1. Skeletal System Axial Skeleton
Skull, Vertebral Column, Hyoid Bone & Thoracic Cage

2. Functions The Skeleton:
Supports – rigid framework to support soft tissue that weighs 5x the amount of the skeleton
Protects - Organs are protected by ribs cage & pelvis & marrow is protected; red blood cell made inside the bones
Moves - body movement occurs b/c the skeleton provides anchoring attachments for skeletal muscles
Produces (Hemopoiesis) - blood cells are produced in bone marrow
Stores (Mineral Storage) - calcium, magnesium, sodium, fluorine, phosphorous

3. Bone Shapes Long – longer than they are wide
Ex: most bones of the extremities
Short – somewhat cubed shaped
Ex: carpal bones (wrist) and tarsal bones (ankle)
Flat – have broad surfaces for muscle attachment or protection of underlying organs
Ex: cranial bones, ribs, scapula (pectoral girdle)
Irregular – varied shapes and many surface features for muscle attachment and articulation. Protect nervous tissue and offer support.
Ex: vertebra, sacrum, and hyoid bone

4. The Skeleton is Divided into 2 parts = 206 bones
1. Axial Skeleton – bones that form the upright axis of the body and support and protect the organs of the head, neck and trunk
Skull
Ribcage (Thoracic cage)
Vertebral Column
Hyoid Bone
2. Appendicular Skeleton - Upper and lower extremities and bony girdles that anchor those appendages to the axial skeleton
Pectoral Girdle
Upper Extremity
Pelvic Girdle
Lower Extremity

5. Skull, 22 bones (8 cranial & 14 Facial)
1. Frontal Bone – anterior bone, above orbit: forms forehead roof of nasal cavity, and superior arch of orbit
2. Parietal Bone (2) – between frontal bone and occipital bone
3. Temporal Bone (2)– lateral bone, auditory opening and
*zygomatic process of temporal bone
4. Occipital Bone – posterior bone, forms the base of the skull has the foramen magnum & occipital condyles
Foramen Magnum – opening in the skull for the spinal cord
Occipital Condyles – articulating surface for C1, atlas
5. Sphenoid – form the anterior base of the cranium (moth shaped), can be viewed laterally & inferiorly
6. Ethmoid – anterior floor of cranium between the orbits, forms the roof of the nasal cavity
7. Maxilla (2) – upper jaw, supports upper teeth forms roof of mouth and medical orbit
8. Palatine Bone (2) - form the posterior third of the hard palate , part of the orbit & part of the nasal cavity
9. Zygomatic Bone (2) – anterior bone, shapes cheek bones, forms lateral orbit and orbital floor:
*temporal process of zygomatic bone
* Zygomatic Arch = zygomatic process of temporal bone & temporal process of zygomatic bone articulate to form a bridge across the side of the skull
10. Lacrimal (2) – form the anterior part of the medial wall of each orbit. These are the smallest facial bones
11. Nasal Bone - bridge of nose
12. Inferior Nasal Concha (2) – fragile scroll like bones that project horizontally & medially from the lateral wall of the nasal cavity
13. Vomer – thin flattened bone that forms the lower part of the nasal septum
14. Mandible – lower jaw, largest & strongest bone in the face, only moveable bone of the skull, articulates with the temporal bone
* Orbit – cone shaped fossa, opening for the eye
Made up of 7 separate bones: frontal, sphenoid, zygomatic, maxilla, lacrimal, ethmoid, and palantine

7. Skull – Anterior View

8. Skull – Inferior View

9. Vertebral Column
Made up of 7 Cervical Vertebrae, 12 Thoracic Vertebrae, 5 Lumbar Vertebrae, Sacrum & Coccyx
The vertebral column protects the spinal cord & nerve roots

10. Cervical Vertebrae Seven, C1 – C7
C1 has no body & is called the ATLAS. C1 allows you to shake your head yes (flexion & extension). C1 also articulates with the occipital condyles of the skull
C2 has the odontoid process, also called the dens . C2 is called the AXIS. C2 allows you to shake your head no (rotation)
C7 has the most prominent spinous process of all cervical vertebrae.
Cervical vertebrae are the smallest of all vertebrae, but the bone tissue is more dense than any other vertebrae.

11. Thoracic Vertebrae Twelve, T1 – T12
The twelve thoracic vertebrae articulate with the ribs posteriorly (thoracic cage, anchors to axial skeleton through thoracic vertabrae)
Thoracic vertebrae are bigger than cervical vertebrae.
Each thoracic vertebrae gradually increases in size from T1 – T12.

12. Lumbar Vertebrae Five, L1 – L5 Lumbar Vertebrae have very heavy bodies
Back muscles attach to the very large, thick, blunt spinous processes.
Lumbar vertebrae are the largest in the vertebral column.
The sciatic nerve originates from the space between L4 & L5. The sciatic nerve is the longest nerve in the body.

13. Sacrum & Coccyx
The sacrum is the foundation of the pelvic girdle, but still part of the axial skeleton.
The sacrum articulates with the ilium to form the Sacroiliac Joint. The SI joint is where the appendicular skeleton attaches to the axial skeleton (lower extremity)
The sacrum is wedge shaped
The sacrum consists of 3-5 vertebrae that fuse after age 26
The coccyx is also know as the tailbone.
The coccyx is triangular in shape
The coccyx consists of 3-5 fused coccygeal vertebrae.

14. Thoracic Cage, AKA Ribcage
The thoracic cage is a cone shaped, flexible cage that encloses & protects vital body organs. The thoracic cage is directly involved in breathing. The thoracic cage is made up of 12 thoracic vertebrae, 12 pair of ribs, costal cartilage & the sternum. The thoracic cage protects the lungs, gall bladder, liver, kidneys, stomach, pancreas, spleen & heart.

15. Ribs 12 pair attach posteriorly to the thoracic vertebrae.
All ribs have a neck, angle & body.
TRUE RIBS
1st seven pair, anchored individually by costal cartilage
FALSE RIBS
Pair 8- 12, attach to sternum by a web of cartilage located at rib 7
FLOATING RIBS
Pair 11 & 12, do not attach to the sternum.

17. Sternum Also known as the breastbone. The sternum protects the heart.
The sternum also supports the pectoral girdle & upper extremities.
The appendicular skeleton attaches to the axial skeleton at the Sternoclavicular Joint. The SC joint is where the sternum & clavicle articulate.
The sternum is comprised of 3 separate bones
Upper = Maubrium (sword handle)
Central = Body (sword blade)
Lower = Xiphoid Process (sword tip)