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Questions and Answers
Which of the following functions does the central (Haversian) canal NOT perform?
Lacunae are responsible for the production of blood cells in bone.
False
What is the primary function of osteocytes?
To maintain bone tissue and communicate with other bone cells.
The ________ are thin, bony plates found in spongy bone that provide structural support.
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What happens to bones that experience inactivity?
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Match the following terms with their descriptions:
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The layers of mineralized matrix surrounding the central canal are called ________.
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Which suture separates the frontal bone from the parietal bones?
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The sagittal suture runs along the midline of the skull, separating the occipital and parietal bones.
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What is the function of the paranasal sinuses?
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The _____ is the largest fontanel found at the junction of the frontal and parietal bones.
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Match the ossicle with its description and function:
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What is the main function of osteoblasts?
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Osteoclasts help in maintaining bone density by producing new bone tissue.
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What role do osteocytes play in the bone remodeling process?
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The internal structure of spongy bone is organized into ____, which contains osteocytes and canaliculi.
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Where can spongy bone tissue be found in the human skeleton? (Select all that apply)
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Yellow bone marrow primarily functions in blood cell production.
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Name two functions of red bone marrow.
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Match the following parts of a long bone with their functions:
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Osteocytes obtain nutrients and oxygen through tiny channels called ____.
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Which function of the skeletal system involves protecting vital organs?
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The appendicular skeleton consists of the skull, vertebrae, and sternum.
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Name one of the bones that form the nasal septum.
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The large opening at the base of the skull is called the ______.
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Match each cranial bone with its corresponding description:
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Which of the following is NOT a surface marking on bones?
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A facet on a bone typically forms a joint allowing gliding movements.
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What is the function of the external auditory meatus?
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The bones of the skull are divided into cranial and ______ bones.
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Which of the following bones is part of the axial skeleton?
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Which bone forms the lower part of the nasal septum?
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The mandible is the only movable facial bone in the skull.
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List two primary functions of the facial bones.
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The __________ bone forms part of the medial wall of the orbit.
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Match the following bones with their descriptions:
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Which bones contribute to the hard palate?
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The temporal bone articulates with the mandible at the temporomandibular joint.
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Name the cranial bone that forms the back and base of the skull.
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The __________ bones serve as attachment points for various muscles involved in facial expressions.
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What is the primary function of the infraorbital foramen?
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Study Notes
Microscopic Structures of Compact Bone
- Compact bone contains an abundant extracellular matrix primarily made of calcium salts surrounding collagen fibers.
- Central (Haversian) Canal: Houses blood vessels, nerves, and lymphatic tissue, providing nourishment and signaling to bone cells.
- Lacunae: Small cavities that hold osteocytes, ensuring the health and maintenance of bone tissue.
- Osteocytes: Mature bone cells found within lacunae, responsible for maintaining bone tissue and regulating mineral content.
- Concentric Lamellae: Layers of mineralized matrix surrounding the central canal, providing structural support and strength.
- Canaliculi: Tiny channels connecting lacunae to each other and the central canal, facilitating nutrient and waste exchange between osteocytes.
- Trabeculae: Thin plates found in spongy bone, providing structural support and distributing forces throughout the bone.
Osteoblast, Osteocyte, and Osteoclast Collaboration
- Osteoblasts: Bone-building cells that produce new bone matrix and help mineralize it.
- Osteocytes: Mature bone cells derived from osteoblasts that maintain bone tissue, act as sensors for mechanical stress, and communicate with other bone cells.
- Osteoclasts: Bone-resorbing cells that break down old or damaged bone tissue by dissolving the mineral matrix.
- These three cell types work together, maintaining a balance between bone formation and resorption.
- This balance helps maintain bone density and strength.
Function of Osteocyte Cytoplasmic Extensions
- Communication: Extensions allow osteocytes to connect with neighboring osteocytes and other bone cells.
- Nutrient Exchange: Extensions facilitate the exchange of nutrients, oxygen, and waste products between osteocytes and the surrounding bone tissue or blood vessels.
Macroscopic Structures of Long Bones
- Epiphysis (Proximal and Distal): Ends of the long bone, containing spongy bone and red marrow, reducing friction at joints.
- Diaphysis (Shaft): Long, cylindrical main portion, providing structural support and strength, containing compact bone.
- Periosteum: Dense connective tissue covering the bone, serving as an attachment point for tendons and ligaments, involved in growth and repair.
- Endosteum: Thin membrane lining the medullary cavity, involved in bone growth, repair, and remodeling.
- Medullary (Marrow) Cavity: Central cavity within the diaphysis, containing yellow marrow (fat storage) and red marrow (blood cell production).
- Epiphyseal Line or Plate: Hyaline cartilage layer in growing bones, becoming a line when growth stops, allowing for bone growth during childhood.
Nutrient and Oxygen Supply for Osteocytes in Spongy Bone
- Osteocytes in spongy bone obtain their nutrients and oxygen through tiny channels called canaliculi.
- Nutrients and oxygen diffuse from the blood vessels in the surrounding bone marrow or in the spaces of the trabeculae into the canaliculi.
Red Bone Marrow vs. Yellow Bone Marrow
- Red Bone Marrow Structure: Rich network of blood vessels and hematopoietic (blood-forming) cells, appears red due to the presence of red blood cells and high vascularity.
- Yellow Bone Marrow Structure: Primarily composed of adipose (fat) tissue, appears yellowish, contains fewer blood-forming cells.
- Red Bone Marrow Function: Responsible for hematopoiesis (production of red blood cells, white blood cells, and platelets), plays a crucial role in the body's immune response and blood cell regulation.
- Yellow Bone Marrow Function: Serves as an energy reserve due to its fat content, can be converted back to red marrow to assist in hematopoiesis in cases of severe blood loss or increased demand.
Adult Bones Containing Red Bone Marrow
- Pelvic Bones (e.g., ilium)
- Sternum
- Ribs
- Vertebrae (spinal bones)
Functions of the Skeletal System
- Support
- Protection of vital organs
- Movement
- Mineral storage
Axial Skeleton
- The axial skeleton provides a framework for the attachment of the appendicular skeleton and protects internal organs.
- It includes the skull, vertebrae, sternum, ribs, and hyoid bone.
Bone Surface Markings
- Foramen/Foramina: An opening or hole in a bone, allowing the passage of nerves, blood vessels, and ligaments.
- Fossa: A shallow, basin-like depression in a bone, serving as an attachment point for muscles or forming joints with other bones.
- Meatus: A canal-like passageway within a bone, providing a route for nerves and blood vessels or involved in sound conduction in the ear.
- Process: A projection or bump on a bone, providing attachment points for muscles, tendons, and ligaments.
- Condyle: A rounded, knuckle-like projection at the end of a bone, forming joints with other bones.
- Crest: A narrow, ridge-like projection, serving as an attachment point for muscles or ligaments.
- Facet: A smooth, flat surface on a bone, forming joints with other bones.
- Head: A rounded, prominent end of a bone, forming joints with other bones.
Skull Bones and Surface Markings
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Cranial Bones:
- Frontal: Forms forehead and upper portion of eye sockets.
- Ethmoid: Contributes to the roof of the nasal cavity, nasal septum, and orbits.
- Occipital: Forms the back and base of the skull, protects the brainstem.
- Sphenoid: Forms part of the base of the skull and floor of the cranium.
- Parietal: Forms sides and roof of the skull.
- Temproral: Forms sides and base of skull.
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Facial Bones:
- Mandible: Lower jawbone.
- Maxilla: Upper jawbone.
- Zygomatic: Cheekbone.
- Palatine: Forms part of the hard palate.
- Vomer: Forms part of the nasal septum.
- Inferior Nasal Concha: Increases surface area in the nasal cavity.
- Nasal: Forms the bridge of the nose.
- Lacrimal: Forms part of the medial wall of the orbit.
Skull Features
- Sutures: Fibrous joints between cranial bones.
- Fontanels: Soft spots in a baby's skull (unossified membrane).
- Sinuses: Air-filled cavities within cranial and facial bones.
- Nasal Septum: Divides the nasal cavity into two sections.
- Hard Palate: Roof of the mouth.
- Orbit: Bony cavity that houses the eye.
Skull Bone Markings
-
Frontal Bone:
- Supraorbital Foramen: A small opening above the eye socket that allows for the passage of the supraorbital nerve and blood vessels.
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Ethmoid Bone:
- 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, facilitating the sense of smell.
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Occipital Bone:
- Occipital Condyle: Rounded projections that articulate with the first cervical vertebra, allowing for nodding motion of the head.
- Foramen Magnum: A large opening at the base of the skull through which the spinal cord passes, connecting the brain to the spinal column.
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Sphenoid Bone:
- Optic Foramen: A small opening that allows the optic nerve to pass from the eye to the brain, crucial for vision.
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Temporal Bone:
- Mandibular Fossa: A depression that forms the socket for the mandibular condyle, allowing for the movement of the jaw.
- Styloid Process: A slender projection serving as an attachment point for muscles and ligaments of the neck.
- 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 that leads to the eardrum, playing a vital role in hearing.
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Maxilla:
- Infraorbital Foramen: A small opening below the eye socket that allows passage of the infraorbital nerve and blood vessels.
- Palatine Process: A horizontal plate that forms the anterior part of the hard palate.
Bones Forming the Orbit
- Frontal Bone
- Sphenoid Bone
- Zygomatic Bone
- Maxilla
- Ethmoid Bone
- Lacrimal Bone
- Palatine Bone
Unpaired Skull 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 the Facial Bones
- Support and structure
- Protection
- Articulation
- Airway and sinus function
- Muscle attachment
Bones Involved in Articulation
- Mandible (temporomandibular joint)
Temporal Bone
- Articulates with the mandible at the temporomandibular joint
Maxilla
- Primarily fixed
- Important for chewing, providing stability for teeth to occlude against
Sutures
- Immovable joints found only in the skull
- Four main sutures:
- Coronal suture: Separates frontal bone from parietal bones, located at the front of the skull.
- Sagittal suture: Separates parietal bones, runs along the midline of the skull.
- Lambdoid suture: Forms boundary between parietal bones and occipital bone, located at the back of the skull, shaped like an inverted "V".
- Squamous suture: Connects temporal bone to parietal bone, located on the sides of the skull, more curved than other sutures.
- Sutural bones may occur in the lambdoid and sagittal suture
Fetal Skull
- Fontanels present, areas where ossification is incomplete
- Fontanels allow for compression during birth and brain growth
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Fontanels:
- Anterior fontanel: Largest, located at the junction of frontal and parietal bones, diamond-shaped.
- Posterior fontanel: Smaller, triangular, 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, found on the sides and back of the head.
- Frontal suture usually fuses by age six
Paranasal Sinuses
- Four skull bones contain sinuses: frontal, sphenoidal, ethmoidal, and maxillary.
- Functions:
- Lighten the weight of the skull
- Contribute to voice resonance, enhancing sound quality during speech
Hyoid Bone
- Does not articulate with any other bones, suspended by muscles and ligaments
- The geniohyoid muscle is attached to the hyoid bone
Ossicles
- Three pairs of bones in the middle ear cavity of the temporal bone
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Ossicles:
- 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.
- Stapes (stirrup): Smallest ossicle, connected to the oval window of the cochlea, transmits sound vibrations to the inner ear, amplifying sound.
Vertebral Column
- Supports the head, protects the spinal cord, and provides attachment points for muscles.
- Intervertebral discs cushion and absorb shock, located between vertebrae from the cervical region to the sacrum.
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Vertebra Parts:
- Body/Centrum: Thick, cylindrical front part, provides weight-bearing support and stability.
- Vertebral Foramen: Large hole in the center, forms the vertebral canal for the spinal cord.
- Transverse Process: Lateral projections, attachment points for muscles and ligaments, provide leverage for movement.
- Spinous Process: Single posterior projection, attachment for muscles and ligaments, protects the spinal cord.
- Superior Articular Process: Upward projection, forms joints with the inferior articular process of the vertebra above.
- Inferior Articular Process: Downward projection, forms joints with the superior articular process of the vertebra below.
- Facets on Articular Processes: Smooth surfaces, allow for articulation between vertebrae, facilitating movement.
Vertebral Column Regions
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Cervical Vertebrae (7): Located in the neck.
- C1 (Atlas): Highly specialized, articulates with the occipital condyles of the skull, lacks a body and spinous process.
- C2 (Axis): Has the dens or odontoid process, a peg-like projection from the body.
- C2-C6: Bifid spinous processes and transverse foramina.
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Thoracic Vertebrae (12):
- Have facets for rib articulations.
- Body has demifacets for articulation with rib heads.
- Transverse processes have facets for the tubercle of the rib.
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Lumbar Vertebrae (5):
- Largest vertebrae with short, thick processes for muscle attachment.
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Sacrum:
- Formed by five fused vertebrae.
- Articulates with the pelvic girdle at the sacroiliac joints.
- Contains the sacral canal, continuation of the vertebral canal.
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Coccyx:
- Union of 3-5 fused bones.
Thoracic Cage
- Formed by the sternum, ribs, and costal cartilages.
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Sternum:
- Consists of manubrium, body, and xiphoid process.
- Xiphoid process fuses to the body by age 25.
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Ribs (12 pairs):
- True Ribs (first 7 pairs): Attach directly to the sternum via costal cartilage.
- False Ribs (last 5 pairs): Cartilages do not attach directly to the sternum, cartilage of 8th, 9th, and 10th ribs attach to each other and to the 7th rib.
- Floating Ribs (last 2 pairs): No sternal attachment.
- Costal Cartilage: Composed of hyaline cartilage tissue.
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Description
This quiz explores the intricate microscopic structures of compact bone, including the central canal, lacunae, and roles of various bone cells. Test your understanding of how these structures contribute to bone health and function. Perfect for students studying anatomy and physiology.
