Skeletal System and Introduction to Bone Markings Flashcards
Each bone is an organ composed of what tissues?
bone, cartilage, dense connective tissues,
epithelium, blood-forming tissue, adipose tissue, and nerve tissue
the skeletal system is
the entire framework of bones and their cartilages
Osteology
the study of bone structure and the treatment of bone disorders
Functions of the skeletal system
Support Protection Assistance in movement mineral homeostasis blood cell production triglyceride storage
Storage
structural framework for soft tissues to attach
Protection
protects internal organs from injury
Assistance in movement
muscles pull on bones to create movement
Mineral homeostasis
minerals are stored in bone to be released later
Blood cell production
some bones contain red bone marrow which produce red blood cells,
white blood cells, and platelets
Triglyceride storage
some bones contain yellow bone marrow which is made of adipose and
stores triglycerides
4 classifications of bone
long bones
short bones
flat bones
irregular bones
long bones
greater length than width; consist of a shaft and a variable number of ends; usually
somewhat curved for strength
examples of long bones
Femur, tibia and fibula, humerus, ulna and radius
short bones
somewhat cube-shaped and nearly equal in length and width
examples of short bones
Wrist and ankle bones
flat bones
generally thin, afford considerable protection, and provide extensive surfaces for muscle attachment
examples of flat bones
Cranial bones, sternum, ribs, scapula
Irregular bones
have complex shapes and do not fit in the other categories
examples of irregular bones
Vertebrae and some facial bones
seasmoid bone
a bone that forms directly in the connective tissue of tendons; embedded in a tendon;
acts like a pulley and improves the transmission of muscle force by the tendon; largest in the body is the
patella, but there are also small sesamoid bones in the hands, wrists, feet, and ears
typical long bone consists of
diaphysis
epiphysis
metaphysis
diaphysis
the bone’s shaft or body
epiphysis
the distal and proximal ends of the bone
metaphysis
the region in a mature bone where the diaphysis joints the epiphysis
A growing bone contains an epiphyseal (growth) plate in each metaphysis to allow the diaphysis to grow in length
Articular cartilage
a thin layer of hyaline cartilage covering the part of the epiphysis where the
bone forms an articulation with another bone
periosteum
a tough sheath of dense irregular connective tissue and its associated blood vessels
that surrounds the bone surface wherever it is not covered by articular cartilage
medullary cavity
a hollow, cylindrical space within the diaphysis that contains fatty yellow
bone marrow in adults
endosteum
a thin membrane that lines the medullary cavity
4 major types of cells in bone tissue
Osteogenic
Osteoblasts
Osteocytes
Osteoclasts
Osteogenic
unspecialized stem cells that undergo cell division (the only ones) to create
osteoblasts
Osteoblasts
bone-building cells; synthesize and secrete collagen fibers and other organic
components needed to build the extracellular matrix of bone tissue
Osteocytes
mature bone cells; the main cells in bone tissue and maintain the exchange of
nutrients and wastes with the blood
Osteoclasts
huge cells that release enzymes and acids that digest the protein and mineral
components of bone; responsible for resorption (the breakdown of bone extracellular matrix)
Bone is made of
50% crystallized mineral salts (give bone hardness and strength)
25% collagen fibers ( gives bone flexibility and reinforcement)
25% water
Bone is not completely solid because
many small spaces between cells and extracellular matrix components
Bone can be classified as spongy or compact
Depending on the size and distribution of the spaces
What percent of skeleton is compact and spongy bone?
80% skeleton is compact bone
20% is spongy bone
Compact bone tissue
contains few spaces; strongest type of bone tissue
Arranged in repeating structural units called osteons
concentric lamellae
lacunae
canacliculi
perforating canals
Osteons
repeating structural units
Osteons have a central canal containing blood vessels, nerves, and lymphatic vessels;
longitudinal to the bone
Concenctric lamellae
rings of hard, calcified extracellular matrix around the canals
Lacunae
small spaces between the lamellae which contain osteocytes
Canaliculi
small channels radiating from the lacunae; filled with extracellular fluid
Perforating canals
allow blood vessels, lymphatic vessels, and nerves from the periosteum to
penetrate the compact bone transversely
Spongy bone tissue
makes up most of the bone tissue of short, flat, and irregularly shaped bones
contains no osteons
trabeculae
has red bone marrow
trabeculae
irregular lattice-works of thin columns of bone that make up spongy bone
between the trabeculae, the space is filled with red bone marrow
contains concentric lamellae, osteocytes that lie in lacunae, and canaliculi radiating from the lacunae
spongy bone is different from compact in 2 major ways
Spongy is light which reduces the weight so it moves more readily
The trabeculae of spongy bone tissue support and protect the red bone marrow and is the
only site of red bone marrow in adults
bone formation
called ossification
occurs in 4 stages
4 stages of ossification
Initial formation of bones in an embryo and fetus
The growth of bones during infancy, childhood, and adolescence
The remodeling of bone (replacement of old bone tissue by new bone tissue throughout
life)
The repair of fractures throughout life
Initial bone formation
Embroyonic sksleton is composed of
mesenchyme
mesenchyme
meshwork of embryonic connective tissue)
shaped like bones
become ossified, providing a template for continuing ossification beginning during the 6th week of embryonic development
happens by intramembranous ossification
endochondral ossification
bone growth
intramembranous ossification
simpler method of bone formation; bone forms directly
within mesenchyme in sheet-like layers
endochondral ossification
bone forms within hyaline cartilage that develops from
mesenchyme
bone growth
bones grow in length and thickness during infancy, childhood, and
adolescence (until 18-25 years old)
bone length is related to
epiphyseal plate
chondrocytes that are constantly dividing and being converted to bone
When growth is complete, all of the chondrocytes are ossified and the bone stops growing
An epiphyseal line is present after the epiphyseal plate ossifies
bone thickness is produced by
the cells in the perichondrium
these differentiate into osteoblasts which secrete bone extracellular matrix
bone remodeling is
the ongoing replacement of old bone tissue by new bone tissue
takes place at different rates in different regions of the body
can be triggered by exercise, lifestyle, and changes in diet
bone resorption
the removal of minerals and collagen fibers from bone by osteoclasts
bone deposition
the addition of minerals and collagen fibers to bone by osteoblasts
fracture
any bone in a bone
partial fracture
an incomplete break across the bone, such as a crack
complete fracture
a complete break across the bone; the bone is broken into two or more pieces
closed ( simple)
the fractured bone does not break through the skin
open (compound)
the broken ends of the bone protrude through the skin
repair of a fracture
Phagocytes begin to remove any dead bone tissue
Chondroblasts form fibrocartilage at the fracture site that bridges the broken ends of the bone
The fibrocartilage is converted to spongy bone tissue by osteoblasts
Bone remodeling occurs; dead portions of bone are absorbed by osteoclasts and spongy bone is converted to compact bone
bone formation depends on several factors
Adequate vitamins (A, C, and D) and minerals (calcium, phosphorus, and magnesium)
Several hormones (androgens, estrogens, hGH)
Weight-bearing exercise
exercise and bone tissue
bone requires mechanical stress to remodel normally
When placed under stress, bone tissue becomes stronger through increased deposition of mineral
salts and production of collagen fibers
Demineralization
Primary mechanical stresses:
Pull of skeletal muscles
Pull of gravity
demineralization
loss of bone minerals
calcitonin
a hormone produced by the thyroid that can decrease the level of calcium in the
blood by inhibiting the action of osteoclasts; function isn’t totally clear because it can be present in excess or completely absent without causing clinical symptoms
parathyroid hormone ( PTH)
major regulator of the levels of calcium, magnesium, and
phosphate ions in the blood; increases the number and activity of osteoclasts
calcitrol
the active form of vitamin D, produced in the kidneys; acts on the gastrointestinal
tract to increase the rate of calcium, magnesium, and phosphate ions absorbed from foods into the blood
Testosterone, estrogen, human growth hormone, and insulin-like growth factor
hormones that
promote anabolism and bone growth
bony landmakers/nomenclature/ bone markings
serve as regions for ligament and tendon attachment or
provide passage or space for nerves and vessels to pass
depressions
basins & channels that house muscles, tendons, nerves, & vessels
fossa
sulcus/groove
fossa
shallow depression (distal end of humerus, ilium)
sulcus or groove
narrow depression (head of humerus)
openings
holes & channels that allow passage of nerves, vessels, muscles, & tendons
sinus fissure foramen meatus canal
sinus
air-filled cavities (nose)
fissure
cleft or enlarged crack or slit in a bone (cranium sphenoid)
foramen
small to large, usually circular opening (vertebral foramen)
meatus
a tiny passageway (part of the skull that extends to the ear)
canal
tunnel or tube in a bone (Cranium)
Projections
form joints
condyle head facet process trochlea
condyle
a rounded projection at the end of a bone that articulates with other cones to
form a joint (femur)
head
a rounded projection atop the neck of a bone (Head of femur)
facet
a smooth, flat surface (rib meets vertebrae)
process
any prominent, bony growth that projects (olecranon process of ulna)
trochlea
a pulley-shaped structure (trochlea of the humerus)
attachment sites
attachment sites for tendons and ligaments
rounded
long & narrow sites
other prominences
long & narrow sites
crest,line, rdige
rounded
tubercle, tuberosity, trochanter
other prominences
epicondyles, processes, spines
