Axial Skeleton

Axial Skeleton

• Three major regions:1) Skull2) Vertebral Column3) Bony Thorax

• Function: Supports the head, neck, and trunk, and it protects the brain, spinal cord, and the organs in the thorax

The Skull

• Cranial Bones – Enclose and protect the brain– Sites of attachment for head & neck muscles

• Facial Bones– Form framework of the face– Contain cavities for sense organs of sight, taste, and

smell– Provide openings for air & food passage– Secure the teeth– Anchor muscles of facial expression

Cranium

• Consists of 8 bones:– Frontal bone– Occipital bone– Sphenoid bone (keystone of the cranium)– Ethmoid bone– Parietal bones (paired)– Temporal bones (paired)

Parietal Bones and the Major Sutures

• Sutures – immovable fibrous joints which unite the bones of the skull

• The four largest sutures occur where the parietal bones articulate (form a joint) with other cranial bones:

1) coronal suture – at articulation with frontal bone

2) sagittal suture – where parietal bones meet superiorly at the cranial midline

Sutures cont. 3) lambdoid suture – at articulation with occipital

bone 4) squamous sutures – where parietal bones and temporal bones meet on the lateral aspect of skull

Facial Bones (14)

• Vomer• Paired maxillae or maxillary bones• Paired zygomatic bones• Paired palatine bones• Paired lacrimal bones• Paired nasal bones• Paired inferior nasal conchae• Mandible

Vertebral Column

• Cervical Vertebrae – 7• Thoracic Vertebrae – 12• Lumbar Vertebrae – 5• Sacral Vertebrae – 5 (fused to form single

sacrum)• Coccyx – single bone formed from fusion of 4

vertebrae