Bones and Joints Flashcards
(84 cards)
1
Q
What are the functions of Bone? (6 points)
A
- Provides a framework for the body
- Gives attachment to muscles and tendons
- Allows for movement of the body as a whole and of parts of the body by forming joints that are moved by muscles.
- Forms the boundaries of the cranial, thoratic and pelvic cavaties, protecting the organs they contain.
- haemopoiesis: the production of blood cells in red bone marrow.
- Mineral storage, especially calcium phosphate - Note: the mineral reservoir within bone is essential for maintenance of blood calciium levels, which must be tightly controlled.
2
Q
What are the main types of bone? (5 points)
A
- Long
- Short
- Irregular
- Flat
- Sesamoid
3
Q
What are the characteristics of long bones? (2 points)
A
- They consist of a shaft and two extremities.
2. They are longer than they are wide.
4
Q
What are three examples of long bones?
A
- The Femur
- Tibia
- Fibula
5
Q
What are the main characteristics of short, irregular, flat and sesamoid bones? (2 points)
A
- they have no shafts or extremities
2. they are diverse in shape and size
6
Q
What is an example of a short bone?
A
- Carpals (wrist)
7
Q
What are two examples of irregular bones?
A
- vertebrae
2. some skull bones
8
Q
What are three examples of flat bones?
A
- sternum
- ribs
- most skull bones
9
Q
What is an example of a sesamoid bone?
A
- Patella (the knee cap)
10
Q
Explain the general structure of long bones and what each part is composed of. (7 points)
A
- They have a dia-phy-sis (Shaft) and 2 e-pip-hy-ses (Extremities).
- The Dia-phy-sis is composed of compact bone with a central medullary canal, containing fatty yellow bone marrow.
- The E-pip-hy-ses consist of an outer covering of compact bone with spongy (cancellous) bone inside.
- The Dia-phy-sis and E-pip-hy-sis are separated by e-pip-hy-seal cartilages, which ossify when growth is complete.
- They are almost completely covered (just apart from within joint cavities) by a vascular membrane, the peri-o-ste-um, which has two layers.
- The peri-o-ste-um allows attachment of tendons and is continuous with the joint capsule.
- Hy-a-line Cartilage replaces periosteum on bone surfaces that form joints.
11
Q
How does thickening of a long bone occur? (1 point)
A
- by the deposition of new bone tissue uder the peri-o-ste-um.
12
Q
What are the functions of the two layers of the Peri-o-ste-um? (2 points)
A
- the outer layer is tough and fibrous, and protects the bone underneath.
- the inner layer contains osteoblasts and osteoclasts, the cells responsible for bone production and breakdown. (it an important part when it comes to repair and remodelling of the bone)
13
Q
Where is the blood supply to the shaft (dia-phy-sis) of long bone derived from? (1 point)
A
- One or more nutrient arteries
14
Q
Where do the (e-pip-hy-ses) get their blood supply from? (1 point)
A
- They have thier own blood supply.
15
Q
What are the capillary networks arising from the epiphyses and diaphysis like in mature bone? (1 point)
A
- Heavily interconnected.
16
Q
Where does the sensory supply to long bones come from and where does it go? (2 points)
A
- It usually enters the bone at the same site as the nutrient artery
- and branches extensively throughout the bone.
17
Q
Why is bone injury normally very painful? (1 point)
A
- Because of the fact that bones have a sensory supply.
18
Q
What is the general structure of short, irregular, flat and sesa-moid bones? (2 points)
A
- They have a relatively thin outer layer of compact bone inside containing red bone marrow.
- They are enclosed by periosteum, except the inner layer of the cranial bones where it is replaced by dura matter.
19
Q
What type of tissue is bone? (1 point)
A
- Bone is a strong and durable type of connective tissue.
20
Q
Explain the microscopic structure of bone? (4 points + 2 notes)
A
- Primarily (i.e 65%) composed of a mixture of calcium salts, mainly calcium phosphate.
- This inorganic matrix (composed of calcium salts) gives bone great hardness (but on its own would be brittle and prone to shattering). - The remaining third of bone is organic material, called osteoid, which is composed of mainly colagen.
- Collagen is very strong and gives bone slight flexibility. - The cellular component of bone contibutes less than 2% of bone mass.
21
Q
What are the cells responsible for bone formation called? and what do they secrete? (2 points)
A
- Osteo-blasts
2. Both the organic and inorganic componets of bone.
22
Q
What do Osteo-blasts later mature into?
A
Osteo-cytes
23
Q
What is the name of the cartilage-forming cells?
A
Chon-dro-cytes
24
Q
What are the cells responsible for breaking down bone?
A
Osteo-clasts
Large multinucleate cells made from the fusuion of up to 20 monocytes
25
What maintains normal bone structure and functions?
A fine balance of osteo-blast and osteo-clast activity
26
Where do Osteo-blasts and Chon-dro-cytes develop from?
The same parent fibrous tissue cells.
27
Where are Osteo-blasts present? (4 points)
1. In the deeper layers of periosteum
2. In the centres of ossification of immature bone
3. At the ends of the dia-phy-sis adjacent to the epiphyseal cartilages of long bones.
4. At the site of a fracture
28
What are Oseo-cytes, how are they nourished and when are they formed?
1. They are the mature bone cells that monitor and maintain bone tissue.
2. they are nourished by tissue fulid in the canaliculi that radiate from the central canals.
3. They form as bone develops and osteo-blasts become trapped within the newly formed bone.
29
What is the main function of osteo-clasts? and where do they carry out thier functions?
1. Reabsorbtion of bone to maintain the optimum shape.
2. This takes place at bone surfaces:
- Under the periosteum, to maintain the shape of bones during growth and to remove excess callus formed during healing of fractures.
- round the walls of the medullary canal during growth and to canalise callus during healing.
30
What is compact (cortical) bone made up of and what are the functions of these smaller parts? (6 points)
1. A large number of parallel tube-shaped units called osteons (Haversian systems), each of which is made up of a central canal surrounded by a series of expanding rings, similar to the growth rings of a tree.
- These osteons tend to be aligned the same way that force is applied to the bone, so for example in the femur (thigh bone), they run from one epiphysis to the other. This gives the bone great strength.
2. The central canal contains nerves, lymphatics and blood vessels, and each (central canal) is linked with neighbouring canals by tunnels running at right angles between them, called perforating canals.
3. The series of cylindrical plates of bone arranged around each central canal are called lamellae.
4. Between adjacent lamellae of the osteon are strings of little cavities called lacunae, in each of which sits an osteocyte.
5. Lacunae communicate with each other through a series of tiny channels called canaliculi, which allows the circulation of interstitial fluid through the bone, and direct contact between the osteo-cytes, which extend fine processes into them.
6. Between the osteons are interstitial lamellae, the remanants of older systems partially broken down during remodelling or growth of bone.
31
What percent of body bone mass is made up of compact (cortical) bone?
1. 80% of the body bone mass.
32
What does Spongy (cancellous, trabecular) bone look like?
1. To the naked eye, it looks like a honeycomb.
33
What is spongy bone made up of?
1. A framework formed from trabeculae (meaning 'little beams'), which consist of a few lamellae and osteocytes interconnected by canaliculi.
2. Osteo-cytes are nourished by interstitial fluid seeping into the bone through the tiny canaliculi.
3. The spaces between the trabeculae contain red bone marrow.
34
Which type of bone is lighter, and why is this necessary?
1. Spongy bone is lighter than compact bone.
| 2. This reduces the weight of the skeleton
35
When does the development of bone tissue (Osteo-genesis or ossification) begin and around what age is the process completed?
1. Begins before birth
| 2. Not complete until about the 21st year of life.
36
Where do long, short and irregular bones develop and what from?
1. In the fetus
| 2. from rods of cartilage, cartilage models.
37
What do flat bones develop from in the fetus?
1. Membrane models
38
What do sesamoid bones develop from in the fetus?
1. Tendon models
39
What happens during the process of bone development?
1. Osteo-blasts secrete osteoid, which gradually replaces the initial model
2. then this osteoid is progressively calcified, also by osteo-blast action.
3. As the bone grows, the osteo-blasts become trapped in the matrix of thier own making and become osteo-cytes.
40
How do long bones continue to lengthen druing childhood?
1. it is because the epiphyseal plate at each end of the bone, which is made of cartilage, continues to produce new cartilage on its diaphyseal surface (the surface facing the shaft of the bone).
2. This cartilage is then turned into bone
41
What equation ensures that the bone continues to lengthen (during childhood)?
1. As long as cartilage production matches the rate of ossification, the bone continues to lengthen.
(Rate of cartilage production = rate of ossification --> the bone keeps lengthening)
42
How/why does bone growth slow down in puberty?
1. Under the influence of sex hormones, the epiphyseal plate growth slows down, and is overtaken by bone deposition.
43
What happens once the whole epiphyseal plate is turned to bone?
1. No further lengthening of the bone is possible
44
What role does growth hormone and the thyroid hormones, thyroxine and tri-iodothyronine play in regulating the growth of bone?
1. They are especially important during infancy and childhood.
2. Deficient or excessive secretion of these results in abnormal development of the skeleton.
45
What role do Testosterone and Oestrogen play in the regulation of bone growth?
1. in summary, they influence the physical changes that occur at puberty and help maintain bone structure throughout life.
2. More specifically, rising levels of these hormones are responsible for the growth spurt of puperty
3. but later stimulate closure of the epiphyseal plates, so that bone growth lengthways stops (bones can grow in thickness throughout life).
3. Oestrogens are responsible for the wider female pelvis that develops during puberty, and for maintaining bone mass in the adult female.
4. Falling oestrogen levels after menopause can put post-menopausal women at higher risk of bone fracture (oesteoporosis).
46
Why is the average male adult usually taller than the average female adult? (1 point)
1. Because male puberty tends to occur at a later age than female puberty, giving a male child's bones longer to keep growing.
47
What role do Calcitonin and Parathyroid hormone play in the regulation of bone growth? (2 points)
1. Control blood levels of calcium by regulating its uptake into and release from bone.
2. Calcitonin increases calcium uptake into bone, and parathyroid decreases it.
48
Does the lenth and shape of bones normally change after ossification is complete? (2 points)
1. No, but bone tissue is continually being remodelled and replaced when damaged.
- Osteo-blasts continue to lay down osteoid and osteo-clasts reabsorb it.
2. The rate at which this occurs varies depending on the bone.
49
How does excercise/lack of excercise impact on bone growth? What is involved? (3 points)
1. Weight-bearing excercise stimulates thickening of bone, strengthening it and making it less liable to fracture.
2. This involves the laying down of new osteons at the periphery of the bone through the action of osteo-blasts in the inner layer of the periosteum.
3. Lack of excercise reverses these changes, leading to lighter, weaker bones.
50
Why is diet important when it comes to bones?
1. Healthy bone tissue requires adequate dietary calcium and vitamins A, C and D.
2. Calcium, and smaller amounts of other minerals such as phosphate, iron and manganese, is essential for adequate mineralisation of bone.
51
What is Vit. A needed for (in terms of bones)?
1. Osteo-blast activity.
52
What is Vit. C used for (in terms of bones)?
1. it is used in collagen synthesis
53
What is Vit. D required for (in terms of bones)?
1. calcium and phosphate absorption from the intestinal tract.
54
How are bone fractures classified?
1. Simple: the bone ends do not protrude through the skin.
2. Compound: the bone ends protrude through the skin.
3. Pathological: fracture of a bone weakened by disease
55
How are the broken ends of bone joined by the deposition of new bone, following a fracture? (What are the stages?) (5 points)
1. A haematoma (collection of clotted blood) forms between the ends of bone and in surrounding soft tissues.
2. There follows development of acute inflamation and accumulation of inflammatory exudate, containing macrophages that phagocytose the haematoma and small fragments of bone without blood supply (this takes about 5 days). + Fibroblasts migrate to the site; granulation tissue and new capillaries develop.
3. New bone forms as large numbers of osteo-blasts secrete spongy bone, which unites the broken ends, and is protected by an outer layer of bone and cartilage; these new deposits of bone and cartilage are called callus.
4. Over the next few weeks, the callus matures and the cartilage is gradually replaced with new bone.
5. Reshaping of the bone continues and gradually the medullary canal is reopened through the callus (in weeks or months). In time the bone heals completely with the callus tissue completely replaced with mature compact bone.
Note: Often the bone is thicker and stronger at the repair site than originally, and a second fracture is more likely to occur at a different site.
56
List the factors delay the healing of fractures. (5 points)
1. Tissue fragments between bone ends.
2. Deficient blood supply. (the most vulnerable sits for this, because of thier normally poor blood supply are: the neck of femur, the scaphoid and the shaft of tibia.
3. Poor alignment of bone ends ( may result in the formation of a large and irregular callus that heals slowly and often results in permanent disability.)
4. Continued mobility of bone ends
5. Miscellaneous (eg. infection, systematic illness, malnutrition, drugs like corticosteroids and ageing)
57
What are two complications of fractures? (2 points)
1. Infection: Pathogens enter through broken skin, although they may occasionally be blood-borne.
- healing will not occur until the infection resolves.
2. Fat embolism: Emboli consisting of fat from the marrow in the medullary canal may enter the circulation through torn veins.
- They are most likely to lodge in the lungs and block blood flow through the pulmonary capillaries.
58
What is a joint and what is thier function?
1. A joint is the site at which any two or more bones articulate or come together.
2. Joints allow flexibility and movement of the skeleton and allow attachment between bones.
59
What are the characteristics of Fibrous joints?
1. The bones forming these joints are linked with tough fibrous material.
- This (such an arrangement) often permits no movement.
60
Give 2 examples of a Fibrous joint? what are it's characteristics?
1. The joints between the skull bones, the sutures. They are completely immovable.
2. A healthy tooth is cemented into the mandaible by the peridontal ligament.
61
What is an example of a fibrous joint that does allow a limited amount of movement?
1. A sheet of fibrous tissue called the interosseous membrane, which holds together the tibia and fibula in the leg (along their shafts).
(This fibrous joint allows a limited amount of movement and stabilises the alignment of the bones.
62
What are the characteristics of Cartilaginous joints?
1. Formed by a pad of fibrocartilage (a tough material that acts as a shock absorber).
2. Either immovable or allow a limited degree of movement.
63
What is an example of a cartilaginous joint that allows a limited degree of movement?
1. The intervertebral discs between vartebrae.
64
What are synovial joints characterised by? (3 points)
1. The presence of a space or capsule between the articulating bones.
2. The ends of the bones are held close together by a sleeve of fibrous tissue, and the capsule is lubricated with a small amount of fluid.
3. Most of them permit a range of movement.
65
What are the characteristics that all synovial joints have in common?
1. Articular or hyaline cartilage
2. Capsule or capsular ligament
3. Synovial membrane
4. Synovial fluid
5. Other intracapsular structures
6. Extracapsular structures (Ligaments, muscles or tendons)
7. Nerve and blood supply
66
Explain the role that articular or hyaline cartilage plays in synovial joints?
1. It always covers the parts of the bones which are in contact with one another.
2. This provides a smooth articular surface, reduces friction and is strong enough to absorb compression forces and bear the weight of the body.
67
What happens to the cartilage lining of synovial joints as we age? what is the consequence of this?
1. becomes thinner
2. becomes less comressible
3. Leads to increasing stress on other structures of the joint.
68
Explain the role of the 'capsule or capsular ligament' in synovial joints? + what it is?
1. The joint is surrounded and enclosed by a sleeve of fibrous tissue which holds the bones together (i.e it is encapsulated).
2. It is sufficiently loose to allow freedom of movement but strong enough to protect it from injury.
(so: it holds the bones together, allows freedom of movement and protects the joint from injury).
69
Explain the role of the synovial membrane in synovial joints? + what it is?
1. It is an epithelial layer which lines the capsule and covers all non-weight-bearing surfaces inside the joint.
2. It secretes synovial fluid.
70
Explain the role of synovial fluid in synovial joints? + what it is? + what it's role is in particular joints for example the knee?
1. This is a thick sticky fluid which fills the synovial cavity.
2. It nourishes the structures within the joint cavity.
3. Contains phagocytes, which remove microbes and cellular debris.
4. Acts as a lubricant
5. Maintains joint stability
6. Prevents the ends of the bones from being separated
7. Littlle sacs of this fluid (bursae) are present in some joints, e.g the knee.
8. They act as cushions to prevent friction between a bone and a ligament of tendon, or skin where a bone in a joint is near the surface.
71
Explain what other intracpsular structures might be preasent within a synovial joint?
1. Some have structures within the capsule, which assist in the maintanence of stability.
2. For example: Fat pads and menisci in the knee joint.
3. When these structures do not bare weight they are covered by synovail membrane.
72
Explain what extracapsular structures are and what thier role is in synovial joints?
1. Ligaments, muscles or thier tendons.
2. Ligaments that blend with the capsule provide additional stability at most joints.
3. Muscles or their tendons also provide stability and stretch across the joints they move.
4. Muscles are what move joints: when a muscle contracts it shortens, pulling one bone towards the other.
73
What is the role of nerve and blood supply in synovial joints?
1. Nerves and blood vessels crossing a joint usually supply the capsule and the muscles that move it.
74
What factors influence the movement of synovial joints?
1. Movement at any given joint depends on various factors.
2. For example: the tightness of the ligaments holding the joint together, how well the bones fit and the presence or absence of intracapsular structures (eg. fat pads).
3. Generally, the more stable the joint, the less mobile it is.
75
How are synovial joints classified?
1. According to the range of movement possible, or to the shape of the articulating parts of the bones involved.
76
Describe ball and socket joints and what kind of movement they allow for? 2 examples?
1. The head of one bone is ball shaped and articulates with a cup-shaped socket of another.
2. the joint allows for a wide range of movement including: Flexion, extension, adduction, abduction, rotation and circummduction.
3. Eg: the shoulder and hip
77
Describe Hinge joints and what kind of movement they allow for? 4 examples?
1. The articulating ends of the bones form an arrangement like a hinge on a door, and movement is therfore restricted to flexion and extension.
2. eg. the elbow joint permits only flexion and extension of the forearm.
3. Other examples = the knee, ankle and the joints between the phalanges of the fingers and toes (i,e interphalangeal joints).
78
Describe Gliding joints and what kind of movement they allow for? 3 examples?
1. The articular surfaces are flat or very slightly curved and glide over one another, but the amount of movement possible is very restricted.
2. This group of joints is the least moveable of all the synovial joints.
3. eg: joints between the carpal bones in the wrist, the tarsal bones in the foot and between the processes of the spinal vertebrae. (note: the joints between the vertebral bodies are the cartilaginous discs.)
79
Describe Pivot joints and what kind of movement they allow for? an example?
1. These joints allow a bone or limb to rotate.
2. One bone fits into a hoop-shaped ligament that holds it close to another bone and allows it to rotate in the ring thus formed.
3. eg. the head rotates on the pivot joint formed by the dens of the axis held within the ring formed by the transverse ligament and the odontoid process of the atlas.
80
Describe Condyloid joints and what kind of movement they allow for? 3 examples?
1. A condyle is a smooth, rounded projection on a bone and in a condyloid joint it sits within a cup-shaped depression on the other bone.
3. They permit: flexion, extensioin, abduction, adduction and circumduction.
2. eg: the joint between the condylar process of the mandible and the temporal bone, the joints between the metacarpal and phalangeal bones of the hand, and between the metatarsal and phalangeal bones of the foot.
81
Describe Saddle joints and what kind of movement they allow for? what is the main example?
1. The articulating bones fit together like a man sitting on a saddle.
2. The range of movement is similar to that at a Condyloid joint but with additional flexability; (e.g opposition of the thumb, the ability to touch each of the fingertips on the same hand (due to the nature of the thumb joint).
3. The most important saddle joint is at the base of the thumb, between the trapezium of the wrist and the first metacarpal bone.
82
What forms the shoulder joint? Discuss factors related to the stability of the Shoulder joint.
1. It is formed by the glenoid cavity of the scarpula and the head of the humerus, and is well padded with protective bursae.
2. This ball and socket joint is the most mobile in the body, consequently it is the least stable and is prone to dislocation (especially in children).
3. The capsular ligament is very loose inferiorly to allow for the free movement normally possible at this joint.
4. The glenoid cavity is deepened by a rim of fibrocartilage (i,e the genoidal labrum) which provides additional stability without limiting movement.
5. The joint is stabalised partly by a number of ligaments (the glenohumeral, coracohumeral and transverse humeral)
6. ... but mainly by the muscles (and their tendons) present in the shoulder.
7. Certain of these muscles collectively are called the rotator cuff, and rotator cuff injury is a common cause of shoulder pain.
8. The stability of the joint may be reduced if these structures together with the tendon of the biceps muscle, are stretched by repeated dislocations of the joint.
83
What forms the Hip joint? Discuss factors related to the stability of the Hip joint.
1. This ball and socket joint is formed by the cup-shaped acetabulum of the innominate (hib) bone and the almost spherical head of the femur.
2. The capsular ligament encloses the head and most of the neck of the femur.
3. The cavity is deepened by the acetabular labrum (a ring of fibrocartilage attached to the rim of the acetabulum), which stabilises the joint whitout limiting its range of movement.
4. The hip joint is necessarily a sturdy and powerful joint, since it bears all body weight when standing upright.
5. It is stabilised by its surrounding musculature, but its ligaments are also important.
6. The three main external ligaments are: the iliofemoral, pubofemoral and ischiofemoral ligaments, which are localised thickenings of the joint capsule.
7. Within the joint, the ligament of the head of the femur (ligamentum teres) attaches the femoral head to the acetabulum.
84
What forms the knee joint? Discuss factors related to the stability of the knee joint.
1. This is the largest and most complex joint.
2. It is a hinge joint formed by the condyles of the femur, the condyles of the tibia and the posterior surface of the patella.
3. The anterior part of the capsule is formed by the tendon of the quadriceps femoris muscle, which also supports the patella.
4. Intracapsular structures include two cruciate ligaments that cross each other, extending from the intercondylar notch of the femur to the intercondylar eminence of the tibia. (They help to stabalize the joint!)
5. Semilunar cartilages or menisci are incomplete discs of white fibrocartilage lying on top of the articular condyles of the tibia. (They are wedge shaped, being thicker at their outer edges, and they provide stability!!) - They prevent lateral displacement of the bones, and cushion the mving joint by shifting within the joint space according to the relative positions of the articulating bones.
6. External ligaments of the joint provide further support, making it a hard joint to dislocate.
7. The main ligaments are: the petellar ligament, an extension of the quadriceps tendon, the popliteal ligaments at the back of the knee and the colleteral ligaments to each side.
