The Skeletal System Flashcards
What are the parts of the skeletal system
Bones, Joints, Cartilages, and ligaments
How many named bones does the adult skeleton have
206
What are the 2 divisions of the skeleton
- Axial Skeleton
- Appendicular Skeleton
Axial Skeleton
forms the longitudinal axis of the body
- includes bones of skull, vertebral column and rib cage
- 80 bones
Appendicular skeleton
- Bones of upper/lower limbs and girdles that attach them to the axial skeleton
- help in locomotion and manipulation
-126 bones
What are the functions of the bones
- support
- protection
- movement
- storage
- blood cell formation/ hematopoiesis
- triglyceride storage
- hormone production
Bones are classified by their
shape and size
Long bones
- longer than they are wide (shafts with ends)
- all limb bones are long bones except patella and wrist and ankle bones
Short bones
- roughly cube shaped
- bones of the wrist and ankle
Sesamoid bones
short bones that form in a tendon
- patella
- act to alter the pull of a tendon
Flat bones
thin, flattened, and usually curved
- sternum, scapula, ribs, and most skull bones
Irregular bones
complicated shaped that fit none of the above
- vertebrae and hip bones
Besides osseous tissue bones also contain
- nervous tissue
- cartilage
- dense connective tissue
- epithelial tissues
Every bone has 2 basic types of bone or osseous tissue
- compact bone
- spongy bone
compact bone
dense outer layer that looks smooth, homogeneous, and solid
spongy bone
a honeycomb of small, needle-like pieces of bone called TRABECULAE
- open spaces between the trabeculae are filled with red or yellow bone marrow
The compact bone is covered outside and inside by connective tissue membranes known as
- periosteum
- endosteum
All long bones have the same general structure
- Diaphysis
- Epiphysis
Diaphysis
- Tubular shaft
- Collar of compact bone surrounding a central MEDULLARY CAVITY
- medullary cavity contains YELLOW BONE MARROW in adults
Epiphysis
- exterior made compact bone, and interior contains spongy tissue
- Thin layer of HYALINE CARTILAGE covers joint surface of each epiphysis (epiphyseal cartilage)
Between the diaphysis and epiphysis of an adult long bone is a __ which is a remnant of the ____
- epiphyseal line
- epiphyseal plate
Epiphyseal plate
a disc of HYALINE CARTILAGE that grows during childhood to lengthen the bone
Epiphyseal line
end of puberty, hormones inhibit long bone growth
- epiphyseal plates have been completely REPLACED BY BONE leaving behind only epiphyseal lines
periosteum
covers external surface of entire bone except the JOINT SURFACES which is covered by the hyaline cartilage
Periosteum is richly supplied with nerve fibers and blood vessels which pass through the shaft to enter the marrow cavity through a
Nutrient Foramen
Perforating (Sharpey’s) fibers
tufts of collagen fibers secure the periosteum to underlying bone
Hematopoiesis
Stem cells of the red bone marrow produces all the blood cells
- red blood cells
- white blood cells
- platelets
Projections, depressions, openings
sites of attachments for muscles, tendons, and ligaments, as joint surfaces or as conduits for blood vessels and nerves called FORAMINA
Projections/ processes
grow out from the bone surface
- tuberosity
- trochanter
- spine
- process
tuberosity
large rounded projection (tibial tuberosity)
trochanter
very large blunt irregularly shaped process
( greater and lesser trochanter of femur)
spine
sharp, slender, pointed projection (ischial spine)
process
any bony prominence (transverse process)
crest
narrow ridge of bone
projections that help to form joints
- head
bony expansions carried on a narrow neck - condyle
rounded articular projection
depressions
indentations in the bone
openings
- foramen
rounded or oval opening through a bone
(foramen magnum)
other bone markings
sinus and fossa
sinus
cavity within a bone (paranasal sinuses)
fossa
shallow, basin like depression (olecranon fossa)
- microscopic anatomy
- cells of bone tissues
what are the 4 major cell types that populate bone tissue
( compact bones)
- osteogenic cells
-osteoblasts - osteocytes
- osteoclasts
osteogenic cells
(compact bones)
mitotically active stem cells found in the periosteum and endosteum
osteoblasts
(compact bones)
bone forming cells that secrete the bone matrix including collagen and calcium binding proteins
osteocytes
(compact bones)
spider-shaped, are mature bone cells that occupy spaces, LACUNAE, in the matrix
Osteoclasts
(compact bones)
bone destroying cells
- microscopic structure
- histology of compact bone
osteon (haversian system)
(compact bone)
structural unit of compact bone containing central canal and matrix rings
central (haversian) canal
(compact bone)
an elongated cylinder oriented parallel to the long axis of the bone
Lamellae
(compact bone)
hollow tubes of bone matrix arranges in concentric rings around the central canal, like the growth rings of a tree trunk
Lacunae
(compact bone)
- cavities containing osteocytes
- located at junctions of the lamellae
osteocytes
(compact bone)
bone cells
perforating (volkmann’s) canals
(compact bone)
- lie at right angles to the central canal
- carry blood vessels and nerves of the medullary cavity to the central canals
canaliculi
(compact bone)
- tiny, hair-like canals
- radiate from the central canal, connect the lacunae to each other
- microscopic structure of spongy bone
only a few cells thick, TRABECULAE contain irregularly arranged lamellae and osteocytes interconnected by canaliculi
- NO OSTEONS ARE PRESENT
Chemical composition of bone
bone contains both organic and inorganic substances
organic components
- bone cells
osteoblasts, osteocytes, and osteoclasts - ground substance
OSTEOID is composed of proteogycans and glycoproteins and collagen fibers
inorganic components
- mineral salts such as calcium phosphates
- responsible for their exceptional hardness
*formation of the human skeleton
before 8 weeks
the embryonic skeleton is constructed entirely from fibrous membranes and hyaline cartilage
after 8 weeks
two types of ossification take place
Intramembranous Ossification
development of bone from the fibrous membranes
Endochondral Ossification
replacement of hyaline cartilage with bone
- Bone growth (ossification)
linear growth
growth in length of a long bone occurs at the EPIPHYSEAL PLATE during childhood
As adolescence ends, plate becomes thinner and thinner until entirely replaced by
Bone tissue (Ossification) at the EPIPHYSEAL LINE
appositional growth
growing bones widen as they lengthen
- Bone remodeling
Bone growth during infancy and childhood is controlled by hormones such as
- growth hormone
- thyroid hormones
- sex hormones
growth hormone
the stimulus for epiphyseal plate activity
thyroid hormones
modulates the activity of the growth hormone
Sex hormones
at puberty, testosterone in males and estrogen in females induce epiphyseal closure
- bone fractures
fracture
a break in a bone
Fractures may be classified based on
- position of bone ends after fracture
- completeness of the break
- whether bone ends penetrate the skin
position of bone ends after fracture
- nondisplaced fracture
- displaced fracture
completeness of the break
- complete fracture
- incomplete fracture
whether bone ends penetrate the skin
- open (compound) fracture
- closed (simple) fracture
- common types of fractures
- comminuted
- compression
- depressed
- impacted
- spiral
- transverse
- green stick
comminuted
bone breaks into many fragments
compression
bone is crushed
depressed
broken bone portion is pressed inward
impacted
broken bone ends are forced into each other
spiral
ragged break occurs when excessive twisting forces are applied to a bone
transverse
bone broken horizontally
greenstick
bone breaks incompletely
Four major events
- hematoma forms
- fibrocartilaginous callus forms
- bony callus forms
- bone remodeling occurs
hematoma forms
when a bone breaks, blood vessels are torn and hemorrhage results in a mass of clotted blood is formed at the fracture site
fibrocartilaginous callus forms
within few days capillaries grow into the hematoma, and fibroblasts, and cartilage, and osteogeic cells invade fracture site
- begin reconstructing the bone forming a soft granulation tissue or soft callus
bony callus forms
within a week, new bone trabeculae appear and gradually convert it to body or hard callus
bone remodeling occurs
bony callus is remodeled and removal of exess material on the diaphysis within the medullary cavity and compact bone is laid down to reconstruct the shaft walls
