Axial Skeleton

Longitudinal axis of the body Longitudinal axis of the body 80 bones 80 bones Skull Skull Hyoid Hyoid Vertebral column Vertebral column Thoracic cage (sternum and ribs) Thoracic cage (sternum and ribs)

Functions Adjust the positions of the head, neck & trunk Adjust the positions of the head, neck & trunk Perform respiratory movements Perform respiratory movements Stabilize or position parts of the appendicular skeleton Stabilize or position parts of the appendicular skeleton

Skull Protects the brain Protects the brain Guards entrance to the digestive and respiratory system Guards entrance to the digestive and respiratory system

Vertebral Column 7 Cervical 7 Cervical 12 Thoracic 12 Thoracic 5 Lumbar 5 Lumbar 5 Sacral – fuse into 1 sacrum (25-30) 5 Sacral – fuse into 1 sacrum (25-30) 4 Coccygeal – fuse into 1 coccyx 4 Coccygeal – fuse into 1 coccyx

Vertebral Column Function: Function: Support for the head, neck & trunk Support for the head, neck & trunk Protects the spinal cord Protects the spinal cord Helps maintain an upright body posistion Helps maintain an upright body posistion

Primary Curvature Present at birth Present at birth Which 2 are you born with? Which 2 are you born with? Thoracic Thoracic Sacral Sacral

Secondary Curvature Appear several months after birth Appear several months after birth Why do they appear? Why do they appear? Cervical Cervical Hold your head up Hold your head up Lumbar Lumbar Ability to stand up Ability to stand up

Curvature Problems Kyphosis Kyphosis hunchback hunchback

Curvature Problems Lordosis Lordosis swayback

Curvature Problems Scoliosis Scoliosis Common in late childhood, early teens Common in late childhood, early teens Girls more likely than boys Girls more likely than boys May run in families May run in families

Thoracic Cage Functions: Functions: Protects the heart, lungs, thymus, & other structures in the thoracic cavity Protects the heart, lungs, thymus, & other structures in the thoracic cavity Serves as an attachment point for muscles involved in Serves as an attachment point for muscles involved in Respiration Respiration Maintenance of the position of the vertebral column Maintenance of the position of the vertebral column Movements of the pectoral girdle & upper limbs Movements of the pectoral girdle & upper limbs

Ribs 12 pairs 12 pairs 3 Divisions 3 Divisions Vertebrosternal (true) – ribs 1-7 Vertebrosternal (true) – ribs 1-7 Connect vertebrae and sternum Connect vertebrae and sternum Vertebrochondral (false) –ribs 8-10 Vertebrochondral (false) –ribs 8-10 Connect vertebrae and cartilage Connect vertebrae and cartilage Vertebral (floating) – ribs 11 & 12 Vertebral (floating) – ribs 11 & 12 Vertebrae only Vertebrae only

Sternum 3 Components 3 Components Manubrium Manubrium Articulates with the clavicles & 1 st pair of ribs Articulates with the clavicles & 1 st pair of ribs Body Body Articulates with ribs Articulates with ribs Xiphoid process Xiphoid process Can be broken with strong pressure or impact Can be broken with strong pressure or impact Damage to liver Damage to liver