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Skeletal System Axial Skeleton. Introduction Skull, vertebral column, thoracic cage (ribs & sternum)

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Presentation on theme: "Skeletal System Axial Skeleton. Introduction Skull, vertebral column, thoracic cage (ribs & sternum)"— Presentation transcript:

1 Skeletal System Axial Skeleton

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3 Introduction Skull, vertebral column, thoracic cage (ribs & sternum)

4 Function 1. framework that supports organs 2. surface area for muscle attachment

5 Skull Protects the brain and guards the entrance to the digestive and respiratory tract Cranial Bones – occipital, parietal (2), frontal, temporal (2), sphenoid & ethmoid bones Cranial bones protect the brain

6 Skull Facial bones Function – protect and support entrances to digestive & respiratory tracts Function – protect and support entrances to digestive & respiratory tracts Superficial bones – maxillary, nasal, zygomatic, Mandible. Allow for attachment of muscles that control facial expressions and help in manipulation of food Superficial bones – maxillary, nasal, zygomatic, Mandible. Allow for attachment of muscles that control facial expressions and help in manipulation of food

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14 Deeper facial bones – palatine & vomer (separates oral and nasal cavities) Deeper facial bones – palatine & vomer (separates oral and nasal cavities) Several bones of skull have sinuses Air filled chambers Air filled chambers Function Function 1. helps to make bones lighter 2. has a mucus membrane that helps moisten and clean air

15 Sutures – immoveable joints that are connections b/n skull bones 4 major sutures 4 major sutures 1. lamboidal suture – across posterior surface of skull. Separates occipital bone from the 2 parietal bones. 2. coronal suture – attaches frontal bone to parietal bones on either side 3. saggital suture – from lamboidal suture to coronal suture b/n the 2 parietals 4. squamosal suture – on each side of the skull; boundary b/n temporal and parietal bones Cranial and Facial Bones – see handout

16 Orbital and nasal complexes 1. Orbital complex – formed form cranial and facial bones which surround each eye 2. Nasal complex – surrounds nasal cavity

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19 Skulls of Infants and Children Right before birth, brain enlarges and bones cannot keep up. So at birth some bones are connected by fibrous connective tissue. Flexible so brain is not damaged. Right before birth, brain enlarges and bones cannot keep up. So at birth some bones are connected by fibrous connective tissue. Flexible so brain is not damaged. Fontanels – fibrous areas b/n cranial bones Fontanels – fibrous areas b/n cranial bones 4 types: 1. frontal fontanel – largest intersection of saggital, & coronal sutures 2. occipital fontanel – b/n lamboidal and saggital sutures

20 Skulls of Infants and Children 3. sphenoidal fontanel – junctions b/n squamousal and coronal sutures 4. mastoid fontanel – b/n squamousal and lamboidal sutures Occipital, sphenoid, and mastoid – disappear within 1-2 months after birth Occipital, sphenoid, and mastoid – disappear within 1-2 months after birth Frontal – until 2 years of age Frontal – until 2 years of age

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22 Vertebral Column Adult vertebral column 26 bones – 24 vertebrae, sacrum & coccyx Function 1. support 2. bears weight of head, neck and trunk 3. transfers weight to appendicular skeleton 4. protects spinal cord 5. maintains upright position

23 Divided into 7 cervical 12 thoracic (articulates with ribs) 5 lumbar 1 sacrum 1 coccyx With development, sacrum is made up of 5 vertebrae until 25 than 1

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26 Spinal curvature – 4 curves 1. Cervical 2. Thoracic 3. Lumbar 4. Sacral Primary curves (accomodation curves) – thoracic and sacral b/c appear late in fetal development Primary curves (accomodation curves) – thoracic and sacral b/c appear late in fetal development Secondary curves (compensation curves) – lumbar and cervical appear several months after birth Secondary curves (compensation curves) – lumbar and cervical appear several months after birth Cervical – infant learns to balance head Cervical – infant learns to balance head Lumbar – infants learns to stand Lumbar – infants learns to stand

27 Cervical vertebrae 7 of them 7 of them C1 – atlas; nod head “yes” C1 – atlas; nod head “yes” C2 – axis; rotation to say “no” C2 – axis; rotation to say “no” C7 – vertebral prominens C7 – vertebral prominens

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29 Throracic 12 of them 12 of them Contain facets for rib articulation Contain facets for rib articulationLumbar 5 largest 5 largest Bear most weight Bear most weightSacrum Fused components of 5 sacral vertebrae Fused components of 5 sacral vertebraeCoccyx “tailbone” “tailbone”

30 Thoracic Cage Ribs 12 pairs 12 pairs First 7 = true. Connected to sternum First 7 = true. Connected to sternum Ribs 8-12 = false b/c do not attach directly to sternum Ribs 8-12 = false b/c do not attach directly to sternum Ribs 11 & 12 = floating. Attach to vertebrae Ribs 11 & 12 = floating. Attach to vertebrae Sternum (breast bone) – flat Manubrium – articulates with clavicles; first pair of ribs Manubrium – articulates with clavicles; first pair of ribs Body – ribs 2-7 Body – ribs 2-7 Xiphoid process – smallest part Xiphoid process – smallest part

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