The Axial Skeleton

I highly recommend Professor Wissman’s sites For bones: http://homepage.smc.edu/wissmann_paul/bones/EBbonestutorial.html Check out all his links: http://homepage.smc.edu/wissmann_paul/anatomy1/ Also check out: Site for xrays & other diagnostic procedures: http://www.radiologyinfo.org/en/sitemap/category.cfm?category=diag

Prof Wissman’s bone site; this doesn’t show the roll-over answers This is an example of Prof Wissman’s bone site; this doesn’t show the roll-over answers http://homepage.smc.edu/wissmann_paul/bones/EBbonestutorial.html

THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of Bones (206) Cartilages Joints – also called articulations, are the junctions between skeletal elements Ligaments – connect bones Divided into axial and appendicular

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

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

The Skull Cranial bones (or cranium) Enclose the cranial cavity, which supports and protects the brain Attachment sites for some head and neck muscles Facial bones (anterior aspect of skull) Form framework of face Form cavities for sense organs of sight, taste and smell Provides openings for passage of air and food Hold the teeth Anchor the muscles of the face

Cranial bones Frontal bone Parietal bones (paired) Occipital bone Temporal bones (paired) Sphenoid bone Ethmoid bone

Cranial bones frontal parietal parietal parietal _______sphenoid temporal _____ethmoid occipital occipital

Cranial “cavity” – houses brain Smaller cavities Housing middle and inner ear Nasal cavity Orbits Sinuses Openings (foramina, canals, fissures) for: Spinal cord Blood vessels Twelve cranial nerves: I-XII

Remember, the skull is composed of: Cranial bones (or cranium) [these were just reviewed] and Facial bones (anterior aspect of skull) Form framework of face Form cavities for sense organs of sight, taste and smell Provides openings for passage of air and food Hold the teeth Anchor the muscles of the face

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

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

Cranium Vault – “calvaria” = skullcap Base or floor: inferior part Forms superior, lateral and posterior aspects of skull, and forehead Base or floor: inferior part Prominent bony ridges divide cranial base into 3 “fossae” (steps) – anterior, middle and posterior Anterior cranial fossa Middle cranial fossa Posterior cranial fossa (looking down on the floor of the skull)

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

Hyoid bone 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 Fetus and infant: 33 separate bones, or vertebrae Adult: 24 vertebrae Inferior 9 have fused forming The sacrum (5) and The coccyx (4)

Vertebrae Cervical – 7 Thoracic - 12 Lumbar - 5 Sacrum (5 fused) Coccyx (4 fused)

Spinal curvatures Cervical and lumbar are concave posteriorly* (lordosis) Thoracic and sacral are convex posteriorly* (kyphosis) Abnormal (see lab book p120): Too much of either Scoliosis (more than 10 degrees of lateral curvature) *when viewed from the side

The Sacrum Coccyx Shapes posterior wall of pelvis 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 Manubrium Body Xiphoid process True ribs 1-7 False ribs 8-12 Floating ribs 11,12

Typical rib