Lecture 1 - Basic concepts Flashcards by Anmol Landa

6 functions of bone

Support
Protection e.g skull 
Metabolism 
Storage e.g calcium phosphate 
Movement 
Haematopoiesis

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6 functions of skeletal muscle

Locomotion
Posture - postural muscles 
Metabolism - glycogen 
Venous return 
Heat production - shivering 
Continence - pelvic floor muscles

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Types of connective tissue

Tendon - bone to muscle
Ligament - bone to bone
Fascia - compartmentalisation of muscles
Cartilage - hyaline/ fibrous

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Synovial membrane

Found within joints, bursae and tendon sheaths

Produces synovial fluid which lubricates joints

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3 classifications of joints

Fibrous
Cartilaginous
Synovial

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Fibrous joints

Collagen fibres
Very limited mobility
High stability

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Examples of fibrous joints

Sutures of the skull
Inferior tibiofibular joint (ankle)
Joint between the roots of a tooth and the bone of the mandible or maxilla
Radioulna interosseous membrane (forearm)
Posterior sacroiliac joint (Pelvis)

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Cartilaginous joints

Hyaline cartilage

Found in the midline typically and in epiphyseal plates of long bones

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Primary cartilaginous joints

Completely immobile
Hyaline cartilage
First sternocostal joint
Epiphyseal growth plates

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Secondary cartilaginous joints

Also known as symphases
Articulating bones covered with hyaline cartilage with a pad of fibrocartilage between them

E.g symphysis pubis
Intervertebral discs
Manubriosternal joint

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Periosteum arteries

Supply the periosteum and the outer third of the cortex of bone

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Metaphyseal arteries

Enter at the site of attachment of the capsule

Children- do not cross the growth plates

Adulthood - anastomosis formed between the epiphyseal and metaphyseal arteries

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Avascular necrosis

Death of bone due to the lack of blood supply

Common cause:
Fracture

Other cause:
alcoholism
Excessive steroid use
Thrombosis
Hypertension
Decompression sickness - small bubble of nitrogen which impede blood supply
Radiation - obliteration of small arteries

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Bone remodelling

Response to environmental factors
E.g sustained application to load
Change in balance between osteoclast and osteoblasts activity

I.e increased use - higher osteoblasts activity therefore thicker

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Synovial joints

Joint cavity containing synovial fluid

Articulating surfaces covered in hyaline cartilage - avascular

Fibrous capsule

Synovial membrane

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Synovial fluid function

Provides lubrication to the articulating surfaces
Prevents friction
Shock absorber
Transport nutrients and waste products to and from articulate cartilage

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Synovial articulating surfaces

hyaline cartilage
smooth,low friction movements
resists compressive forces - shock absorber

Fibrous capsule

composed of collagen in longitudinal and interlacing bundles.

Encloses joint

Except at bursae - synovial protrusions

Poor blood supply

Stabilises joint
Permits movement
Resists dislocation
Continuous with the periosteum

Synovial membrane

Thin
Highly vascularised- rich blood supply- transfer of nutrients
Produces synovial fluid
Lines joint capsule and covers any exposed osseous surfaces
Lines tendon sheaths and bursae

(Does not cover articulating cartilage or intra- articulating discs/menisci

Shapes of synovial joint (6)

Plane - move in one pla
Hinge 
Saddle 
Condyloid (ellipsoid) 
Pivot 
Ball and socket

Plane joints

Two flat surfaces slide against each other
Smooth movement
Single plane
Several direction

Examples

Carpal bones of wrist
Facet joints

Condyloid joints

Atlanto- occipital joint at base of skull

Radiocarpal joints - between radius and the carpals

Saddle joints

Motion in 2 planes at the same time
Degree of sliding

Example:

1st carpometacarpal joint at base of thumb

Hinge joint

Stable flexion and extension
No sliding or deviation
Single plane

Example:
Elbow

Pivot joint

Peg within a ring shaped hole Rotational motion with gliding Without bending or sideways displacement Example: Atlanto - axial joint - allows head to rotate whilst maintains stability

Ball and socket joint

Stable movement in several directions Without slippage Most mobile - least stable Permit flexion and extension, adduction and abduction, lateral rotation and medial rotation, circumduction Examples: Hip Shoulder

Bursa

Small sac lined by synovial membrane Contains a thin layer of synovial fluid Provides cushion between bones and tendons/ muscle around a joint - reduce friction and promotes free movement Filled with synovial fluid Communicating or non-communicating with joint cavity

Tendon sheaths

Elongated bursae that wrap around a tendon | Reduce friction associated with the movement of a tendon

Synovial fluid

Clear or pale yellow Viscous Slightly alkaline ``` Contains: hyaluronic acid Lubricin Proteinases Collagenases ```

Intervertebral discs

Between vertebrae | No synovial membrane

Plexus of arteries

Surround synovial joints | Maintain blood supply regardless of the position

Where do synovial joints form

Between adjacent cartilage models - joint interzone

How do synovial joints form

Chondrocytes at the centre of the interzone region undergo apoptosis - joint cavity Surrounding mesenchymal cells from the perichondrium form the periosteum where they lie in contact with bone Form the articulating capsule and supporting ligament which ch lie in contact with the developing joint

Knee joint cartilage

Some cartilage is preserved within the joint and develops into intra articulating ligaments Examples: Anterior and posterior cruciate ligaments of the knee

Role of tendon

Force transmission

Role of ligament

Support joints | Restrict range of movement

Hyaline cartilage

Smooth | Reduces friction

Fibrocartilage

Higher collagen content shock absorption Increase congruity- better shape

Hydroxyapatite

Calcium Phosphate (CaPO4) Mineralises extracellular matrix Makes bone rigid Compressive strength

Bone made of

``` Collagen - tensile strength Elastin Water Glycosaminoglycans Proteoglycans ```

Factors influencing range of motion of a joint

``` Structure of articulating bone Strength and tension of the ligaments Tone of muscle Apposition of neighbouring soft tissue Hormones (relaxin) Disuse ```