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Questions and Answers
Which part of the skull is known as the neurocranium?
Which part of the skull is known as the neurocranium?
What is the primary function of the axial skeleton?
What is the primary function of the axial skeleton?
Which bones are considered part of the viscerocranium?
Which bones are considered part of the viscerocranium?
Which structure does not belong to the axial skeleton?
Which structure does not belong to the axial skeleton?
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What is the role of the vertebral column within the axial skeleton?
What is the role of the vertebral column within the axial skeleton?
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Which of the following bones is located in the pectoral girdle?
Which of the following bones is located in the pectoral girdle?
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What feature is commonly associated with the thoracic cage?
What feature is commonly associated with the thoracic cage?
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Which of the following structures does the pectoral girdle articulate with?
Which of the following structures does the pectoral girdle articulate with?
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What is the primary feature of the appendicular skeleton?
What is the primary feature of the appendicular skeleton?
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Which component is included in the axial skeleton?
Which component is included in the axial skeleton?
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What is the typical number of bones in an adult human skeleton?
What is the typical number of bones in an adult human skeleton?
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Which bone forms part of the medial wall of the orbit?
Which bone forms part of the medial wall of the orbit?
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What feature is associated with the ischium in the pelvic girdle?
What feature is associated with the ischium in the pelvic girdle?
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Which bone is described as having a dome-like roof in the skull?
Which bone is described as having a dome-like roof in the skull?
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Which part of the skull houses the pituitary gland?
Which part of the skull houses the pituitary gland?
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Which of the following bones contributes to forming the upper jaw?
Which of the following bones contributes to forming the upper jaw?
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What is the significance of alveolar sockets in the skull?
What is the significance of alveolar sockets in the skull?
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Which suture is located at the junction of the two parietal bones?
Which suture is located at the junction of the two parietal bones?
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Where is the foramen rotundum located, and what does it transmit?
Where is the foramen rotundum located, and what does it transmit?
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What is the primary function of the lacrimal sac?
What is the primary function of the lacrimal sac?
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Which bone forms the inferomedial wall of the orbit?
Which bone forms the inferomedial wall of the orbit?
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Which of the following structures is known to project into the nasal cavity?
Which of the following structures is known to project into the nasal cavity?
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What is the role of the foramen spinosum in the skull?
What is the role of the foramen spinosum in the skull?
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What structure protects the pituitary gland and is situated in the skull base?
What structure protects the pituitary gland and is situated in the skull base?
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What is the shape of the largest fontanel in an infant's skull?
What is the shape of the largest fontanel in an infant's skull?
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At what age does the bregma fontanel typically fuse?
At what age does the bregma fontanel typically fuse?
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Which structure serves as a passageway for the carotid artery?
Which structure serves as a passageway for the carotid artery?
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What is the term used to describe the space between unfused cranial bones in infants?
What is the term used to describe the space between unfused cranial bones in infants?
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Which of the following bones does NOT contribute to the cranial vault?
Which of the following bones does NOT contribute to the cranial vault?
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What are the paired bones of the neurocranium?
What are the paired bones of the neurocranium?
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Which fontanel is bounded by occipital and parietal bones?
Which fontanel is bounded by occipital and parietal bones?
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What is the primary function of cranial bones?
What is the primary function of cranial bones?
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What aligns with the occipital condyles to hold the spinal cord?
What aligns with the occipital condyles to hold the spinal cord?
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Which of the following best describes the cranial cavity?
Which of the following best describes the cranial cavity?
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What happens to the fontanels as a child grows?
What happens to the fontanels as a child grows?
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What is the shape of the fontanel that fuses at 6-8 months of age?
What is the shape of the fontanel that fuses at 6-8 months of age?
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Which bone forms part of the cheekbone structure?
Which bone forms part of the cheekbone structure?
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What part of the skull assists in forming the forehead?
What part of the skull assists in forming the forehead?
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Study Notes
Regions of the Skeleton
- Axial Skeleton: The central axis of the body, consisting of the skull, vertebral column, ribs, sternum, and sacrum
- Appendicular Skeleton: Limbs and girdles, including the pectoral girdle (shoulder) and pelvic girdle (hip)
- Skull: Consists of two parts: neurocranium (cranial vault), which protects the brain; and viscerocranium (facial bones)
Features of the Skull
- Neurocranium: Consists of 8 bones that form the protective shell of the brain
- Viscerocranium: Consists of 14 bones including facial bones, which support the eyes, nose, and mouth
Features of the Vertebral Column and Thoracic Cage
- Vertebral Column: Supports the trunk and protects the spinal cord
- Thoracic Cage: Protects the heart and lungs, and serves as a point of attachment for skeletal muscles
Features of the Pectoral Girdle
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Pectoral Girdle: Supports the upper limbs and connects them to the axial skeleton
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Consists of two bones: clavicle (collar bone) and scapula (shoulder blade)### Cranium
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The cranium is formed by eight bones, which are fused together in adults.
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These bones develop from cartilage and are called "chondrocranium"
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They enclose and protect the brain.
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The bones of the cranium can be classified as flat:
- Coronal
- Sagittal
- Lambdoid
- Squamous
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The cranium is made up of a roof (calvaria) and a floor (cranial base).
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The roof is formed by the frontal, parietal, and occipital bones.
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The floor is formed by the sphenoid and ethmoid bones.
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The sphenoid bone is the largest and most complex bone of the cranium.
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It is situated in the middle of the cranial base.
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It forms part of the orbit and the floor of the cranial cavity.
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The ethmoid bone is a light and porous bone that forms part of the roof of the nasal cavity and the medial wall of the orbit.
Facial Skeleton
- Also referred to as the viscerocranium
- Formed by 14 bones, providing structure for facial features.
- The maxilla (upper jaw) is the largest bone of the facial skeleton.
- It forms the upper part of the mouth.
- The mandible (lower jaw) is the strongest bone of the face, and is the only movable bone.
- It forms the lower part of the mouth.
- The zygomatic bone forms the cheekbone and part of the orbit (eye socket).
- The lacrimal bone is located in the medial wall of the orbit, housing the lacrimal sac which collects and drains tears into the nasal cavity.
The Pectoral Girdle
- Composed of two bones:
- Clavicle (collarbone)
- Scapula (shoulder blade)
The Pelvic Girdle
- Composed of two bones:
- Ilium
- Ischium
- Pubis
- The two hip bones meet at the symphysis pubis
- The sacrum is a wedge-shaped bone that forms the back of the pelvic girdle
- The coccyx is a small, triangular bone that forms the tailbone.
Upper Limb Bones
- Composed of 30 bones in each limb
- Bones of the arm:
- Humerus
- Bones of the forearm:
- Radius
- Ulna
- Bones of the wrist:
- Carpals (8 total)
- Bones of the hand:
- Metacarpals (5 total)
- Phalanges (14 total)
Lower Limb Bones
- Composed of 30 bones in each limb
- Bones of the thigh:
- Femur
- Bones of the leg:
- Tibia
- Fibula
- Bones of the ankle:
- Tarsals (7 total)
- Bones of the foot:
- Metatarsals (5 total)
- Phalanges (14 total)
Neurocranium
- Formed by 10 bones: 4 single bones, 3 paired bones
- 8 bones in contact with meninges (membranes)
- Bony case of the brain and spinal cord
- Cranial vault is the dome-like roof
- Cranial base is the floor
- 3 basins comprising the cranial floor:
- anterior fossa: holds the frontal lobe of the brain
- middle fossa: holds the temporal lobes of the brain
- posterior fossa: contains the cerebellum
- Swelling of the brain can force tissue through foramen magnum resulting in death
The Skull
- Consists of 22 bones joined together by sutures
- Cranial bones surround the cranial cavity
- 8 bones are in contact with the brain and spinal cord
- Calvaria (skullcap) forms the roof and walls
- Viscerocranium comprises the 14 bones that do not have direct contact with the brain
Frontal Bone
- Forms the forehead and part of the roof of the cranium
- Contains frontal sinuses
- Forms the roof of the orbit
Parietal Bone
- Forms the roof and part of the lateral wall of the cranium
- Forms part of the roof of the orbit
Occipital Bone
- Rear and base of the skull
- Foramen magnum holds the spinal cord
- Occipital condyles articulate with the atlas (C1)
- External occipital protuberance for nuchal ligament
Temporal Bone
- Lateral wall and part of the floor of the cranial cavity
- Contains the external auditory meatus (ear canal)
- Temporal lines mark the temporalis muscle
- Mandibular fossa and TMJ (temporomandibular joint)
- Contains temporal sinuses
Openings in Temporal Bone
- Carotid canal: passage for internal carotid artery supplying the brian
- Jugular foramen: irregular opening between temporal and occipital bones for drainage of blood from the brain to the internal jugular vein
- Hypoglossal canal: transmits hypoglossal nerve (CN XII) supplying tongue muscles
Sphenoid Bone
- Forms part of the base of the skull
- Body of the sphenoid: houses the pituitary gland
- Lesser wing contains the optic foramen
- Greater wing contains the foramen rotundum and ovale for the trigeminal nerve
- Foramen spinosum for meningeal artery
Ethmoid Bone
- Located behind the incisors (front teeth)
- Cribriform plate and crista galli
- Forms part of the nasal septum and roof and walls of the nasal cavity
- Forms the lateral walls and roof of the nasal cavity
- Ethmoid air cells (sinuses) form ethmoid sinus
Maxillary Bone
- Forms the upper jaw
- Alveolar processes: bony points between teeth
- Alveolar sockets hold teeth
- Palatine processes meet at the intermaxillary suture
- Failure to join causes cleft palate
- Infraorbital foramen
- Forms the inferomedial wall of the orbit
- Forms the anterior 2/3’s of the hard palate
Palatine Bone
- L-shaped bone
- Forms the posterior 1/3 of the hard palate
- Part of the lateral nasal wall
- Part of the orbital floor
Zygomatic Bone
- Forms the angles of the cheekbones and part of lateral orbital wall
- Forms the zygomatic arch with the temporal bone
- Contains zygomatic sinuses
Lacrimal Bone
- Forms part of the medial wall of each orbit
- Lacrimal fossa houses the lacrimal sac
Nasal Bone
- Forms the bridge of the nose and supports nasal cartilages
Inferior Nasal Conchae
- Separates bone, not part of the ethmoid
- Forms the inferior half of the nasal septum
- Supports cartilage of the nasal septum
Vomer
- A separate bone
- Supports cartilage of the nasal septum
Mandible
- Only movable bone of the skull
- Holds the lower teeth
- Forms the jaw joint between the mandibular fossa and condyloid process
- Attachment of muscles of mastication:
- temporalis muscle: onto the coronoid process
- masseter muscle: onto the angle of the mandible
- Mandibular foramen
Fontanels
- Spaces between unfused brain bones called "fontanels"
- Filled with fibrous membrane
- Allow shifting of bones during birth and growth of the brain
- Anterior Fontanelle: largest, diamond shape; bounded by halves of frontal & parietal bones; fused at 18 months of age; becomes 'bregma'
- Posterior Fontanelle: small, triangular shape; bounded by parietal and occipital bones; fused at 6-8 months of age; becomes 'lambda'
Locations of Paranasal Sinuses
- Maxillary sinus fills the maxillae bone
- Frontal, ethmoid, and sphenoid bones also contain sinuses
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Description
This quiz covers the major regions and features of the human skeleton, including the axial and appendicular skeletons, the skull, vertebral column, thoracic cage, and pectoral girdle. Test your understanding of the bones and their functions within the skeletal system.
