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Skeletal Tissue - Week 3 CONNECTIVE TISSUE Connective Tissue (CT) an important and abundant substance within the body, especially in the muscular and skeletal systems Connective Tissue found in:  Ligaments  Tendons  Muscles Bones  Adipose (Fat) Tissue Roles of Connective tissue:  Bind and support  Protection  Insulation  Transportation All connective tissue have the same basic elements - all have different amounts and proportions are scattered in different ways Elements of Connective Tissue Ground Substance (EC Matrix) Fills space between connective Tissue cells and contains the fibres Fibres (EC Matrix) 1. Collagen - High Tensile Strength (e.g. tendons and ligaments) strongest 2. Elastic - Strength and recoil (ability to return to original shape - blood vessels) 3. Reticular - Thin, delicate networks (e.g Soft Tissue) like a spider web Ground Substance + Fibres = Extracellular matrix Cells 

Each major class of CT has a fundamental cell type o Immature "-blast" o Mature "-cyte"

TYPES OF CONNECTIVE TISSUE CTP

CARTILAGE

BONE BLOOD

1. CONNECTIVE TISSUE PROPER (CTP) fibro Dense Connective Tissue • Flexible structures with great resistance to tension – e.g. Tendons & Ligaments Loose Connective Tissue • Frameworks for storage, immunity and binding – e.g. Adipose Tissue (Fat) 2. CARTILAGE chondro • Considered to be a specialised connective tissue • Tissue is “avascular”: Low blood supply > Low oxygen supply > Limited healing of cartilage (ALL CARTILAGE IS avascular) Most things heal because blood supply is running through it bringing nutrients to it

Cartilage use absorption method Nutrients come in and out of it but not through blood vessels that run through it • 3 types: (VITAL) 1. Hyaline Cartilage: Reduces friction also does a lot of shock absorption o Found in  Nose  End of every long bones  Costal (Ribs)  Growth Plates (epiphyseal lines) 2. Fibrocartilage: Shock absorption o Knee (meniscus) big pad in your knee o Pubic Symphysis between coxal bones o Intervertebral Disc 3. Elastic Cartilage: Springs back to shape (recoils back to where it was) o External Ear 3. BONE osteo  Considered to be a specialised connective tissue  A connective tissue that forms the bony skeleton  2 types o Compact Bone o Spongy Bone 4. BLOOD A unique body fluid that transports: • Nutrients and oxygen to the cells • Metabolic waste products away from the cells Summary Table

BONE ANATOMY & PHYSIOLOGY Functions of the Skeleton  Support - Hard framework supports body  Protection - Shield for internal organs  Movement - Muscles attach to skeleton to create movement  Storage/Supply o Storage of calcium, phosphate and fluoride o When other things need calcium they take it from the skeleton o Red Blood Cells are produced within bone marrow cavities Components of Bones Compact Bone • Dense outer layer, smooth & solid Spongy Bone • Internal ‘honeycomb’ network called trabeculae • Trabeculae created by irregular laydown of bone • Spaces between trabeculae filled with red / yellow bone marrow (RULE: If it's red it has blood in it, if it's yellow it has fat in it) Structure of a Flat Bone - Compact and Spongy Composition of Bones Collagen  Important part of organic make-up of bone  Constitutes 35% of bone tissue  Provides flexible strength and resilience  Easy to bend, hard to break Minerals  Inorganic material: calcium, phosphate, fluoride  Make up 65% of bone tissue  Provides great hardness, rigidity weight bearing strength  If you had a bone with lots of minerals, it would be like glass. Inability to bend 

Right combination of these 2 ensures bones are very durable without being brittle

BONE CLASSIFICATION • Bones classified according to their shape • Each unique shape fulfils a particular need. For example: The Femur – Hollow and cylindrical – Maximum strength with minimum weight 1. Long Bones • Longer than wide. “Rectangle” • Shaft + 2 ends, slightly curved for strength • Primarily compact with smaller amounts of spongy bone

• ‘Long’ refers to shape not size (e.g. phalanges vs. femur) Examples: All limb bones (Except for carpals / tarsals / patella) 2. Short Bones • About the same length all sides. “Cube” • Mostly spongy within compact bone surface layer Examples: Carpals / Tarsals 3. Flat Bones • Thin & slight curve • 2 parallel compact surfaces surround layer of spongy • Large surface area for muscle attachment and protection Examples: Scapula / Clavicle / Ribs / Sternum / Skull Reason these are flat and not long bones because there is no shaft with bone ends - have a sandwich structure 4. Irregular Bones • Complex shape • Mainly spongy with thin layer compact • Vertebral Column / Pelvic Girdle Examples: Coxal Bone / Vertebrae / Sacrum / Coccyx 5. Sesamoid Bones ‘sesame seed shape’ • A bone found within a tendon • Specialised short bone • Distributes force by changing angle of pull of the tendon When a muscle pulls on something sesamoids have the ability to change direction of the pull Examples: Patella

STRUCTURE OF LONG BONES

Diaphysis (Shaft) 1. Periosteum  Peri = around | Osteum = bone  "Wrap" of blood vessels and nerves  Contains blood vessels & nerves  Acts as an anchor for tendons & ligaments 2. Compact Bone  Thickest part of diaphysis  Full of osteocytes  Bloods runs in and out of the Haversion System  Appears very dense but microscopic view displays a complex arrangement of canals These canals are known as the Haversion System The Haversion System is a system of passageways for nerves and blood vessels. Each passageway is called an osteon. 3. Endosteum  Endo = inside | Osteum = bone  Covers the inner layer of compact bone  Contains both osteoblasts and osteoclasts  -clast refers to a destructive cell. Therefore an osteoclast would be a cell which breaks down bone.  Sometimes to get the calcium out you need to break the bone down 4. Medullary Cavity “marrow cavity”

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Infants: Red bone marrow (RBC production) Adults: Yellow bone marrow (fat) In adults red bone marrow mostly found in spongy bone of flat or irregular bones When anaemic, the body converts yellow bone marrow to red bone marrow for increased RBC production

Diaphysis (Shaft) 1. Periosteum 2. Compact Bone 3. Endosteum 4. Medullary Cavity

Epiphysis (Bone End) 1. Articular Cartilage  Joint surface of each epiphysis covered by hyaline cartilage  Absorbs stress and decreases friction during movement 2. Spongy Bone o Predominant component o Lies under thin layer of compact o Irregular lay down of bone called trabeculae (woven bone) o Arrangement enables it to withstand stresses & supports compact bone o Contains Red Bone Marrow and osteocytes o Always has two components - trabeculae and bone marrow 3. Epiphyseal Line o Between the diaphysis and each epiphysis of adult long bones  Remnant of the epiphyseal (growth) plate  Hyaline cartilage which grows during childhood to lengthen bone  When you stop growing the bone is filled in  Longitudinal bone growth ceases when the epiphyseal plate fuses: – ~21yr for males – ~18yr for females Epiphysis is made of spongy bone

Bone Formation and Development – Week 4 BONE FORMATION Bones are DYNAMIC, living tissues - always changing in size, shape, density, thickness etc. Density is always changing throughout entire lifespan The process of bone formation is called Ossification "Oss" = bone "ification" = formation Ossification - Process of Bone Formation 1. Begins as an embryo 2. First 8 weeks: Fibrous membranes & hyaline cartilage 3. Bones grow until early adulthood (~25 years) 4. Bones remodel during adulthood Mesenchymal Cell - Origin cell Osteoblast - Immature Bone Cell Osteocyte - Mature bone cell Compact Bone - Bone: Dense and hard Trabeculae - Bone: Random struts with spongy bone Spongy Bone - Bone: Porous with trabeculae Periosteum - Bone: Outside layer Osteoid - Bone making Red Marrow - Blood making Two Types of Ossification Intramembranous Ossification occurs in a fibrous membrane • Intra = Inside | Membranous = Membrane • Creates all flat bones Stage 1:  Ossification centres appear in the fibrous connective tissue membrane  Mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification centre  Lay down osteoid. Osteoid is un mineralised bone Stage 2:  Osteoid is secreted within the fibrous membrane and calcifies into a bone matrix.  Osteoblasts begin to secrete osteoid, which is calcified within a few days.  Osteoid is unmineralised bone  Trapped osteoblasts become osteocytes. Stage 3:  Woven bone and periosteum form.  Osteoid is randomly laid down between blood vessels resulting in a network of trabeculae called woven bone.  Vascularised mesenchyme condense outside the woven bone, creating the periosteum.

Stage 4:  Lamellar bone replaces woven bone, beneath the periosteum.  Red marrow appears.  Trabeculae beneath periosteum thicken > Replaced with lamellar bone (packed together bone) > Forms compact bone.  Spongy bone consisting of trabeculae remains inside, becoming red marrow.

Endochondral Ossification • Endochondral Ossification occurs in a hyaline cartilage model • Endo = Within | Chondral = Cartilage • Endochondral Ossification creates all bones (except flat bones)

Bone Remodelling The Law of Bone Remodelling  Wolff’s Law - A bone will grow and remodel in response to the forces & demands placed upon it. – Simply: A bone will adapt to suit its needs 1. Gravitational Forces (Supporting body weight) • Larger body = larger bones • Vertebral column is a clean example 2. Muscle Pull • Bony Landmarks • Weight lifters have large thickenings at muscle attachment sites For example the femur:  Large to support body weight  Curved to absorb stress  Has bony landmarks where muscles attach Wolff’s law also explains that bones atrophy when placed under no stress • Example: Bedridden people • Example: Astronauts Remodelling & Repair • Bone Remodelling is controlled by bone deposition (adding) & bone resorption (removing) • Bone is recycled at a rate of 5-7% per week. To completely replace it takes: – ~3-4 years for spongy bone – ~10 years for compact bone

Child/Adolescent

Deposition > Resorption

Adult

Deposition = Resorption

Elderly

Deposition < Resorption

Bone Remodelling Units Osteoblasts  Bone forming cells  Responsible for bone deposition o Repair following injury o Increasing bone strength Osteoclasts  Bone destroying cells  Responsible for bone resorption o Destroys bone into minerals so they can be used by the body

Control of Remodelling Negative Feedback Loop • A negative feedback loop is a system which responds with the opposite effect of the original stimulus until balance is achieved

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Osteoporosis  Imbalances between deposition & resorption is the main cause of most diseases affecting the skeleton. For example: Osteoporosis Bone resorption > Bone deposition Leads to reduction in bone mass / density

JOINTS: STRUCTURE & FUNCTION – Week 5 INTRODUCTION TO JOINTS • An Articulation is the anatomical name given to a point of contact between 2 bones, commonly referred to as a JOINT • Joints are versatile and allow for a wide range of movements

• As movement is increased, stability is decreased. This makes joints the weakest part of the skeleton

Why do I need joints? Joint Classification • To classify a joint you need ≤ 4 pieces of information 1. Structural Class 2. Type 3. Mobility 4. Axis of Rotation • Once you have these 4 pieces of information you would write it like this: Structural Class / Type / Mobility / Axis of Rotation

Joint Mobility Synarthrotic Amphiarthrotic Diathrotic

Mobility of Joints No movement Slight movement (‘little bit of give’) Freely moveable

• Synarthrotic and amphiarthrotic joints mainly in axial skeleton • Diathrotic joints mainly in appendicular skeleton Structural Classification

Structural Classification determined by: 1. Type of connective tissue binding bones together 2. Whether or not a joint cavity is present Structural Classes of Joints Fibrous Joined by fibres Cartilaginous Joined by cartilage Synovial Have a joint cavity 1.Fibrous Joints  Bones connected by fibres

 Fibre length determines amount of movement Types of Fibrous Joints

2. Cartilaginous Joints  Bones connected by cartilage  Cartilage type determines amount of movement Types of Cartilaginous Joints 1. Synchondroses – Connected by hyaline cartilage e.g. 1st rib to sternum or Epiphyseal Plate (growth plate) Mobility: Synarthrotic 2. Symphyses – Connected by a fibrocartilage pad e.g. Intervertebral joint or Pubic Symphyses Mobility: Ampiarthrotic 3. Synovial Joints  Bones are separated by a fluid filled cavity  Bone structure determines amount of movement  All synovial joints are diathrotic (freely moveable)

Types of Synovial Joints  Plane Joints o Joint surfaces are flat or slightly curved o ‘Gliding’ movements in any direction o Examples :  Between carpals (Intercarpal joint)  Between tarsals (Intertarsal Joint)  Between facets of vertebrae (Zygapophyseal Joint)  THEY ARE EVERYWHERE! If you don’t know...IT’S A PLANE  Hinge Joints o ‘U-Shape’ and cylinder o Movements - Flexion/Extension o Examples:

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Elbow, ankle, between phalanges (Interphalangeal joint – fingers or toes)

Pivot Joints o Round bone end enclosed by bony ring & ligaments o Rotation (longitudinal axis) o Examples  Atlantoaxial joint (Between atlas and axis)  Proximal Radioulnar joint (Between radius and ulna)  Distal Radioulnar joint (Between radius and ulna) Condyloid Joints o Oval convex surface fits into oval concave surface o Movements – Flexion / Extension & Abduction / Adduction o Examples  Radiocarpal joint (Wrist)  Metacarpophalangeal Joint (Base of fingers ‘knuckles)  Metatarsophalangeal Joint (Base of toes ‘toe knuckles’) Saddle Joints o Each surface has convex and concave area, like a saddle o Movements – Flexion / Extension & Abduction / Adduction & Opposition o Examples – Carpometacarpal 1 Joint (Base of thumb) Ball and Socket Joints o Spherical head of one bone articulates with the socket of another o Movements – Flexion / Extension & Abduction / Adduction & Medial / Lateral Rotation o Examples – Glenohumeral joint (Shoulder) and Hip

Joint Classification Table

Axis of Rotation  Nonaxial – No axis of movement – Example: Plane Joints  Uniaxial – 1 axis of movement – Example: Hinge and Pivot Joints  Biaxial – 2 axes of movement – Example: Condyloid and Saddle Joints  Multiaxial – 3 axes of movement – Ball & Socket Joints Problem Joint Number 1 Tibiofemoral Joint (Knee) Classification – Synovial / Bi-Condylar / Diathrotic / Biaxial  A Bi-Condylar joint is where two condyles are found next to each other (only the knee) o Allows for: Flexion / extension and slight rotation  The knee is also sometimes referred to as a modified hinge  Therefore: o Synovial / Modified Hinge / Diathrotic / Biaxial Problem Joint Number 2 Sternoclavicular Joint Synovial / Shallow Saddle / Diathrotic / Multiaxial  The sternoclavicular joint is a shallow saddle  A shallow saddle is still a saddle shape, but shallower or ‘flatter’ o allows for more movement than a normal saddle, allowing it to also perform rotation  This makes the shallow saddle a multiaxial joint

Joint Stability and Injury – Week 6 FACTORS AFFECTING JOINT STABILITY Joint Mobility-Stability Trade-off Joints are connections between bones which need to be both mobile and stable. Joint Mobility-Stability Trade-off When mobility is emphasized, stability is reduced When stability is emphasized, mobility is reduced Range of Motion (ROM) Fitness  Increased ↑ Fitness = Increased ↑ ROM o Due to greater flexibility and Strength Age  Increased ↑ Age = Decreased ↓ ROM o Ligaments and Tendons: Stiffen and shorten Fat Tissue  Increased ↑ Fat Tissue = Decreased ↓ ROM o Increased Age = Increased Fat Tissue

Muscle Tissue  Increased ↑ Muscle Tissue = Decreased ↓ ROM o Increased Age = Decreased musculature

Factors Affecting Joint Stability     

Shapes of Articulating Surfaces Ligaments Muscle Arrangement Skin & Fibrous Connective Tissue (Fascia) Atmospheric Pressure

1. Shape of Articulating Surfaces  The ‘shape of articulating surfaces’ refers to the shape of the two bones creating a joint For example:  The ball shaped head of the femur articulating with the ball shaped socket on the coxal bone is highly stable  The oval shaped condyles of the femur articulating with the oval shaped sockets on the tibia is highly unstable Hip  Deep Socket ‘locks in’ femur  Acetabulum + Femoral Head  Highly Stable Knee  Nothing ‘locked in’  Tibia Head + Femoral Condyles  Highly unstable Shoulder  Shallow socket  Glenoid Cavity + Humerus Head  Highly unstable

2. Ligaments  A ligament is made of connective tissue proper and connects bones together providing joint stability  1. Restricts undesirable movements 2. Offers support & stability 3. Susceptible to injury  Note: When ligaments are the major means of support, the joint is considered unstable Knee

Anterior Cruciate Ligament Posterior Cruciate Ligament Fibular Collateral Ligament Tibial Collateral Ligament Oblique Popliteal Ligament Arcuate Popliteal Ligament

Ankle Deltoid Ligament – Also known as the “Medial Ligament”

Intracapsular Extracapsular

3. Muscle Arrangement  The muscle tendons that cross the joint are very important joint stabilisers. Especially when bone articulations are poor. Examples: Knee and shoulder  Muscle Tone o Low level of contractile activity in relaxed muscle that enables muscle to react to any postural changes or movement o Muscle is stretched > sends signal to nervous system > system reacts by contracting local muscle via a reflex Stability of the Knee Articulating Surfaces Ligaments Muscle arrangement 4. Skin and Fibrous Connective Tissue (Fascia)  Forms a sheath around muscles and joints offering great stability 5. Atmospheric Pressure  A vacuum within the joint is created when the joint surfaces are being separated further improving joint stability  Example - If muscles and ligaments surrounding the hip joint are cut the head of the femur would remain in place

LIGAMENT INJURY      

Up to 4% deformation can occur with the ligament being able to return to its normal shape and alignment Greater than 4% deformation leads to ligament damage which is an injury called a sprain Grade I: Some fibres stretched or torn Grade II: Some fibres torn with effusion (damage to synovial lining) Grade III: Complete rupture Avulsion Fracture: Ligament pulls away with piece of bone

Apply RICER for Grade I and Grade II Surgery for Grade III and Avulsion Fracture as a disconnected ligament will not grow back together without surgical help FRACTURES  A fracture is any damage to a bone  Fractures can be classified by 4 factors 1. Completeness 2. Orientation 3. Position These factors are determined by using ‘a OR b’ questions Common Fracture Types  Comminuted – Bone fragments into three or more pieces. Common in aged, as bones are more brittle  Compression – Bone is crushed. Generally caused by falling, particularly in porous bones  Spiral – Ragged break occurs when excessive twisting forces are applied to a bone. Common sports fracture  Epiphyseal – Epiphysis separates from the diaphysis along the epiphyseal plate

4. Skin

COPS

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Depressed – Broken bone portion is pressed inward. Typical of skull fracture Greenstick – Bone breaks incompletely. One side breaks, the other bends. Common in children, as they have a higher collagen percentage in bone

Stages of Bone Healing 1. Hematoma Formation  Blood vessels are torn and...