Bones

The axial system or the core of the skeleton consists of the skull, vertebrate column and the rib cage.

AXIAL SKELETON

This is the movement of a body part away from an imaginary midline of the body. It occurs in the frontal plane

Abduction

a thick protein filament found in the sarcomere responsible for muscle contraction.

Actin

This is movement of a body part towards an imaginary midline of the body. It can occur in the frontal or horizontal planes.

Adduction

Muscles are continually in a state of 'tone' that affects their ability to help our body to maintain an upright posture when awake and to function safely during sleep. People with poor muscle tone generally have poor posture and resultant aches and pains because gravity is defeating the muscles' resistance. Muscles of the upper back — such as the trapezius, rhomboids and the latissimus dorsi — particularly influence posture maintenance. Regular exercise helps improve muscle tone, which allows resting muscles to resist being stretched and keeps them in constant readiness

Adequate posture

All bones in the body are sites for muscle attachment. When connected muscles contract they cause the bone to move. Change in a bones surface is a possible site for a muscle to attach.

Assisting in movement

Muscle fibres branch out to both sides of the central tendon

Bipennate

The skeletal system serves more then one purpose in the human body. There are six functions of bones which include: 1. Support 2. Protection 3. Assisting in movement 4. Storage of minerals 5. Production of blood cells 6. Storage of chemical energy

Bone Functions

Occurs in the area of the bone known as the epiphyseal (or growth) plate. The epiphyseal is: located at the end of the shaft, made of cartilage. As the cartilage grows wider the outside cells ossify or harden thereby gradually increasing the length of the bone.

Bone growth

Covered with a tough membrane called periosteum Periosteum contains blood vessels enter that enter the bone at many points, nourishing cells inside This membrane also contains cells for growth and repair

Bones

Bones and Joints: Muscles are attached to bone: when muscles contract, they pull on the bones and movements occurs. Where two bones meet a joint is formed. There are more synovial joints in the body than any other joint. They allow the highest amount of movement. All synovial joints have a synovial capsule made up of collagenous material, surrounding the entire joint. A synovial membrane on the inner layer of the capsule secretes a lubricating fluid known as syno0vial fluid and hyaline cartilage completes the joint and provides padding at the ends of the articulating bones.

Bones and Joints:

These muscles make up the wall of the heart. They are involuntary and have a striped appearance.

Cardiac muscles

Circumduction occurs when a limb moves in circular fashion and is generally only possible at the ball and socket joints because flexion, extension, abduction and adduction are required. This occurs in the median and frontal planes.

Circumduction

Very similar to the hinge joint but also allows slight rotation: hence biaxial eg. Flexion extention example the wrist

Condyloid

Dorsiflexion occurs at the ankle when the toes are pointing towards the tibia and generally higher than the heel. This occurs in the median plane about a horizontal axis.

Dorsiflexion

Eversion occurs in the sole of the foot is turned outwards from the imaginary midline of the body and this is in the frontal plane.

Eversion

Diet- Osteoporosis Illness- Cancer- Lymphoma Injury- Damage to growth plates Exercise- Growing to meet the needs- Bone Girth

Factors affecting bone growth

Synovial membrane lines the inside of the capsule produces and secretes synovial fluid Synovial fluid lubricates the joint Ligaments hold bones together controls movement

Features of Synovial joints

Hyaline cartilage lines the bones, protects, reduces friction Joint capsule surrounds the joint, adds stability, stops substances leaving or entering the joint

Features of synovial joints

Usually thin. Two layers of compact bone covering a thin layer of spongy bone. Provide protection of organs and a large area for muscle attachment. E.g. Cranium, sternum and ribs.

Flat bones

The angle between articulating bones is decreased and flexion occurs in the median plane about the horizontal axis. Muscles responsible for flexion are called flexors.

Flexion

muscles with their longer fibres cannot generate the same high forces that pennate muscles can with their shorter fibres and greater cross-sectional area.

Fusiform

Inversion occurs in the sole of the foot is turned inwards towards the imaginary midline of the body and this is in the frontal plane.

Inversion

Mainly provide protection and support. Have no regular shape characteristics E.g. Pubis and vertebrae.

Irregular bones

Isokinetic contractions Resistance changes according to joint angle This is made possible by specialised equipment (cybex) which allows maximal contractions through the range of movement

Isokinetic contractions

The muscle length creates a force but the muscle length does not change E.g. Gripping a tennis racquet, holding & gripping in rockclimbing & wrestling, Pushing against a wall

Isometric contractions

Isotonic contractions The muscle length changes during contractions (a) concentric - the muscle length shortens (bicep curl up) E.g. The quadriceps shorten during the kicking of a ball & the abdominals during a sit-up. (b) eccentric - the muscle length increases (bicep curl down) E.g. Quadriceps when walking down a hill, the quadriceps when lowering during a squat.

Isotonic contractions

A joints structure determines how it functions. The closer the bones fit the stronger the joint. Tightly fitting joints restrict movement. The looser the fit the greater the movement, although the joint is weaker.

Joints

Long Bones Have a hollow shaft containing marrow E.g. femur, humerus, philanges Found in limbs (legs, arms) Serve as levers for movement. Greater length than width. Mostly compact bone.

Long bones

cellular structures containing enzymes responsible for the production of energy under aerobic conditions.

Mitochondria

Transmit messages to the musvcle to tell it to contract. Each Neuron contains a axon and a cell body. The motor neuron consists of a cell body that directs the neuron's activities, branches that pick up the impulse called dendrites and an axon that transmits the message to the muscle.

Motor Neurons

A single motor neuron joins with many muscle fibres. The motor neuron & the number of muscle fibres that it innervates is called a motor unit. All muscle fibres will respond when the motor neuron is activated.

Motor Unit

Circumduction - the bone makes a cone shape as it moves Supination - move palms to face up Pronation - move palms to face down Eversion - move ankle so sole faces out Inversion - move ankle to face sole inward Dorsi flexion - raise toes / foot up Plantar flexion - point toes down or raise up onto tip-toes.

Movements

Flexion - decreasing the angle between two bones (Bending) Extension - increasing the angle between the bones (Straightening) Abduction - to take away from the midline of the body Adduction - to bring back towards the midline of the body Rotation - movement around an axis Lateral - move outwards Medial - Move inwards

Movements

Muscle fibres branch out repeatedly from the number of tendons. E.g. the deltoid of the shoulder.

Multipennate

Muscles are attached to bones by tendons which is mainly situated at the end of the muscle belly. Tendons are made up of connective tissue and can cross joints to provide support to specific sites. Ligaments attach one bone to another bone, and these two provide strength around the joint. The points of attachment for each muscle are known as the origin and insertion. The origin is the site where the muscle is attached to a stable bone, which the muscle can pull against. In most cases, that is the flat bone. The insertion occurs where the muscle attaches to a bone that is pulled by the action of the muscle. Muscle never work in isolation and always work in a team to bring about successful movements. The bicep contracts at the elbow because it causes movement the bicep is known as the prime mover or agonist. But allow the bicep to contract the triceps must lengthen. It is known as the antagonist because its actions are the opposite to that of the bicep.

Muscle Attachment

A thick protein filament found in the sarcomere responsible for muscle contraction.

Myosin

Many muscles found in the legs and torso contract isometrically for extended periods of times to enable us to stay upright.

Other muscle functions

where a muscle has fascicles or fibres that attach obliquely to the tendon

Pennation

Plantarflexion occurs in the ankle when the toes are pointed downwards and the heel is raised. This occurs in the median plane about a horizontal axis.

Plantarflexion

Lorddosis- Accentuated lumbar curve Kyphosis- Round shoulders Scoliosis- C or S shaped curve of the back

Postural Conditions

Pronation occurs when the forearm is rotated while the palm of the hand faces downwards. When this occurs the radius and ulna are crossed over each other.

Pronation:

Many bones protect your vital organs to reduce the chance of damaging them. For example the skull protects the brain and the ribs protect the heart, lungs and kidneys.

Protection

Rotation occurs when a bone turns on its own axis within a joint. Rotation towards the body's midline is known as medial or internal rotation; rotation away from the midline is known as lateral or external rotation.

Rotation

A basic unit of a striated muscle which causes it to contract.

Sarcomere

Are small bones developed in tendons around some joints E.g. patella

Sesamoid Bones

Very strong but have less movement (carpal and tarsal bones or foot) Nearly equal in length and width. Mostly spongy bone with an outer of compact bone.

Short bones

:These external muscles are attached to the bones that make up the skeleton. They are under direct control and so they are known as voluntary muscles. They are made up of striped/ striated cells.

Skeletal Muscles

These are found internally in blood vessels and walls of the intestines. You have no control over them so smooth muscles are also known as involuntary muscles. They are made up of the spindle cells.

Smooth Muscles

Supination occurs when the forearm is rotated, turning from hand to palm down to palm up, so that the radius and ulna lie parallel to each other and are uncrossed.

Supination

The skeletal system is the the frame of the human body. It supports soft tissue and is a point of attachment for muscles. Example of attachment: the knee

Support

Joints are lubricated by "synovial" fluid. Connections called "synovial" joints are sturdy enough to hold the skeleton together and at the same time permit a range of motions. The ends of these joints are coated with cartilages which reduce friction and cushion against jolts.

Synovial Joints

Exists where bones with flat surfaces meet. Surfaces slide over each other allowing sideways, backwards and forwards movement - Eg. carpals/Tarsals

Synovial Joints- Gliding joint

Has only one axis and allows flexion and extension only. - eg. knee, elbow

Synovial Joints- Hinge Joint

Has only 1 axis, allowing only rotation. Rotation of one bone around another - eg. neck (atlas & axis)

Synovial Joints- Pivot joint

Is a bi-axial joint. like structures interlocking, allowing forwards, backwards and sideways movement - eg. base of the thumb

Synovial Joints- Saddle joint

The Appendicular skeleton is comprised of the bones in the arms, legs, shoulder and the pelvis. The pectoral girdle (collarbone) has 4 bones, The upper limbs contain a total of 60 bone (54 of which are in the hands and wrist).The pelvic girdle consists of 2 bones The lower limbs contain 60 bones (54 of which are in the feet and ankles).

The Appendicular skeleton

Each vertebrae has a hollow centre through which travels the spinal cord The vertebrae increase in size as they descend from the cervical to the lumbar region Movement between 2 vertebrae is very limited, but the range of movement of the vertebral column as a whole allows bending and twisting

The Vertebral Column

The cervical vertebra: These seven unfused bones make up the neck and are responsible for supporting the head. The thoracic vertebrae: These 12 unfused bones basically connect the rib cage to the spinal column to form a protective shield for the heart and lungs. The first seven pairs attach directly onto the sternum and each rib is attached to the ribs via intercostal muscles which assist the body to breath in and out. The lumbar vertebrae: These five unfused bones are the largest of the vertebrae and have a high weight- carrying capacity. The sacrum: The five fused c=sacral vertebrae are connected to form the sacrum which fuses to the pelvis. The coccyx: The coccyx is sometimes referred to as the 'tail bone' and compromises four fused bones that form the base of the vertebral column.

The vertebrae column

Compact Bone is found in the shaft or diaphysis of the long bone Is strong, heavy and dense used for strength Cancellous Bone (spongy bone) Provides some of the shock absorption required at the end of long bones Is of honeycombed appearance, strong yet lightweight

Types of Bone Tissue

There are 5 types of bones which are distinguished by their shape. Long Short Flat Irregular Sesamoid

Types of Bones

Fibrous or immovable joints Offer no movement E.g. skull, pelvis, sacrum, sternum Cartilagenous or semi-movable joints Are joined by cartilage and allow small movements E.g. the vertebrae, where the ribs join the sternum Synovial joints Are freely movable E.g. shoulder, knee ankle

Types of Joints

Fixed or fibrous None Skull, pelvis, radioulnar and tibiofibular joints Cartilaginous, Slightly Ribs attaching to sternum , lumbar vertebrae Synovial Freely Hip and knee joints, cervical and thoracic vertebrae

Types of Joints Amount of movment and examples

The body can move in many different ways, each bones ability to move depends on the muscle attached and the type of joint. Each movement has an opposite movement

Types of Movements

muscle fibres only branch out to one side of the tendon

Unipennate