Guide – Bone Structure, Functions,
Joints & Anatomy (Complete Review
2026)
the _____ provides structure, support, rigidity, and protection to organs
skeletal system
_____ skeletons belong to organisms without bones, especially backbones
invertebrate
insects tend to have _____, which are skeletons on the outside of the organism
exoskeletons
_____ skeletons belong to organisms that have a backbone
vertebrate
vertebrates have _____, which are skeletons on the inside of the organism
endoskeletons
what are the two parts of human endoskeletons?
axial; appendicular skeletons
which bones are included in the axial skeleton?
bones at the core of the endoskeleton like the skull, vertebral column, and rib cage
which bones are included in the appendicular skeleton?
bones of the appendages as well as the pectoral and pelvic girdle
what are the types of bones?
long; short; flat; sesamoid; irregular
of which bone types are long bones composed?
cortical and cancellous
what are some examples of long bones?
femur; radius; ulna
what are some of the predominant structural features of long bones?
epiphyses; diaphysis; a medullary cavity; metaphyses; epiphyseal growth plates
_____ are the bumpy parts at the ends of long bones
epiphyses
_____ covers epiphyseal compact bone in synovial joints
articular cartilage
articular cartilage covers epiphyseal compact bone in _____ joints
synovial
what type of joint is formed between long bones?
synovial joints
_____ bone marrow is located in spongy trabecular bone of adults
red
hematopoiesis occurs in the _____ bone marrow of _____ bone
red; spongy trabecular
,the _____ of a long bone is the shaft between the ends
diaphysis
the _____ is the "hollow" part of the diaphysis, which contains _____ bone
marrow in adulthood
medullary cavity; yellow
_____ are found between the medullary cavity and epiphyseal plates of a long
bone
metaphyses
metaphyses have a similar structure to the _____ of a long bone
epiphyses
(structure is spongy trabecular bone)
which type of cartilage are epiphyseal plates composed of during adolescence?
hyaline cartilage
during puberty, epiphyseal plates form an epiphyseal line via _____
ossification
epiphyseal plates grow before ossification to promote _____
bone lengthening
epiphyseal plates grow toward the _____ to lengthen the _____ of a long bone
metaphyses; diaphysis
epiphyseal lines are found between long bone _____ and _____ in adults
epiphyses; metaphyses
(same holds true for epiphyseal plates in adolescents)
cartilage is _____, which makes it difficult to heal
avascular
breaking a bone at the epiphyseal plate can stunt growth because epiphyseal
plates are made of _____, which is avascular and difficult to heal
hyaline cartilage
_____ bones are cuboidal and provide support with little movement
short
short bones are primarily _____ bone covered by a thin layer of _____ bone
cancellous (spongy trabecular); cortical (dense)
what are some examples of short bones?
carpals of the wrist or tarsals of the ankle
_____ bones are thin, with outer layers of cortical bone surrounding spongy,
cancellous interiors
flat
what are some examples of flat bones?
sternum and the bones forming the skull
sesamoid bones are found in _____, and they act to increase muscle power - what
is an example of a sesamoid bone?
tendons; patella
irregular bones have _____ layers surrounding _____ interiors; however, their
shapes do not fit any other bone class
dense, cortical; spongy, cancellous
, what are some examples of irregular bones?
vertebrae; sacrum; pelvis
_____ bone is the outer layer of bones
cortical
what allows bones to support weight?
cortical bone density
what are the microstructures in cortical bone?
osteons; Haversian canals; lamella; lacunae; canaliculi; Volkmann's canals
_____ are the functional unit of cortical bone, and they appear as multi-layer
cylinders
osteons
what direction do osteons travel within cortical bone?
parallel to the bone's long axis
the layers that make-up an osteon are called _____
lamellae
_____ contain cortical bone and collagen fibers
lamellae
_____ are the central canals of an osteon
Haversian canals
Haversian canals contain blood vessels to supply nutrients to the _____ of an
osteon
osteocytes
(Haversian canals connect to osteocytes through canaliculi)
_____ are small spaces between lamellae that house bone cells
lacunae
canaliculi connect _____ and _____ of a single osteon
lacunae (housing osteocytes); Haversian canals
_____ connect adjacent Haversian systems as well as peripheral osteons to the
periosteum
Volkmann's canals
_____ bone is soft and flexible, and it is made of _____ that soak up bone marrow
like a sponge
cancellous; trabeculae
(trabecular/cancellous bone = spongy bone)
_____ are precursors to osteoblasts
osteoprogenitors
osteoblasts contain _____ nucleus
1
what is the main function of osteoblasts?
to build bone (secrete collagen + proteins that make osteoid)
_____ are mature bone cells that develop from osteoblasts
osteocytes
how do osteoblasts become osteocytes?
osteoblasts get trapped in the osteoid they secrete