The Axial Skeleton Salt Lake City Community College

The Axial Skeleton Salt Lake City Community College Human Anatomy Laboratory

http: //homepage. smc. edu/wissmann_paul/bones/EBbonestutorial. html

n Axial skeleton - forms long axis of body ¨ Skull ¨ Vertebral column ¨ Thoracic cage n Appendicular skeleton (next week) – appendages and what they attach to ¨ Upper limbs (arms) ¨ Pectoral girdle (shoulder) ¨ Lower limbs (legs) ¨ Pelvic girdle

Axial skeleton Skull Vertebral column Thoracic cage Axial skeleton is shown in green

The Skull = cranial bones and facial bones n Cranial bones (or cranium) ¨ Frontal bone ¨ Parietal bones (paired) ¨ Occipital bone ¨ Temporal bones (paired) ¨ Sphenoid bone ¨ Ethmoid bone n Facial bones ¨ Mandible ¨ Vomer ¨ Maxillae (paired) ¨ Zygomatics (paired) ¨ Nasal (paired) ¨ Lacrimal (paired) ¨ Palatines (paired) ¨ Inferior nasal conchae (paired)

Cranial bones frontal parietal _______sphenoid temporal _____ethmoid occipital

Temporal bones this is the right temporal bone looking at it from the right side

Small cranial bones… Sphenoid Ethmoid

Sutures n Largest 4 skull sutures: where bones articulate with parietal bones ¨ Coronal ¨ Sagittal ¨ Squamous ¨ Lambdoid (FIND THEM)

Find: coronal, squamous and lamboid sutures

Find: sagittal and lambdoid sutures

Facial bones: Mandible Vomer Maxillae (paired) Zygomatics (paired) Nasal (paired) Lacrimal (paired) Palatines (paired) Inferior nasal conchae (paired)

Maxilla (there are 2 that fuse, forming the upper jaw) Mandible (lower jaw)

Paranasal sinuses Air-filled sacs in the bones n “Paranasal” because they cluster around and connect to the nasal cavity n

Hyoid bone n n n Only bone which does not articulate with any other bone Moveable base for the tongue Points of attachment for neck muscles that raise and lower the larynx during swallowing

Remember that the Axial skeleton includes: Skull Vertebral column Thoracic cage Axial skeleton is shown in green

The Vertebral Column Adult: 24 vertebrae n Cervical – 7 n Thoracic - 12 n Lumbar - 5 n Sacrum (5 fused) n Coccyx (4 fused)

Structure of a typical vertebra

Shapes posterior wall of pelvis The Sacrum Composite bone of 5 fused vertebrae Sacral foramina allow passage of vessels & nerves Coccyx (the tailbone)

Remember that the Axial skeleton includes: Skull Vertebral column Thoracic cage Axial skeleton is shown in green

The Thoracic Cage

Sternum Ribs n Manubrium n True ribs 1 -7 n Body n False ribs 8 -12 n Xiphoid process n Floating ribs 11, 12

Fontanels n n n Unossified remnants of membranes Present at birth Anterior fontanel largest Called “soft spots” Ossify by 1 ½ - 2 years Continue to ossify into adulthood; the sutures can become fused in old age