The Skeletal System
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- What are the functions of bones?
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support and protection
body movement
blood cell formation
storage of inorganic salts - How do bones support and protect?
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bones give shape to structures such as the head, rib cage and pelvic girdle
they support the body's weight - How do bones help the body move?
- skeletal muscles attached to bones by tendons, use the bones as levers to move body parts
- How do bones help blood cell formation?
- blood cells are formed within the bone marrow
- What is hematopoiesis?
- the process by which blood cells are formed
- What is red marrow?
- where red blood cells, white blood cells and platelets are formed
- What is another name for red blood cells?
- erythrocytes
- What is another name for white blood cells?
- leukocytes
- What is another name for platelets?
- thrombocytes
- What does yellow marrow do?
- stores fat
- What inorganic salts do bones store?
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calcium
potassium
sodium
magnesium - Why is calcium the most important inorganic salt? when calcium is low what do the bones do? when calcium is high what do the bones do?
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it's important because it helps to make bones strong
when it's low osteoclast is stimulated to break down bones
when it's high osteoblast is stimulated to build bones by storing calcium - How are bones classified?
- according to their size and shape
- What are some examples of long bones?
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femur
humerus - What is an example of short bones?
- carpals
- What are some examples of flat bones?
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the skull
pelvic - What are the two major parts of the long bone?
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epiphysis
diaphysis - where is the epiphysis (spongy bone)located and what is covering it?
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located at the end of the bone
the outer surface is covered with a layer of hyaline cartilage called articular cartilage - What is another name for the diaphysis (compact bone)? What does it consist of?
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the shaft
it's covered with a tough layer of fibrous tissue called the periosteum. it also consists of a hollow chamber called the medullary cavity which is filled with marrow - What are 2 microscopic structures?
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osteocytes
blood vessels - What are osteocytes?
- mature bone cells
- Where are blood vessels and what do they do?
- located throughout the bone, nourishes blood cells
- When is bone built?
- when osteocytes arrange themselves in circles called osteons. the middle of each osteon is called the osteonic canal. this is where blood vessels and nerves are located.
- How do bones form?
- by replacing existing connective tissues in 2 ways (intramembraneous and endochondral bones)
- What are intramembraneous bones?
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bones that are formed from fibrous membrane
this includes the flat bones of the skull - What are the steps of intramembraneous bone formation?
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step 1- the fibrous tissue cells differenciate into osteoblast. the osteoblast deposits a bony matrix around themselves
step 2- as the cells accumulate, spongy bone tissue is formed in all directions
step 3- a layer of tissue condenses on the outside of the fibrous membrane, which forms the periosteum
step 4- osteoblast on the inside of the periosteum forms a layer of compact bone over the layers of spongy bone - What is ossification?
- when bone is formed from pre-existing tissues
- What does the vascular tissue in spongy bone turn into?
- red marrow
- What are endochondral bones?
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bones that are formed from hyaline cartilage
forms most bones of the skeleton - What are the steps of the endochondral bone formation?
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step 1- the osteoblast forms the periosteum on the outside of the hyaline cartilage
step 2- osteoblasts and blood vessels from the periosteum invades the hyaline cartilage and form spongy bone in the center. this is called the primary ossification center
step 3- osteoclast breaks down the newly formed spongy bone to form the medullary cavity
step 4- the osteoblasts from the periosteum deposit a layer of bone between the medullary cavity and the periosteum
step 5- a secondary ossification center appears in the epiphysis, spongy bone is formed in all directions - What is a bond of cartilage called and where is it located?
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epiphyseal disk or growth plate
remains between the diaphysis and the epiphysis - What happens when the bone gets longer?
- the cells of the epiphyseal disk grow, divide and thickens
- What are the 2 major portions of the skeleton?
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axial skeleton
appendicular skeleton - What makes up the axial skeleton?
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the skull
hyoid bone
vertebral column
thoracic cage - What are the 2 sets of bones in the skull?
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cranial bones
facial bones - How many bones are in the skull? how many cranial bones? how many facial bones?
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22 bones
8 cranial
14 facial - What is the skull's function?
- protects the brain and sensory organs
- What is the function of the cranium?
- it encloses and protects the brain and provides attachments for muscles
- What are the 8 bones of the cranium?
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1 frontal bone
2 parietal bones
1 occipital bone
2 temporal bones
1 sphenoid bone
1 ethmoid bone - What is the frontal bone?
- the bone that forms the forehead of the skull
- What are the parietal bones?
- the bones that form each side of the skull
- What is the occipital bone?
- the bone that forms the back of the skull
- What are the temporal bones?
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the bones on each side of the skull by the ear
they serve as attachments for muscles - What is the sphenoid bone?
- the large bone located at the bottom of the cranium
- What is the ethmoid bone?
- it's the small bone located in front of the sphenoid bone aka crista galli because it's shaped like a cock's comb
- What are sutures?
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immovable joints
the areas where bones come together or meet - What are the names of the sutures?
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coronal
saggital
lambdoidal
squamous - Where is the coronal suture?
- where the parietal bones meet the frontal bone
- Where is the saggital suture?
- where the two parietal bones meet
- Where is the lambdoidal suture?
- where the parietal bones meet the occipital bone
- Where is the squamous suture?
- where the parietal bones and temporal bones meet
- What is the function of the facial bones?
- these bones form the shape of the face and provide attachments for muscles
- What is the keystone bone of the face?
- maxillae
- What is the keystone bone of the cranium?
- sphenoid
- What is the maxillae?
- bones that form the upper jaw
- What is the mandible?
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a u-shaped bone that forms the lower jaw
largest, strongest facial bone - What is the coronoid process?
- serves as attachment for the temporalis
- What are the palatine bones?
- L-shaped bones that help to form the hard palate
- What are the zygomatic bones?
- cheek bones that help to form the lateral walls and floors of the orbits
- What are the lacrimal bones?
- finger nail shaped bones that articulate with the frontal bone superiorly, posteriorly with the ethmoid and anteriorly with the maxillae
- What are the nasal bones?
- rectangular shaped bones that fuse medially to form the bridge of the nose
- What is the vomer bone?
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a slender plow shaped bone located in the middle of the nasal cavity
it joins the ethmoid bone to form the nasal septum - What is the inferior nasal conchae?
- a thin scroll shaped bone that is attached to the lateral walls of the nasal cavity
- Where is the vertebral column? what is it's function? what separates the vertebrae?
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extends from the skull to the pelvis
protects the spinal cord
separated by intervertebral disks - What does a typical vertebra consist of?
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a body and bony vertebral arch, which surrounds the spinal cord
notches on the upper and lower surfaces provide intervertebral foramina through which spinal nerves pass - In a cervical vertebrae what do transverse processes bear? what is the first vertebra called and what does it do? what is the second vertebra called? what do dens do?
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transverse formina
the atlas supports and balances the head
the axis
provides a pivot for the atlas when the head is turned from side to side - Compare the size of the thoracic vertebrae and the cervical vertebrae. What do the facets on the sides articulate with?
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thoracic is larger than the cervical
the ribs - What are lumbar vertebrae and what are their function?
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large and strong
they support more body weight that any other vertebrae - What is the sacrum? What forms the sacral canal?
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a triangular structure formed of 5 fused vertebrae
vertebral formina - What is the coccyx composed of and where is it located? What is it's purpose?
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4 fused vertebrae
forms the lowest part of the vertebral column
it acts as a shock absorber when a person sits - What does the thoracic cage include and what is it's function?
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the ribs, thoracic vertebrae, sternum and costal cartilages
it supports the pectoral girdle and upper limbs, protects the viscera, and functions in breathing - How many pairs of ribs are there? What are true ribs joined to? What are false ribs joined to? What does a typical rib include?
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12 pairs attached to the 12 thoracic vertebrae
costal cartilages join the sternum directly
costal cartilages join the sternum indirectly or not at all
a shaft, a head, and tubercles that articulate with the vertebrae - What does the sternum consist of and what does it articulate with?
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a manubrium, body, and xiphoid process
the clavicles - What is another name for the pectoral girdle?
- the shoulder
- What does the pectoral girdle consist of? What does it form? What does it provide?
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2 clavicles and 2 scapulae
it forms an incomplete ring that supports the upper limbs
it provides attachment for muscles that move the arms, chest and back - What is another name for clavicles and what are they?
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collar bones
slender, rodlike bones that extend horizontally across the upper thorax - What is another name for scapulae and what are they? What does it articulate with?
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shoulder blades
broad triangular bones located on either side of the upper back
the humerus bone - What do the upper limbs include? What does it provide?
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includes the bones of the arm
(humerus), forearm (radius and ulna) and hands
provides attachments for muscles, also function as levers - What is the humerus and what does it articulate with?
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the largest and longest bone of the upper limbs
it articulates with the glenoid cavity - What is the radius and ulna?
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the two bones that form the forearm
the ulna is longer and more slender - What is the hand composed of?
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8 carpal bones (wrist)
5 metacarpals (palm)
14 phalanges (fingers) - What does the pelvic girdle and what is it's function?
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it consists of 2 coxal bones that articulate with each other anteriorly and with the sacrum posteriorly
it supports the trunk of the body, provides attachments for the lower limbs, and protects the urinary bladder, the distal end of the large intestine, and they internal reproductive organs - What forms the bowl shaped pelvis? What does each coxal bone consist of?
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the sacrum, coccyx, and pelvic girdle
an illium, ischium, and pubis, which are fused in the region of the acetabulum - What is the illium?
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it is the largest portion of the coxal bone
it joins the sacrum at the sacroiliac joint - What is the ischium?
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the lowest portion of the coxal bone
it supports body weight when sitting - What is the pubis?
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the anterior portion of the coxal bone
it's bones are fused anteriorly at the symphysis pubis - What do the bones of the lower limbs provide?
- frameworks of the thigh (femur), leg (tibia and fibula), and foot
- What is the femur?
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it extends from the hip to the knee
the patella articulates with the femur's anterior surface - What is the tibia?
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it is located on the medial side of the leg
it articulates with the talus of the ankle - What is the fibula?
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it is located on the lateral side of the tibia
it articulates with the ankle but does not bear body weight - What is the foot?
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it consists of an ankle, an instep, and 5 toes
it includes 7 tarsal bones that form the tarsus, 5 metatarsal bones, and 14 phalanges
the tarsal bones or tarsus can move freely