The human skeleton can be divided into two main parts; the first part is the axial skeleton and second part is the appendicular skeleton (but we will be focusing on the axial skeleton). As shown in the illustration, the axial skeleton consists of the bones in the head and trunk of the human body. This area can be further divided into five main parts. These parts consist of; the skull, ossicles of the inner ear, hyoid bone of the throat, chest, and the vertebral column.

• This site has an interactive skull but goes into more detail about each bone. It also allows you to manipulate (move, enlarge, rotate) the bones of the skull to get a better view.
• This site shows the skull at different angles and helps you learn the bones.
• Here are flashcards made by fellow students

a) What other functions do the bones of the axial skeleton perform.

a) What are the two groups of skull bones

i) Be able to name and describe the 8 cranial bones.

(1) Understand the relationship of each bone and how they fit together.

(a) What is the anatomical name for the roof of the cranium.

(2) Be able to name and locate the places where the bones join.

(a) At what age do the bones of the skull usually fuse.
(b) What happens when the bones fuse too soon.
(c) What is the name for the bones which form in the suture itself

ii) Be able to name and describe the 14 facial bones.

(1) Understand the relationship of each facial bone and how they fit together.

(a) What is a common deformity that happens when embryonic bones fail to fuse properly

(2) Be able to name and locate the articulations of each bone.

iii) What bones come together to form the orbit.
iv) What bones, features and landmarks can you feel on your own face.

b) What are the major cavities of the skull

i) What is the name and function of each cavity.

c) What are the different views of the skull and which features are visible in each.
d) What are the landmark features of each bone in the skull
e) Know the names of the canals, fissures, and foramen in the cranial bones.
f ) Know the names of the canals, fissures, and foramen in the facial bones. g) What are the names of the other bones associated with the skull
h) What are the names, function, and position of the auditory ossicles.

ii) What and where is the hyoid bone and what function does it serve.

i) What are the sex differences in the skull.
j) How does the skull age.
k) What are the differences between a fetal, child, and an adult skull

ii) What are fontanels

(1) Be able to name the different fontanels and at what age they close.

a) What is the function of the vertebral column.
b) What are the names of each bone in the vertebral column.
c) What are the divisions in the vertebral column.

i) What are the names of each cervical vertebrae

(1) Be able to describe and identify the atlas and axis.

(a) Know the names of their identifying landmarks.

General Description Name of Bone No. of Bones Additional Information Cranium (8) frontal 1 upper front skull bone parietal 2 posterior to frontal, left/right temporal 2 inferior-lateral to parietal sphenoid 1 inner winged bone ethmoid 1 inner anterior bone occipital 1 bone at the back of skull Facial bones (14) mandible 1 lower jawbone maxilla 2 upper jawbone zygomatic bone 2 cheek bones nasal bone 2 lacrimal bone 2 palatine 2 inferior nasal concha 2 vomer 1 Hyoid hyoid 1 Ear Ossicles malleus, incus, stapes 6 2 each Vertebral Column (26) cervical vertebrae 7 C1-C7 thoracic vertebrae 12 T1-T12 lumbar vertebrae 5 L1-L5 sacrum 1 5 fused S1 - S5 coccyx 1 4 fused Thorax (thoracic cage) sternum 1 true ribs (7 pair) 14 vertebrosternal false ribs (3 pair) 6 vertebrochondral false ribs (floating ribs) 4 vertebral ribs First: The Skull Skull: Cranium and Facial Bones The skull consists of 8 cranial bones and 14 facial bones. Some of the bones exist as pairs. The bones of the skull provide protection for the brain and the organs of vision, taste, hearing, equilibrium, and smell. The bones also provide attachment for muscles that move the head and control facial expressions and chewing. For some additional information on bones of the cranium, visit the Cranium Crushers Group page! Figures 1 and 2 illustrate specific characteristics of these bones, while some general features of the skull follow: Sutures are immovable interlocking joints that join skull bones together. Figure 1 The right lateral view and anterior view of the skull's bones. Fontanels are spaces between cranial bones that are filled with fibrous membranes. The spaces provide pliability for the skull when it passes through the birth canal and for brain growth during infancy. Bone growth eventually fills the spaces by age two. Sutural (Wormian) bones are very small bones that develop within sutures. Their number and location vary. The cranial vault denotes the top, sides, front, and back of the cranium. The cranial floor (base) denotes the bottom of the cranium. Cranial fossae are three depressions in the floor of the cranium. These fossae, called the anterior, middle, and posterior cranial fossae, provide spaces that accommodate the shape of the brain. The nasal cavity is formed by cartilage and several bones. Air entering the cavity is warmed and cleansed by mucus lining the cavity. Sinuses (paranasal sinuses) are mucus-lined cavities inside cranial and facial bones that surround the nasal cavity. The cavities secrete mucus that drains into the nasal cavity. The cavities also act as resonance chambers that enhance vocal (and singing) quality Here is a video of someone pointing out the main bones of the skull. The story of the Turkish Cowboy The Turkish Cowboy high and mighty in his Turkish saddle (sella turcica, which means Turkish saddle), with a lasso (foramen lacerum) at his hip, proudly rides his loyal stallion over to the ol' valley (foramen ovale), turns his head and spits into the spinosum (foramen spinosum), then gallops off into the setting sun of the rotundum (foramen rotundum). In addition to these foramina, there are optic foramina (where optic nerves enter orbit) at the top front of the saddle and there are superior orbital fissureslesser wing of the sphenoid (you can see both the optic foramen and the superior orbital fissure by looking into the orbit as well as from within the cranium). under the Second: The Vertebral Column Not sure if this will work, but here are the lecture slides. ~Kevin Vertebral Column The vertebral column (spine) consists of 26 vertebrae bones (See Table 1 ). It provides support for the head and trunk of the body, protection for the spinal cord, and connecting points for the ribs and muscles. TABLE 2 Bones of the Vertebral Column Vertebra Body Spinous Process Transverse Process Vertebral Process Cervical C1 (atlas) none, bony ring none with transverse foramen large; lightbulb-shaped C2 (axis) relatively small; with dens (odontoid process) bifid with transverse foramen large; heart-shaped C3-C6 relatively small; oval bifid with transverse foramen large; triangular C7 (vertebra prominens) relatively small; oval prominently long; not bifid with transverse foramen large; triangular Thoracic T1-T10 C2-C7, heart-shaped; 2 facets or demifacets for articulating with rib head long; points down with facets for articulating with rib tubercle circular T11-T12 larger than C2-C7, heart-shaped; 1 demifacets for articulating with rib head long; points down no facets for rib joints circular Lumbar L1–L5 largest of all vertebrae; kidney- shaped short, thick; points horizontally Sacrum 5 fused S1-S5 fusion of 5 vertebrae forms a triangular bone fuse to become the median sacral crest becomes the lateral sacral crest becomes sacral canal Coccyx 4 fused

A typical vertebra has the following characteristics (see Figure 3 ).

Figure 3 The four regions of the vertebral column.

Thorax

Skull:
Frontal bone: Large paired bone located in the superior lateral portion of the skull
Frontal sinus: Cavity within the frontal bone
Supraorbital margin: The superior border, or margin, of the eye socket

Parietal bone: Large paired bone located in the superior lateral portion of the skull

Coronal suture: Runs laterally joining the frontal and parietal bones
Sagittal suture: Runs anterioposteriorally joining the two parietal bones

Temporal bone: Paired bone located on the lateral sides of the skull

Squamosal suture: Runs dorsoventrally joining the temporal and parietal bones
Mandibular fossa: Articulates with the condylar process of the mandible
Temporomandibular joint: Articulation of the mandibular fossa and the condyloid process of the mandible
External auditory meatus: Hole in the temporal bone extending medially to the inner ear
Internal auditory meatus: Short canal in petrous portion of temporal bone extending laterally towards the inner ear
Styloid process: Long sharp process of the temporal bone extending inferiorly
Mastoid process: Rounded process of the temporal bone slightly posterior and inferior to the external auditory meatus
Petrous portion: Dense bony ridge on interior surface of temporal bone
Carotid canal: Located on petrous portion of the temporal bone, anterior to the jugular foramen
Jugalar foramen: Located on inferior, petrous part of the temporal bone posterior to the carotid canal
Zygomatic process: Arch of bone extending anteriorly from the temporal process

Zygomatic bone: Paired bone which participates with other zygomatic process in forming the "cheek bone"
Temporal process: Arch of bone extending posteriorly from the zygomatic bone

Occipital bone: Most posterior and inferior bone of the skull
Lambdoidal suture: Runs laterally joining the occipital and parietal bones
Sutural (wormian) bone: Any small, irregular bone within a cranial suture
Superior nuchal line: Runs horizontally from external occipital protuberance
Foramen magnum: Large opening on the inferior part of the skull
Occipital condyle: Paired rounded process lateral to the foramen magnum
Hypoglossal canal: Paired canal anterior to occipital condyle

Sphenoid bone: Butterfly-shaped bone forming the floor of the cranium
Superior orbital fissure: Fissure between grreater and lesser wings of sphenoid, visible from the orbits
Sella turcica: saddle-like depression posterior to lesser wing
Optic foramen: Paired opening through lesser wing of the sphenoid for optic nerve
Foramen lacerum: Paired opening posterior and lateral to sella turcica
Foramen ovale: Paired oval opening distal to the base of the sella turcica
Foramen rotundum: Paired round opening anterior to the foramen ovale for maxillary division of trigeminal nerve
Foramen Spinosum: Paired opening at the posterior margin of the sphenoid bone

Ethmoid bone: Located between the orbits and between sphenoid and nasal bones; forms roof of nasal cavity
Crista galli: Superior projection in the middle of the cribriform plate of the ethmoid bone
Cribriform plate: Porous bone surrounding the crista galli in the floor of the cranium through which olfactory nerves transverse
Perpendicular plate: Median inferior projection of ethmoid; forms superior nasal septum

Inferior nasal concha: Bone that protrudes into the inferior part of the nasal cavity

Vomer: Bone forming the inferior and posterior portion of the nasal septum

Palatine bone: Posterior portion of the hard palate associated with maxilla

Maxilla: Paired fused bone of the upper jaw and central face
Palatine process: Anterior portion of the hard palate
Infraorbital foramen: Paired opening inferior to the orbit

Lacrimal bone: Paired bone forming part of the medial wall of the orbit
Nasolacrimal canal: Opening in the lacrimal bone allowing passage for the nasolacrimal duct

Nasal bone: Paired bone composing the superior portion of the nose

Mandible: The bone of the lower jaw
Ramus: The vertical portion of the mandible extending from the angle
Coronoid process: Anterior process of the mandibular ramus which provides insertion of the temporalis muscle
Condylar (condyloid) process: The most posterior process of the mandibular ramus which contributes to the temporomandibular joint
Mandibular notch: Separates the coronoid and condyloid processes of the ramus
Mandibular foramen: Paired opening on the medial surface of the mandibular ramus
Mental foramen: Paired opening on the anterolateral aspect of the mandibular body
Alveolus: Socked lined with connective tissue in which a tooth is fastened

Hyoid bone: "U-shaped" bone located in the neck superior to the larynx; tongue muscle attachment

Vertebra: Basic bone unit of the vertebral column
Body: Anterior portion of vertebra
Pedicle: Posterior projection to vertebral body that supports the lamina
Transverse process: Lateral projections of the vertebra for muscle/ligament attachment
Lamina: Paired arches supported by the pedicles located posterior to the vertebral body
Spinous process: Most posterior projection of the vertebra for muscle/ligament attachment
Vertebral foramen: Opening surrounded by vertebral body and arch through which spinal cord extends
Articular process: Paired (superior and inferior) process which articulates with process of adjacent vertebrae

Cervical vertebrae: C1-C7; Smallest of the vertebrae
Transverse foramen: Paired opening on the transverse process for passage of blood vessels
Atlas: C1, Supports the head
Axis: C2, Pivotal point for atlas and skull

Thoracic vertebrae: 12 total (T1-T12) vertebrae with circular vertebral foramen and long spinous process

Lumbar vertebrae: 5 total (L1-L5) vertebrae with strongly built components for weight bearing

Sacrum: (S1-S5) Composed of 5 fused vertebrae forming posterior wall of pelvis

Coccyx: 4 fused vertebrae forming the tailbone

Sternum: Anterior midline anchor to the ribs
Manubrium: Superior portion of the sternum that articulates with the clavicle
Body: Middle portion of the sternum that articulates with T1-T7 rib cartilage
Xiphoid process: Small inferior portion of the sternum

Ribs: 12 Pair, attached to T1-T12 thoracic vertebrae
True ribs: Attached posteriorly to T1-T7 vertebrae and anteriorly to the sternum via costal cartilage
False Ribs: Attached posteriorly to vertebrae T8-T10; they are not directly attached to the sternum
Floating ribs: Attached posteriorly to vertebrae T11-T12 but are not attached to the sternum
Head: Rounded part of rib which articulates with the thoracic vertebrae via two costal facets
Neck: Region of rib between head and tubercle
Tubercle: Bump near the neck of the rib which articulates with vertebral transverse process on costal facet of thoracic vertebrae
Angle: The curved portion of the rib
Shaft: Elongated part of the rib associated anteriorly with costal cartilage

Review Questions

1. How many thoracic vertebrae are there?

2. On which bone is the cristi galli located on?

3. What type of cartilage will you find connecting ribs to the sternum?

4. What type of verterbrae will you find transverse foramen?

5. How many facial bones are there? and can you name them all?

• The thoracic cage, formed by the costal cartilages and sternum anteriorly, the thoracic vertebrae posteriorly, and the ribs laterally serve as protection to a couple of the human body's most vital organs. The heart and the lungs are in-caged and protected by the thoracic cage. The trachea and esophagus are also protected by the thoracic cage.

• When all stacked the vertebrae form a superior to inferior vertebral canal that houses and protect the crucial spinal cord. It also however, provides passage way for the spinal nerves through the intervertebral foramina to the other parts of the body. A fracture of the vertebrae and damage of spinal cord can lead to paralization of the lower extremities (paraplegic), or to both the lower and upper extremities (quadriplegic)