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Chapter 5. Axial Skeleton 3 parts: skull, vertebral column, bony thorax. Skull: cranium and facial – all but one joined by sutures. Cranium: 8 large flat bones – 2 paired – rest single Frontal Parietal (pair) Meet at sagittal suture Coronal suture – btw parietal and frontal. - PowerPoint PPT Presentation
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Chapter 5
Axial Skeleton
3 parts: skull, vertebral column, bony thorax
Skull: cranium and facial – all but one joined by sutures
• Cranium: 8 large flat bones – 2 paired – rest single– Frontal– Parietal (pair)
• Meet at sagittal suture• Coronal suture – btw
parietal and frontal
– Temporal (pair) – meet parietal at squamous suture• External acoustic meatus – canal to
eardrum• Styloid process – inferior to acoustic
meatus – neck muscle attachment• Zygomatic process – joins cheek bone• Mastoid process – posterior and inferior to
acoustic meatus–Mastoid sinuses – air cavities
• Jugular foramen – allow passage of jugular vein
– Occipital – joins parietal at lamboid suture• Foramen magnum – large opening for spinal
cord• Occipital condyles – sit on 1st vertebra
– Sphenoid bone – butterfly shaped – floor of cranial cavity• Sella turcia – depression that holds pituitary• Foramen ovale – opening for cranial nerve to
mandible• Optic canal and
superior orbital fissure – allow nerves for eye
– Ethmoid bone – anterior to sphenoid• Roof of nasal cavity and medial walls of
orbits• Crista galli – outer brain covering attaches• Cribriform plates – allow nerves through
• Facial: 14 bones – 6 paired – 2 single– Maxillae (maxillary bones)
• Upper jaw – keystone of face• Alveolar margin – holds teeth• Palatine processes – anterior portion of
hard palate• Paranasal sinuses –
openings – drain into nasal passage
– Palatine bones• Posterior to palatine processes• Posterior part of hard palate• Failure to fuse = cleft palate
– Zygomatic bones – cheekbones – Lacrimal bones
• Fingernail size• Medial wall of orbit• Grooved for tear
passage
– Nasal bones - bridge of nose– Vomer – single – nasal septum– Inferior Nasal Conchae
• Project from lateral walls of nasal cavity– Mandible – single
• Lower jaw• Only free movable joint of skull – meets
temporal bones• Body – horizontal part• Rami (ramus) –
upright bars
• Hyoid bone– Suspended in midneck region
• 2cm above larynx– Held by ligaments – touches
no other bones– Body and 2 pairs of horns
(greater and lesser)– Movable base for tongue
• Fetal skull– Fontanels – soft spots
• allow compression during birth
Vertebral column (spine)
• Before birth – 33 vertebrae• 9 fuse to form sacrum and coccyx• 24 single vertebrae
– 7 cervical – neck– 12 thoracic – back– 5 lumbar – lower back
• Vertebrae separated by intervertebral discs– Cushion and absorb shock
• Primary curvature– In thoracic and sacral – present from birth
• Secondary curvature– Cervical – appears when baby begins to raise
head– Lumbar – appears when baby begins to walk
• Vertebrae– Parts
• Body (centrum) – weight bearing – faces anterior• Vertebral arch – joining of lamina and pedicle• Vertebral foramen – canal for spinal cord• Transverse processes – projection off arch• Spinal processes –
projection off posterior• Superior and inferior
articular processes – Lateral to vertebral
foramen– Joints w/ other vertebrae
• Cervical – C1 – C7– 1st – atlas – no body
• Depressions in transverse processes to receive occipital condyles
• Allow nodding– 2nd – axis – acts as a pivot
• Dens – pivot point– All have transverse foramen for cranial nerves
• Thoracic – T1 – T12– Costal facets – receive ribs– Have long spinous processes
• Lumbar – L1 – L5– Short, chunky spinous processes
• Sacrum – 5 fused vertebrae– Alae – wings – articulate w/ hips– Median sacral crest – fused
spinous processes– Sacral foramen – openings– Sacral canal – for spinal cord – ends @ sacral hiatus
• Coccyx – 3-5 fused vertebrae – tailbone
Bony Thorax – thoracic cavity• Sternum – breastbone
– Fusion of manubrium, body, and xiphoid process
– 7 ribs attach– Jugular notch – upper border
of manubrium– Sternal angle – where
manubrium and body meet– Xiphisternal joint – where
body and xiphoid process meet
– Sternal puncture – w/draw hematopoietic tissue
• Ribs – 12– True ribs – 1st 7 – attach to
sternum– False ribs – next 5
• 3 – attach to ribs by costal cartilage
• 2 – floating – don’t attach to anything
– Intercostal space – btw ribs – filled w/ muscle