exam 3 Flashcards
What does the term foramen mean?
an opening in the bone
What does the term fossa mean?
a shallow depression in the bone
What does the term process mean?
an extension from the bone, usually for muscle attachment
What does the term canal mean?
a narrow passageway through the bone
What does the term alveolus/alveoli mean?
a pit or socket
What does the term sinus mean?
a hollow cavity inside a bone that lessens its weight
What does the term head mean?
a rounded, ball-shaped portion of bone
What does the term tubercle mean?
a rough area like a bulge/bump, usually for muscle attachment
What does the term tuberosity mean?
a rough ridge for muscle attachment
What does the term condyle mean?
a smooth surface that rocks back & forth
What does the term meatus mean?
a passageway or canal
What does the term suture mean?
an immovable joint between 2 bones
What is the skeletal system?
includes bones (206 in adults, more in children), ligaments that connect bone-to-bone, & cartilages; all are made of connective tissue
What are the 2 groups of bones?
axial skeleton & appendicular skeleton
What is the axial skeleton?
along the central axis of the body; includes ribs, sternum, vertebrae, skull/cranial bones, & auditory ossicles
What is the appendicular skeleton?
includes appendages (arms & legs) and girdles (bones that anchor arms & legs to torso)
What are the 2 types of girdles?
pectoral & pelvic
What is the pectoral girdle?
collar bone (clavicle) & shoulder blade (scapula)
What is the pelvic girdle?
2 hip bones (os coxa)
What tissue are bones made of?
connective (cells scattered apart in abundant extracellular matrix)
What is bone matrix?
hard; made of 2 main components which are hydroxyapatite & collagen
What is hydroxyapatite?
contains Ca++ that is very hard & strong yet brittle
What is collagen?
a flexible protein that gives bone matrix slight flexibility to prevent it from shattering
What are the different types of cells found in bone?
osteoblasts, osteocytes, osteoprogenitors, & osteoclasts
What are osteoblasts?
cells that secrete bone matrix; as matrix flows around them, they become trapped and change into osteocytes
What are osteocytes?
osteoblasts trapped in matrix; these cells reside in oval-shaped spaces called lacunae
What are osteoprogenitors?
cells that become osteoblasts when matured
What are osteoclasts?
large, multinucleate cells that release enzymes that dissolve bone matrix for 2 reasons
What are the 2 reasons that osteoclasts dissolve bone matrix?
to remodel the bone’s structure & release Ca++ from the bone to help keep blood calcium levels within normal range
One of bone’s main functions is to act as a “Ca++ bank,” what are the different roles of this process?
osteoblasts deposit Ca++, osteoclasts withdraw Ca++, & hydroxyapatite is the bank that stores Ca++; this process is controlled hormonally
What is osteoporosis?
results from too much calcium being withdrawn, making the matrix weak
What are the different shapes of bone?
flat, long, short, sesamoid, irregular, & Wormian/sutural
What are flat bones?
found in skull, sternum, scapula, os coxa; site of hematopoiesis
What is hematopoiesis?
site of blood cell formation; major bone function
What is erythropoietin?
a hormone that controls hematopoiesis; released by the kidneys
What are long bones?
longer than they are wide; have specific internal anatomy & lots of features/parts; include femur, humerus, radius, ulna, fingers, toes, etc.
What are short bones?
cube-shaped; absorb or transfer force; includes ankle & wrist bones
What are sesamoid bones?
smooth & seed-shaped; includes the patella
What are irregular bones?
oddly shaped & do not fit into any other categories; includes vertebrae & some facial bones
What are Wormian/sutural bones?
tiny bone chips found in the skull where 2 bones meet; vary in size, number, & position
In what 2 ways can bone cells be arranged?
compact bone or spongy/cancellous bone
What type of bone looks solid which provides strength to bear weight?
compact bone
What is compact bone made of?
cylinders of bone called osteons with an opening in the center called the central canal for passage of blood vessels & nerves
What are the walls of an osteon made of?
rings of matrix called lamellae arranged in concentrix fashion; along the lamellae, there are osteocytes inside lacunae
What are perforating canals?
they connect with the central canal to form passageways for blood vessels to reach all areas of the osteon
What are canaliculi?
tiny cracks that form around the lacunae to act as passageways for nutrients & waste to enter/exit the osteocyte
What are interstitial lamellae?
they fill in the gaps between multiple osteons & cement them together to add strength
What bones does compact bone travel the length of?
long bones; it provides strength & structure & acts as a lever for motion
What type of bone looks poorly organized but is not?
spongy/cancellous bone
What is spongy bone made of?
osteocytes inside lacunae arranged in a fashion that forms needle-like pieces of bone called trabeculae
What is spongy bone made to do?
to withstand force of muscle action & it changes based on muscular activity
Where can spongy bone be found?
at ends of long bones; abundant in flat bones where it produces blood cells & acts as a cushion for protection
What is red bone marrow?
the site of hematopoiesis; found between the trabeculae of spongy bone
What are the functions of bone?
allows movement by permitting leverage, protects delicate internal organs, provides strength, blood cell production, and stores Ca++ & allows for its withdrawal when needed
What are the possible arrangements for compact & spongy bone?
diploe bone structure & long bone structure
What is the diploe bone structure?
“spongy bone sandwich” = a layer of spongy bone located between 2 layers of compact bone; used to protect from injury & act as a shock absorber
What is the long bone structure?
found only in long bones; made of specific parts
What are epiphyses?
the ends of a long bone
What is the diaphysis?
shaft of a long bone
What is the metaphysis?
narrow zone which is the zone of growth in length of immature bones
What is articular cartilage?
narrow “cap” of hyaline cartilage (smooth, slick, glassy white connective tissue) which provides a slick surface for movement
What are characteristics of the matrix of hyaline cartilage?
sturdy but slightly flexible; contains glucosamine, chondrotin, & hyaluronic acid
What are the 2 types of bone membranes?
endosteum & periosteum
What is the endosteum?
thin membrane that comes from blood vessel walls; found inside the marrow cavity & between trabeculae of spongy bone
What is the periosteum?
superficial membrane made of 2 portions
What are the 2 portions of the periosteum?
osteogenic & fibrous
What is the osteogenic portion?
deeper layer of the periosteum; contains osteoblasts, osteoprogenitors, & osteoclasts; acts to increase bone size in diameter
What is the fibrous portion?
very tough fibrous connective tissue that fuses into muscles’ tendons
What are Sharpey’s fibers?
small, short tufts of fibers that tightly hold the periosteum onto the bone
What is the marrow cavity?
filled with yellow bone marrow; in healthy adults, this is mostly fat
What is the epiphyseal plate/growth plate?
area in or near metaphyses & is made of cartilage that pushes the diaphysis & epiphyses apart as it develops; made of 4 zones
What are the 4 zones of the epiphyseal plate?
zone of resting cartilage, zone of proliferation, zone of hypertrophy, & zone of calcified cartilage
What is the zone of resting cartilage?
anchors plate onto bone
What is the zone of proliferation?
made of rapidly dividing cartilage cells; increases number of cells in the growth plate
What is the zone of hypertrophy?
where newly formed cartilage cells increase in size
What is the zone of calcified cartilage?
Ca++ is added to matrix to change it into bone matrix; represents newest part of bone
What happens to the epiphyseal plate as bones reach maturity?
it becomes inactive; at that point, it is known as the epiphyseal line
What is the last bone to ossify?
the clavicle (collar bone)
At what age do bones fully mature in men & women?
men= 25ish; women= 21ish
What are the nutrient foramina?
small openings in the bone where blood vessels & nerves penetrate; they are scattered along the bone, but concentrated in & near the epiphyses
What are the 2 processes through which bone can be formed?
interosseus formation & endochondral ossification
What is interosseus formation?
forms flat bones
What is endochondral ossification?
forms long bones
At conception, nuclei of sperm & egg fuse to form what?
a 1-cell embryo which undergoes rapid cell division
What is a morula?
a solid ball of cells where the DNA can result in the formation of any type of tissue
What are mesenchyme cells?
the stem cells from the morula that become connective tissue; some of these will become bone
What do mesenchyme cells do as they migrate through the embryo?
assemble at the proper location & in the proper shape of the future bone
What are chondroblasts?
some mesenchyme cells specialize into these; they secrete hyaline cartilage matrix
How does the cartilage matrix receive nutrients & remove wastes?
it is avascular, so diffusion supplies nutrients & removes waste from chondroblasts & chondrocytes
What are chondrocytes?
chondroblasts that have become trapped in matrix; they reside in small oval-shaped spaces called lacunae
What do the cartilage cells form?
a tiny “bone model” (not actually bone — just cartilage)
What is the perichondrium?
a membrane that covers the cartilage bone model; this membrane is penetrated by blood vessels
Once the perichondrium is formed, how are nutrients delivered throughout the cartilage matrix?
the blood vessels in the perichondrium deliver nutrients to the cartilage & diffusion carries these nutrients to the lacunae & cells
As the cartilage bone model increases in size, what happens to the cells in the center?
they die & disintegrate from not receiving adequate nutrients; this leaves a hole in the center which becomes the marrow cavity
What occurs simultaneously as the marrow cavity is formed?
Ca++ enters the matrix through the blood vessels at the perichondrium; this causes the previously flexible matrix to harden; bone cells also flow into this region
What is the bone collar?
a ring of matrix surrounding the periosteum; formed by osteoblasts; this structure prevents nutrient diffusion
Now that blood vessels can pass through the matrix of the model, what happens?
more osteoprogenitors are allowed to enter; they become osteoblasts which later become osteocytes
Ca++ & bone cells enter the cartilage matrix & the bone collar is formed allowing even more bone cells inside. What do these processes do?
they replace the cartilage bone model with bone; this forms the long bone’s diaphysis, but the epiphyseal plate is still active
How is the endosteum formed?
some blood vessels penetrate the marrow cavity & the walls of these blood vessels become this membrane
In embryos & very young children, hematopoiesis can occur in a place that it cannot in adults. Where?
the endosteum/marrow cavity; at this stage, this is red bone marrow which will later become yellow bone marrow & can no longer produce blood cells
What phenomenon can occur in cases of extreme anemia in adults?
the yellow bone marrow can revert back to red bone marrow for blood cell production
Where does bone growth in length take place?
at the epiphyseal plate
What does appositional bone growth (in width) take place?
at osteogenic portion of the periosteum
What does bone growth require?
proper minerals, vitamin C, vitamin D, vitamin A, & specific hormones
What are the proper minerals that are used to form the matrix (hydroxyapatite) ?
calcium ions, phosphorus, flouride, & iron
Why is vitamin C required for bone growth?
it manufactures collagen
Why is vitamin D required for bone growth?
it absorbs Ca++ from the gastrointestinal tract
Why is vitamin A required for bone growth?
it stimulates osteoblasts
What hormones are required for bone growth?
thyroid hormone, estrogen, testosterone, insulin-like growth factor, & growth hormone
What does the thyroid hormone do?
stimulates osteoblasts
What do estrogen & testosterone do?
stimulate osteoblasts
What does insulin-like growth factor do?
stimulates cell division at the epiphyseal plate
What does growth hormone do?
causes liver to release insulin-like growth factor; released from pituitary gland
What is the normal blood Ca++ levels?
9-11 mg Ca++ per 100 mL of blood
What happens when blood Ca++ levels are too high?
heart rhythm is affected
What happens when blood Ca++ levels are too low?
breathing is compromised
Blood Ca++ levels are controlled hormonally by what?
PTH (parathyroid hormones) & calcitonin
PTH (parathyroid hormones) act to increase blood Ca++ levels. How?
increase osteoclast action, increase g.i. absorption of Ca++, & decrease amount of Ca++ excreted in urine (kidneys)
What are parathyroid glands?
small, round glands on the posterior side of the thyroid gland; they release PTH
Calcitonin is released by the thyroid gland & acts to decrease blood Ca++ levels. How?
increases osteoblast activity & decreases osteoclast activity
What is the thyroid gland?
it is butterfly-shaped & on the anterior side of the voice box
What are articulations?
joints; where 2 bones meet; classified by the range of motion (ROM)
What is a synarthrosis?
articulation that allows little to no movement; includes synostoses, sutures, gomphoses, & synchondroses
What is a synostosis?
2 bones fuse into 1 bone
What is a suture?
2 bones fit together closely like a puzzle with many tiny ligaments that lock the bones together
What is a gomphosis?
connects root of tooth into socket (alveolus); holds the tooth securely in place using the periodontal ligament
What is a synchondrosis in a synarthrotic joint?
2 bones are held together by a bridge of rigid cartilage; ex. = 1st rib + sternum & 2nd rib + sternum
What is an amphiarthrosis?
articulation that allows slight movement; includes synchondrosis & syndesmosis
What is a synchondrosis in an amphiarthrotic joint?
2 bones are joined by a pad of fibrocartilage; these cushion the bones, space the bones apart at a proper distance, & allow movement; ex. = intervertebral disks
What is a syndesmosis?
long sheet-like ligament that holds bones together but allows motion; ex. = interosseus membrane
What is a diarthrosis?
articulation that is freely moving with the greatest ROM; it has a complex anatomy with a lot of parts
What parts are included in a diarthrotic joint?
joint capsule, ligaments, & tendons
What parts may be in a diarthrotic joint but not always?
meniscus, bursae, & tendon sheath
What is the joint capsule?
where the periosteum of 1 bone extends like a sleeve to adjacent bone; this space is filled with synovial fluid
What is synovial fluid?
clear, watery, & slick which allows smooth motion, decreases friction, distributes nutrients, & removes waste
What are ligaments?
tough bands of connective tissue that join adjacent bones
What are tendons?
tough bands of connective tissue that attach muscle to bone
What is a meniscus?
a pad of fibrocartilage that cushions the ends of bones
What are bursae?
sacks of fluid that cushion the ends of bones
What is a tendon sheath?
a tubular bursa that surrounds tendons, nerves, & sometimes blood vessels
What is flexion?
decreasing the angle on the anterior/posterior plane
What is extension?
increasing the angle on the anterior/posterior plane
What is hyperextension?
increasing the angle on the anterior/posterior plane to greater than 180°
What is lateral flexion?
decreasing the angle between head & vertebra on a lateral plane
What is lateral extension?
increasing the angle between head & vertebra on a lateral plane
What is dorsiflexion?
lifting toes off the ground
What is plantarflexion?
lifting heel off the ground
What is abduction?
moving away from the body’s midline
What is adduction?
moving toward the body’s midline
What is circumduction?
making a circle with the distal end of a bone
What is rotation?
turning the head left or right
What is pronation?
palm of hand turns posteriorly
What is supination?
palm of hand turns anteriorly
What is protraction?
moving a body part anteriorly in a horizontal plane
What is retraction?
reversing the protracted movement
What is opposition?
moving the thumb to the fingers
What is elevation?
raising a body part to a superior level
What is depression?
lowering a body part to an inferior level
