Axial Skeleton Skull and Backbone Axial vs Appendicular

Axial Skeleton (Skull and Backbone)

Axial vs. Appendicular The Axial skeleton consists of the skull, vertebral column and bony thorax, or thoracic cage (the sternum and ribs). The Appendicular skeleton consists of the appendages.

Bones of the skull Frontal bone: the forehead Parietal bones (2): top back half sides of skull Maxillae (2): upper lip area where top teeth are connected Palatine bones (2): roof of the mouth Zygomatic bones (2): cheek bones Lacrimal bones (2): inside the corner of the eye

More Skull flat bones…. Nasal bones (2): both sides of the nose Vomer bone: center bottom of the nose Mandible: lower jaw, helps you chew Temporal bones (2): sides of the head behind the eye and in front of the ear Occipital bone: bottom back of the head Sphenoid bone: between temporal and zygomatic bones Ethmoid bone: in front of sphenoid ( back of eye socket)

Hyoid bone: In the neck between lower jaw and larynx. It supports the tongue and muscles attach to it to help in swallowing. Why is the hyoid bone unique? Not attached to any other bone!

Vertebral Column Spine extends from skull to pelvis. 26 irregular bones connected by ligaments-> flexible and curved and Has spinal cord down the middle. Think …. Meal Times 1 st 7= cervical (neck) 7 am (1 st= atlas ; 2 nd= axis concave) 12= Thoracic (chest) 12 noon 5= Lumbar ( lower back) 5 pm

More about the spine…. Fetus= 33 bones 9 vertebrae will fuse to form the Sacrum and Coccyx Vertebrae separated by pods of Fibrocartilage = intervertebral disks (cushions & is a shock absorber) Young > 90% water, spongy Adults there is less H 20, harder less compressible herniated disks “slipped” This disks protrudes into the spinal nerves numbess and pain Primary curvatures --> Thoracic / sacral there at birth Secondary curvatures--> Cervical--> baby raises head --> lumbar baby walks

Abnormal Spine Curvatures VIDEO LINK Scoliosis--> sideways Lordosis (ex) Kyphosis (ex)

Vertebrae Structure Body/ Centrum-- > anterior weight bearing Vertebral arch --> joining of all posterior extensions to body Vertebral foramen--> canal for nerve cord Tranverse processes --> 2 lateral projections from body Spinous process--> single projection from arch Articular processes --> lateral to foramen follows joints w/ adjacent vertebral

Subdivisions of the spine… Cervical ( C 1 - C 7) * Have 2 foramen for cranial arteries 1. Atlas --> no body, indention’s, receive occipital condlyes-- > nod head (yes) 2. Axis --> C 2 pivot for rotation of atlas (odontoid process/dense) pivot pt. “no”

More about the spine… Thoracic ( T 1 -T 12) spinous process long and hooked, larger 2 costal facets to receive ribs Lumbar ( L 1 -L 5) massive block bodies w/short hatched spinous process sturdiest for stress on column Sacrum- five vertebrae fused --> posterior wall of pelvis w/sacral canal Coccyx- 3 -5 small fused. Tailbone (remnant of tail)

Bony Thorax Sternum +Ribs +Thoracic Vertebrae + Thoracic Cage goes around the lung and heart Sternum (breastbone ) flat 3 fused bones … Attaches to the 1 st seven ribs. Ribs- 12 pairs * Men don’t have one less rib than women* T ilt downward. 1 st 7 pairs of ribs are called True Ribs= attach to sternum by costal cartilage. The next 5 pairs of ribs are called False Ribs = indirectly to sternum or not at all Last 2 pairs of False ribs are called Floating Ribs. (no attachment) Intercostal Spaces --> filled w/ muscles to help breathing.