Topic 3 - The Skeletal System (I-IV) Flashcards
What is the function of the skeletal system? (5 things)
- Provides structure, support and protection
- essential for locomotion and movement
- site of blood cell formation (hematopoiesis)
- storehouse for some inorganic minerals, especially calcium
- indicator of sex, age, height, weight, racial background, and (to some extent) medical history
How are bones classified?
by shape and location
What are the shape classifications of bones?
- long bones
- short bones
- flat bones
- irregular bones
- pneumatic bones
- sesamoid bones
Description of long bones
Longer than wide, cylindrical with a medullary cavity
What are long bones the main components of? (And examples of the bones themselves)
- limbs
- humerus, radius, ulna, femur, tibia, fibula, metacarpals, metatarsals, phalanges
Short bones description and examples
- roughly cubical
- carpals and tarsals
Where are short bones found?
where mobility is needed, but space is limited
Description of flat bones
Relatively thin bones
Function of flat bones
Examples of the bones
- provide broad surfaces for muscle attachment and/or protection of underlying organs
- main site of blood cell formation in adults (hematopoiesis)
- i.e.: frontal, parietal, innominate, ribs, scapula
Description of irregular bones
Examples of irregular bones
- irregular shape with numerous projections
- vertebrae some bones of skull (sphenoid, ethmoid), scapula
What do pneumatic bones contain?
Pneumatic bone purpose?
Where are they found?
Examples of them:
- sizable air spaces
- reduce weight of the skull, thus reducing need for large neck muscles
- only found in some bones of he skull
- frontal, maxilla, sphenoid, ethmoid, temporal (mastoid process)
Whet are sesamoid bones?
small round bones embedded within a tendon
What is the purpose of sesamoid bones?
Alter the angle of muscle attachment to increase mechanical leverage
Examples of sesamoid bones
Patella and sesamoids of hands and feet
How are bones classified by location?
- axial vs. appendicular skeleton
- cranial skeleton vs. post-cranial skeleton
Axial skeleton:
Bones of the skull, hyoid, vertebral column, and rib cage
Appendicular skeleton:
Bones of the limbs and their attachment onto the axial skeleton
Appendicular skeleton examples
Bones of the limbs and their attachment (Pectoral and pelvic girdles [excluding the sacrum])
Cranial skeleton
Bones of the skull
Post-cranial skeleton
Bones of vertebral column, hyoid, rib cage, limbs, pectoral girdle, pelvic girdle
Bone Tissue: subcategories
- matrix
- bone cells
- abnormal growth of bone tissue
Bone tissue composition has:
- matrix
- bone cells
Bone matrix contains:
- fibers
- ground substance
Bone matrix fibers:
What do they do?
- Type I collagen fibers;
- Provide strength to resist tensile forces (forces that are trying to tear them apart)
Ground substance of bone matrix:
- organic component
- inorganic component
What is the organic component of the ground substance of bone matrix?
Proteoglycans (primarily composed of sulfate, keratin sulfate, nad hyaluronic acid) and glycoproteins (especially osteonectin and osteocalcin)
- osteonectin: connects on to collagen fibers
- osteocalcin: facilitates deposition of inorganic
What is the inorganic component of the ground substance of bone?
Hydroxyapatite, a calcium mineral composite, which provides strength to resist compressive forces
Bone cells consist of:
- osteoprogenitor cells
- osteoblasts
- osteocytes
- osteoclasts
Osteoprogenitor cells give rise to ___________
osteoblasts
Where are osteoprogenitor cells located?
located within the central and perforating canals of osteons, within the periosteum (cellular layer) and endosteum
Osteoblasts are originate from _____________.
Osteoprogenitor cells
Osteoblasts give rise to ______________
Osteocytes
What do osteoblasts do?
Lay down new bone tissue
Where are osteoblasts located
Within the central and perforating canals of osteons and within the periosteum (cellular layer) and endosteum
Osteocytes were formerly ______________.
Osteoblasts
Osteocytes are located ____________
Within the lacunae of the osteons of compact bone and bony struts of spongy bone
What do osteocytes do?
Maintain surrounding bone tissue and regulate mineral content.
Osteoblasts function is what?
Bone-destroying cells (destroy bone tissue). They refine the shape of the bone that osteoblasts laid down.
Describe osteoclasts
Large and multinucleated
Where do osteoclasts originate?
From the fusion of several monocytes.
What are the types of bone tissue?
- primary bone tissue (woven bone)
- secondary bone tissue (mature or lamellar bone)
- abnormal growth of bone tissue
Primary bone tissue is AKA
Woven bone
When does primary bone develop?
First, during fetal development
What is primary bone associated with?
The repair of fractures
What kind of fibers are found in primary bone, and how are they arranged?
- Collagen fibers
- randomly arranged
In primary bone, is the mineral content high or low?
Low
Primary bone contains more ________ than __________/___________ bone tissue
Osteocytes
Mature/secondary
Secondary bone tissue is AKA
Mature or lamellar bone
What types of bone are classified under Secondary bone tissue (mature or lamellar bone)?
- compact (cortical) bone
- spongy (cancellous or trabecular) bone
- subchondral bone
What is compact bone AKA?
Cortical bone
What is compact (cortical) bone composed of?
Outer layer of densely packed bone tissue, composed of osteons (aka, Haversian systems), circumferential lamellae, and interstitial lamellae
What are osteons made up of?
- lamellae
- central (osteons or Haversian) canal
- lacunae
- canaliculi
- perforating (communicating or Volkmann’s) canals
- circumferential lamellae
- interstitial lamellae
Lamellae are what?
What are the fibers made up of, and at what angle(s) are the fibers oriented to the adjacent layers?
Concentric layers of bone tissue.
Collagen
Right angles to the fibers in the adjacent layers
What is the central canal AKA?
Osteonic or Haversian
What does the central (osteonic or Haversian) canal contain?
What is it lined by?
- vascular structures and nerves
- osteoprogenitor cells and osteoblasts
What are lacunae?
What is contained in them?
- Holes found between lamellae
- osteocytes
What are canaliculi?
Passageways connecting lacunae to each other and to the central and perforating canals
Perforating (communicating of Volkmann’s) canals do what?
Connect central canals to each other
What are perforating canals lined by?
Osteoprogenitor cells and osteoblasts
Circumferential lamellae are?
Multiple layers of mineralized matrix
What are the 2 kinds of circumferential lamellae?
External and inner circumferential lamellae
Where are the external circumferential lamellae located?
Immediately deep to the periosteum
Inner circumferential lamellae are located where?
At the perimeter of the medullary cavity
What are interstitial lamellae?
Layers of mineralized matrix, lying between and around osteons; the remains of partially destroyed osteons
Spongy (cancellous or trabecular) Ben is found where?
The interior of a bone
Describe spongy bone
Lattice/network of bony bars and struts (trabeculae), each consisting of just a few concentric layers of bone tissue
How many layers of concentric bone tissue are there in spongy bone?
A few
Where is the site that blood cells are manufactured?
Within the lattice/network of bony bars and shuts within spongy bone
What is subchondral bone?
Very thin layer of modified compact bone, lacking the extensive vascular channels
Where is subchondral bone found?
Underlying articular cartilage, making up the articular/facet surface
What is the morphology of a typical bone?
- diaphysis
- epiphysis
- epiphyseal plate (epiphyseal disk, growth plate)
- periosteum
- endosteum
- medullary cavity (marrow cavity)
- articular cartilage
What is the diaphysis of a bone?
body/shaft of the bone. Also the primary center of ossification
Epiphysis is often associated with what?
the area of articulation with another bone or site of excessive muscle tension
Where is the secondary center of ossification?
The epiphysis
Where is the primary site of ossification?
The diaphysis
What does the epiphyseal plate (epiphyseal disk, growth plate) do?
Connects diaphysis and epiphysis
What is the epiphyseal plate composed of?
Hyaline cartilage
The periosteum is what?
Fibrous structure covering the outer bone surface.
Where is periosteum not found?
Articular bone surfaces and where tendons and ligaments attach onto the bone
What are the 2 layers of periosteum?
- Fibrous layer
- Cellular layer
How are tendons and ligaments anchored to the periosteum?
Via perforating/Sharpey’s fibers
Which layer of periosteum is deep?
The cellular level
Which layer of periosteum is superficial?
Fibrous layer
The fibrous layer of periosteum consists of what?
sheet of dense irregular connective tissue containing type I collagen fibers, plus fibroblasts, blood vessels and nerve fibers (stressed for pathology)
The cellular layer of periosteum is _______ and contains bone ________ (primarily _________ ________ and ________.
Thin
Cells
Osteoprogenitor cells
Osteoblasts
What is endosteum?
A very thin connective tissue layer covering inner bone surfaces
Endosteum primarily consists of what?
A single layer of osteoprogenitor cells and osteoblasts
Where is the medullary cavity (marrow cavity) located?
The center of a long bone
What is the fxn of the medullary cavity in children? In adults?
- additional site of blood cell manufacture (‘red bone marrow’)
- adipose storage (‘yellow bone marrow’)
Where is articular cartilage found?
What is it composed of?
- covering articular surfaces
- hyaline cartilage
