1. Skeletal System
Axial Skeleton

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
Superficial bones – maxillary, nasal, zygomatic, Mandible. Allow for attachment of muscles that control facial expressions and help in manipulation of food

14. Several bones of skull have sinuses
Deeper facial bones – palatine & vomer (separates oral and nasal cavities)
Several bones of skull have sinuses
Air filled chambers
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
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

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.
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
Frontal – until 2 years of age

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

26. Spinal curvature – 4 curves
Cervical
Thoracic
Lumbar
Sacral
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
Cervical – infant learns to balance head
Lumbar – infants learns to stand

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

29. Throracic Lumbar Sacrum Coccyx 12 of them
Contain facets for rib articulation
Lumbar
5 largest
Bear most weight
Sacrum
Fused components of 5 sacral vertebrae
Coccyx
“tailbone”

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