Skeletal SystemSkeletal System
ComponentsComponents
- Cartilage - Bone - Joints - Ligaments (bone to bone) - Tendons (muscle to bone)
FunctionsFunctions
- Support - Movement - Protection - Mineral storage - Blood cell synthesis -
hematopoiesis
CartilageCartilage
• Hyaline• Elastic• Fibrocartilage
Hyaline cartilage Hyaline cartilage - Articular cartilage – covers ends of bones
and moveable joints
- Costal cartilage – attach ribs to the sternum
- Respiratory cartilage – forms respiratory passages and larynx
- Nasal cartilage – forms external nose
Articular cartilageArticular cartilage
Costal cartilageCostal cartilage
Respiratory cartilageRespiratory cartilage
Nasal cartilageNasal cartilage
Elastic cartilageElastic cartilage
- Forms external ear
- Forms epiglottis
Elastic cartilageElastic cartilage
FibrocartilageFibrocartilage
Withstands heavy pressure & tensile forces
- Intervertebral disks - Knees and elbows
FibrocartilageFibrocartilage
BoneBone
• Cell, tissue, organ
• Skeleton – Greek for dried up body• Composed of 206 bones 1. Axial skeleton – 80 bones 2. Appendicular skeleton – 126 bones
Classification of boneClassification of bone
• Long bones
• Short bones • Sesamoid bones • Flat bones • Irregular bones
Long bonesLong bones - Diaphysis – shaft
- Epiphysis – ends of bone; contain red marrow
- Medullary cavity – contains yellow marrow
- Epiphyseal plate – found between diaphysis and epiphysis; long bone growth
Short bonesShort bones
• Roughly cuboidal in shape
Sesamoid bones Sesamoid bones
form within a tendon e.g. patella
Flat bonesFlat bones
Thin, flattened, and slightly curved
Diploe – spongy bone found between compact bone layers
DiploeDiploe
Irregular bones Irregular bones
• complicated shapes e.g. vertebrae, pelvis
Bone cellsBone cells • Osteoclast – cells which dissolve bone
(puts calcium into the blood for muscular contraction, nerve transmission, blood clotting, etc…)
• Osteoblast – cells which build bone by removing calcium and phosphates from the blood in the presence of the enzyme alkaline phosphatase secreted by osteoblasts
• Osteocyte – mature cells found within compact bone (living bone)
Bone remodelingBone remodeling
Occurs under the periosteum (White, double layered membrane) which is held to bone by Sharpey’s fibers
Osseous tissueOsseous tissue
• Compact bone (Lamellar bone) – Dense and hard; found on the external surfaces of bones
• Spongy bone - contain trabeculae (little beams) which align along lines of stress; and open spaces filled with red or yellow marrow
Compact bone = Lamellar Compact bone = Lamellar bonebone
Lamellar boneLamellar bone Osteon or Haversian System – structural
unit of compact bone (cylindrical in shape) which bear weight
- Lamella – each ring of an osteon
- Haversian canal – contains blood vessels & nerve fibers which travel vertically in bone
- Volkmann’s canal – contain blood vessels and nerve fibers which travel horizontally in bone
Lamellar boneLamellar bone- Lacuna – spaces found in compact bone
occupied by osteocytes
- Canaliculi – lateral canals which connect lacunae which allow osteocytes to diffuse nutrients and wastes into or out of bone tissue through gap junctions
Spongy bone = Spongy bone = Trabecular Trabecular bonebone
Chemical compositionChemical composition - Hydroxyapatites 60-70% of bone weight mineral salts; mainly calcium phosphates
*source of stiffness and compressive strength - Collagen fibers ~ 10% of bone weight made up of glycoproteins *source of flexibility & tensile strength Aging causes decrease in collagen & an increase in fragility - Water ~ 25-30% important contributor to bone strength
Bone markingsBone markings
Sites of tendon and ligament attachment
Projections that help form joints
Depressions and openings allowing blood vessels and nerve fibers to pass
Sites of muscle and Sites of muscle and ligament attachmentligament attachment
- Tuberosity – large rounded projection
- Crest – narrow prominent ridge
- Trochanter – large, blunt, irregularly shaped process (Only found on the femur)
Sites of muscle and Sites of muscle and ligament attachmentligament attachment
- Tubercle – small rounded projection or process
- Epicondyle – raised area above a condyle
- Spine – sharp, slender, often pointed projection
- Process – any bony prominence
TuberosityTuberosity
CrestCrest
TrochanterTrochanter
TubercleTubercle
EpicondyleEpicondyle
SpineSpine
ProcessProcess
Projections that help form Projections that help form jointsjoints
- Head – bony expansion carried on a narrow neck
- Condyle – rounded articular projection
- Ramus – arm like bar of bone
HeadHead
CondyleCondyle
RamusRamus
Depressions and openings Depressions and openings allowing blood vessels and allowing blood vessels and
nerve fibers to passnerve fibers to pass - Meatus – canal like passage way
- Sinus – Cavity within bone filled with air and lined with mucous membrane
- Fossa – shallow basin like depression in bone
Depressions and openings Depressions and openings allowing blood vessels and allowing blood vessels and
nerve fibers to passnerve fibers to pass - Fissure – narrow, slit like opening
- Foramen – round or oval opening through a bone
MeatusMeatus
SinusSinus
FossaFossa
FissureFissure
ForamenForamen
Hormone Control of Bone Hormone Control of Bone RemodelingRemodeling
• PTH (Parathyroid hormone) is released by parathyroid glands when serum calcium levels are low which increase osteoclast activity.
• Calcitonin is released by the thyroid gland when serum calcium levels are too high which stimulate osteoblast activity (causes them to release alkaline phosphatase)
Calcitonin
PTH
Homeostatic ImbalanceHomeostatic Imbalance
Fracture – a break in the bone
Open fracture – bone penetrates through the skin
Closed fracture – bone does not penetrate skin
Depressed FractureDepressed Fracture
Compression FractureCompression Fracture
Fracture treatmentFracture treatment
• Closed reduction – When a physician pulls on bone to realign bone ends
• Open reduction – When a physician surgically inserts pins or wires to realign bones
Open Reduction - Open Reduction - MandibleMandible
Fracture healingFracture healing
1. Hematoma formation2. Fibrocartilaginous callus
formation3. Bony callus formation4. Bone remodeling
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