Ch 7 Anatomy- Skeletal

this originally was Calabria ch 7 but altered to fit my 101 class

what are the parts of the skeletal system?

bones, joints, cartilage, and ligaments

structural functions of bone

gives shape to things, support (ie: vertebrae), protection (like ribs protect organs), and movement (interact with muscles and move at joints, also stabilizes)

function of bone- blood cell formation

hematopoiesis (process of blood cell formation) occurs in bone marrow. bone marrow produces ALL types of blood cells and platelets. The marrow is a net-like mass of CT found within the bones

function of bone- yellow marrow

yellow marrow stores fat, inactive in blood cell produciton

inorganic salt storage: what does the extracellular matrix of the bone tissue include

collagen and inorganic mineral salts. 70% of the EC matrix is calcium phosphate

inorganic salt storage- what is calcium required for?

blood clot formation, nerve impulse conduction, and muscle contraction

inorganic salt storage- what happens when the blood is low on calcium?

the parathyroid hormone stimulates osteoclasts to break down bone tissue and release calcium from the EC and into the blood.

inorganic salt storage- what happens when the blood is high on calcium?

osteoclast activity is inhibited, and calcitonin stimulates osteoblasts to form bone tissue, storing/depositing excess calcium in the bone tissue

what kinds of tissues do bones contain?

bone tissue, cartilage, dense, CT, blood, and nervous

what r the 2 major subdivision of the skeleton

axial and appendicular

what does the appendicular skeleton include

bones of upper and lower limbs. ex: pectoral and pelvic gridle, bones of arms and legs

what does the axial skeleton include?

boney cartilage to protects and support the organs of the head, neck, and trunk. Exs: skull, vertebrae, ribs, and sternum

How are bones classified?

according to shape

long bones +examples

longer than they are wide. expanded/rounded ends. ex: femur, tibia, metacarpals

short bones + examples

same width and length- cube like. Examples: wrist bones (carpals) and ankle bones (tarsals)

• sesamoid bones r a short bone that form with tendons (patella)

flat bones + examples

very thin and broad in shape, almost like a plate, a sandwich of compact bone with layer of spongy bone in between. protects underlying organs and muscle attachment. ex: sternum, ribs, scapula

Irregular Bones

+examples

unique shape, fits location. ex: skull, vertebrae, hip bones

what are the 2 basic types of bone (osseus) tissue

• compact bone: smooth and homogenous

• spongy bone: many open spaces

how can you define spongy bone?

as light, low density, flexible, and weak bone

what's other names for spongy bone?

trabeculae or cancellous

where is spongy bone found

on epiphysis of long bones, near joints, and inside vertebrae

describe the formation of spongy bone

the spongy bone itself is the bony rods/branches- the trabeculae. the osteocytes are within the trabeculae (which are within lacuna). unlike compact bone, the osteocytes do not get their nutrients from canals, instead their canaliculi branch to the surface of the trabeculae, which is where blood vessels are. between the lacunae is the lamella.

describe the formation of the trabeculae, why's it the way it is?

to bear mechanical stress. the cavities in between the spongy bone contain bone marrow.

osteoblasts

secrete bone matrix that consists of collagen and other proteins. responsible for bone growth. synthesizes bone and mineralizes it.

how do osteoblasts become osteocytes

once it's surrounded by enough of the matrix it produced, it has completed its job and turns into an osteocyte

osteocytes

mature bone cells that monitor and maintain bone matrix, communicating the info to other cells. remain in lacuna

osteoclasts

multinucleate cells that can break down bone with the help of enzymes.

lamellae

layers that are parallel inside trabeculae and compact bone that help with bone strength. kinda like layers of tree trunk rings

what are units of compact bone called

osteons

describe the lamellae within each osteon

made of collagen, each layer having a different direction of collagen opposite of the one next to it. the purpose of this is to resist torsion

middle of osteon

Haversion canal/central canal. contains blood vessels and nerve fibers that nourish the osteon (to get to the osteocytes, canaliculi branch to it through the lacuna)

Volkmann/perforating canal

run perpendicular to the Haversion canals. allows for connections to run all the way from the periosteum (outside) to central canals, to medullary cavity

where is compact bone usually found?

diaphysis. In 80% of skeleton, crucial for resisting stress. Also a layer around the epiphysis to protect the spongy bone

proximal epiphysis

closest point of attachment, closest to shoulder or hip joints. identifiable by that ball that sticks out, goes into the glenoid cavity

distal epiphysis

farthest from point of attachment

what is found at both epiphyses to articulate

articular cartilage, made of hyaline. this is to stop friction of bones rubbing together when they're connected

where is red bone marrow found (in relation to the long bone)

at the epiphysis, but also a small bit on the outside of the medullary cavity. it will be found in between the spaces of the trabeculae (spongy bone)

epiphyseal plate

where your bone will grow as it gets longer. made of hyaline cartilage.

-once fully grown, you can see the epiphyseal line, which is a remnant of the plate

yellow bone marrow

fills the medullary cavity within the diaphysis. stores fat and nutrients

medullary cavity

hollow space inside the diaphysis, but is filled with yellow bone marrow. contains red marrow until around 6/7

Periosteum

outer layer of bone material. it is a covering of dense CT, and helps repair the bone (bc osteoblasts line it)

• perforating (Sharpey’s) fibers secure periosteum to underlying bone

endosteum

the inner layer, kinda lines the medullary cavity and is made of CT. if the compact bone needs to grow thicker, it deposits new bone material along the endosteum

ossification

process of bone formation

for this class, what is the way (long bone) grows and develops?

endochondral ossification

what are the 2 major phases of ossification in long bones

• osteoblasts cover the cartilage model and form the bone matrix

• the cartilage is covered by bone, and the cartilage starts to break down to eventually form the medullary cavity

endochondral ossification- or long bone formation in an embryo, fetus, and young child

1) hyaline cartilage model is made for future bones

2) as cartilage degenerate, a calcified periosteum form around the cartilage. blood is located on the sides, so that a bony collar can be made

3) (now fetus) blood penetrates into the empty spaces left by the degeneration of the chondrocytes. bones starts to get made on the inside. note that the blood carries osteoblasts and osteoclasts. you first start making bone in the diaphysis, around the area of where the medullary cavity will be.

4) blood penetrates into the epiphysis and creates spongy bone

5) note that as the child grows, the medullary cavity will cut using osteoclasts to make the middle bigger and grown appositionally using osteoblasts

5) the space between spongy bone compact bone of the diaphysis is the epiphyseal plate, and once the 2 meet, it all becomes bone

how do bones grow like upwards when a person is a child?

• cartilage is constantly formed on the epiphyseal plate and on the articular cartilage

• old cartilage constantly broken down and replaced by bony matrix

bone resorption

osteoclasts break down bone, take away calcium

bone deposition

osteoblasts form new bone

how is a bone remodeled and have appositional growth?

• appositional growth: outwards bone growth

• osteoblasts in periosteum add bone matrix to outside of diaphysis

• osteoclasts inside, in endosteum remove bone from it

basically, just changes the proportions, just reshaping

what controls bone growth?

hormones

what are the 2 reasons why bone would ever need to be remodeled (breaking down or building up)

• blood calcium level

• break a bone

Vitamin D

necessary for absorption of calcium

how is the axial skeleton divided into 3 ways?

skull, vertebral column, and bony thorax

what are parasinuses and what do they do?

they’re hollow portions of bone around the nasal cavity that lighten the skull and amplify sound

what are examples of paranasal sinuses?

frontal, ethmoid, sphenoid, maxillary

primary curvatures

curve outwards, a c-shape. is the thoracic and sacrum and the shape is present at birth, like developed first

secondary curvatures

curves that are develop after birth, go inwards and point anteriorly. includes the cervical and lumbar region

bony thorax

is the thoracic cage, which is the sternum, ribs, and the thoracic vertebrae

what parts make up the appendicular skeleton?

limbs, pectoral girdle, and pelvic girdle

shoulder/pectoral girdle

composed of clavicle and scapula. very weak girdle

pelvic girdle

• formed by 2 coxal (hip) bones, which formed by 3 pairs of fused bones: the ilium, ischium, and the pubis.

• the girdle also includes the sacrum

what does the pelvis include?

same as pelvic girdle, but also includes the coccyx

what functions does the pelvic girdle have

• holds weight of body

• protects organs

arches of feet

• the 2 longitudinal arches run front to back. medial and lateral

• transverse arch goes across

• bones usually form those arches, but if any of them are fallen it can result in flat feet

what do bones start out as?

-long bones r hyaline cartilage

-flat bones r fibrous membranes

growth of cranium and in relationship to body

• growth related to brain growth

• 2 yrs: skull is ¾ size of adult skull

• 8 or 9: skull is near adult in size and proportion

• 6 through 11: face grows out from the skull

skeletal changes

• at birth, head and trunk are proportionately longer than limbs

• during puberty, the female pelvis broadens, while the male skeleton becomes robust

osteoporosis

loss of bone density, bones become very brittle. due to low intake of dietary calcium, lack of physical activity, and decrease of blood estrogen in females

• affects mainly women, 50% of women over 65

• still affects men, 20% over 70