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Questions and Answers
Which of the following bones are part of the cranial skeleton?
What are the primary functions of the facial bones?
How many bones comprise the axial skeleton?
What bones articulate with the occipital bone?
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Which cranial bone is shaped like a butterfly and articulates with all other cranial bones?
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What is the primary role of the foramen magnum in the occipital bone?
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Which part of the temporal bone surrounds the external acoustic meatus?
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What is found within the cranial cavity for protection?
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What structures do the cranial bones primarily protect?
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Which cranial bone contains the pituitary gland?
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Which of the following bones are classified as flat bones?
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Which of the following structures is NOT part of the cranium?
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How many facial bones are included in the human skeleton?
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Which of the following best describes the role of sutures in the skull?
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What structure does the cribriform plate form?
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Which bones are classified as unpaired facial bones?
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What is the primary function of the paranasal sinuses?
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What structures are found in the lateral masses of the ethmoid bone?
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Which suture connects the frontal bone to the two parietal bones?
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Which bone forms the lower jaw?
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What do the superior and middle nasal conchae belong to?
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Which bones articulate to form the cheekbone?
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What is the function of the olfactory foramina?
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What does the palatine bone contribute to?
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What is the main portion of the maxillary bone known for?
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Which of the following bones does not articulate with any other bone in the body?
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Which bones are categorized as sutural bones?
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What is the role of the alveolar margin of the mandible?
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Study Notes
Skeleton
- 206 bones in the human skeleton, making up about 20 percent of body weight
- Divided into the axial skeleton and the appendicular skeleton
- Axial skeleton: bones of the skull, vertebral column, and rib cage
- Appendicular skeleton: bones of the upper and lower limbs, pectoral and pelvic girdles
###Â Axial Skeleton
- 80 bones
- Most complex part of human anatomy
Skull
- 22 bones, divided into the cranial and facial bones
- Most skull bones are flat bones, with the exception of the mandible
- Bones are joined together by sutures
- Facial bones form the anterior part of the skull, cranial bones form the rest
- Has eye orbits and paranasal sinuses, houses the organs of hearing and balance
- It has 85 openings for nerves, blood vessels, and the spinal cord
Cranium
- Can be divided into a vault and a base:
- Vault: forms the superior, lateral, and posterior aspects of the skull, and the forehead
- Base: inferior aspect of the skull
- Surrounds and protects the brain, the organs of hearing, and balance
- Three bony ridges internally divide the cranial base into three areas: the anterior (highest) fossa, middle fossa, and posterior (lowest) fossa
Facial Bones
- Form the framework of the face
- Contain cavities for vision, smell, and taste
- Provide openings for passage of air and food
- Secure the teeth
- Anchor the muscles of the face
Cranial Bones
- Eight cranial bones: the paired parietal and temporal bones, and the unpaired frontal, occipital, sphenoid, and ethmoid bones
- Curvature allows for self-bracing, making them strong despite being thin
Frontal Bone
- Dome-shaped bone, forms the roof of the orbits and contributes to the anterior cranial fossa
- Articulates with the paired parietal bones posteriorly
- Notable features: supraorbital margin, supraorbital foramen, and glabella
- Left and right frontal sinuses are lateral to the glabella
Parietal Bones
- Paired bones, forming the superior and lateral aspects of the skull
- Form the bulk of the cranial vault
Occipital Bone
- Single bone at the base of the skull, helping to form the posterior aspect of the skull and the walls of the posterior cranial fossa
- Attaches anteriorly to the two parietals and the two temporals, and attaches to the sphenoid
- Has the foramen magnum: a passage for the spinal cord
- Occipital condyles on each side of the foramen magnum form the site of articulation with the first cervical vertebra
- External occipital protuberance is a projection at the back of the skull, more prominent in males
Temporal Bones
- Paired bones, form the inferior and lateral aspects of the skull and parts of the cranial floor
- Located just below the two parietal bones, with three regions:
- Squamous part: flattened, forms the zygomatic process to the cheekbone, mandibular fossa receives the condyle of the mandible
- Tympanic part: surrounds the external acoustic meatus
- Petrous part: on the internal aspect of the temporal bone, contributes to the cranial base, houses the middle and inner ear cavities
- Â Mastoid process: attachment site for some neck muscles
- Styloid process: attachment area for tongue muscles and some neck muscles
- Several important foramina: jugular foramen, carotid canal, and internal acoustic meatus
Sphenoid Bone
- Complex bone, articulates with all other cranial bones
- Forms the base of the middle cranial fossa and contributes to the base of the anterior cranial fossa
- Central body contains sphenoid sinuses
- Three projections:
- Greater and lesser wings: orbits, middle cranial fossa and anterior cranial fossa
- Pterygoid processes: for muscles
- Optic foramina: canals for optic nerves
- Â Superior orbital fissure: between greater and lesser wings, cranial nerves for eye movement
Ethmoid Bone
- Cube-shaped bone, located between the orbits and the nasal cavities
- Â Cribriform plate forms the roof of the nasal cavity and the floor of the anterior cranial fossa, tiny holes (olfactory foramina) transmit olfactory nerves
- Perpendicular plate projects inferiorly to contribute to the nasal septum
- Â Crista galli projects superiorly to attach to the dura mater of the brain
- Lateral masses contain ethmoid sinuses
- Â Superior and middle nasal conchae are located medially
- Â Orbital plates are located laterally, contributing to the medial walls of the orbits
Major Cranial Sutures
- Four main sutures connecting the cranial bones:
- Coronal suture: frontal bone and two parietal bones
- Squamous suture: parietal bone and temporal bone -Â Lambdoid suture: occipital bone and two parietal bones
- Sagittal suture: two parietal bones
- Sutural bones: tiny irregular bones, can occur within cranial sutures, additional ossification centers that appeared rapidly during fetal development
Facial Bones
- 14 bones, mandible and vomer are unpaired
- Paired bones: maxillae, zygomatic, nasal, lacrimal, palatine, and inferior conchae
Mandible
- Lower jawbone, strongest and largest bone of the face
- Body is the horizontal part containing the chin, left and right rami join the body at the mandibular angle
- Notable features: mandibular notch, coronoid process (insertion of temporalis muscle), mandibular condyle, alveolar margin (contains tooth sockets), mandibular foramina (nerves to teeth in lower jaw), and mental foramina (blood vessels and nerves to chin and lower lip)
Maxillary Bones
- Fused medially
- Alveolar margins hold teeth of the upper jaw
- Palatine processes project posteriorly forming the anterior two-thirds of the hard palate
- Notable features: incisive fossa (passage of blood vessels and nerves), frontal processes, and zygomatic processes
- Maxillary sinus is located on each side of the main portion of the bone - often gets infected
Zygomatic Bones
- Cheekbones
- Articulate with the zygomatic processes of the maxilla, frontal, and temporal bones
- Contribute to the inferolateral margins of the orbit
Nasal Bones
- Two tiny rectangular bones that fuse medially to form the bridge of the nose
- Articulate with the frontal bone superiorly and the maxillary bones laterally
Lacrimal Bones
- Two fingernail-shaped bones in the anterior, medial portion of the orbit
- Articulate with:
- Frontal bone -Â Ethmoid bone
- Maxillae
- Contains a depression (lacrimal fossa) for the lacrimal sac
Orbits
- The bones of the orbits are:
- Zygomatic
- Frontal
- Maxilla
- Ethmoid
- Lacrimal
- Sphenoid
- Palatine (orbital process)
Palatine Bones
- Two L-shaped bones
- Horizontal plates form part of the hard palate
- Vertical plates form the nasal cavity and orbit
Vomer
- Single thin bone that forms the nasal septum
Inferior Nasal Conchae
- Thin curved bones that project medially
- Largest of the three pairs of conchae
Paranasal Sinuses
- Frontal
- Â Maxillary
- Â Sphenoid
- Ethmoid
- These are mucosa-lined, air-filled cavities
- They lighten the skull and enhance the resonance of the voice
- Â Connect to the nasal cavity, which helps to warm and humidify the incoming air
Hyoid Bone
-  Only bone of the body that does not articulate with any other bone
- Â Supports the tongue and gives attachment to muscles for swallowing and speech
- Â Horseshoe-shaped with a body and two pairs of horns
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Description
Explore the intricate structure of the human skeleton, which comprises 206 bones divided into the axial and appendicular skeletons. This quiz will take you through the components of the axial skeleton, including detailed insights into the skull and cranium's anatomy. Test your knowledge of these essential aspects of human anatomy!
