Cranial Bones (from The Axial Skeleton Chapter 7) Flashcards
What are the two divisions of the skeletal system? How many bones are in each?
- The axial skeleton (80 bones)
2. Appendicular Skeleton (126 bones)
How many named bones make up the adult skeleton?
206
What is the axial skeleton?
Includes bones along the central axis of the body
- skull
- vertebral column
- thoracic cage
What is the appendicular skeleton?
Bones of the appendages
- upper and lower limbs
- bones that hold the limbs to the trunk of the body
What are the two sets of bones found in the skull?
- 8 Cranial bones form the cranial cavity
2. 14 Facial bones form the face
What are three characteristics of the skull bones?
- Skull forms the large cranial cavity, and smaller cavities (orbits (eye sockets)/nasal cavity)
- Skull bones contain cavities (eg paranasal sinuses)
- Bones of the skull have numerous surface markings which aid in their identification (eg holes through the bone (foramina) and bony projections (eg spine)
Name the 8 cranial bones
*any bone that touches brain* 1 x frontal bone 2x Parietal Bone 2x Temporal Bone 1x Occipital 1x Sphenoid 1x Ethmoid \_\_\_\_\_\_\_\_\_\_\_ =8
Name the 14 Facial bones
*Does not touch brain* 2x nasal 2x maxillae 2x zygomatic 1x mandible 2x lacrimal 2x palatine 2x inferior nasal conchae 1x vomer
What is the frontal bone?
one of the 8 cranial bones
-forms the anterior roof of the cranium, nasal cavity and arches of the orbits
What are four features of the frontal bone?
- Frontal squama is plate-like bone - forms the forehead
- Supraorbital margin is a prominent bony ridge
- Supraorbital foramen is an opening in the supraorbital margin where the supraorbital nerve and artery pass
- Frontal sinuses reduce the weight of the skull
What are the Parietal Bones?
2 of the cranial bones
-form much of the sides and roof of the cranial cavity
What are two notes about parietal bones?
- Each bone articulate with 5 other bones
- frontal, temporal, occipital, the other parietal and the sphenoid bone - is separated by coronal, squamous and lambdoid sutures
What are the temporal bones?
2 of the 8 cranial bones
-Form the inferio-lateral part of the cranial floor plus part of the lateral wall near the ear
What do the temporal bones articulate with and where?
the mandible at the temperomadibular joint
Each temporal bone has:
8
- temporal squama
- zygomatic process
- mandibular fossa
- articular tubercle
- mastoid process
- mastoid portion
- external auditory meatus
- styloid process
What three features are found in the mastoid portion?
- Auditory meatus
- Internal Auditory meatus
- Mastoid process
What is the auditory meatus?
- rounded projection of the mastoid portion of the temporal bone
- serves the attachment for several neck muscles
What is the internal auditory meatus?
Serve the opening for the favial (VII) and vestibulocochlear (VIII) cranial nerves
What is the Mastoid process?
Prominent surface feature of the mastoid portion
What is the styloid process?
Attachment for muscles and ligaments of the tongue and neck
What is the stylomastoid foramen?
-Stylomastoid foramen is the passage for facial (VII) and stylomastoid artery
What is the petrous process?
3
- Largest part of the temporal bone
- Houses the internal and middle ear structures for hearing and balance
- Houses the carotid foramen (passage of carotid artery) and the jugular foramen (passage of jugular vein)
What is the occipital bone?
1 of the 8 cranial bones
-Forms the posterior part and most of the base of the cranium
What are four prominent surface features of the occipital bone?
- Foramen magnum
- Occipital condyles
- External occipital protuberance
- Superior and inferior nuchal line
What is the Foramen magnum?
feature of Occipital bone
Passage of vertebral, spinal arteries and accessory (XI) nerve
What is the Occipital condyles
Feature of the Occipital bone
-articulate with the first cervical vertebra (atlas) to form the atlanto-occipital joints
What is the External Occipital Protuberance?
Feature of Occipital Bone
-attached by ligamentum nuchae to C7
What is the Superior and Inferior nuchal line
Feature of Occipital Bone
Muscle attachment
What is the sphenoid bone?
one of the 8 cranial bones
- middle part of the base of the skull
- Shaped like a butterfly keystone bone of cranial floor
What are four surface features of sphenoid bone?
- Sphenoidal sinus
- Pterygoid process
- Optic foramen
- Foramen rotundum
What is the sphenoidal sinus?
Feature of Sphenoid Bone:
-drains into the superior aspects of the nasal cavity
What is the Pterygoid Processes?
Feature of Sphenoid Bone:
-Attachment sites for muscles that move the mandible
What is the Optic Foramen?
Feature of Sphenoid Bone:
Passage for the optic (II) nerve and ophthalmic artery
What ist he Foramen rotundum?
Feature of Sphenoid Bone:
Is the passage of the maxillary branch of the trigeminal (V) nerve
What is the superior orbital fissure?
a passage for ophthalmic, trigeminal, occular, trochlear and abducens nerves
What is the Foramen ovale?
Passages mandibular nerve
What is the foramen spinosum?
Passages internal carotid and pharyngeal artery
What is the ethmoid bone?
Major superior supporting structure of the nasal cavity
-forms extensive surface area in the nasal cavity
What does the ethmoid bone form?
- Part of the anterior portion of the cranial floor
- The thin, medial wall of the orbits
- the superior portion of the nasal septum (partition that sagittally divides the nasal cavity)
- Most of the superior sidewalls of the nasal cavity
What are the lateral masses?
Compose most of the wall between the nasal cavity and the orbits
-contain 3-18 air spaces (ethmoidal cells) which form the ethmoidal sinuses
What is the olfactory foramina?
Passes olfactory nerve (I)
What is the Crista Galli?
attachment point for the membrane that separates the two hemispheres of the brain (Flax cerebri)
What is the function of the conchae (superior and middle nasal concha)
Increase vascular and mucous membrane surface area in the nasal cavity
- warms, moistens and humidifies inhaled air
- help cleanse inhaled air
- help sense of smell
