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Musculoskeletal System - Coggle Diagram
Musculoskeletal System
1. Anatomy of the Skeletal System
TYPE OF BODY MOVEMENTS
1. Flexion & Extension
Flexion
refers to a movement that decreases the angle between two body parts.
Extension
refers to a movement that increases the angle between two body parts.
2. Abduction & Adduction
Abduction
is a movement away from the midline – just as abducting someone is to take them away. For example, abduction of the shoulder raises the arms out to the sides of the body.
Adduction
is a movement towards the midline. Adduction of the hip squeezes the legs together.
3. Medial & Lateral Rotation
Medial rotation
is a rotational movement towards the midline. It is sometimes referred to as internal rotation.
Lateral rotation
is a rotating movement away from the midline.
4. Pronation & Supination
Supination
is palm up.
Pronation
is palm down.
These terms also apply to the whole body
5. Dorsiflexion & Plantarflexion
Dorsiflexion
refers to flexion at the ankle, so that the foot points up.
Plantarflexion
refers extension at the ankle, so that the foot points down
6. Circumduction
During
circumduction
, the limb or extremity moves in a manner that traces the shape of a cone, with one end of the limb remaining relatively stationary while the other end moves in a circular or angular pattern.
The musculoskeletal system forms the body's framework, allowing us to move, support our weight, and protect vital organs.
The skeletal system is comprised primarily of bone but also composed of joints, cartilage, ligaments, and tendons.
BONES
Types of Bones
Long Bone
has a long, thin shape. Examples include the bones of the arms and legs (excluding the wrists, ankles and kneecaps).
Short bone
has a squat, cubed shape. Examples include the bones that make up the wrists and the ankles
Flat bone
has a flattened, broad surface. Examples include ribs, shoulder blades, breast bone and skull bones..
Irregular bone
has a shape that does not conform to the above three types. Examples include the bones of the spine (vertebrae).
are made up of a composition of collagen, protein, calcium phosphate, calcium carbonate and other minerals which help ensure that bones remain strong and flexible.
Have many layers. They are
Periosteum
Compact or dense tissue
Spongy or cancellous tissue
Bone marrow
Bone Cells
Our body is constantly remodelling its skeleton by building up and breaking down bone tissue as required. As a result, each bone is rebuilt from scratch about every decade.
The bone cells involved in this process include:
Osteoblasts
- the cells that build bone tissue
Osteocytes
- the cells that maintain bone tissue by controlling the mineral and calcium content
Osteoclasts
- the cells that break down old bone tissue
Bone Marrow
Is where blood cells are made.
Red blood cells
- carry oxygen around the body.
White blood cells
- make up the body’s immune system.
Platelets
- are used for clotting.
Joints
A joint is defined as a connection between two bones in the skeletal system.
There are fibrous, cartilaginous and synovial joints
Key Structures of a Synovial Joint
(I) Articular Capsule
- surrounds the joint consists of Fibrous (outer) and Synovial (inner) layers.
(II) Articular Cartilage
- the articulating surfaces of a synovial joint
(III) Synovial Fluid
- located within the joint cavity of a synovial joint. It's 3 primary functions are lubrication, nutrient distribution, shock absorption.
Axial Skeleton
made up of the bones in your head, neck, back and chest. So your skull, rib cage and vertebral column
Appendicular Skeleton*
made up of the bones that attach to your axial skeleton.
Fun fact: You are born with about 300 bones, but many of them “fuse” so you have 206 as an adult. 51% of your bones are in your hands and feet (27 bones per hand and wrist, 26 bones per foot).
2. Anatomy of the Muscular System
FUNCTIONS OF THE MUSCLES
Production of movement
Maintenance of posture and body postion
Stabilisation of joints
Generation of heat - helps maintain normal body temperature
CLASSIFICATION OF MUSCLE TISSUES
Skeletal
- Voluntary muscles which you can control
Smooth
- Involuntary muscles are found around organs and in blood vessels. We do not consciously have the ability to control this type of muscle; they contract and relax automatically.
Cardiac
- Is found solely in the walls of the heart.
CHARACTERISTICS OF MUSCLE TISSUES
Excitability
- The ability of the muscle to respond to stimulus from the brain
Contractility
- Ability to flex or shorten, like in lifting a spoon and bringing to mouth
Extensibility
- Ability to stretch or lengthen... to put the spoon back in the bowl
Elasticity
- The ability of the muscle to recoil or bounce back from a lengthened position
STRUCTURE OF THE SKELETAL MUSCLES
Skeletal muscle is composed of bundles of elongated muscle fibres which are cylindrical and multi-nucleated.
Muscle fibres are surrounded by supportive layers of connective tissue:
Endomysium
- surrounds individual muscle fibres
Perimysium
- surrounds a bundle of muscle fibres forming a fascicle (functional unit)
Epimysium
- surrounds the entire muscle
Muscle fibers also contain glucose as a stored energy source, and myofibrils, which are made up of two types of protein: (i) Actin myofilamets, (ii) Myosin myofilaments
SLIDING FILAMENT THEORY
Describes the mechanism of skeletal muscle contraction, at a cellular level.
When a nerve impulse arrives at the muscle, it causes a release of a chemical called acetylcholine. The presence of acetylcholine causes depolarisation, enabling calcium to be released from the sarcoplasmic reticulum. The calcium binds to troponin, changing its shape, and so moving tropomyosin form the active site of the Actin. The myosin filaments can now attach to the Actin, forming a Crossbridge.
Adenosine triphosphate (ATP) = Adenosine diphosphate (ADP) + Phosphate (P) + Energy. The breakdown of ATP releases energy which enables the myosin to pull the actin filaments inwards, contracting the muscle. This occurs along the entire length of every myofibril in the muscle cell.
Fun fact: Muscles are needed for many body activities, including breathing, talking, walking, and even sneezing.
3. Physiology of the Musculoskeletal System
Muscular System Physiology
Motor unit & muscle recruitment
A motor unit comprises of a single motor neuron + all the muscle fibres it controls.
Different muscles contain different sizes of motor units - that is, more or less muscle fibers innervated by the same neuron. Larger motor units generate more tension as they're composed of more muscle fibers. Generally speaking, larger muscles responsible for larger movements contain larger motor units.
Muscle Force Production
Motor unit
- the contractile unit of a muscle; a motor neuron and all the muscle fibres that it innervates
Slow-twitch
- slow oxidative (type I); motor neuron size is smaller; recruited first, lower force
Fast-twitch
- fast oxidative (type IIa) & fast-glycolytic (type IIb); motor neuron size is larger; recruited when higher force output needed
Types of Muscle Contractions
Concentric
- muscles shortens as it overcomes gravity/ load
Eccentric
- muscle lengthens as it resist gravity/ load
Isometric
- muscle length is unchanged as it produces force
Bone formation, Growth and remodelling
The skeleton begins to form early in fetal development as a flexible skeleton made of hyaline cartilage and dense irregular fibrous connective tissue.
As development progresses, osseous tissue slowly replaces the cartilage and fibrous tissue in a process called calcification.
As we grow through childhood, the growth plates grow under the influence of growth and sex hormones, slowly separating the bones. At the same time the bones grow larger by growing back into the growth plates. This process continues until the end of puberty, when the growth plate stops growing and the bones fuse permanently into a single bone.
Minerals and Bone Health
Minerals play a crucial role in maintaining and promoting bone health.
Minerals like Calcium, Phosphorus, Magnesium and Fluoride help create the Strength
Vitamins A, C, D, and K help maintain mass
4. Age-Related Physiology Changes
1. Decline in muscle strength
Muscle strength tends to decline with age, partially as a result of loss of motor units and muscle fibers.
However, a large body of evidence indicates regular appropriate exercise can slow loss of muscle strength and also increase strength, even in very old age.
2. Muscle Atrophy
Lean body mass decreases. This decrease is partly caused by a loss of muscle tissue (atrophy).
The speed and amount of muscle changes seem to be caused by genes. Muscle changes often in the 20s in men and in the 40s in women.
3. Hunch Back Develops
Often a result of thinning vertebrae and muscle stiffness.