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Which of the following describes the structure that serves as the unit of bone containing the central canal and matrix rings?
Which of the following describes the structure that serves as the unit of bone containing the central canal and matrix rings?
Trabeculae are the large, solid pieces of bone found in spongy bone.
Trabeculae are the large, solid pieces of bone found in spongy bone.
False
What is the function of canaliculi in bone structure?
What is the function of canaliculi in bone structure?
To connect bone cells to a nutrient supply.
The __________ canal carries blood vessels and nerves and is found in the center of an osteon.
The __________ canal carries blood vessels and nerves and is found in the center of an osteon.
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Match the following terms to their descriptions:
Match the following terms to their descriptions:
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What is filled by the open spaces within spongy bone?
What is filled by the open spaces within spongy bone?
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Lacunae are unnecessary for the structure of compact bone.
Lacunae are unnecessary for the structure of compact bone.
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What is the primary process by which bone forms?
What is the primary process by which bone forms?
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What is the first major event in the repair of bone fractures?
What is the first major event in the repair of bone fractures?
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By birth, most cartilage in long bones is converted to bone, except for articular cartilages and epiphyseal plates.
By birth, most cartilage in long bones is converted to bone, except for articular cartilages and epiphyseal plates.
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The mandible is the only bone in the skull attached by a freely movable joint.
The mandible is the only bone in the skull attached by a freely movable joint.
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What type of cells are responsible for bone formation?
What type of cells are responsible for bone formation?
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The process of bone growth in width is known as __________ growth.
The process of bone growth in width is known as __________ growth.
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How many cranial bones are there in the human skull?
How many cranial bones are there in the human skull?
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The _________ is formed after the hematoma in the bone fracture repair process.
The _________ is formed after the hematoma in the bone fracture repair process.
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Match the following components with their roles in bone growth:
Match the following components with their roles in bone growth:
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Match the following cranial bones with their associated functions:
Match the following cranial bones with their associated functions:
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Which of the following substances makes bone hard and able to resist compression?
Which of the following substances makes bone hard and able to resist compression?
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Hormones such as growth hormone and sex hormones do not play a role in bone growth.
Hormones such as growth hormone and sex hormones do not play a role in bone growth.
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Which of the following is NOT part of the axial skeleton?
Which of the following is NOT part of the axial skeleton?
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What happens to old cartilage as new cartilage is formed?
What happens to old cartilage as new cartilage is formed?
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The bony callus is formed before the fibrocartilage callus.
The bony callus is formed before the fibrocartilage callus.
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Osteoblasts in the ___________ add bone matrix to the outer surface of the diaphysis.
Osteoblasts in the ___________ add bone matrix to the outer surface of the diaphysis.
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What connects bones in the skull, creating immovable joints?
What connects bones in the skull, creating immovable joints?
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The _________ skeleton forms the longitudinal axis of the human body.
The _________ skeleton forms the longitudinal axis of the human body.
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What is one function of the paranasal sinuses?
What is one function of the paranasal sinuses?
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The hyoid bone is articulated with other bones in the body.
The hyoid bone is articulated with other bones in the body.
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How many vertebral bones are in the human vertebral column?
How many vertebral bones are in the human vertebral column?
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The sacrum is formed by the fusion of _____ vertebrae.
The sacrum is formed by the fusion of _____ vertebrae.
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Match the following regions of the vertebral column to their number of vertebrae:
Match the following regions of the vertebral column to their number of vertebrae:
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Which of the following accurately describes the primary curvatures of the spinal column?
Which of the following accurately describes the primary curvatures of the spinal column?
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Secondary curvatures form at birth and are seen in infants.
Secondary curvatures form at birth and are seen in infants.
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What is the primary function of the hyoid bone?
What is the primary function of the hyoid bone?
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The vertebral column extends from the _____ to the pelvis.
The vertebral column extends from the _____ to the pelvis.
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Which part of the vertebral column is associated with the lower back?
Which part of the vertebral column is associated with the lower back?
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What is the primary function of the lateral malleolus?
What is the primary function of the lateral malleolus?
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The fibula plays a significant role in the formation of the knee joint.
The fibula plays a significant role in the formation of the knee joint.
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How many tarsal bones are there in the human foot?
How many tarsal bones are there in the human foot?
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The two largest tarsals are the __________ and __________.
The two largest tarsals are the __________ and __________.
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Match the type of joint with its classification:
Match the type of joint with its classification:
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Study Notes
Essentials of Human Anatomy & Physiology - Chapter 5: The Skeletal System
- The skeletal system is composed of bones, joints, cartilages, and ligaments.
- The skeleton is divided into two subdivisions: axial and appendicular.
- The axial skeleton forms the longitudinal axis of the body and includes the skull, vertebral column, and bony thorax.
- The appendicular skeleton includes the limbs (appendages), pectoral girdle, and pelvic girdle.
- The adult human skeleton has 206 bones.
- Osseous (bone) tissue comes in two basic types: compact and spongy.
- Compact bone is dense, smooth, and homogeneous.
- Spongy bone consists of small, needlelike pieces of bone and many open spaces.
- Flat bones, like those in the skull, consist of a layer of spongy bone between two thin layers of compact bone.
- Bones are also classified by shape into long, flat, short, and irregular bones.
- Long bones are typically longer than wide, with a shaft containing mostly compact bone; spongy bone is at the ends.
- Examples of long bones include the femur and humerus.
- Flat bones are thin, flattened, and usually curved, with two layers of compact bone sandwiching spongy bone. Examples are ribs, sternum, and most skull bones.
- Short bones are generally cube-shaped and contain mostly spongy bone with an outer layer of compact bone. Examples include carpals (wrist bones) and tarsals (ankle bones).
- Irregular bones have an irregular shape and do not fit into other bone classification categories. Examples include vertebrae and hip bones.
Functions of the Bones
- Bones provide support for the body.
- Bones protect soft organs, including the brain and spinal cord (skull and vertebrae), and organs within the thoracic cavity (rib cage).
- Bones allow movement via their attachment to muscles.
- Bones store minerals (calcium and phosphorus) and fat (in the internal marrow cavity); fat acts as cushioning.
- Bones are involved in blood cell formation (hematopoiesis).
Structure of Bone
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Long bone anatomy:
- Diaphysis (shaft): Makes up most of the bone's length and is composed of compact bone.
- Periosteum: The outside covering of the diaphysis, a fibrous connective tissue membrane. Perforating (Sharpey's) fibers secure the periosteum to the underlying bone.
- Epiphysis (ends): Composed mostly of spongy bone enclosed by a thin layer of compact bone. Articular cartilage covers the external surface of the epiphyses, made of hyaline cartilage and decreasing friction at joint surfaces.
- Epiphyseal line: A remnant of the epiphyseal plate (a flat plate of hyaline cartilage seen in young growing bones) where lengthwise growth of a long bone occurs.
- Endosteum: Lines the inner surface of the shaft, made of connective tissue.
- Medullary cavity: Cavity inside the shaft, containing yellow marrow (mostly fat) in adults, and red marrow for blood cell formation until age 6 or 7.
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Bone markings: Used for muscle, tendon, and ligament attachment; nerve and blood vessel passageways.
- Projections (processes) begin with "T" (e.g., tuberosity, trochanter, crest).
- Depressions (cavities) begin with "F" (except facet) (e.g., fissure, foramen, fossa, sinus, groove).
Bone Formation, Growth, and Remodeling
- Ossification: Bone formation. Occurs on hyaline cartilage models or fibrous membranes in the embryo and fetus.
- Long bone growth involves two major phases:
- Osteoblasts (bone-forming cells) cover the hyaline cartilage model with bone matrix.
- The enclosed cartilage is replaced with bone, while the cartilage is digested away to form a medullary cavity.
- By birth, most cartilage is converted to bone, except articular cartilages and epiphyseal plates.
- New cartilage is continuously formed on external faces of articular cartilages and epiphyseal plates; old cartilage is replaced with bony matrix.
- Appositional growth: Bones grow in width. Osteoblasts in the periosteum add bone matrix to the outside of the diaphysis, while osteoclasts in the endosteum remove bone from the inner surface.
- Bone growth is controlled by growth hormone and sex hormones.
- Bones continually remodel throughout life in response to calcium ion levels in the blood and the pull of gravity and muscles on the skeleton.
- Parathyroid hormone (PTH): Released when calcium ion levels are low; activates osteoclasts.
- Hypercalcemia: High blood calcium levels; promotes calcium storage in bones by osteoblasts.
Bone Fractures
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Fracture: A break in a bone.
- Closed (simple) fracture: A break that does not penetrate the skin.
- Open (compound) fracture: A broken bone that penetrates through the skin.
- Bone fractures are treated by reduction and immobilization. Closed reduction involves coaxing bones into position with the physician's hands; open reduction involves surgery to secure bones with pins or wires.
- Healing time for a bone fracture is typically 6-8 weeks.
- Bone fracture repair involves four events:
- Hematoma formation.
- Fibrocartilage callus formation.
- Bony callus formation.
- Bone remodelling.
Axial Skeleton
- Includes the skull, vertebral column, and bony thorax.
Skull
- Formed by two sets of bones: cranium (encloses the brain) and facial bones (hold the eyes and allow facial expression).
- Cranium includes 8 bones (frontal, occipital, ethmoid, sphenoid, parietal, temporal).
- Facial bones include 14 bones (maxillae, palatine, lacriminal, zygomatic, nasal, vomer, inferior nasal conchae, mandible)
- Paranasal sinuses are hollow portions of bones surrounding the nasal cavity, lightening the skull and amplifying sounds.
- The hyoid bone is the only bone in the body that does not articulate with another bone. It supports the tongue and aids in swallowing and speech.
Vertebral Column (Spine)
- Extends from skull to pelvis.
- Consists of 26 vertebrae separated by intervertebral disks.
- Contains 7 cervical, 12 thoracic, and 5 lumbar vertebrae; sacrum (5 fused vertebrae), coccyx (3–5 fused vertebrae).
- Vertebrae have a body (centrum), vertebral arch, pedicle, lamina, vertebral foramen, transverse processes, spinous process, and superior and inferior articular processes.
- Primary curvatures (thoracic and sacral regions) are present from birth; form a C-shape.
- Secondary curvatures (cervical and lumbar regions) develop after birth; form an S-shape for posture.
Thoracic Cage
- Protects the organs of the thoracic cavity.
- Consists of the sternum, ribs (true, false, floating), and thoracic vertebrae.
Appendicular Skeleton
- Includes the limbs(appendages), pectoral girdle, and pelvic girdle.
Bones of the Shoulder Girdle
- Includes the clavicle and scapula. Lightweight and flexible for exceptional upper limb movement.
Bones of the Upper Limbs
- Includes the humerus (arm), ulna and radius (forearm), carpals (wrist), metacarpals (palm), and phalanges (fingers and thumb). The forearm consists of the ulna (the medial bone) and the radius (the lateral bone). Each are articulated on each end to the humerus and to each other.
- Humerus has significant articulations to the scapula and the forearm bones (radius and ulna). The ulna and radius are articulated at both their proximal and distal ends.
Bones of the Pelvic Girdle
- Consists of the ilium, ischium, and pubis.
- Supports the weight of the upper body and protects internal organs – reproductive organs, urinary bladder, and part of the large intestine.
- Two coxal bones are joined by the pubic symphysis. The coxal bones (illium, ischium, and pubis that fuse) connect the sacrum and coccyx by the sacroiliac joint.
- Key differences between male and female pelvis: Female inlets are larger and more circular; ilia flare further; sacrums are shorter; ischial spines are further apart creating a larger outlet; and the female pubic arch is more rounded.
Bones of the Lower Limbs
- Includes the femur (thigh), tibia and fibula (lower leg, shinbone is larger medial, fibula is thinner lateral), tarsals (ankle), metatarsals (sole), and phalanges (toes).
- The femur is the longest and strongest bone in the body, with notable articulations to the coxal bone (acetabulum) and the tibia at the distal end.
- The tibia and fibula articulate to form the knee joint, and distal articulations form the ankle joint.
- Arches of the foot are crucial for balance, structure, and flexibility. Two longitudinal arches and the transverse arch contribute to this function.
Joints
- Joints (articulations): Occur where bones meet; hold bones securely and allow for mobility.
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Functional Classifications:
- Synarthroses: Immovable joints (e.g., sutures in the skull).
- Amphiarthroses: Slightly movable joints (e.g., pubic symphysis, intervertebral joints).
- Diarthroses: Freely movable joints (e.g., synovial joints).
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Structural Classifications:
- Fibrous Joints: Generally immovable (e.g., sutures, syndesmoses, gomphoses).
- Cartilaginous Joints: Immovable or slightly movable (e.g., synchondrosis, symphysis).
- Synovial Joints: Freely movable joints (e.g., plane, hinge, pivot, condylar, saddle, ball-and-socket)
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Synovial Joint Components:
- Articular cartilage: Smooth layer of hyaline cartilage covering bone ends.
- Articular capsule: Encloses the joint cavity.
- Joint cavity: Space between bone ends containing synovial fluid.
- Reinforcing ligaments: Strengthen the joint.
- Bursae and tendon sheaths: Fluid-filled sacs that cushion and reduce friction around joints.
- Various types of synovial joints based on mobility and shape (i.e. Plane, Hinge, Pivot, Condylar, Saddle, Ball-and-Socket).
Developmental Aspects of the Skeleton
- Birth to adulthood: Fetal long bones are hyaline cartilage; earliest flat bones are fibrous membranes; all models convert to bone.
- Fetal skull: Includes fontanels (soft spots), spaces of fibrous membranes to allow skull compression and brain growth.
- Cranial growth after birth: Related to brain growth. Facial skeleton expands with tooth development and increases respiratory passages. Cranium size relative to the body changes through development (initially 3/4 the adult skull size).
- Puberty: Female pelvis broadens; entire male skeleton becomes more robust.
- Adolescence: Epiphyseal plates fully ossify.
- Older adults: Osteoporosis (a bone-thinning disease) is common; causes brittle bones; vertebral collapse causing kyphosis.
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Description
Test your knowledge on the anatomy of bones including their structure, functions, and processes. This quiz covers topics related to bone cells, growth, and the unique features of spongy and compact bone. Perfect for students in anatomy or biology courses.
