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Axial Skeleton
Bones of the Axial Skeleton
• Number of bones
• Names of regions
• Special features (handout)
– Suture
– Meatus
– Process
– Fossa
– Foramen
– Fissure
– Condyle
Bones of the Skull
• 28 Bones
– Cranium – 8
– Face – 14
– Ossicles - 6
• All joined by immoveable joints except the
lower jaw (mandible).
Cranial Bones – 8 Bones
• Enclose and protect the brain.
• Dome shape – strongest architectural shape.
• Connected by immoveable joints – sutures.
Parietal
Temporal
Occipital
Frontal
Sutures
Coronal
Sagittal
Lambdoidal
Squamous
Temporal Bone – Special Features
Mandibular
Fossa
External Auditory
Meatus
Zygomatic
Process
Mastoid Process
Styloid Process
Occipital Bone – Special Features
• Foramen magnum
Sphenoid
• Single bone which extends
across the skull behind each
orbital cavity.
• Forms the temples.
Sphenoid Special Features
• Optic foramen
• Superior orbital fissure
Ethmoid
• Posterior to the nasal bone.
• Not visible from the outside.
Ethmoid
Sinuses
•
•
•
•
•
Frontal
Ethmoid
Sphenoid
Sphenoid
Maxillary
• Air filled cavities.
• Used for speech.
• Passageways for blood vessels
and nerves.
• Named for the bone that contains
them.
Facial Bones - 14
• Enclose and protect the facial organs.
• Mandible – 1
– Largest and strongest bone of the skull.
– Only moveable bone of the skull.
– Mandibular condyle
• TMJ.
– Tooth socket
Maxilla
• Upper jaw bone and extends into the mouth forming
the hard palate.
• 2 bones which fuse before birth.
• Tooth socket
Clef Palate/Hair lip
Facial Bones
Palatine
Nasal
Zygomatic
Inferior Concha
Lacrimal
Vomer
Ossicles - 6 bones
•
•
•
•
3 bones in each middle ear region.
Smallest bones of the body.
Completely ossified at birth.
Vibrate to carry sound waves into the inner ear where
the sound receptors are located.
• Malleus – hammer
• Incus – anvil
• Stapes - stirrup
Hyoid
• Single bone
• Located in the neck
under the tongue.
• Only floating bone
of the body.
– Does not
articulate with
any other bone.
Vertebral Column
• Flexible group of 26 articulated vertebra.
• Cervical Curve
– Holds head up
• Thoracic curve
– To sit up
• Lumbar curve
– To stand up and walk
Cervical Vertebra
• 7 bones – breakfast
• 1st cervical vertebra is the atlas
– Articulates with occipital bone
– Allows for nodding head “yes”
• 2nd cervical vertebra is the axis
– Articulates with atlas
– Allows for shaking the head “no”
• Thoracic Vertebra
– 12 bones – lunch.
– All of the ribs connect to thoracic
vertebra.
– Looks like a giraffe.
• Lumbar Vertebra
– 5 bones – supper.
– Looks like a moose.
• Sacrum
– Several bones fuse into one bone.
• Coccyx
– Several bones fuse into one bone.
– Tail bone.
• Spinous process
– Process on the posterior side.
– Can be palpated.
• Transverse process
– Processes on the lateral sides.
• Vertebral foramen
– Hole in the center of all vertebra
except sacrum and coccyx
– Houses the spinal cord
• Body
– Flat area separated by
intervertebral disks.
• Cervical
– 3 foramen
• Thoracic
– Giraffe
• Lumbar
– Moose
• Vertebral column is
flexible due to a pad of
cartilage between the
bones.
– Intervertebral disk
• Holes between each of
the vertebra except the
sacum and coccyx for
nerves to connect to the
spinal cord.
– Intervertebral foramen
Hunchback
Swayback
Sternum
• Manubrium – upper shield
– Contains the jugular notch for the
jugular veins.
• Body
– Used in CPR to compress the heart
between the sternum and vertebral
column.
• Xiphoid process
– Cartilage section
CPR
Compression of the
heart between the
sternum and the
thoracic vertebra.
Ribs
• 24 bones
• Attached to the sternum by costal
cartilage.
• True ribs – 14 bones
– Direct attachment to sternum
• False ribs – 6 bones
– Attach to the last true ribs
• Floating ribs – 4 bones
– Do not attach to the sternum
• All attach to thoracic vertebra