilage in your ribcage

  •  limited movement

    
    
      SYNOVIAL JOINTS
    freely moving joints

  • have a synovial capsule around a joint

  • Ex: most of the appendicular skeleton

  
  Features of a synovial joint:

  1. Articular/Joint capsule –the sleeve-like structure enclosing the cavity of a synovial joint

  2. Articular cartilage – smooth surface where bones meet; reduces friction and absorbs shock

  3. Synovial membrane - secretes synovial fluid, inside the lining of the articular capsule 
     Synovial fluid – lubricates joint capsule

  4. Bursae - small fluid-filled sacs between tendons and bone

  5. Meniscus - a disk of fibrocartilage that acts as a cushion between the ends of bones in a joint

  6. Ligaments- connective tissue: bone to bone

  
  
  6 Types of synovial joint:

  Hinge – Bend and straighten in one direction (elbow, knee)
  
  Pivot - Rotation of one bone on another (neck)

  Ball and socket – movement in all directions (shoulder, hip
   Saddle – side-to-side and up-and-down movement (thumb)

  
  Condyloid – allows movement in two directions 

  less range than saddle(radius and carpals in wrist)

  Gliding – bones glide against each other (carpal bones)
  

Function of Cartilage Tissue

• Cartilage is a hard, strong connective tissue that provides support for some soft tissues and forms a sliding area for joints so that bones can move easily.
  

• During the fetal stage of development, cartilage forms most of the skeleton. It is gradually replaced by bone. In a mature individual, it is found mainly at the end of bones, in the nose, trachea, and in association with the ribs and vertebrae.

Function of Tendons

• Tendons connect muscles to bones. They are specialized skeletal structures that generally transmit muscular pull to bones.

Function of Fascia

• Fascia is a type of connective tissue that is located between and surrounding other tissue in the  body like muscle and bones. 

  • Made of fibrous tissue, fatty tissue, and fluid.

Connective Tissue

1. Bones

   • Example of a Long Bone: The femur (thigh bone) supports the weight of the body and allows for movement.

   • Example of a Short Bone: Carpals in the wrist provide stability and support with limited movement.

   • Example of a Flat Bone: The scapula (shoulder blade) protects internal organs and provides surface area for muscle attachment.

   • Example of an Irregular Bone: Vertebrae in the spine protect the spinal cord and support body structure.

2. Tendons

   • Example: The Achilles tendon connects the calf muscles (gastrocnemius and soleus) to the heel bone (calcaneus), aiding in walking, running, and jumping.

3. Ligaments

   • Example: The Anterior Cruciate Ligament (ACL) in the knee connects the femur to the tibia, providing stability and preventing excessive forward movement of the tibia.

4. Cartilage

   • Hyaline Cartilage Example: The articular cartilage covering the ends of long bones in joints, such as the knee, reduces friction during movement.

   • Elastic Cartilage Example: The external ear (pinna) maintains shape and flexibility.

   • Fibrocartilage Example: Intervertebral discs between vertebrae act as shock absorbers in the spine.

Muscular System

1. Characteristics of Muscle Tissue

   • Contractibility: The biceps brachii contract to bend the elbow.

   • Extensibility: The hamstrings stretch when you kick your leg forward.

   • Elasticity: The calf muscles (gastrocnemius) return to their resting length after a jump.

     Atrophy and Hypertrophy

     • Atrophy: The decrease in size or wasting away of an organ or tissue due to a reduction in cell size or number. Common causes include disuse, aging, or disease.

     • Hypertrophy: The increase in the size of an organ or tissue through the enlargement of its cells. This often occurs in response to increased workload or stress, such as in muscle tissue from exercise.

2. Muscle Attachments

   • Origin Example: The origin of the biceps brachii is the scapula (shoulder blade).

   • Insertion Example: The insertion of the biceps brachii is the radius (forearm bone), allowing elbow flexion.

   • Synergist Example: The brachialis assists the biceps brachii in elbow flexion.

   • Fixator Example: The rotator cuff muscles stabilize the shoulder joint during arm movements.

3. Muscle Contraction Types

   • Concentric Example: Lifting a dumbbell during a bicep curl, where the biceps muscle shortens.

   • Eccentric Example: Lowering a dumbbell back down in a bicep curl, where the biceps muscle lengthens under tension.

   • Isometric Example: Holding a plank position, where the core muscles contract without changing length.

Joints and Joint Movements

1. Types of Joints

   • Fibrous Joint Example: The sutures in the skull, where bones are fused and immovable.

   • Cartilaginous Joint Example: The pubic symphysis in the pelvis, which slightly moves during childbirth.

   • Synovial Joint Example:

     • Hinge Joint: The elbow, which allows flexion and extension.

     • Ball-and-Socket Joint: The shoulder, which allows for a wide range of movements, including rotation.

     • Pivot Joint: The atlas and axis vertebrae in the neck, allowing head rotation.

     • Saddle Joint: The thumb joint (carpometacarpal joint), allowing thumb movement across the palm.

     • Plane Joint: The intercarpal joints in the wrist, allowing sliding movements.

     • Condyloid Joint: The wrist joint, allowing flexion, extension, abduction, and adduction.

2. Joint Movements

   • Flexion Example: Bending the elbow to bring the hand closer to the shoulder.

   • Extension Example: Straightening the knee when kicking a ball.

   • Abduction Example: Raising the arms or legs sideways away from the body.

   • Adduction Example: Bringing the arms or legs back toward the body's midline.

   • Rotation Example: Rotating the head to look over the shoulder.

   • Circumduction Example: Moving the arm in a circular motion, as in swimming a backstroke.

   • Supination Example: Turning the palm upward to hold a bowl of soup.

   • Pronation Example: Turning the palm downward to rest it flat on a table.
     

Neurons

• Dendrite: Link neurons to other neurons

• Axons: Main component to transmit nerve signals

• Motor End Plate: Area where neuron joins muscle fiber

• Synapse: Area where signal reaches muscle

• Muscle fiber: responsible for movement

• Action potential: Change in electrical state of muscles

Types of Synovial Joints

1. Hinge Joints: Allow movement in one plane (e.g., elbow, knee).

2. Ball-and-Socket Joints: Permit rotational movement (e.g., shoulder, hip).

3. Pivot Joints: Enable rotation around a single axis (e.g., neck).

4. Saddle Joints: Allow movement in two planes (e.g., thumb).

5. Condyloid Joints: Permit movement but no rotation (e.g., wrist).

6. Gliding Joints: Allow sliding movements (e.g., between carpal bones).

Memory updated

Here's a study guide for IB Sports Science topics:

Connective Tissue

1. Bones

   • Functions: Support, protection, movement, storage (minerals), blood cell production (bone marrow).

   • Types:

     • Long (e.g., femur)

     • Short (e.g., carpals)

     • Flat (e.g., skull)

     • Irregular (e.g., vertebrae)

2. Tendons

   • Function: Connect muscle to bone, transmit the force of muscle contractions to bones.

   • Structure: Composed of dense, fibrous connective tissue, primarily collagen.

3. Ligaments

   • Function: Connect bone to bone, provide joint stability, prevent excessive movement.

   • Structure: Made of fibrous connective tissue, but slightly more elastic than tendons.

4. Cartilage

   • Function: Reduce friction in joints, absorb shock, support.

   • Types:

     • Hyaline: Found in joints, reduces friction.

     • Elastic: Found in structures like the ear, provides shape and flexibility.

     • Fibrocartilage: Found in intervertebral discs, provides support and rigidity.

Muscular System

1. Characteristics of Muscle Tissue

   • Contractibility: Ability to shorten and generate force.

   • Extensibility: Ability to be stretched beyond normal resting length.

   • Elasticity: Ability to return to original length after stretching.

2. Muscle Attachments

   • Origin: The fixed attachment, usually proximal (closer to the body).

   • Insertion: The movable attachment, usually distal (further from the body).

   • Synergist: Muscles that assist the prime mover in a movement.

   • Fixators: Muscles that stabilize the origin of the prime mover.

3. Muscle Contraction Types

   • Isotonic: Muscle changes length during contraction.

     • Concentric: Muscle shortens (e.g., lifting a weight).

     • Eccentric: Muscle lengthens (e.g., lowering a weight).

   • Isometric: Muscle length does not change during contraction (e.g., holding a plank).

   • Isokinetic: 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

Joints and Joint Movements

1. Types of Joints

   • Fibrous: Immovable (e.g., sutures of the skull).

   • Cartilaginous: Partially movable (e.g., intervertebral discs).

   • Synovial: Freely movable (e.g., knee, shoulder).

     • Subtypes: Hinge, ball-and-socket, pivot, saddle, plane, and condyloid.

2. Joint Movements

   • Flexion: Decreasing the angle between two bones (e.g., bending the elbow).

   • Extension: Increasing the angle between two bones (e.g., straightening the elbow).

   • Abduction: Moving a limb away from the midline (e.g., raising the arm sideways).

   • Adduction: Moving a limb toward the midline (e.g., lowering the arm).

   • Rotation: Circular movement around an axis (e.g., turning the head).

   • Circumduction: A conical movement of a limb (e.g., arm circles).

   • Supination/Pronation: Movements of the forearm; supination turns the palm upward, pronation turns it downward.