2. The Axial Skeleton forms the longitudinal axis of the body
The Axial Skeleton forms the longitudinal axis of the body. It is divided into three parts
Skull
Vertebral column
Bony thorax

3. Cranium (eight large flat bones)
The skull consists of two sets of bones, which are joined by sutures. Only the mandible is attached by a freely movable joint.
Cranium (eight large flat bones)
Frontal, Parietal(2), Temporal(2), Occipital, Sphenoid, Ethmoid
Facial bones (all paired except mandible and vomer)
Paired Maxilla, Palatine, Zygomatic, Lacrimal, Nasal, and Inferior Nasal Conchae and Single Mandible and Vomer(plow)

4. The Fetal Skull
The fetal skull is large compared to the infant’s total body length
Fontanels—fibrous membranes connecting the cranial bones
Allow the brain to grow
Convert to bone within 24 months after birth

5. Skeletal Changes Throughout Life
Figure 5.33a

6. Paranasal Sinuses
The Paranasal Sinuses are hollow portions of bones surrounding the nasal cavity
Functions of paranasal sinuses
Lighten the skull
Give resonance and amplification to voice

7. Serves as a moveable base for the tongue Aids in swallowing and speech
The Hyoid bone is the only bone that does not articulate with another bone-it is held into place by thyroid ligaments.
Serves as a moveable base for the tongue
Aids in swallowing and speech
Notice the bruising around the neck area. The appearance of finger indentations indicate manual strangulation. The impression was confirmed by finding bruising deep in the neck, along with a fracture of the hyoid bone.

8. The Vertebral Column
Each vertebrae is given a name according to its location
There are 24 single vertebral bones separated by intervertebral discs
Seven cervical vertebrae are in the neck (C1-C7)
Twelve thoracic vertebrae are in the chest region (T1-T12)
Five lumbar vertebrae are associated with the lower back (L1-L5)

10. The Vertebral Column
The remaining nine vertebrae fuse to form two composite bones
Sacrum
Coccyx (tailbone)

11. Sacrum and Coccyx Sacrum Coccyx Formed by the fusion of five vertebrae
Formed from the fusion of three to five vertebrae
“Tailbone,” or remnant of a tail that other vertebrates have

12. The spine has a normal curvature
Primary curvatures are the spinal curvatures of the thoracic and sacral regions
Present from birth
Secondary curvatures are the spinal curvatures of the cervical and lumbar regions
Develop after birth (cervical with head raising and lumbar with walking)

13. Abnormal Spinal Curvatures of the Vertebral Column
Scoliosis- “crooked”-side to side curvature-causes multifactorial
Kyphosis-”hunchback” causes include trauma “slouching”, osteoporosis with compression fractures.
Lordosis “swayback” an inward curvature of the vertebrae usually caused by differing anterior and posterior disc thickness

14. The Bony Thorax forms a cage to protect major organs
The Bony Thorax forms a cage to protect major organs. It consists of three parts
Sternum
Ribs
True ribs (pairs 1–7 attached to sternum)
False ribs (pairs 8–12)
Floating ribs (pairs 11–12)
Thoracic vertebrae

15. The Appendicular Skeleton is composed of 126 bones
Limbs (appendages)
Pectoral girdle
Pelvic girdle

16. The Pectoral (shoulder) Girdle is composed of two bones, which allow the upper limb to have exceptionally free movement
Clavicle—collarbone (acts as a brace to hold arm away from thorax and prevents shoulder dislocation)
Scapula—shoulder blade
(provides exceptional range of motion for the arm)

18. Bones of the Upper Limbs
Humerus
Forms the upper arm
Single bone

19. Bones of the Upper Limbs
The forearm has two bones
Ulna
Medial bone in anatomical position (pinky side)
Radius
Lateral bone in anatomical position (thumb side)

21. Bones of the Upper Limbs
The hand (27 bones)
Carpals—wrist
Metacarpals—palm
Phalanges—fingers