TP4 Skeletal System Flashcards
Describe the functions of the skeletal system
- Support: major support tissue of the body and weight bearing
- Protection
- Movement
- Storage: minerals
- Blood cell production
List the parts of the skeletal system
- Bones
- Joints
- Cartilage
- Ligaments (bone to bone)
- Tendons (muscle to bone)
Name the five types of bones
- Long bones
- Short bones
- Flat bones
- Irregular bones
- Specialised bones
List the structures of the Axial skeletal division
- Skull
- Vertebral column
- Sternum
- Ribs
List the structures of the Appendicular skeletal division
- Scapula/pelvis
- Humerus/femur
- Radius + Ulna/Tibia + Fibula
- Carpus/Tarsus
- Metacarpals/Metatarsals
- Phalanges/digits
Describe the two bones of the skull
Cranium: provide protection to the brain
Facial bones: provide a location and protection for the organs of the special senses
What bones make up the cervical, axial skeleton division and what are the functions?
- Neck bones
- C1 Atlas (free movement of head)
- C2 Axis (spinal cord protection)
- Atlanto - occipital joint
Describe the roles of the ribs and sternum
- Limits and provides protection for the thoracic viscera
- Assists in respiration and blood flow
- Attachment for the costal cartilages and bony origin for pectorals
Describe the parts of the vertebral axial skeleton
- Cervical (C), thoracic (T), lumbar (L), sacral (S), caudal (Cd)
- Species specific vertebral formulae
Describe cervical vertebrae shape
- Cervical vertebrae: well developed articular process - help with neck movement
- Atlas: C1 - no spinous process, articulates with the skull
- Axis: C2 - articulates with the atlas in a pivot joint
Describe the thoracic, lumbar, sacral & caudal vertebrae shape
- Thoracic vertebrae: well developed spinous process & articular facets for the ribs
- Lumbar vertebrae: large, flat transverse process, more robust articular processes
- Sacral vertebrae: fused to form a single, wedged shaped bone (sacrum)
- Caudal vertebrae: from the bony basis of the tail
What makes the appendicular skeleton
- The appendages
- Bones of the front (thoracic) & hind (pelvic) limbs
- The pectoral girdle (shoulder) & pelvic girdle (pelvis)
Describe the location of the digits
Region of the limb below metacarpo phalangeal joint
Describe the compact/dense/cortical bone
Hard layer covering most bones, forms shaft of long bones
Describe Cancellous (spongy) bone
Composed of spicules arranged to form porous network
Spaces usually filled with red marrow
Describe the Organic component of the matrix
- 30-40% of matrix
- Type I collagen
- Glycoproteins
Describe the medullary (marrow) cavity
- Space surrounded by cortex of a long bone
- Filled with red marrow in young animals
- Replaced by fatty, yellow marrow as animal ages
Describe the Inorganic component of the matrix
- 60-70%
- Minerals: hydroxyapatite crystals
Describe the Gross Anatomical Structures of long bones
- Epiphysis
- Diaphysis
- Metaphysis
- Periosteum
- Endosteum
- Epiphyseal plate/growth plate
- Articular cartilage
Describe the Gross Anatomical Structures of flat bones
- External and internal surfaces composed of compact bone
- Middle layer of spongy bone
- Contains bone marrow between the trabeculae but no marrow cavity
- Some sutures not fully fused until after birth
Describe microscopic bone structure
Look at diagram in book
Describe Osteocytes
- Mature bone cells: account for most of the cell population
- Cant divide
- Maintain protein and mineral content of matrix
- Involved in bone repair
Describe Osteoblasts
- Bone Formation
- Produce new bone matrix by making & releasing proteins and organic components
- Assists in elevating local conc. of calcium, phosphate, promoting Ca deposition
Describe Osteoclasts
- Bone resorption
- Cells that remove & recycle bone matrix
- Release stored minerals
- Important in Ca & PO4 regulation
Describe the structures of cartilage
- Cells embedded in extracellular matrix
- Matrix: H2O, Collagen, proteoglycans
- Avascular - no nerve or lymphatic supply
Describe the function of cartilage
- Structural support
- Sliding area for joints
- Allows growth in long bones
List the types of cartilage and their location
- Hyaline Cartilage: provisional embryo skeleton, part of epiphyseal growth plates, lines articular joint, respiratory airway walls.
- Elastic Cartilage: Auricle of ear, epiglottis and Eustachian tube.
- Fibrocartilage: attaches bone to tendon, menisci of synovial and vertebral discs
Describe the different classifications for joints.
- Fixed: Axial skeleton, most are fibrous joints
- Semi-moveable: Axial skeleton
- Moveable: Predominate in limbs and lined with articular cartilage
Describe Fibrous joints
Connected by dense connective tissue: mainly collagen
Fixed/immovable: do not have a joint cavity
Describe Cartilaginous joints
United by cartilage, no intervening joint cavity
Describe synovial Joints
Bones separated by a joint cavity filled with synovial fluid - lubricant and nutrients
Describe the two types of cartilaginous joints
- Synchondroses: immovable
- Symphyses: flattened discs of fibrocartilage between bones
Describe the parts of a synovial joint
- Synovial membrane: lines the cavity, sensitive and supplied with blood vessels
- Articular cartilage: covers the surface between the attachment of the joint capsule and the end of each bone
- Fibrous membrane: surrounds capsule and attaches bones on either side, so the movement on joint are limited
Describe the types of joint movement
- Gliding: Intercarpal & intertarsal joints, vertebrocostal joints
- Hinge: move only in the sagittal plane
- Pivot: atlas/axis, proximal radioulnar joint
- Condylar joint: flexion-extension & rotation
- Ellipsoidal: radiocarpal joint, metacarpophalangeal joints
- Saddle: 1st carpometacarpal joint, distal interphalangeal joint
- Ball & Socket: Shoulder, hip
Describe tendons
- Join muscle to bone
- Pull bone to flex joints
- Have little stretch
- Made of collagen and ground substance
- Ground substances = proteoglycans, glycosaminoglycans
- Higher % collagen
- Lower H2O and proteoglycans
Describe the structure of tendons
densely packed collagen, more parallel -> Cells in parallel lines
Describe ligaments
- Join bone to bone
- Stabilise bones
- Stretchy
- Made of collagen and ground substance
- Ground substances = proteoglycans, glycosaminoglycans
- Lower % collagen
- Higher H2O and proteoglycans
Describe the structure of ligaments
densely packed collagen , not totally parallel -> Cells more scattered
What are the three bones of the stifle joint
Femur, tibia, patella
Describe the features of the synovial joint
- Capsule: lined by synoviocytes
- Filled with synovial fluid
- Articular cartilage on the surface of the bones
AND… - 2x Menisci
- Cartilage pads between the femur and tibia
- Ligaments: patella and collateral
inside the joint -> cruciate ligaments
Describe the horse stifle
Femur - medial epicondyle is large and has a depression above it, forming a hook
Medial patellar ligament thick and robust
->uses muscles to hook patellar ligament in grove - ‘locks’ the stifle
Describe the key features of claws
cuticle: hard keratin, no nerves
live dermis: under keratin cuticle, painful if damaged
- Protects end of toe
- Used for: grooming, grasping, digging, defence
Describe the key role of hooves
- Protects the toe
- Used for: walking/weight bearing
Describe the key features of external of hooves
Hoof wall: made of keratin, 3x layers
Sole, heal, toe
coronary band: junction between skin and horn of hoof wall
Frog: spongy triangle shaped tissue in sole
White line: junction between wall and sole
Describe intramembranous ossification
- Bone formed directly into connective tissue
- Formation of ossification center
- Calcification
- Formation of trabeculae
- Development of periosteum
Describe the key features of internal of hooves
Tendons: extensor and flexor
Bones: middle and distal phalanx, distal sesamoids
Fat pad: under heel
Laminae/lamellae: interdigitating tissue - holds hoof horn of the wall to underneath bone
Describe endochondral ossification
- Development of cartilage model
- Growth of cartilage model
- Development of primary ossification center
- Development of secondary ossification center
- Formation of articular cartilage and epiphyseal plate
Describe the process of bone growth in length
Chondrocytes produce new cartilage in epiphyseal plate ->epiphyseal plate widens = bone lengthens -> chondrocytes die -> osteoblasts replace chondrocytes & lay down bone
Describe the role of Growth hormone in bone growth
- Stimulates release of IGF-1
- IGF-1 stimulates chondrocyte proliferation = bone length
Describe the process of bone growth in width
- New bone deposited on outer surface of bone
- Osteoclasts in endosteum dissolve bone in center = bone enlarges
Describe the role of Sex hormones during puberty and bone growth
- Causes increased growth during puberty
- Causes epiphyseal plate to close so no more growth
Describe the role of Thyroxine hormone in bone growth
Required for skeletal mineralisation
Describe the role of bone morphogenic proteins in bone growth
- Embryonic development of skeleton
- Intramembranous ossification
List other important factors of bone metabolism
- Environment: Vitamin D deficiency
- Diet: Vitamin C deficiency, scurvy, oxalate containing pastures
- Mechanical load: body mass/exercise = increased bone density
Explain the role of Ca homeostasis and bone
Contains 99% body’s Ca & 85% of Phosphate
- stored as hydroxyapatite
- forms Ca reserve
List the three major hormones in Ca homeostasis and bone
- Parathyroid hormone (PTH)
- 1,25-dihydroxy vitamin D3
- Calcitonin (CT)
Describe the response to low blood [Ca2+]
PTH secretion!!!
- stimulates osteoclast activity
- decreases Ca2+ excretion from kidneys
- increase intestinal absorption of Ca2+
Describe the response to high blood [Ca2+]
Calcitonin secretion!
- Inhibits osteoclast activity
- increases Ca2+ excretion from kidneys
