Skeleton System

support by carrying the weight of the body

protection of organs

assist in movement along with the muscular system

mineral homeostasis by controlling blood levels of calcium and phosphorus

blood cell production (hemopoeisis)

triglyceride storage

bones that are longer than they are wide

tibia

bones that are equally long and wide

wrist bones

bones that are thin, broad and commonly curved

skull bones

bones that do not fit into any other category

vertebrae

specialized bones found within tendons

patella

nerves, blood vessels and cartilage

major structural and supportive connective tissue in the body

the bone tissue

yellow is for fat storage

red is the site of blood cell production

also called cortical bone

solid and relatively dense external surface of all bones

also called trabecular bone, main feature is trabeculae

contains no osteons or central canal

makes up most of smaller bones and epiphysis of long bones

found where stress comes from many directions

resembles a sponge and is the internal surface of bones

proximal portion of a bone

region of bone growth (upwards)

shaft or middle portion of a bone

consists of osteogenic cells

consists of dense, irregular connective tissue

where bone meets another bone

can be facets, fovea, fossa or a groove (sulcus)

allow blood vessels, nerves or something else to pass through

can be a canal, fissure, foramen or fenestra

attachment of muscles, tendons and ligaments

can be a condyle, crest, head, tubercle, tuberosity, process, spine, trochanter or protuberance

mitotically active stem cells that are found in periosteum

differentiate into osteoblasts

secrete the bone matrix and initiate calcification

mature bone cells that have developed from osteoblasts

occupy lacunae and maintain the matrix

giant, multinucleated cells related to macrophages

breaks down the bone matrix

regulates and forms new bone cells

most important for disease repair

1/3 organic compounds of cells, collagen and ground substances

2/3 inorganic compound of hydroxyapatite

one or more depending on the bone and supply most of the diaphysis

can be periosteal, metaphyseal or epiphyseal

called ossification

either intramembranous or endochondral

when bone develops within a membrane

starts off as mesenchyme cells into osteogenic cells and than osteoblasts

osteoblasts secrete osteoid and are trapped within newly formed bone

form trabeculae surrounded by periosteum in flat sheets

bone develops from hyaline cartilage

6 stages

fetal hyaline cartilage model develops and grows as chondrocytes divide

cartilage calcifies and bone collar forms

cavity forms within the cartilage model

nutrient artery penetrates , delivering osteogenic cells and osteoclasts

the primary ossification center forms

bone replaces all cartilage except articular cartilage

secondary ossification in epiphysis forms

nutrient artery penetrates into the primary ossification centre

area of continued growth

5 zones

first area of the epiphyseal plate

nothing occurs here

second area of the epiphyseal plate

actively divides chondrocytes

third area of the epiphyseal plate

chondrocytes die

fourth area of the epiphyseal plate

where the matrix becomes calcified

last area of the epiphyseal plate

osteoblasts lay down bone

growth at the epiphyseal plates responsible for bones increasing in length

osteoblasts lay down new bone under the periosteum to increase the diameter of bone

protects the brain and sense organs

sites of muscle attachment

8 cranial bones

14 facial bones

has four sutures

2 bones

back of the head

has the foramen magnum and occipital condyles

in the tympanic and mastoid regions

2 bones

forehead and upper part of the eye socket

where the pituitary gland is and the optic nerve passes

where the cribriform plate and nasal septum is

at birth there are six spots to allow the baby to pass through the birth canal easier

anterior fontanelle normally closes in 15 months

2 bones that form the bridge of the nose

2 bones that form the cheekbones

2 bones

upper jawbone that is connected to all other bones of the face

lower jaw

only moveable skull bone

part of the nasal septum

2 bones apart of the palate

2 smallest facial bones

medial part of the orbit that the tear ducts pass through

2 bones

nasal cavity and surface lind by olfactory epithelium

high metabolic rates require rapid digestion

palate enables chewing and breathing at the same time

doesn't articulate with any other bone and is maintained by ligaments

supports the tongue and is involved in swallowing

starts off as 33 bones and fuses into 26 bones

provides a flexible rod that aids in movement and protects the spinal cord

neck area (C1-C7)

attached to pairs of ribs (T1-T12)

largest and strongest region (L1-L5)

attached to the pelvis (S1-S5)

last region of the vertebral column (Co1-Co4)

starts with the thoracic vertebrae to better distribute body weight

cervical region develops for crawlings

lumbar and sacral region forms to hold up the head and start to walk

hunchback

excessive anterior curvature in thoracic region

excessive posterior curvature in lumbar region

vertebral column curves laterally

first cervical vertebrae that is specialized

supports the head and allows it to move up and down

lacks a body and spinous process

second cervical vertebrae that is specialized

has an odontoid process

allows for side to side movement of the head

have a typical vertebral structure

foramen transversarium

larger and stronger than cervical vertebrae

have a longer transverse process to articulate with the ribs

largest and strongest vertebrae

have short and thick processes

formed by the fusion of five vertebrae

attached to the pelvic girdle and hips

formed by the fusion of four vertebrae

tip

sit between adjacent vertebrae

cushion and absorb physical shock

facilitates movement

resists grinding between bones

when intervertebral discs bulge laterally

pain is caused by a nucleus pressing against a nerve

flat bone that articulates with the ribs

3 parts

top portion of the sternum

articulates with the pectoral girdle and first ribs

articulates with 2-7 ribs

bottom portion of the sternum

attachment for some abdominal muscles

12 pairs that articulate with 12 thoracic vertebrae

3 types

ribs 1-7 that connect directly through the intercostal cartilage

ribs 8-12 that attach indirectly or not at all to the sternum

ribs 11 and 12 that don't attach to the sternum

attaches bones of upper limbs to the axial skeleton

2 bones that make up the shoulder

articulates with the manubrium (sternal end) and scapula (acromial end)

apart of the pectoral girdle

provide an attachment site for muscles, acts as braces and transmits forces to the axial skeleton

not directly connected to the vertebral column

apart of the pectoral girdle

thin, triangular flat bones

only bone of the arm

radius and ulna forms the elbow, articulate with each other at both end

olecranon prevents hyperextension

thin at proximal end

8 carpals, marble-sized bones

5 metacarpals, palm of the hand

3 phalanges per finger except thumb, distal, middle and proximal

differs from the pectoral girdle as it connects directly to the vertebral column

3 bones on each side that are fused together and come together at the acetabulum

superior region of the pelvis that connects to the sacrum

anterior region of the pelvis that joins at the pubis synphysis

posterior region of the pelvis

"sit bones"

bones are thicker and heavier in males

female pelvic inlet is wider and the subpubic angle is wider

bony basin inferior to pelvic brim containing the pelvic organs

part of the colon, rectum, bladder, uterus/ovaries

superior to pelvic brim bound by the ilia laterally and abdominal wall anteriorly

intestines and muscle attachment sites