1. Skeletal System: The Axial Skeleton
Skull Vertebral Column
Ribs
Sternum

2. The Skull 22 separate bones, many fused together Two divisions:
Cranial Bones (8 bones)
Facial Bones (14 bones)

3. Bones of the Cranium Enclose and protect the brain Bones: Frontal (1)
Parietal (2)
Temporal (2)
Occipital (1)
Sphenoid (1)
Ethmoid (1)
Ethmoid bone
Sphenoid bone

4. Ethmoid and Sphenoid Bones
Ethmoid Bone: anterior part of the cranium base
Forms the floor of the cranium
Makes up the medial wall of the orbits (eye sockets)
The major supporting structure for the nasal cavity
Sphenoid Bone: medial base of the skull
Connects the frontal, temporal, and parietal bones
Sella Turcica: a “saddle” for the pituitary gland in the brain

5. Sutures in the Skull
Suture: An immovable joint found only in the skull bones
Coronal Suture: between the frontal and two parietals
Sagittal Suture: between the two parietals
Lambdoid Suture: between the two parietals and the occipital
Squamous Sutures: between the parietals and temporal bones

6. Fontanels
Membrane-filled spaces found between cranium bones in infants
“Soft Spots”
Eventually become ossified (replaced by bone)
Allow for:
The babies skull to compress, thus allowing childbirth
The brain to grow before the skull is completely fused

7. Facial Bones
Your face grows the most in the first two years; then stops by the age of 16.
Nasal Bones
Maxillae: form the lower orbit and upper jaw
Zygomatic Bones: cheekbones
Mandible: lower jawbone
Lacrimal Bones: smallest bones in the face; have a foramen for the tear duct to pass
Palatine Bones: form the hard palate in the roof of the mouth

8. Hyoid Bone
A U-shaped bone located in the neck between the mandible and the larynx (voicebox)
Does not articulate with any other bone
Supports the tongue
Provides attachment for muscles to allow for neck movement and swallowing

9. Vertebral Column Protects the Spinal Cord
Allows the major nerves to enter and exit the spinal cord
Usually 33 Bones
7 Cervical
12 Thoracic
5 Lumbar
5 Sacral (fused to form the sacrum)
4 Coccygeal (fuse to form one or two fused = coccyx)

10. Typical Vertebra Body: the thick weight bearing portion
Vertebral foramen: the hole that holds the spinal cord
Spinous Process: a single projection for muscle attachment
Transverse Process: two lateral projections for muscle attachment
Articular Processes: the facets that allow the vertebrae to move with the vertebrae superior and inferior to them

11. Atlas and Axis Atlas (C1): supports the head
Articulates with the occipital condyles of the skull (nod your head “yes”)
Axis (C2): The “peglike” dens makes a pivot for the head to rotate (move your head “no”)

12. Sacrum and Coccyx Sacrum (holy bone): 5 fused vertebrae
Usually starts to fuse at age and end in mid 20s)
Provides a foundation for the pelvis and allows nerves to pass
Coccyx: Usually 4 vertebrae that fuse
Fusion occurs between years of age

13. Epidural Anesthesia
Numbing medicine is delivered near the spinal cord through the sacrum

14. Sternum Aka: Breastbone Three separate bones:
Manubrium
Body
Xiphoid Process
Articulates with the ribs, provides attachment point for some abdominal muscles, hemopoiesis
Fuses in late teens; completely by age 40.

15. Ribs
12 pairs (24 total)
True Ribs: pairs 1-7 directly attach to the sternum by costal cartilage
False Ribs: pairs 8-12, their cartilage attaches to the 7th rib cartilage
Floating Ribs: pairs 11-12; don’t attach to the sternum