Anatomy Chapter 6: The Skeletal System: Osseous Tissue
Tommy Johns surgery
Collateral ligament reconstruction; the ligament in medial elbow is replaced with a tendon from somewhere else in the body -first done in 1974 -repetitive force of pitching causes ulnar collateral ligament to tear; this surgery takes a tendon from somewhere else in the body and threads it through the humerus and ulna to replace that damaged ligament -today, 90% of patients completely recover and many pitchers even say they can pitch better, most likely because they're in less pain -33% of patients today are under 18 -problem with this surgery is that people are now looking at it as an elective procedure; high school students are electing to have it in hopes that it will make them a better pitcher -many high school pitchers are overtraining because they think that they can rely on this surgery later on
axial skeleton
includes every bone that's connected to the midline of the body
weight-bearing activities
increase mechanical stress, helping to build and retain bone mass
calcitonin
inhibits activity of osteoclasts, speeds blood Ca2+ uptake by bone, and accelerates Ca2+ deposition into bones; promotes bone formation and decreases blood Ca2+ level. -secreted by the thyroid glands parafollicular cells
osteocytes
mature bone cells; they're the main cells found in bone tissue and they're responsible for maintaining bone's daily metabolism (exchanging nutrients and wastes within the blood); they don't undergo cell division; if there is stress in an area, these cells signal osteoblasts and osteoclasts to repair bone *the ending cyte in the name of a bone cell/ any tissue cell means that the cell maintains and monitors the tissue.
skeletal system functions: assistance in movement
most muscles attach to bones; when they contract, they pull on bones to produce movement.
acetabular labrum of articular discs
Fibrocartilage rim attached to the margin of the acetabulum that enhances the depth of the acetabulum. As a result, dislocation of the femur is rare.
saddle joints
carpometacarpal joint of the thumb; functions include flexion and extension and abduction and adduction (can more side-to-side and front and back)
hormones affecting bone growth
-During childhood, the hormones most important to bone growth are the insulin‐like growth factors (IGFs), which are produced by the liver and bone tissue; IGFs stimulate osteoblasts, promote cell division at the epiphyseal plate and in the periosteum, and enhance synthesis of the proteins needed to build new bone; they're produced in response to the secretion of growth hormone (GH) from the anterior lobe of the pituitary gland. -Thyroid hormones (T3 and T4) from the thyroid gland promote bone growth by stimulating osteoblasts. -Insulin from the pancreas promotes bone growth by increasing the synthesis of bone proteins. -sex hormones: responsible for increased osteoblast activity, synthesis of bone extracellular matrix, and the sudden "growth spurt" that occurs during the teenage years; Estrogens promote changes in the skeleton that are typical of females, such as widening of the pelvis; the sex hormones shut down growth at epiphyseal (growth) plates, causing elongation of the bones to cease; typically ends earlier in females than in males due to their higher levels of estrogens.
organic & inorganic constituents of bone
-Organic constituents: collagen fibers -Inorganic Constituents: •Calcium Phosphate [Ca3(PO4)]2- most abundant •Calcium hydroxide [Ca(OH)2] •Calcium Carbonate (CaCO3) •Other trace elements: magnesium, fluoride, potassium and sulfate
elevation of blood Ca+2
-Parathyroid hormone (PTH): regulates free Ca2+concentration in blood -Bone: increases the number and activity of osteoclasts -Kidneys: decrease loss of Ca2+ in the urine, stimulates the synthesis of calcitriol (active VitD): a hormone that promotes absorption of calcium from foods in the gastrointestinal tract into the blood.
factors that affect a joint's range of motion
-Structure & shape of articulating bones -Strength & tension of the surrounding ligaments: if the tendons and ligaments themselves are tight, that will reduce the flexibility of the joint -Arrangement of tendons across the joint; anytime muscles contract (shorten) tendons tighten, which reduces joint range of motion -Contact of soft pads: the more soft tissue you have, the less range of motion you have -Hormones: Relaxin is secreted by females when pregnant and this hormone can make all your joints more flexible -Disuse: if you don't use the joint, it loses flexibility
vitamins affecting bone growth
-Vitamin A stimulates activity of osteoblasts. -Vitamin C is needed for synthesis of collagen, the main bone protein. -As you will soon learn, vitamin D helps build bone by increasing the absorption of calcium from foods in the gastrointestinal tract into the blood. -Vitamins K and B12 are also needed for synthesis of bone proteins.
bone formation
-bone length is usually completed by 18-21 years -bones continue to thicken and are capable of repair after the epiphyseal growth plates close -tends to end earlier in females because they produce more estrogen which causes more rapid calcification of bone, thus making the epiphyseal plates close earlier. -the clavicle is the last bone to stop growing
bone scan process
-injection of a radioactive tracer (a dye) -tracer uptake is related to blood flow -MRI measures the radiation from the bone
endochondral ossification process (step-by-step)
1. Development of cartilage model: specific chemical messages cause the cells in mesenchyme to crowd together in the general shape of the future bone and then develop into chondroblasts; chondroblasts secrete cartilage extracellular matrix, producing a cartilage model consisting of hyaline cartilage; A covering: perichondrium develops around the cartilage model. 2. Growth of cartilage model: once chondroblasts are buried in extracellular matrix, they become chondrocytes. Cartilage model grows in length + width (interstitial + appositional growth). As the cartilage model continues to grow, chondrocytes in mid-region hypertrophy (increase in size) and the surrounding cartilage extracellular matrix begins to calcify. Other chondrocytes within the calcifying cartilage die b/c nutrients can't diffuse quickly enough through the extracellular matrix. 3. Development of primary ossification center: After perichondrium starts to form bone, it's known as the periosteum; periosteal capillaries grow into the disintegrating calcified cartilage, inducing growth of a primary ossification center, a region where bone tissue will replace most of the cartilage; Primary ossification spreads from this center toward both ends of the cartilage model. 4. Development of medullary cavity: As the primary ossification center grows toward the ends of the bone, osteoclasts break down some of the newly formed spongy bone trabeculae; leaves a cavity, the medullary (marrow) cavity, in the diaphysis (shaft). 5. Development of secondary ossification centers: develop usually around time of birth; branches of epiphyseal artery enter the epiphyses; similar to what occurs in primary ossification centers except bone remains in the interior of epiphyses (no medullary cavities are formed here); secondary ossification proceeds outward from the center of the epiphysis toward the outer surface of the bone. 6. Formation of articular cartilage and the epiphyseal growth plate: the hyaline cartilage that covers the epiphyses becomes the articular cartilage.
Why might someone's left arm be shorter than their right arm?
A fracture in an adolescent at the epiphyseal plate may damage the avascular cartilage and speed up calcification. Calcification is stimulated sooner by the stress of the injury to the bone which cause osteoblasts to come in and repair it.
Thalidomide
A mild tranquilizer that, taken early in pregnancy, can produce a variety of malformations of the limbs, eyes, ears, and heart; an over-the-counter drugs used to treat morning sickness between 1957 and 1961 (largely in Germany and other European countries); it was thought to impair the development of new blood vessels (nutrient artery) because it was found to increase the production of free radicals in the body, which impairs angiogenesis (production of new blood vessels) -over 10,000 babies were born with defects such as "flipper" hands and feet
bone spurs
Abnormal projections of bone, also known as osteophytes. Usually caused by increased stress on the ends of the bones; caused by too much mineral material
aging & bone tissue
As the level of sex hormones diminishes during middle age, especially in women after menopause, a decrease in bone mass occurs because bone resorption by osteoclasts outpaces bone deposition by osteoblasts; loss of bone through resorption occurs more rapidly than bone gain. -women's bones generally are smaller and less massive than men's bones to begin with, so loss of bone mass in old age typically has a greater adverse effect in females; contributes to the higher incidence of osteoporosis in females. •2 effects of aging on bone tissue -demineralization: loss of bone mass; loss of calcium and other minerals from bone extracellular matrix. -brittleness: decreased collagen synthesis; causes loss of tensile strength, which causes the bones to become very brittle and susceptible to fracture.
blood and nerve supply of bone
Bone is richly supplied with blood. -Blood vessels (especially abundant in portions of bone that contain red bone marrow) pass into the bones through the periosteum -Periostial arteries enter the diaphysis through interosteonic canals and supply the periosteum and outer part of compact bone with blood. -Nutrient artery passes through the bone through the nutrient foramen (small hole in compact bone) into the medullary cavity where it divides into proximal and distal branches; these branches supply both the inner part of compact bone tissue of the diaphysis and the spongy bone tissue and red bone marrow as far as the epiphyseal plates (or lines) with blood. -Metaphyseal arteries enter the metaphysis of a long bone and with the nutrient artery, they supply the red bone marrow and bone tissue of the metaphyses with blood. -Epiphyseal arteries enter the epiphyses of long bones and supply the red bone marrow and bone tissue of the epiphysis with blood.
bone's role in calcium homeostasis
Bone is the body's major calcium reservoir, storing 99% of total body calcium. The blood plasma level of Ca2+ is very closely regulated between 9 and 11 mg/100 mL. Plasma Ca++ homeostasis is maintained by bone resorption and deposition: -nerve and muscle cells depend on Ca2+ to function properly -Blood clotting also requires Ca2+ -Many enzymes require Ca2+ as a cofactor **Any alteration from this concentration can be fatal
exercise & bone tissue
Bone tissue remodels in response to mechanical stress, which causes an increase in strength of the bones by causing more mineral deposition and collagen fiber synthesis. -in unstressed bones, bone resorption exceeds bone deposition
interstitial growth
Chondrocytes divide and secrete new matrix, expanding cartilage from within; results in bone LENGTH increases. -the thickness of the epiphyseal growth plate remains constant; the diaphysis only increases in length
tendon sheaths
Elongated bursa wrapped completely around tendon subjected to friction; they wrap around tendons and reduce friction from other structures -can become inflamed from overuse of a joint
meniscus
Fibrocartilage that separates the articulating surfaces of bones in the knee; soft pad that gives the knee bones a better surface area to connect on -functions to improve the fit of bones, absorb shock, distribute weight bearing, and allow for movement in multiple directions. -if this becomes damaged, the knee becomes more vulnerable to arthritis.
athroscopy
Joints that have been severely damaged by diseases such as arthritis, or by injury, may be replaced surgically with artificial joints in this procedure; During the procedure, the ends of the damaged bones are removed and metal, ceramic, or plastic components are fixed in place. -Goals of this procedure are to relieve pain and increase range of motion (ROM). -the joints most commonly replaced by this procedure are the hips, knees, and shoulders.
Minerals affecting bone growth
Large amounts of calcium and phosphorus are needed while bones are growing, as are smaller amounts of magnesium, fluoride, and manganese. These minerals are also necessary during bone remodeling.
glenoid labrum of articular discs
Narrow rim of fibrocartilage around the edge of the glenoid cavity that slightly deepens and enlarges the glenoid cavity; it's shallowness allows the shoulder to move
synostosis
Some sutures, although present during growth of the skull, are replaced by bone in the adult and become known as this; becomes a bony joint—a joint in which there is a complete fusion of two separate bones into one. -these are classified as synarthroses because they're immoveable
articular cartilage of synovial joints
The bones at a synovial joint are covered by a layer of hyaline cartilage. Functions to: -reduce friction and absorb shock
synovial joints
The bones forming the joint have a synovial cavity and are united by the dense irregular connective tissue of an articular capsule, and often by accessory ligaments. -permits a greater amount of movement -majority of the joints in the human body are this type; examples include the hip, shoulder, elbow, and knee joints.
orthodontics
The movement of teeth by braces places a stress on the bone that forms the sockets that anchor the teeth. In response to this artificial stress, osteoclasts and osteoblasts remodel the sockets so that the teeth align properly. -an example of bone remodeling
appendicular skeleton
The portion of the skeleton that attaches to the axial skeleton; consists of our appendages such as the arms and legs
range of motion (ROM)
The range, measured in degrees of a circle, through which bones of a joint can be moved
cartilaginous joints
There is no synovial cavity, and the bones are held together by cartilage; 3 types of these joints: synchondroses, symphyses, and epiphyseal cartilages. -there is a small degree of movement with this type of joint -examples include the intervertebral joints, the pubic symphysis, and the joint between the manubrium and the body of the sternum.
fibrous joints
There is no synovial cavity, and the bones are held together by dense irregular connective tissue that is rich in collagen fibers. -permits little to no movement -examples include the skull joints, teeth sockets, and the distal joint between the tibia and fibula. * 3 types: sutures, syndesmoses, interosseous membrane
parathyroid hormone (PTH)
This hormone increases blood Ca2+ level and regulates Ca++ concentration in the blood. This hormone's secretion operates via a negative feedback system: The presence of higher levels of this hormone increases the number and activity of osteoclasts (effectors), which step up the pace of bone resorption. The resulting release of Ca2+ from bone into blood returns the blood Ca2+ level to normal.
torn cartilage (meniscus)
Trauma to the knee may cause tearing of the menisci; Such an injury may occur in sports such as football and rugby when the knee receives a blow from the lateral side while the foot is fixed on the ground.
skeletal system functions: blood cell production: hemopoiesis
Within certain bones, a connective tissue called red bone marrow produces red blood cells, white blood cells, and platelets
skeletal system functions: triglyceride storage
Yellow bone marrow consists mainly of adipose cells, which store triglycerides. The stored triglycerides are a potential chemical energy reserve.
osteoporosis
a condition of porous bones, affects 10 million people a year in the United States. The basic problem is that bone resorption (breakdown) outpaces bone deposition (formation); due to depletion of calcium from the body—more calcium is lost in urine, feces, and sweat than is absorbed from the diet. Bone mass becomes so depleted that bones fracture, often spontaneously, under the mechanical stresses of everyday living. Females: -demineralization begins at 30, accelerates at 45 -8% calcium loss each decade -by age 70 - 30% calcium loss Males: -demineralization begins at age 60 at a rate of 3% per decade
spina bifida
a congenital defect that occurs during early pregnancy when the spinal canal fails to close completely around the spinal cord to protect it -congenital defect of the vertebral column -L5 and S1 laminae don't unite at the midline -may result in paralysis, loss of reflexes, urinary and bowel control -associated with low levels of folic acid during pregnancy
rickets
a disease of children in which the growing bones become "soft" or rubbery and are easily deformed. The new bone formed at the epiphyseal (growth) plates fails to ossify, which commonly causes bowed legs and deformities of the skull, rib cage, and pelvis. -prevention consists of exposure to moderate amounts of sunlight and administration of vitamin D
syndesmosis
a fibrous joint in which there is a greater distance between the articulating surfaces and more dense irregular connective tissue than in a suture. The dense irregular connective tissue is typically arranged as a bundle (ligament), allowing the joint to permit limited movement. -Example: the distal tibiofibular joint, where the anterior tibiofibular ligament connects the tibia and fibula, allowing slight movement
articulation
a joint or arthrosis; the point of contact between two bones, between bone and cartilage, or between bone and teeth. They are classified structurally, based on their anatomical characteristics, and functionally, based on the type of movement they permit.
epiphyseal growth plate
a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length; the hyaline cartilage we have during adolescence; it's only visible until active longitudinal growth stops; cellular division at this plate causes elongation of the bone at each epiphysis; in adults this cartilage is ossified and becomes the epiphyseal line -consists of 4 zones
bone
a living, dynamic tissue that is continually remodeling: being broken down and replaced with new ______ -it's composed of osseous tissue, cartilage, dense connective tissue, epithelium, adipose tissue, and nervous tissue. -206 in the body; more than 1/2 are in the hands and feet -contains an abundant extracellular matrix composed of about 15% water, 30% collagen fibers, and 55% crystallized mineral salts.
autologous chondrocyte implantation
a medical procedure used to repair damaged cartilage in joints of the body; super effective for people experiencing repetitive wear and tear but not effective for people with arthritis -Step 1: isolation of healthy chondrocytes from the non-weight bearing femoral condyle -Step 2: removal of damaged cartilage, the cultured chondrocytes are injected under a "patch" sewn onto the damaged site -6 month return to activities
labrum
a piece of fibrocartilage attached to the rim of the shoulder and hip sockets that helps keep the ball of the joints in place; it increases the surface area between the articulating bones: increased surface area between articulating bones = less stress on the individual bones. -often times hip pain can be due to excessive wear and tear on this fibrocartilage
articular cartilage
a thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms a joint with another bone; reduces friction and absorbs shock and freely moving joints; lacks perichondrium and freely moving blood vessels, making repair of damage limited.
endosteum
a thin membrane that lines the medullary cavity. It contains a single layer of bone‐forming cells and a small amount of connective tissue.
periosteum
a tough connective tissue sheath and its associated blood supply that surrounds the bone surface wherever it is not covered by articular cartilage; protects the bone, assists in fracture repair, helps nourish bone tissue, and serves as an attachment point for ligaments and tendons -it's composed of dense irregular C.T. -it's highly vascularized; provides nourishment for osseous tissue -it's highly innervated -it contains osteoblasts that promote appositional bone growth (thickness)
synovial fluid
a viscous, clear or pale yellow fluid; this fluid is thicker in people who are immobile; it's an important part of synovial joints; it's secreted by synovial cells in the synovial membrane; it functions to: -reduce friction by lubrication -absorb shocks -supply oxygen and nutrients to cartilage -remove carbon dioxide and wastes from cartilage
bursitis
acute or chronic inflammation of a bursa; caused by repetitive use, trauma, or infection -Treatment: oral or injected anti-inflammatory agents
perforating fibers
aka Sharpey's fibers; think bundles of collagen that extend from the periosteum into the extracellular matrix of bone; they attach the periosteum to underlying bones
medullary cavity
aka marrow cavity; it's a hollow, cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in adults -it's highly vascularized -it minimizes the weight of long bones
articular discs
an accessory structure of synovial joints; Two fibrocartilage discs between the tibial and femoral condyles help compensate for the irregular shapes of the bones and circulate synovial fluid.
synarthrosis joint
an immovable joint; includes the sutures between the bones of the skull and the teeth sockets
growth in thickness
appositional growth: 1. Osteogenic cells beneath the periosteum differentiate into osteoblasts on either side of a periosteal blood vessel; ridges in the periosteum create a groove for the periosteal blood vessel 2. Osteoblasts mature into osteocytes which fuse together forming a tunnel enclosing the blood vessel; periosteal ridges fuse, forming an endosteum-lined tunnel 3. osteoblasts in the endosteum build new concentric lamellae inward toward the center of the tunnel, forming a new osteon 4. bone grows outward as osteoblasts in the periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessels.
how does the medullary cavity enlarge during growth in thickness?
as new bone tissue is being deposited on the outer surface of bone, the bone tissue lining the medullary cavity is destroyed by osteoclasts in the endosteum. In this way, the medullary cavity enlarges as the bone increases in thickness
structural classification of joints
based on 2 criteria: 1. the presence or absence of a space between the articulating bones, called a synovial cavity 2. the type of connective tissue that binds the bones together. -can be classified as either fibrous, cartilaginous, or synovial.
veins
blood vessels that carry blood away from long bones back to the heart; remove waste. Evident in 3 places: -Nutrient veins accompany the nutrient artery and exit through the diaphysis -Epiphyseal and Metaphyseal veins accompany their respective arteries and exit through the epiphysis and metaphysis -Periosteal veins accompany their respective arteries and exit through the periosteum.
deposition
bone building process; osteoblasts build bone
calcification
bone hardening process; osteoblasts initiate this process by secreting collagen fibers in the extracellular matrix, these collagen fibers form the framework that mineral salts are then deposited into; once the collagen framework is formed, crystallization of mineral salts can occur. -collagen fibers must be present for this process to occur
osteoprogenitor cells
bone stem cells derived from mesenchyme; only bone cells to undergo cell division; the resulting cells develop into osteoblasts. These cells are found mainly in the periosteum, endosteum, and in the canals within bone that contain blood vessels.
skeletal system functions: mineral homeostasis (storage and release)
bone tissues make up about 18% of the human body; bone tissue stores several minerals, especially calcium and phosphorus, which contribute to the strength of bone; stores about 99% of the body's calcium. On demand, bone releases minerals into the blood to maintain critical mineral balances (homeostasis) and to distribute the minerals to other parts of the body.
long bones
bones composed of both compact and spongy bones; they're longer than they are wide; examples include the humerus (arm bone) and femur (thighbone). Parts of this type of bone: -Diaphysis -Epiphyses -Metaphyses -Articular cartilage -Periosteum -Medullary cavity -Endosteum
osteoblasts
cells that build bone; they synthesize and secrete collagen fibers and other organic compounds such as magnesium and vitamin D, which are needed to build the extracellular matrix of bone tissue; they also initiate calcification; as these cells surround themselves with extracellular matrix and become trapped in their secretions, they become osteocytes
lamellae
circular plates/rings of mineralized extracellular matrix of increasing diameter, surrounding a small network of blood vessels and nerves located in the central canal
the skeletal system
consists of the entire framework of bones and their cartilage. It's a living, dynamic organ; it's constantly changing over your lifetime. -only 10% of animals in the world have this system
bone's flexibility
depends on its collagen fibers; collagen fibers provide bone with tensile strength: the ability to being stretched and/or torn apart.
bone's hardness
depends on the crystallized inorganic mineral salts. -Soaking a bone in an acidic solution, such as vinegar, dissolves its mineral salts, causing the bone to become rubbery and flexible.
spongy bone
does not contain osteons; this bone tissue is always located in the interior of bones (forms the epiphysis and internal cavity of long bones), protected by a compact bone covering. It's less organized than compact bone; consists of lamellae that are arranged in an irregular pattern of thin columns called trabeculae; the spaces between the trabeculae are filled with red bone marrow in bones that produce blood cells, and yellow bone marrow (adipose tissue) in other bones; lightweight; provide tissue support by resisting pulling forces; makes up most of the short, flat, irregular bones.
structure of spongy bone
doesn't have osteons; projects into different directions; more porous; the basic structure is the same as compact bone, just less organized; marrow is found here; it's much lighter than compact bone; it withstands pulling forces
acromegaly
enlargement of the extremities caused by excessive secretion of growth hormone after puberty (after closure of epiphyseal plates) -too much new tissue is formed -bones become abnormally thick and heavy
ligaments
fibrous membranes of the articular capsule arranged in parallel bundles of dense irregular C.T. -they connect bone to bone -the bigger the joint, the more of these
bursa
fluid-filled sac that allows for easy movement of one part of a joint over another -prevents the ligaments from experiencing friction from other structures -filled with fluid (not synovial but similar) -if you overuse a joint, you can get inflammation in this
diarthrosis joint
freely moveable joint; all of these are synovial joints; they have a variety of shapes and permit several different types of movements.
pivot joints
in these joints the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by a ligament; uniaxial because it allows rotation only around its own longitudinal axis. -Example: the "radioulnar" joint between the head of the radius and the radial notch of ulna; enables the palms to turn anteriorly and posteriorly as the head of the radius pivots around its long axis -Example: the atlanto-axial joint, in which the atlas rotates around the axis and permits the head to turn from side-to-side as when you shake your head "no"
hinge joints
in this joint, the convex surface of one bone fits into the concave surface of another bone; they produce an angular, opening-and-closing motion; they are uniaxial (monaxial) because they typically allow motion around a single axis; they permit only flexion and extension. -Examples include: the knee, elbow, ankle, and interphalangeal joints (between the phalanges of the fingers and toes).
osteoclasts
huge cells derived from the fusion/merging of macrophages/monocytes (type of WBC); they're concentrated in the endosteum; these cells are responsible for bone resorption: the "clearing out" of "gunk"/ removal of old and stressed pieces of bone; these cells help regulate calcium level; they're also target cells used to treat osteoporosis *the ending clast means that the cell breaks down extracellular matrix
epiphyseal cartilages
hyaline cartilage growth centers during endochondral bone formation, not joints associated with movements. -An example is the epiphyseal (growth) plate that connects the epiphysis and diaphysis of a growing bone -Functionally, this cartilage is an immovable joint (synarthrosis). When bone elongation ceases, bone replaces the hyaline cartilage, and becomes a synostosis: a bony joint.
condyloid joints
in these joints the convex oval-shaped projection of one bone fits into the oval-shaped depression of another bone; biaxial because the movement it permits is around two axes (flexion-extension and abduction-adduction) -Examples: the radiocarpal (wrist) and metacarpophalangeal joints (between the metacarpals and proximal phalanges) of the second through fifth digits.
synchondrosis
is a cartilaginous joint in which the connecting material is hyaline cartilage and is slightly movable (amphiarthrosis) to immovable (synarthrosis). - an example of this joint is the joint between the first rib and the manubrium of the sternum
symphysis
is a cartilaginous joint in which the ends of the articulating bones are covered with hyaline cartilage, but a broad, flat disc of fibrocartilage connects the bones. All of these joints occur in the midline of the body. It's a slightly moveable (amphiarthrosis) joint -Example: the pubic symphysis between the anterior surfaces of the hip bones; This type of joint is also found at the junction of the manubrium and body of the sternum and at the intervertebral joints between the bodies of vertebrae
suture
is a fibrous joint composed of a thin layer of dense irregular connective tissue; they occur only between bones of the skull; they form as the numerous bones of the skull come in contact during development. They are immovable or slightly movable; they play an important role in shock absorption in the skull. -In older individuals, they're are immovable (synarthroses) -in infants and children they are slightly movable (amphiarthroses) -Examples: coronal suture (between parietal and frontal bones), lambdoid suture (between occipital and parietal bones), squamous suture (between parietal and temporal bones)
circumfrential lamellae
lamellae that are arranged around the entire outer and inner circumference of the shaft of a long bone; they are connected to the periosteum by perforating (Sharpey's) fibers. -this lamellae that's deep to the periosteum is called external _________ __________ -this lamellae that lines the medullary cavity is called internal ________ ____________
nerve supply of long bone
nerves accompany the blood vessels that supply bone; the periosteum is rich in sensory nerves, some of which carry pain sensations. These nerves are especially sensitive to tearing or tension, which explains the severe pain resulting from a fracture or a bone tumor. For the same reason, there is some pain associated with a bone marrow needle biopsy; as the needle penetrates the periosteum, pain is felt; little-no pain once it passes through
endochondral ossification
one pattern of bone formation where bone forms within hyaline cartilage that develops from mesenchyme; the replacement of cartilage by bone; most bones of the body are formed in this way; the process is best observed in a long bone; forms compact and spongy bone
bone remodeling
ongoing replacement of old bone tissue by new bone tissue. Involves bone resorption: the removal of minerals and collagen fibers from bone by osteoclasts and bone deposition: the addition of minerals and collagen fibers to bone by osteoclasts. -at any given time, about 5% of the total bone mass in the body is being remodeled -this process also removes injured bone, replacing it with new bone tissue. -It may be triggered by factors such as exercise, sedentary lifestyle, and changes in diet. -compact bone undergoes this process 4% of the total time in a year -spongy bone undergoes this process 20% of the total time in a year
fibrous membrane
outer dense fibrous connective tissue layer of the articular capsule that is continuous with the periosteum of the bone; also forms ligaments when fibrous bundles are parallel -permits movement and prevents dislocation -double-jointed people have a more flexible one
functional classification of joints
relates to the degree of movement the joint/articulation permits. -can be a synarthrosis, amphiarthrosis, or diathrosis
interosseous membrane
s a substantial sheet of dense irregular connective tissue that binds neighboring long bones and permits slight movement (amphiarthrosis). -2 principal of these joints: 1. occurs between the radius and ulna in the forearm 2. occurs between the tibia and fibula in the leg Functions: These strong connective tissue sheets: -help hold these adjacent long bones together -they play an important role in defining the range of motion between the neighboring bones -provide an increased attachment surface for muscles that produce movements of the digits of the hand and foot.
achondroplasia
shorter limbs caused by a failure of epiphyseal cartilage cell proliferation due to a dysfunction in the endochondral ossification process; long bones fuse sooner than they need to and stop early. -an inherited condition in which the conversion of hyaline cartilage to bone is abnormal and the long bones of the limbs stop growing in childhood. Other bones are unaffected, and thus the person has short stature but a normal size head and trunk.
amphiarthrosis joint
slightly moveable joint; includes the intervertebral joints, the tibiofibular joint, the pubic symphysis, and the joint between the manubrium and the sternum
intracapsular ligaments
stabilizing ligaments located inside the knee joint's articular capsule, but not in the synovial cavity; they prevent forward and backward movement -Examples include the ACL and PCL -ACL is pulled/stretched during knee extension while the PCL is pulled/stretched during knee flexion
extracapsular ligaments
stabilizing ligaments located outside the knee joint's articular capsule; they prevent side-to-side movements -Examples include the Fibular Collateral Ligament (FCL) and Tibial Collateral Ligament (TCL) in the knee
bone deposition
the addition of minerals and collagen fibers to bone by osteoblasts; results in the formation of bone extracellular matrix
osteomalacia
the adult counterpart of rickets, sometimes called adult rickets. New bone formed during remodeling fails to calcify, and the person experiences varying degrees of pain and tenderness in bones, especially the hip and legs. Bone fractures also result from minor trauma. -prevention consists of exposure to moderate amounts of sunlight and administration of vitamin D
ossification
the bone formation process; it occurs in 4 principal situations: 1. the initial formation of bones in an embryo and fetus 2. the growth of bones during infancy, childhood, and adolescence until their adult sizes are reached 3. the remodeling of bone (replacement of old bone with new bone tissue that occurs throughout life) 4. the repair of fractures (breaks in bones) throughout life
diaphysis
the bone's shaft or body—the long, cylindrical, main portion of the bone.
epiphyseal line
the bony structure that occurs when the bone ceases to grow in length (ages 18-21), this is the result of the replacement of the epiphyseal plates (cartilage) with bone; this is due to an increase secretion of hormones such as estrogen and testosterone with cause rapid calcification of the cartilage
bone resorption
the breaking down of bone; the breakdown of bone extracellular matrix by osteoclasts that is part of the normal development, maintenance, and repair of bone tissue
interosteonic canals
the canals that blood vessels and nerves from the periosteum penetrate the compact bone through; the vessels and nerves of these canals connect with those of the medullary cavity, periosteum, and central canals.
appositional growth
the deposition of extracellular matrix material on the cartilage surface of the model by new chondroblasts that develop from the perichondrium, which results in growth of cartilage thickness.
epiphyses
the proximal and distal ends of long bones
metaphyses
the regions between the diaphysis and the epiphyses. In a growing bone, each of these contains an epiphyseal (growth) plate: a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length. When growth stops at about ages 14-24, the cartilage in the epiphyseal plate is replaced by bone; the resulting bony structure is the epiphyseal line.
aspiration of synovial fluid
the removal of synovial fluid via needle; occurs when there is an excessive buildup of synovial fluid, which can cause pain and decreased range of motion (ROM) -pus or blood indicates damage or infection -anti-inflammatory drugs can be injected in the joint cavity
intramembranous ossification
the simpler pattern of bone formation where bone forms directly within mesenchyme, which is arranged in sheetlike layers that resemble membranes; this process mainly occurs in the womb; produces spongy bone; The flat bones of the skull, most of the facial bones, mandible (lower jawbone), fontanels, and the medial part of the clavicle (collar bone) are formed in this way.
compact bone
the strongest form of bone tissue; contains very few spaces; it's found beneath the periosteum of all bones and makes up the bulk of the diaphyses of long bones; it provides protection and support and resists the stresses produced by movement and body weight gravity (compressive forces); highly organized structure that forms the superficial layer of all bones.
zone of hypertrophic cartilage
the zone in the epiphyseal growth plate that consists of large, maturing chondrocytes arranged in columns
zone of proliferating cartilage
the zone in the epiphyseal growth plate that contains slightly larger chondrocytes arranged like stacks of coins; these chondrocytes undergo interstitial growth (growth in length from within) as they divide and secrete extracellular matrix; The chondrocytes in this zone divide to replace those that die at the diaphyseal side of the epiphyseal plate.
zone of calcified cartilage
the zone in the epiphyseal growth plate that is only a few cells thick and consists of mostly dead chondrocytes because the extracellular matrix has calcified. Osteoclasts dissolve the calcified cartilage and osteoblasts invade the area; The osteoblasts lay down bone extracellular matrix, replacing the calcified cartilage by the process of endochondral ossification (replacing cartilage with bone). As a result, the zone of calcified cartilage becomes the "new diaphysis" that is firmly cemented to the rest of the diaphysis of the bone.
zone of resting cartilage
the zone in the epiphyseal growth plate that's nearest the epiphysis and consists of small, scattered chondrocytes. The cells do not function in bone growth; they anchor the epiphyseal plate to the epiphysis of the bone.
structure of synovial joints
these joints have certain characteristics that distinguish them from other joints: 1. Synovial cavity: a space between the articulating bones; allows considerable movement at a joint (makes all of these joints DIARTHROSES: freely moveable) 2. Articular cartilage: the bones at these joints are covered by a layer of hyaline cartilage known as this; covers the articulating surfaces of the bones with a smooth, slippery surface; reduces friction between bones in the joint during movement and helps to absorb shock; doesn't bind bones together. 3. Articular capsule: composed of an outer fibrous membrane and an inner synovial membrane; The flexibility of the fibrous membrane permits considerable movement at a joint, while its great tensile strength (resistance to stretching) helps prevent the bones from dislocating; ligaments act as supporting structures. 4.Ligaments: act as supporting structures
interstitial lamellae
they fill spaces between osteons; they're fragments of older osteons that have been partially destroyed during bone rebuilding or growth
skeletal system functions: protection
this system protects the most important internal organs from injury. For example, cranial bones protect the brain; rib cage protects the heart and lungs. *our most vital organs (brain, heart, lungs, spinal cord) are completely encased in bone
skeletal system functions: support
this system serves as the structural framework for the body; it supports soft tissues and provides attachment points for the tendons and muscles.
ball and socket joints
this type of joint consists of the ball-like surface of one bone fitting into a cuplike depression of another bone; triaxial (multiaxial), permitting movements around three axes (flexion-extension, abduction-adduction, and rotation). -Examples are the shoulder and hip joints.
plane joints
type of synovial joint; aka a gliding joint; they're flat or slightly curved; they permit back-and-forth and side-to-side movements between the flat surfaces of bones -Many are biaxial, meaning that they permit movement in two axes. An axis is a straight line around which a bone rotates (revolves) or slides. -If plane joints rotate in addition to sliding, then they are triaxial (multiaxial), permitting movement in three axes. -Examples: the intercarpal joints (between carpal bones at the wrist), intertarsal joints (between tarsal bones at the ankle)
articular capsule
very dense and strong capsule in synovial joints; made of dense irregular tissue that connects to the periosteum; with its accessory ligaments, this is one of the strongest structures of the body; it functions to: -permit movement and prevent dislocation
structure of compact bone
very highly organized structure made of mineral salts (more) and collagen fibers (less); osteocytes are the main cells; has a gelatinous extracellular matrix that surrounds the osteocytes; composed of repeating osteons, which run parallel to the diaphysis (ex: they run all the way down the femur); each osteon consists of lamellae; between the lamellae are small spaces called lacunae, which contain the osteocytes; canaliculi are the small channels filled with extracellular fluid that radiate in all directions from the lacunae; contain gap junctions which connect + allow neighboring osteocytes to communicate
