CHAPTER 7

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CHAPTER 7The Axial SkeletonReview your AP
revealed discsCourse objectivesDefine and
identify the bones of the axial skeleton

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Axial Skelton

• 80 total bones
• consists of the bones that form the long axis of
  the body including the
• Skull (total 28 with ear bones)
• Vertebral column (total 26) C7T12 L5 S1 Co1
• Bony thorax ribs and sternum (total 25)
• Hyoid bone (1)
  

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• Bones of the axial skeleton

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Axial Skelton

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Skull BonesReview AP revealed discs animation
of skull

• the skull has two major divisions Cranium and
  Facial bones
• Cranium the 8 bones that enclose the brain.
• -1 occipital, 1 frontal, 2 parietal, 2
  temporal, 1 sphenoid and 1 ethmoid.
• These typical flat bones of the cranium are
  connected by a special kind of joint called a
  suture (Synarthroses).

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Cranial bones

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Cranial Bones Midsaggital section

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Cranial Bones Midsaggital section

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Cranium

• Made up of 2 major divisions
• Calvarium (skull cap)
• Base
• Base contains three large depressions (fossa)
• Anterior cranial fossa where the frontal lobes
  sit
• Middle cranial fossa where the temporal lobes sit
• Posterior cranial fossa where the cerebellum sits

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Cranial Bones

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Cranial Bones

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Sutures/Sutural Bones

• Sutures (synarthroses) are immovable fibrous
  joints.
• -all bones in the skull, except for the jaw, are
  united by sutures. The major sutures are
• -Coronal -Sagittal
• -Squamous -Lamboid
• Sutural bones- small bones that occur within the
  sutures, especially the lamboid suture. They are
  not present in all people.

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Sutures/Sutural Bones
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Facial bones

• There are 14 bones that can be thought of as
  creating the face.
• As part of this function they provide
• - protection for many sense organs,
• -anchors for many muscles
• -the openings for air and food to pass.
• Facial Bones
• 2-maxillae 2-palatine 2-nasal 2- zygomatic
• 2-lacrimal 2-inf nasal conchae 1- vomer and
  1-mandible

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Sphenoid bone

• Looks like a Bat in flight. Greater and lesser
  wings optic foramen sella turcica, superior
  orbital fissure. Dorsal view.
  

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Sphenoid bone

• Dorsal view
• Anterior view

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Ethmoid bone

• Anterior to
• sphenoid bone
• forms anterior
• base of skull
• and nasal cavity.
• Cribriform plate.
• Crista gali
• Perpendicular
• plate

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Ethmoid bone

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Ethmoid bone

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Foramen/ Orbits

• Foramen Special openings in bones where nerves,
  blood vessels enter into the bone cavity.
• - Ex. Foramen magnum, Supraorbital
  Infraorbital, Mental, Jugular, Olfactory,
  Mandibular
• Orbits Cone shaped bony cavities that hold the
  eyes, fat, occular muscles and tear glands.

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Bones of the eye orbit

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Meatus/ Sinuses

• Meatus a canal or opening into bone
• - Ex. external auditory, internal acoustic
• Sinus cavities within bones filled with air.
• -Ex. frontal, ethmoid, sphenoid and maxillary
  sinuses

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Cranial sinuses
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Cranial fossa

• Fossa are depressions or cavities in the skull.

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The Fetal Skull

• Sutures are called fontanels in fetus.
• Fontanels
• -Frontal (anterior)
• -Occipital (posterior)
• -Sphenoidal (anterior lateral)
• -Mastoid (posterior lateral)

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The Fetal Skull

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The Fetal Skull