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Questions and Answers
What is one primary function of the skeletal system?
What is one primary function of the skeletal system?
Osteocytes are immature bone cells that help with the initial formation of bone.
Osteocytes are immature bone cells that help with the initial formation of bone.
False
What is contained within the central (Haversian) canal of an osteon?
What is contained within the central (Haversian) canal of an osteon?
Blood vessels, nerves, and lymphatic tissue
The ______ are tiny channels that connect lacunae to each other and to the central canal.
The ______ are tiny channels that connect lacunae to each other and to the central canal.
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Which structure is responsible for maintaining bone density and mineral content?
Which structure is responsible for maintaining bone density and mineral content?
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Match the following structures of the osteon with their functions:
Match the following structures of the osteon with their functions:
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Trabeculae are found in compact bone and provide structural support.
Trabeculae are found in compact bone and provide structural support.
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Name one way that bones respond to mechanical stress.
Name one way that bones respond to mechanical stress.
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What is the primary function of osteoblasts?
What is the primary function of osteoblasts?
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Osteoclasts are responsible for building new bone tissue.
Osteoclasts are responsible for building new bone tissue.
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What type of bone tissue is found at the ends of long bones?
What type of bone tissue is found at the ends of long bones?
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The cytoplasmic extensions of osteocytes allow for ______ with neighboring cells.
The cytoplasmic extensions of osteocytes allow for ______ with neighboring cells.
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Match the following types of bone marrow with their primary function:
Match the following types of bone marrow with their primary function:
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Which cell type is primarily responsible for sensing mechanical stress in bones?
Which cell type is primarily responsible for sensing mechanical stress in bones?
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Can yellow bone marrow be converted back into red bone marrow?
Can yellow bone marrow be converted back into red bone marrow?
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Name one area in the skeleton where spongy bone tissue is found.
Name one area in the skeleton where spongy bone tissue is found.
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The layer of bone that provides strength and structural support is called ______.
The layer of bone that provides strength and structural support is called ______.
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What connects the osteocytes in spongy bone to their nutrients?
What connects the osteocytes in spongy bone to their nutrients?
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The periosteum is involved in growth and repair of bone.
The periosteum is involved in growth and repair of bone.
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What is the function of osteoclasts?
What is the function of osteoclasts?
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The ______ of long bones is cylindrical and provides structural support.
The ______ of long bones is cylindrical and provides structural support.
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Match the following structures of long bones to their descriptions:
Match the following structures of long bones to their descriptions:
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What is the primary function of the medullary cavity?
What is the primary function of the medullary cavity?
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The epiphyseal line indicates that bone growth has just begun.
The epiphyseal line indicates that bone growth has just begun.
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List one function of the skeletal system.
List one function of the skeletal system.
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The axial skeleton includes the skull, __________, sternum, ribs, and hyoid bone.
The axial skeleton includes the skull, __________, sternum, ribs, and hyoid bone.
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Match each cranial bone to its function:
Match each cranial bone to its function:
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Which of the following is NOT a bone marking?
Which of the following is NOT a bone marking?
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The cranial bones consist of eight bones including the frontal and parietal bones.
The cranial bones consist of eight bones including the frontal and parietal bones.
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What is the function of the foramen magnum?
What is the function of the foramen magnum?
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The passage of nerves and blood vessels through bone occurs via __________.
The passage of nerves and blood vessels through bone occurs via __________.
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Which bone is known for having a large opening that facilitates the connection between the brain and spinal cord?
Which bone is known for having a large opening that facilitates the connection between the brain and spinal cord?
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The glenoid fossa serves as an attachment point for muscles.
The glenoid fossa serves as an attachment point for muscles.
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What type of cartilage is found in the epiphyseal plate?
What type of cartilage is found in the epiphyseal plate?
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The __________ is the bony projection that serves as an attachment point for the falx cerebri.
The __________ is the bony projection that serves as an attachment point for the falx cerebri.
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Which of the following structures is associated with the auditory system?
Which of the following structures is associated with the auditory system?
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Match the following markings to their descriptions:
Match the following markings to their descriptions:
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What is the primary function of the spinous process of a vertebra?
What is the primary function of the spinous process of a vertebra?
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The atlas vertebra has a body and spinous process.
The atlas vertebra has a body and spinous process.
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Which two vertebrae allow you to shake your head 'no'?
Which two vertebrae allow you to shake your head 'no'?
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The thoracic vertebrae can be identified by their facets for _____ articulation.
The thoracic vertebrae can be identified by their facets for _____ articulation.
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Match the following regions of the vertebral column with their descriptions:
Match the following regions of the vertebral column with their descriptions:
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What is the structural characteristic of lumbar vertebrae?
What is the structural characteristic of lumbar vertebrae?
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The coccyx is formed by the fusion of four to five bones.
The coccyx is formed by the fusion of four to five bones.
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What type of tissue forms the costal cartilages?
What type of tissue forms the costal cartilages?
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The _____ is a part of the sternum that typically fuses to the body by age 25.
The _____ is a part of the sternum that typically fuses to the body by age 25.
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Which statement is true regarding true ribs?
Which statement is true regarding true ribs?
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What is the primary function of the mandibular fossa?
What is the primary function of the mandibular fossa?
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The vomer bone is part of the nasal cavity and forms the superior part of the nasal septum.
The vomer bone is part of the nasal cavity and forms the superior part of the nasal septum.
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Which bone contributes to the formation of the hard palate?
Which bone contributes to the formation of the hard palate?
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The ______ bone forms the bridge of the nose.
The ______ bone forms the bridge of the nose.
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Match the following bones with their descriptions:
Match the following bones with their descriptions:
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Which bone is NOT part of the bony wall of the orbits?
Which bone is NOT part of the bony wall of the orbits?
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The temporal bone contributes to the zygomatic arch.
The temporal bone contributes to the zygomatic arch.
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What are the primary functions of the facial bones?
What are the primary functions of the facial bones?
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The ______ process is a rounded projection at the top of the mandible.
The ______ process is a rounded projection at the top of the mandible.
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Match the following facial bones with their functions:
Match the following facial bones with their functions:
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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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The inferior nasal concha is flat and located in the upper part of the nasal cavity.
The inferior nasal concha is flat and located in the upper part of the nasal cavity.
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What bones make up the nasal septum?
What bones make up the nasal septum?
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The _____ bone contributes to the back of the orbit.
The _____ bone contributes to the back of the orbit.
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What function does the external auditory meatus serve?
What function does the external auditory meatus serve?
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Which of the following bones in the skull is movable?
Which of the following bones in the skull is movable?
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The maxilla is fully movable.
The maxilla is fully movable.
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Name the four main sutures of the skull.
Name the four main sutures of the skull.
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The __________ is the smallest ossicle in the middle ear.
The __________ is the smallest ossicle in the middle ear.
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Match the following fontanels with their descriptions:
Match the following fontanels with their descriptions:
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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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Fontanels in a newborn skull are fully ossified at birth.
Fontanels in a newborn skull are fully ossified at birth.
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What is the primary function of the paranasal sinuses?
What is the primary function of the paranasal sinuses?
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The __________ bone does not articulate with any other bones in the body.
The __________ bone does not articulate with any other bones in the body.
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What connects the malleus to the incus in the middle ear?
What connects the malleus to the incus in the middle ear?
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The body of a vertebra provides stability to the spine.
The body of a vertebra provides stability to the spine.
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How do intervertebral discs assist the spine?
How do intervertebral discs assist the spine?
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The __________ process of a vertebra serves as an attachment point for muscles.
The __________ process of a vertebra serves as an attachment point for muscles.
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Match the bones with their functions:
Match the bones with their functions:
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Study Notes
Principle Functions of the Skeletal System
- Supports the weight of the body
- Works with muscles to maintain posture and produce controlled movements
- Involved in mineral and lipid storage
- Site of blood cell production
- Undergoes extensive remodeling throughout life
Microscopic Structures of Compact Bone
- Compact bone is dense and organized into osteons
- The main structures of an osteon are:
- Central (Haversian) canal: Contains blood vessels, nerves, and lymphatic tissue, providing nutrients and signaling to bone cells
- Lacunae: Small cavities within bone that hold osteocytes
- Osteocytes: Mature bone cells that live within the lacunae and maintain bone tissue
- Concentric lamellae: Layers of mineralized matrix surrounding the central canal, providing structural support and strength.
- Canaliculi: Tiny channels that connect lacunae to each other and to the central canal, allowing for nutrient exchange and communication between osteocytes.
Osteocytes, Osteoblasts and Osteoclasts
- Osteoblasts: Bone-building cells that produce and mineralize new bone matrix
- Osteocytes: Mature bone cells that come from osteoblasts, maintain bone tissue, and communicate with other bone cells to regulate bone density.
- Osteoclasts: Bone-resorbing cells that break down old or damaged bone tissue.
- Collaboration: These cells work together to maintain bone density and strength by balancing bone formation and resorption.
Function of Osteocyte Cytoplasmic Extensions
- Connect osteocytes with neighboring osteocytes and other bone cells, facilitating communication and information sharing.
- Facilitate nutrient exchange, oxygen, and waste products between osteocytes and surrounding bone tissue.
- Help to sense mechanical stress or strain on the bone and signal the need for remodeling.
### Macroscopic Structures of Long Bones
- Long bones have a diaphysis (shaft) and two epiphyses (ends)
- Diaphysis: Composed primarily of compact bone and contains the medullary cavity, which holds yellow marrow
- Epiphyses: Contain spongy bone and red marrow, reducing friction at joints.
- Periosteum: A dense connective tissue covering the bone, serving as attachment points for tendons and ligaments and involved in growth and repair
- Endosteum: A thin membrane lining the medullary cavity, involved in bone growth, repair, and remodeling.
### Spongy Bone
- Found in the ends of long bones, vertebrae, and pelvic bones
- Trabeculae are thin, bony plates that provide structural support and distribute forces throughout the bone.
- Osteocytes in spongy bone obtain nutrients and oxygen through canaliculi that connect them to the blood vessels in the surrounding bone marrow.
Red Bone Marrow vs. Yellow Bone Marrow
- Red bone marrow: Found in the spongy bone of certain bones, contains hematopoietic cells that produce red blood cells, white blood cells, and platelets
- Yellow bone marrow: Found in the medullary cavity of long bones, primarily composed of adipose tissue and serves as an energy reserve.
- Yellow bone marrow can convert back to red bone marrow in cases of severe blood loss or increased demand for blood cell production
Adult Bones Containing Red Bone Marrow
- Pelvic Bones (Ilium)
- Sternum
- Ribs
- Vertebrae (spinal bones)
### Structures of a Long Bone
- Epiphysis: Ends of the long bone. The proximal epiphysis is closest to the body trunk, the distal epiphysis is furthest from the body trunk
- Diaphysis: Long, cylindrical main portion Provides structural support and strength.
- Periosteum: Dense connective tissue covering the bone.
- Endosteum: Thin membrane lining the medullary cavity.
- Medullary (marrow) Cavity: Central cavity within the diaphysis.
- Epiphyseal line or plate: Hyaline cartilage layer that allows for bone growth during childhood and becomes a line when growth stops.
### Functions of the Skeletal System
- Support: Provides structural support for the body.
- Protection: Protects internal organs.
- Movement: Works with muscles to produce movement.
- Mineral storage: Stores minerals (calcium and phosphorus) that are essential for many bodily functions.
### Axial vs. Appendicular Skeleton
- Axial Skeleton: Includes the skull, vertebrae, sternum, ribs, and hyoid bone. Provides framework for the appendicular skeleton and protects vital organs.
- **Appendicular Skeleton: ** Includes the pectoral girdle, pelvic girdle, upper and lower limbs
### Bone Surface Markings
- Foramen/Foramina: Openings or holes in a bone that allow for the passage of nerves, blood vessels, and ligaments.
- Fossa: Shallow basin-like depression that serves as an attachment point for muscles or forms joints with other bones.
- Meatus: Canal-like passageway within a bone.
- Process: A projection or bump that provides attachment points for muscles, tendons, and ligaments.
- Condyle: A rounded, knuckle-like projection at the end of a bone that forms joints.
- Crest: A narrow, ridge-like projection that serves as an attachment point for muscles or ligaments.
- Facet: A smooth, flat surface that forms joints with other bones.
- Head: A rounded, prominent end of a bone that forms joints.
### Cranial Bones and Features
-
Frontal Bone: Forms the forehead and the upper part of the eye sockets.
- Supraorbital foramen: A small opening above the eye socket that allows for the passage of the supraorbital nerve and blood vessels.
-
Ethmoid Bone: Forms part of the nasal cavity and the orbits.
- Crista galli: A bony projection that serves as an attachment point for the falx cerebri.
- Cribriform plate: A horizontal plate with small holes that allows for the passage of olfactory nerves.
- Perpendicular plate: Forms the superior part of the nasal septum.
- Olfactory foramina: Tiny openings in the cribriform plate that allow olfactory nerve fibers to pass through.
-
Occipital Bone: Forms the back and base of the skull.
- Occipital condyle: Rounded projections that articulate with the first cervical vertebra
- Foramen magnum: A large opening at the base of the skull through which the spinal cord passes.
-
Sphenoid Bone: Located at the base of the skull.
- Optic foramen: A small opening that allows the optic nerve to pass from the eye to the brain.
- Parietal Bones: Form the sides and roof of the skull.
-
Temporal Bones: Form the sides and base of the skull.
- Mandibular fossa: A depression that forms the socket for the mandibular condyle.
- Styloid process: A slender projection serving as an attachment point for muscles and ligaments.
- Mastoid process: A bony prominence that serves as an attachment point for neck muscles and contains air spaces that help in sound conduction.
- External auditory meatus: The ear canal.
Facial Bones and Features
-
Mandible: The lower jawbone.
- Condylar process: A rounded projection that articulates with the temporal bone.
-
Maxilla: The upper jawbones.
- Infraorbital foramen: A small opening below the eye socket that allows passage of the infraorbital nerve and blood vessels.
- Palatine process: Forms the anterior part of the hard palate.
- Zygomatic bone: Forms the cheekbone.
- Palatine bones: L-shaped bones located at the back of the oral cavity, forming part of the hard palate and the floor of the nasal cavity.
- Vomer: A thin, flat bone forming the lower part of the nasal septum.
- Inferior nasal concha: Curved bones located in the nasal cavity, increasing surface area to warm and humidify air.
- Nasal Bones: Form the bridge of the nose.
- Lacrimal Bones: Located in the medial wall of the eye socket.
### Bones Forming the Orbits
- Frontal Bone
- Sphenoid Bone
- Zygomatic Bone
- Maxilla
- Ethmoid Bone
- Lacrimal Bone
- Palatine Bone
### Unpaired Cranial and Facial Bones
- Frontal Bone
- Occipital Bone
- Sphenoid Bone
- Ethmoid Bone
- Mandible
- Vomer
Bones Forming the Hard Palate
- Maxilla
- Palatine Bones
Bones Forming the Nasal Septum
- Vomer
- Perpendicular Plate of the Ethmoid Bone
### Bones Forming the Zygomatic Arch
- Zygomatic Bone
- Temporal Bone
### Functions of Facial Bones
- Support and Structure: Provide shape and support for the face.
- Protection: Help protect the delicate structures of the face.
- Articulation: Facilitate the movement of the jaw and support the teeth.
### Fontanels in the Fetal Skull
- Soft spots in the fetal skull
- Allow for the skull to deform during birth and the brain to grow
- Typically close up within the first 18 months of life.
### Features of a Typical Vertebra
- Body: The thick, anterior portion that supports weight
- Vertebral arch: Forms the posterior portion of the vertebra and encloses the vertebral foramen
- Vertebral foramen: Opening through which the spinal cord passes
- Spinous process: A bony projection that extends posteriorly from the vertebral arch
- Transverse processes: Bony projections that extend laterally from the vertebral arch
- Superior and inferior articular processes: Joints that connect one vertebra to the next.
### Vertebrae of the Spinal Column
-
Cervical vertebrae: 7 bones in the neck
- Atlas (C1): Articulates with the skull, allowing for head nodding
- Axis (C2): Contains the dens, a tooth-like projection that allows for head rotation
-
Thoracic vertebrae: 12 bones in the chest
- Have articular facets for rib attachment
-
Lumbar vertebrae: 5 bones in the lower back
- Larger bodies to support more weight
- Sacrum: 5 fused vertebrae
- Coccyx: 4 fused vertebrae
The Sternum
- Manubrium: Uppermost portion
- Body: Middle portion
- Xiphoid process: Small, pointed projection at the bottom
Types of Ribs
- True ribs: First 7 pairs - attach directly to the sternum
- False ribs: 8th -10th pairs - attach indirectly to the sternum
- Floating ribs: Last 2 pairs - do not attach to the sternum
Facial Bones and Their Functions
- Airway and Sinus Function: Facial bones contribute to the nasal cavity and paranasal sinuses, essential for breathing and voice resonance.
- Muscle Attachment: Facial bones serve as attachment points for muscles responsible for facial expressions and movements.
- Movable Bone in the Skull: The mandible is the only movable bone in the skull, forming the temporomandibular joint with the temporal bone.
- Maxilla's Role in Chewing: The maxilla, though primarily fixed, assists in mandible movement during chewing by providing a stable structure for teeth occlusion.
Sutures: Immovable Joints of the Skull
- Coronal Suture: Separates the frontal bone from the parietal bones, located at the front of the skull.
- Sagittal Suture: Runs along the midline of the skull, separating the parietal bones.
- Lambdoid Suture: Forms the boundary between the parietal bones and the occipital bone, resembling an inverted "V."
- Squamous Suture: Connects the temporal bone to the parietal bone on the sides of the skull, characterized by a curved shape.
The Fetal Skull: Fontanels and Sutures
- Fontanels: "Soft spots" in the newborn skull where ossification is incomplete, allowing for skull compression during birth and brain growth.
- Anterior Fontanel: Largest fontanel, diamond-shaped, located at the junction of frontal and parietal bones.
- Posterior Fontanel: Smaller, triangular fontanel, located at the junction of parietal and occipital bones.
- Anterolateral Fontanel (Sphenoidal): Located on the sides of the head, at the junction of frontal, parietal, temporal, and sphenoid bones
- Posterolateral Fontanel (Mastoid): Located at the junction of parietal, occipital, and temporal bones on the sides and back of the head.
- Frontal Suture: Usually fuses and disappears by the age of six.
Paranasal Sinuses: Functions and Location
- Location: Found in the frontal, sphenoidal, ethmoidal, and maxillary bones.
-
Functions:
- Weight Reduction: Air-filled cavities lighten the skull, making it easier to support.
- Resonance and Sound Production: Contribute to voice resonance, enhancing sound quality during speech.
Hyoid Bone: Unique Features
- Attachment: Does not articulate with any other bones but is suspended from the styloid process of the temporal bone by muscles and ligaments.
- Muscle Attachment: The geniohyoid is an important muscle attached to the hyoid bone.
Ossicles of the Middle Ear: Structure and Function
- Malleus (Hammer): First ossicle, connected to the eardrum, transmits sound vibrations to the incus.
- Incus (Anvil): Middle ossicle, located between malleus and stapes, acts as a lever to transfer vibrations to the stapes.
- Stapes (Stirrup): Smallest ossicle, connected to the oval window of the cochlea, transmits vibrations from the incus to the inner ear, amplifying sound.
The Vertebral Column: Structure and Functions
- Structure: Composed of vertebrae, intervertebral discs, and spinal nerves.
- Functions: Supports the head, protects the spinal cord, provides attachment points for muscles.
- Intervertebral Discs: Made of fibrocartilage, cushion and absorb shocks between vertebrae.
- Vertebral Foramina: Holes between vertebrae that allow spinal nerves to exit the vertebral column.
Vertebrae: Parts and Functions
- Body/Centrum (Vertebral Body): Thick, cylindrical front part, provides weight-bearing support.
- Vertebral Foramen: Large hole in the center, forms the vertebral canal for the spinal cord.
- Transverse Processes: Lateral projections, attachment points for muscles and ligaments.
- Spinous Process: Posterior projection, attachment point for muscles and ligaments, protects the spinal cord.
- Superior Articular Process: Upward projection, forms joints with the vertebra above.
- Inferior Articular Process: Downward projection, forms joints with the vertebra below.
- Facets on Articular Processes: Smooth surfaces, allow for articulation between vertebrae, facilitating movement and flexibility.
Regions of the Vertebral Column
- Cervical Vertebrae (7): Neck region, C1 (atlas) and C2 (axis) are specialized for head movement.
- Thoracic Vertebrae (12): Chest region, identified by facets for rib articulation.
- Lumbar Vertebrae (5): Lower back region, largest vertebrae, support weight and have strong muscle attachments.
- Sacrum: Five fused vertebrae, articulates with the pelvic girdle.
- Coccyx: Three to five fused bones, forming the tailbone.
The Atlas and Axis: Specialized Functions
- Atlas (C1): Articulates with the occipital condyles of the skull, allowing head nodding.
- Axis (C2): Has a dens (odontoid process) that allows rotation of the head from side to side.
Thoracic Vertebrae: Rib Articulation
- Facets on Thoracic Vertebrae: Articulate with the heads of ribs, allowing rib movement and anchoring them to the spine.
Lumbar Vertebrae: Large and Strong
- Lumbar Vertebrae: Largest vertebrae, designed for weight-bearing and strong muscle attachment.
Thoracic Cage: Structure and Functions
- Structure: Consists of the sternum, ribs, and costal cartilages.
- Functions: Protects vital organs, provides support for respiration.
- Sternum: Composed of the manubrium, body, and xiphoid process.
- Ribs: 12 pairs, articulate with thoracic vertebrae posteriorly, classified as true, false, or floating.
- Costal Cartilages: Hyaline cartilage, connect ribs to the sternum and provide flexibility.
- Costal Groove: Running along the inferior surface of ribs, houses blood vessels and nerves.
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Description
Test your knowledge on the skeletal system's functions, bone cell types, and the structure of osteons. This quiz covers essential concepts related to bone tissue and its response to mechanical stress. Ideal for students studying human anatomy.
