Bone, Cartilage, Joint Anatomy Slides PDF

PT7001 / PT4050 Bone, Cartilage, Joint Anatomy Mia Preece [email protected] Lecture Aims  Explain what bone and cartilage are and describe how they are classified  Describe the structure of spongy (trabecular) and compact bone  List the cell...

PT7001 / PT4050 Bone, Cartilage, Joint Anatomy Mia Preece [email protected] Lecture Aims  Explain what bone and cartilage are and describe how they are classified  Describe the structure of spongy (trabecular) and compact bone  List the cells of cartilage and bone, their matrix components and give their functions  Define the parts and functions of the skeleton  List the anatomical terms used to describe bones  Provide a classification of the different types of joints, and be able to describe these and name examples of each  Describe the structure and role of capsular ligaments and intra-articular discs  Describe the different structures that determine joint stability  Skeleton  ~ 206 bones in adult  (300 in babies -> fuse)  more then half in hand & feet  cartilage also part of skeletal system Axial or Appendicular Axial Skeleton ≈ 80 bones SKULL 22 bones of Face (14) and skull (8) RIB CAGE Sternum and Ribs 12 pairs of ribs True ribs 1-7 False ribs 8-12 (Floating ribs 11 & 12) VERTEBRAL COLUMN Divided into 5 sections: Cervical - 7 Thoracic - 12 Lumbar - 5 Sacral - 5 (fused) Coccyx - 3-5 (fused) Appendicular Skeleton  Consists of 126 bones  Phalanges x 56  Tarsals and Carpals x 30  Metatarsals and metacarpals x 20  Radius, ulnar, tibia and fibula  Humerus and femur  Pelvis (ilium, ischium, pubis)  Patella  Clavicle, scapula Axial vs Appendicular Quiz  This part is mostly responsible for movements such as walking, running, eating, waving..............  This part is responsible for protection of vital organs............  Consists of around 80 bones.....  Consists of around 126 bones...  The part is mostly responsible for posture.................................. Bones Bone Composition 5 Roles of Bone - What are they? Structure of Bones  Diaphysis - long shaft  Epiphysis - rounded ends  Periosteum - outer layer  Epiphyseal line (growth plate)  Medullary cavity - bone marrow  Articular cartilage Structure of Bones  Compact Bone Compact (Cortical) Bone  The basic unit of structure is the osteon - Haversian Systems  Each osteon is composed of calcified matrix called lamellae  Down the centre runs the central canal (Haversian Canal) through which blood, nerves and lymph vessels pass  The osteocytes are located inside spaces called lacunae  Spongy Bone Spongy Bone (Cancellous/Trabecular)  Found in the epiphysis  Mainly in long bones  Porous  Lightweight  Irregular arrangement to increase strength  Consists of a system of struts and plates (Trabeculae)  Red bone marrow fills the spaces  Inside a Bone contd.  Bone marrow – soft gelatin-like tissue found in central medullary cavities of long bones & some short bones. Contains stem cells. Produces most of new RBC in body  2 types of bone marrow:  Red (medulla ossium rubra) in flat & spongy bone  Yellow (medulla ossium flava) in medullary cavity  Red bone marrow  RBC, platelets and WBC stored and produced  Yellow bone marrow  fat cells  Both highly vascular  At birth all bone marrow is red. By By adulthood 50:50 Bone Cells Stem cells: unspecialized cells, Osteoid: non-mineral, able to differentiate organic part of bone into any cell matrix made of collagen & other  Osteocytes proteins. Osteoblasts  mature bone cells secrete these.  lie in lacunae  Osteoblasts  deposition of osteoid  Osteoprogenitor (osteogenic) cells  mesenchymal, stem cell  Osteoclasts  haemopoietic, stem cells  involved in resorption of bone Bone Development During bone development bone replaces cartilage and other connective tissues = ossification Intramembranous bones forming TWO PROCESSES  1. Intramembranous Ossification  bones of the head Extracellular matrix of embryonic  in mesenchyme unspecialized Endochondral connective tissue  no cartilage present bones forming  from mesenchymal stem cells  2. Endochondral Ossification  from pre-existing cartilage model Endochondral Ossification  Bones start as cartilage and change to bone - Ossification  Mostly when we are a foetus  Some develop as we go through early childhood  Mature in adolescence  Bones grow in length at the epiphyseal plate Endochondral Ossification 1 1. First site of ossification occurs in the primary ossification centre, in middle of diaphysis 2. Formation of periosteum - contains osteoprogenitor cells  become osteoblasts later 3. Formation of bone collar - osteoblasts secrete osteoid on the cartilage model = Appositional growth - support for new bone 4. Calcification of matrix - chondrocytes in primary ossification centre grow - begin to deposit minerals. Osteoclasts break down spongy bone to form medullary cavity. diameter growth of bones occurs by deposition of bone beneath periosteum Endochondral Ossification 2 1. Around the time of birth, a secondary ossification centre appears in each end (epiphysis) of long bones. 2. The cartilage between the primary and secondary ossification centres = epiphyseal plate  continues to form new cartilage  replaced by bone = increase in bone length. 3. Process continues until about 20 years until all cartilage is replaced by bone. 4. Point of union between 1ry & 2ry ossification centres = epiphyseal line Diameter growth of bones occurs by deposition of bone beneath periosteum (appositional growth). Osteoclasts resorb  ultimate thickness achieved. Growth (Epiphyseal) Plates Bone Growth and Remodelling Bone Cells Osteoblasts deposition of new bone Formation and resorption of bone occur continuously = remodelling Osteoclasts resorption of old / damaged bone Bone Remodelling  Osteoblasts  deposition of new bone HEALTHY OSTEOPOROSIS  Osteoclasts  resorption of old/damaged bone  Needs a balance The formation and resorption of bone occur continuously = remodelling Bone remodelling is a lifelong process where mature bone tissue is removed from the skeleton and new bone tissue is formed. These processes control the reshaping or replacement of bone following injuries like fractures but also micro-damage, which occurs during normal activity. Bone resorption outpaces bone formation as the body ages. Types of Bones Types of Bones  FLAT  LONG  SHORT  IRREGULAR  SESAMOID  Lumps and Bumps Tubercle - small rounded point Tuberosity / trochanter - larger rounded bit Linea - line Hamulus – hook shape Process - projection Ramus – curved part of a bone (structural) Spine - ridge  Grooves and Holes Fossa – broad shallow dip Foramen – hole (typically for nerves, veins, arteries) Sulcus – groove/dip Notch - groove  Articular Surfaces Condyle – rounded bone end - articulates Epicondyle – a protuberance on the condyle – muscle attachments Capitulum – can be part of a condyle Trochlea – groove like a pulley Facet – flat or curved, synovial gliding joint Cartilage and Joints Cartilage - What is it?  Soft, slightly elastic tissue consisting of a matrix of chondrin (a protein)  Does not contain blood vessels  Chondro = cartilage THREE TYPES Elastic Hyaline cartilage Fibrocartilage cartilage Elastic Cartilage  Consists of YELLOW elastic fibres running through a solid matrix  Chondrocytes large and numerous  Has a perichondrium (thick conn tissue layer)  Provides strength, and elasticity, and maintains the shape of certain structure  Example: Epiglottis, ears Fibrocartilage  Consists of dense mass of WHITE collagen fibres in solid matrix  Lacks a perichondrium  Chondrocytes in rows  Gives it a great tensile strength  Tough, slightly flexible  Example:  intervertebral disc  symphysis pubis  articular discs e.g. menisci in knee  labrum Hyaline Articular cartilage coefficient of friction - as low as 0.002< 0.02 Cartilage - ice on ice = 0.02  Appears as smooth BLUISH-WHITE matrix  Matrix is solid, smooth and firm (glassy)  Smooth, almost frictionless  Chondrocytes housed in lacunae  Has a perichondrium (except articular cartilage)  Example:  on surfaces of bones that form synovial joints  ribs  nose, larynx, tracheae Cartilage locations Growth of Cartilage Appositional growth:  Chondroblasts in perichondrium differentiate into chondrocytes  start producing matrix, and add to existing cartilage (widen) Interstitial growth:  Proliferation and hypertrophy of existing chondrocytes (lengthen) Joints  Arthro = joint  Where two or more bones come together - this gives each joint its name  Allow and control movement between bones - dictated by the shape of the articulating surfaces  Stability of a joint depends on:  shape of articular surfaces  ligaments  muscles Classification of joints FIBROUS CARTILAGINOUS SYNOVIAL Fibrous joints  Bones are united by dense, fibrous connective tissue  No joint cavity  Little or no movement  Syndesmoses - broad fibrous connective tissue  Gomphoses - dento-alveolar joint  Suture - skull… …sutures  Serrated (denticulated) sutures …sutures  Squamous sutures …sutures  Plane sutures Cartilaginous joints PRIMARY  Articulating bones separated by cartilage - binds the bone  No joint cavity  Synchondroses (primary) - hyaline cartilage between the bones e.g. ribs-sternum  Symphyses (secondary) - fibrocartilage between the bones e.g. intervertebral discs SECONDARY  Synovial joints  All peripheral joints  Surrounded by a synovial capsule and synovial fluid  Ends are covered in hyaline/articular cartilage  Ligaments connect, inside and outside capsule  Usually located at the ends of long bones  Allow for a lot of movement  Ligaments support articulating bones Specialised features of synovial joints Synovial joints - 6 types  PIVOT  PLANE/GLIDING  HINGE  SADDLE  CONYLOID  BALL AND SOCKET Synovial joints  PIVOT e.g. radioulnar  Cylindrical shape  Mono / Uniaxial  Ring formed by bone and ligament  Allows rotation Pivot joint between head of radius and radial notch of ulna  PLANE/GLIDING e.g. carpals  Flat/slightly curved  Mono / Uni / Nonaxial  Glides and slides Synovial joints  HINGE e.g. tibiofemoral  Convex and concave  Mono/Uniaxial  Can be ‘modified’  Allows flexion and extension  SADDLE e.g. trapeziometacarpal  Convex and concave  Biaxial (2 axes)  Allows slight movements including flexion, extension, abduction and adduction Synovial joints  CONDYLOID e.g. metacarpophalangeal  Oval convex and concave  Biaxial  Allows flexion, extension, abduction, adduction and circumduction  BALL and SOCKET e.g. GHJ  Obvious convex ball and concave  Multiaxial  Allows flexion, extension, abduction, adduction, medial and lateral rotation, circumduction Capsular Ligaments Thickening of the fibrous capsule that form bands/ triangles which enhance the strength of the joint capsule e.g. KNEE  Intracapsular e.g:  ACL, PCL, transverse ligament  Extracapsular e.g:  MCL, LCL, popliteal Capsular Ligaments e.g. HIP  Intracapsular e.g:  Head of the femur lig.  Transverse  Extracapsular e.g:  Iliofemoral ligament  Pubofemoral ligament  Ischiofemoral ligament Capsular Ligaments SELF-DIRECTED LEARNING  What are the intra/extracapsular ligaments of the shoulder? Intra-articular discs  Fibrocartilage, strong, thick fibres  Attached to the joint capsule/bone Discs located:  Temporomandibular joint  Sternoclavicular joint  Ulnocarpal joint  Incomplete discs = Menisci  On the tibial plateau medial & lateral  Susceptible to injury  FUNCTIONS:  Shock absorption  Increase depth of joint (congruency)  Weight bearing distribution  Nutrition & Lubrication Stability versus Mobility  Joints which have a large range of movement compromise their stability  Stability is dependent on:  Articular shape  Strength of capsule  Ligaments  Muscle  Tendon  Mobility is limited by the same factors Tendons and Ligaments Tendons & Ligaments  Tendons  e.g. Achilles Tendon  Ligaments  e.g. Medial Collateral Ligament (MCL) of the knee Muscles Muscles Human Body consists of OVER 600 muscles  Terms you need to know!  AGONIST (Prime Mover)  one muscle plays major role in accomplishing desired movement  ANTAGONIST  muscle working in opposite direction to another muscle - controls/slows a movement  SYNERGIST / STABILISER  muscle which holds body position to enable agonist to operate - assists agonist  FIXATORS  may stabilise joint(s) crossed by the agonist (hold joint in position) - assists stabiliser Terms you need to know!  BI-ARTICULAR  produces action over TWO joints e.g. rectus femoris  MONO-ARTICULAR (UNI-ARTICULAR)  produces action over ONE joint e.g. soleus Muscle shapes  The shape of the muscle determines the degree a muscle can contract and the force it can generate  The arrangement of the individual fibres within a muscle can be either parallel or oblique to the line of pull of the whole muscle  Muscles only move by shortening  FIVE groups: Parallel Fusiform Pennate Circular Convergent Parallel Muscles  The length of the fascicles run parallel to the long axis of the muscle Fusiform Muscles  The fibres are arranged parallel to the line of pull  The muscle belly is wider than the origin and insertion Pennate Muscles  The fibres are oblique to the line of pull  Come in three forms:  Unipennate  Bipennate  Multipennate Circular Muscles  The arrangement of the fibres are in rings  Surround external body openings, which they close by contracting  General term used is “sphincter” e.g. mouth, gastrointestinal tract Convergent Muscles  Muscle fibres are spread over a broad area, but the fascicles all converge at one common attachment site  Base is wider than insertion = fan shaped  Allows muscle to contract with greater force than parallel muscle  Relatively strong e.g. pectoralis major Origins and Insertions  ORIGIN of a muscle is at the FIXED bone  INSERTION of a muscle is at the MOVING bone  Example: Biceps Brachii  ORIGIN: Coracoid process / Supraglenoid tuberosity  INSERTION: Tuberosity of radius Types of Muscle contraction  CONCENTRIC  ECCENTRIC  ISOMETRIC Types of Muscle contraction  CONCENTRIC Muscles develop sufficient tension to overcome a resistance, and shortening takes place… Muscle is shortening as it contracts Types of Muscle contraction  ECCENTRIC Muscle cannot develop sufficient tension to overcome the force, and net lengthening takes place… Muscle is lengthening as it contracts Types of Muscle contraction  ISOMETRIC Net effect is no joint angle changes Muscle develops force equal to that created by the load it is expected to overcome No movement Types of Muscle Contraction