Axial Skeleton I

Skeleton is comprised of axial and appendicular structures.

I. Skeleton

A. Components

1. Bones

a. 206

2. Cartilage

3. Joints

4. Ligaments


B. Organization


1. Axial

            a. Skull

            b. Vertebral column

            c. Rib cage

2. Appendicular

            a. Limbs

            b. Girdles that attach to axial

                        i. Shoulder and hip bones


II. Axial Skeleton—Skull

A. Skull Bones

1. Organization

a. Cranial

b. Facial

B. Cranial bones

1. Functions

            a. Site for head muscle attachment

            b. Encase brain and particular sense organs

C. Facial bones

1. Functions

            a. Site for facial muscle attachment

            b. Cavities for particular sense organs

                        i. Gustation

                        ii. Olfaction

                        iii. Vision

            c. Framework for the face

            d. Openings for air and food passage

            e. Secure teeth

D. Sutures—connections (joints) between bones of skull

1. All bones of the skull except mandible

2. Cranial bone sutures


a. Coronal

b. Sagittal

c. Squamous

d. Lamboid

3. Sutures of facial bones are named based on name of bones that are connected

E. Organization of the skull

1. Cranial vault (calvaria; skullcap)

            a. Forms the superior, lateral and posterior aspects as well as the forehead

2. Cranial base (floor)

            a. Forms inferior aspect

            b. Fossae—steps


                        a. Anterior

                        b. Middle

                        c. Posterior

3. Cavities

            a. Cranial

                        i. Brain

            b. Orbits

                        i. Eyeballs

            c. Paranasal sinuses

                        i. Nasal cavity

            d. Middle and inner ear

4. Openings

            a. Foramina

            b. Canals

            c. Fissures


III. Bones of the Cranium




A Paired

1. Parietal

2. Temporal

B. Unpaired

1. Frontal

2. Occipital

3. Sphenoid

4. Ethmoid

C. Frontal bone


1. Structural contribution

            a. Anterior portion of cranium

            b. Roofs of the orbits

            c. Anterior cranial fossa

2. Parts

            a. Frontal squama

            b. Supraorbital margins

            c. Glabella

3. Articulations

            a. Coronal suture

                        i. Parietal bones

            b. Frontonasal suture

4. Sinuses and openings

            a. Frontal sinus

            b. Supraorbital foramen

D. Parietal bone

1. Structural contribution

            a. Superior and lateral aspects of the skull

2. Articulations

            a. Coronal

                        i. Anterior; frontal bone

            b. Sagittal

                        i. Midline; parietal bones

            c. Lamboid

                        i. Posterior; occipital bone

            d. Squamous

                        i. Lateral; temporal bones

E. Occipital bone

1. Structural contribution

            a. Posterior wall and base of skull

            b. Walls of the posterior cranial fossa

2. Articulations

            a. Lamboid

                        i. Parietal bones

            b. Occipitomastoid

                        i. Temporal bones

            c. Basioccipital

                        i. Sphenoid bone

3. Openings

            a. Foramen magnum

                        i. Brain connects with spinal cord

4. Protrusions

            a. Occipital condyles

                        i. Articulates with first vertebrae

F. Temporal bones

1. Structural contribution

            a. Lateral surface

            b. Inferior to parietal (inferolateral aspects of skull)

2. Articulations

            a. Squamous

                        i. Parietal

3. Shape—complicated; 4 regions

            a. Squamous

                        i. Zygomatic process meets zygomatic bone—zygotic arch

                        ii. Mandibular fossa and condyle of mandible—temporomandibular joint

            b. Tympanic region

                        i. Surrounds external auditory meatus

                        ii. Styloid—needlelike projection; muscle attachment

            c. Mastoid—mastoid process

                        i. Anchoring point for neck muscles

                        ii. Mastoid sinuses

            d. Petrous region—mountain range

                        i. Cranial base

                        ii. Between occipital and sphenoid bones

                        iii. Middle cranial fossa

                        iv. Houses middle and inner ear cavities

4. Foramen

            a. Jugular

                        i. Jugular veins; three cranial nerves

            b. Carotid canal

            c. Internal acoustic meatus

                        i. Cranial nerves VII and VIII

G. Sphenoid bone


1. Articulates with all other cranial bones

2. Shape

            a. Central Body

            b. Three pairs of processes

                        i. Greater wings

                        ii. Lesser wings

                        iii. Pterygoid


H. Ethmoid bone



1.  Shape

            a. Cribriform plate

            b. Perpendicular plate