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Axial Skeleton: A Checklist of Bones and Select Bony Landmarks
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The axial skeleton is composed of 80 bones that support and protect organs of the head,
neck, and torso
-Includes:
o The skull
o Hyoid bone
o Vertebral column
o Thoracic cage (rib cage)
o ear ossicles (bones)
The Skull
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The skull can be divided into two components:
o Cranial bones form a bony cavity that harbors and protects the brain and houses
organs of hearing and equilibrium.
o Facial bones provide the shape of the face, house the teeth, and provide
attachments for all the muscles of facial expressions
Specific bony regions of the skull include:
o Sutures
o Orbit of eye
o Paranasal sinuses
o Nasal septum
o Hard palate
o Fontanels in the fetus and newborn
Cranial Bones
 Frontal bone (2)
o Frontal sinus
 Parietal bone (2)
 Temporal bone (2)
o External auditory meatus
o Mastoid process
o Styloid process
o Zygomatic process
o Mandibular fossa
o Internal auditory meatus
 Occipital bone (1)
o Foramen magnum
o Occipital condyles
 Ethmoid bone (1)
o Cribiform plates with olfactory foramina
o Crista galli between cribiform plates
o Olfactory foramina
o Perpendicular plate (makes up superior portion of nasal septum)
o Conchae
o Ethmoid sinus
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Sphenoid bone (1)
o Sella turcica
Human Anatomy and Physiology
Jason Taylor MSc
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o Greater and lesser wings
o Optic foramina
o Pterygoid processes (medial and lateral)
o Ethmoid sinus
Skull Sutures (Synarthroses)
 Coronal
 Sagittal
 Lambdoid
 Squamous (2)
Facial Bones:
 Maxilla (2)
o Alveoli
o Palatine process
 Zygomatic bone (2)
o Temporal process
 Lacrimal bone (2)
o Lacrimal fossa
 Nasal bone (2)
 Palatine bone (2)
 Mandible (1)
o Alveoli
o Body
o Mental foramina
o Rami
o Condylar processes (mandibular condyles)
o Coronoid processes
 Vomer (makes up inferior portion of nasal septum)
Specific Bony Regions of the Skull
 Bones of the Eye Orbit
o 7 different bones
 3 Cranial bones
 Frontal
 Sphenoid
 Ethmoid
 4 Facial bones:
 Maxilla
 Zygomatic
 Lacrimal
 Palatine
 Paranasal Sinuses
o Mucous lined membranes found in the ethmoid, frontal, maxillary, and sphenoid
bones
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Nasal Septum:
o Separates nasal cavities
o Composed of 2 bones and cartilage
Human Anatomy and Physiology
Jason Taylor MSc
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 Vomer (inferior bony part of bony septum)
 Perpendicular Plate of ethmoid bone (superior part of bony septum)
o Septal Cartilage (anterior to the 2 bones)
Hard Palate
o Forms bony roof of mouth
o Composed of 4 bones fused together
 2 Palatine Processes of Maxillary bones
 2 Palatine bones
Fontanels
o “Soft spots”; areas of newborn skull that is not completely ossified/developed
 Anterior fontanel
 Posterior fontanel
Hyoid Bone
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Not attached to axial skeleton
Located below mandible and anterior to vertebrae
Vertebral Column
Regions
 5 Regions of Spinal Column
o Cervical (7) vertebrae
o Thoracic (12) vertebrae
o Lumbar (5) vertebrae
o Sacral (1) vertebrae
o Coccygeal (1) vertebrae
Normal Curvatures of Vertebral Column:
 4 Curvatures of Spinal curve
o Cervical curve
o Thoracic curve
o Lumbar curve
o Sacral (pelvic) curve
Parts of Typical Vertebra
 Body (1)
 Pedicle (2)
 Transverse Process (2)
o Superior facet (2)
o Inferior facet (2)
 Lamina (2)
 Spinous Process (1)
 Vertebral Arch
Individual Vertebrae
 Cervical vertebrae (7)
o Distinct landmarks
 Vertebral foramen
 Transverse foramina (2)
Human Anatomy and Physiology
Jason Taylor MSc
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 Bifurcated spinous process (C3-C7)
Special cervical vertebrae
 Atlas
 First vertebra (C1)
 Large superior articular facets articulate w/ occipital condyles of skull
 Axis:
 Second vertebra (C2)
 Dens or Odontoid Process
Thoracic Vertebrae (12)
o Distinct landmarks
 Look like “giraffes”
 Large superior and inferior articular facets
 Well-developed transverse processes with articular surfaces for ribs
 Long narrow spinous processes
Lumbar Vertebrae
o Distinct landmarks
 Look like “moose”
 Large kidney-shaped bodies
 Large hatchet-shaped spinous process
Sacrum and coccyx
o Composed of 5 fused sacral vertebrae and 3 fused coccygeal vertebrae
o Landmarks
 Base
 Allae (2)
 Sacral Promontory
 Sacral Foramina
 Sacral Canal
 Sacral hiatus
 Superior articular processes (2)
 Auricular surfaces
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Thoracic Cage
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Bony cage that protects and supports the heart and lungs
Composed of the sternum and ribs
o Sternum
 Manubrium
 Suprasternal notch / jugular notch
 Sternal angle
 Xiphoid process
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Ribs
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True ribs (7 pairs / ribs 1-7)
 Attach directly to sternum
False ribs (5 pairs / ribs 8-12)
 Do not attach directly to sternum
 Two types
o Vertebrochondral (3 pairs / ribs 8-10)
Human Anatomy and Physiology
Jason Taylor MSc
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o
Human Anatomy and Physiology
 Share attachment with rib 7 above
Floating ribs (2 pairs / ribs 11-12)
 No attachment to sternum and no cartilage
Jason Taylor MSc
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