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Questions and Answers
How many total skull bones are categorized as cranial bones?
How many total skull bones are categorized as cranial bones?
Which bones are classified as facial bones in the skull?
Which bones are classified as facial bones in the skull?
What function does the skull primarily serve?
What function does the skull primarily serve?
Which describes the layout of the cranial cavity?
Which describes the layout of the cranial cavity?
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The zygomatic bones are classified as part of which group of skull bones?
The zygomatic bones are classified as part of which group of skull bones?
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Which of the following is NOT a cranial bone?
Which of the following is NOT a cranial bone?
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What is the common term used for the upper part of the cranial cavity?
What is the common term used for the upper part of the cranial cavity?
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Which bone is unique in its presence as a single structure among the cranial bones?
Which bone is unique in its presence as a single structure among the cranial bones?
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What is the primary structural feature that separates the outer and inner lamina of compact bone in the skull?
What is the primary structural feature that separates the outer and inner lamina of compact bone in the skull?
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Which of the following bones are classified as facial bones?
Which of the following bones are classified as facial bones?
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How many parietal bones are present in the human skull?
How many parietal bones are present in the human skull?
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What is the function of the diploe in the skull?
What is the function of the diploe in the skull?
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Which of the following bones is NOT a cranial bone?
Which of the following bones is NOT a cranial bone?
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Which bone forms the structure of the upper jaw?
Which bone forms the structure of the upper jaw?
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What is the total number of bones listed as cranial bones?
What is the total number of bones listed as cranial bones?
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Which structure does the skull primarily protect?
Which structure does the skull primarily protect?
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What is the primary function of the frontal bone in relation to the skull?
What is the primary function of the frontal bone in relation to the skull?
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Which structure articulates with the maxilla to form the anterior nasal aperture?
Which structure articulates with the maxilla to form the anterior nasal aperture?
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Which of the following bones is NOT associated with the lateral wall of the orbit?
Which of the following bones is NOT associated with the lateral wall of the orbit?
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What is the function of the superciliary arch?
What is the function of the superciliary arch?
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What do the two nasal bones form?
What do the two nasal bones form?
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Which foramen is related to the frontal bone?
Which foramen is related to the frontal bone?
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Which bone primarily forms the prominence of the cheek?
Which bone primarily forms the prominence of the cheek?
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What separates the two nasal cavities?
What separates the two nasal cavities?
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Which bones are visible in the superior view of the skull?
Which bones are visible in the superior view of the skull?
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What is the significance of the temporal lines on the skull?
What is the significance of the temporal lines on the skull?
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What is the location of the bregma in the skull?
What is the location of the bregma in the skull?
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Which suture is located between the occipital and parietal bones?
Which suture is located between the occipital and parietal bones?
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What feature does the metopic suture represent in immature skulls?
What feature does the metopic suture represent in immature skulls?
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What marks the position of the lambda on the skull?
What marks the position of the lambda on the skull?
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Which suture separates the frontal bone from the parietal bones?
Which suture separates the frontal bone from the parietal bones?
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Where is the parietal foramen located on the parietal bone?
Where is the parietal foramen located on the parietal bone?
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What bones are involved at the pterion?
What bones are involved at the pterion?
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What clinical consequence can occur if the pterion is traumatized?
What clinical consequence can occur if the pterion is traumatized?
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Where is the temporo-mandibular joint (TMJ) located?
Where is the temporo-mandibular joint (TMJ) located?
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Which structure is deepest to the ramus of the mandible?
Which structure is deepest to the ramus of the mandible?
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What is the function of the middle meningeal vessels?
What is the function of the middle meningeal vessels?
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What is the location of the mastoid process in relation to the external acoustic meatus?
What is the location of the mastoid process in relation to the external acoustic meatus?
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Which structure forms a bony arch between the temporal and zygomatic bones?
Which structure forms a bony arch between the temporal and zygomatic bones?
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What is the function of the styloid process of the temporal bone?
What is the function of the styloid process of the temporal bone?
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Study Notes
Skull Bone Classification
- Skull bones are divided into two categories: facial bones (14 bones) and cranial bones (8 bones).
- Facial bones form the facial skeleton.
- Cranial bones form the cranial cavity, also known as the braincase.
Facial Bones
- The facial skeleton comprises the following bones:
- Zygomatic bones (2): form the cheekbones
- Maxillae (2): form the upper jaw
- Nasal bones (2): form the bridge of the nose
- Lacrimal bones (2): form the medial wall of the orbit
- Vomer (1): forms the lower part of the nasal septum
- Palatine bones (2): form the posterior part of the hard palate
- Inferior conchae (2): form the lateral walls of the nasal cavity
- Mandible (1): forms the lower jaw
Cranial Bones
- The cranial cavity consists of the following bones:
- Frontal bone (1): forms the forehead and anterior part of the cranial vault
- Parietal bones (2): form the sides and roof of the cranial vault
- Occipital bone (1): forms the posterior part of the cranial vault and base of the skull
- Temporal bones (2): form the sides of the skull and house the organs of hearing and balance
- Sphenoid bone (1): forms part of the base of the skull, the orbit, and the middle cranial fossa
- Ethmoid bone (1): forms part of the roof of the nasal cavity, the orbit, and the cribriform plate
Cranial Cavity Structure
- The cranial cavity is composed of two main parts:
- Vault (calvaria): forms the roof and side walls of the cranial cavity
- Cranial base: forms the floor of the cranial cavity
- The vault is composed of two layers of compact bone separated by a layer of spongy bone called diploe (contains red marrow).
Functions of the Skull
- Encloses and protects the brain.
- Forms the skeleton of the upper parts of the alimentary and respiratory systems.
- Provides protection for the organs of sight, hearing, and smell.
- Is intimately related to the teeth and soft tissues of the oral region.
Anterior View of the Skull
- Bones seen in the anterior view: frontal bone, maxillary bones, zygomatic bones, nasal bone, mandible, nasal bones, vomer, inferior concha, zygoma.
- Landmarks:
- Orbital apertures and anterior nasal aperture (piriform aperture)
- Supraorbital margin formed by the frontal bone
- Superciliary arch, a smooth elevation above the supraorbital margin, forms the eyebrow ridge
- Glabella, a slight elevated area above the bridge of the nose
- Supraorbital notch or foramen in the superior orbital margin
- Infraorbital foramen in the lower margin of the orbit
- Mental foramen in the mandible below the apices of the premolars
- Nasal bones form the bridge of the nose
- Anterior nasal aperture formed by the nasal bones and maxillae
- The nasal septum divides the nasal cavity
- Zygomatic bone forms the prominence of the cheek
Superior View of the Skull
- Bones seen in the superior view: frontal bone, parietal bones, occipital bone.
- Landmarks:
- Sagittal suture between the two parietal bones
- Coronal suture between the frontal and parietal bones
- Lambdoid suture between the occipital and parietal bones
- Parietal foramen on the posterior part of the parietal bone
- Frontal (metopic) suture, a median suture in immature skulls that usually fuses during childhood
- Bregma, the junction of the coronal and sagittal sutures, corresponding to the anterior fontanelle on the fetal skull
- Lambda, the junction of the lambdoid and sagittal sutures, corresponding to the posterior fontanelle on the fetal skull
Lateral View of the Skull
- Bones seen in the lateral view: frontal bone, parietal bones, occipital bone, temporal bone, sphenoid bone, zygoma, maxilla, lacrimal bone, nasal bone, mandible.
- Landmarks:
- Temporal lines (superior and inferior)
- Temporal fossa, an area on the lateral wall of the skull
- Infratemporal fossa located below the temporal fossa
- Pterion, an H-shaped suture where the frontal, sphenoid, parietal, and temporal bones meet, crossed internally by the middle meningeal artery and vein
- Temporomandibular joint (TMJ)
- External acoustic meatus, a bony canal leading to the middle ear
- Mastoid process, a bony prominence behind the external acoustic meatus
- Styloid process, a long, slender process projecting downwards from the temporal bone
- Zygomatic arch, a bony arch formed by the articulation of the temporal and zygomatic bones
Clinical Significance of Pterion
- Trauma to the pterion can lead to tearing of the middle meningeal vessels, which lie between the dura mater and the periosteum of the skull.
- This can cause a build-up of blood, resulting in:
- Compression of the brain tissue
- Decrease in level of consciousness
- Untreated hemorrhage may cause death in a few hours.
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Description
Test your knowledge on the classification of skull bones, including facial and cranial bones. Learn about the various bones that make up the facial skeleton and cranial cavity. This quiz covers essential anatomical details important for understanding skull structure.
