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AA Radiographic Anatomy > The Skeletal System > Flashcards

Flashcards in The Skeletal System Deck (70)
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1
Q

List the typical features of a long bone?

A
  • Diaphysis
  • Epiphysis
  • Metaphysis / epiphyseal plate
  • Articular Cartilage
  • Periosteum
  • Medullary Cavity
  • Endosteum
2
Q

What is the diaphysis of a long bone?

A

Shaft/long main portion of a bone

3
Q

What is the epiphysis of a long bone?

A

Distal and proximal extremities or ends of the bone

4
Q

What is the metaphysis of a long bone?

A

Region in a mature bone where diaphysis joins the epiphysis

In a growing bone it includes the epiphyseal plate where cartilage is replaced by bone.

5
Q

What is the epiphyseal plate?

A

Layer of hyaline cartilage that allows the diaphysis of the bone to grow in length.

6
Q

What is articular cartilage?

A

Thin layer of hyaline cartilage covering the epiphysis where the bone forms an articulation (joint) with another bone.

Cartilage reduces friction and absorbs shock at freely moveable joints.

7
Q

What is the periosteum?

A

The membrane around the surface of the bone not covered by articular cartilage.

Two layers – outer fibrous layer (dense, irregular connective tissue contain blood vessels lymphatic vessels and nerves that pass into the bone), inner osteogenic layer contains elastic fibres, blood vessels and bone cells.

Periosteum is essential for bone growth in diameter, repair and nutrition, also serves as a point of attachment for ligaments and tendons.

8
Q

What is the medullary (marrow) cavity?

A

The space within the diaphysis that contains the fatty yellow bone marrow in adults.

9
Q

What is the endosteum?

A

Lining the medullary cavity is the endosteum, a membrane that contains osteoprogenitor cells and osteoclasts.

10
Q

What is ossification?

A

Process whereby existing connective tissue is replaced by bone

11
Q

What are the two methods of ossification?

A
  1. Intramembranous eg.

▪Bones of the skull

▪Bone formation occurs within loose fibrous connective tissue membranes

  1. Endochondral eg.

▪Long bones

▪Bone formation occurs within hyaline model

▪Most common method of ossification

12
Q

When does ossification start?

A

Ossification begins 6th or 7th week of embryonic life and continues throughout adulthood.

13
Q

What is intramembranous ossification simply?

A

Formation of bone directly on or within loose fibrous connective tissue membranes- eventually replaced by bone through intramembranous ossification.

14
Q

What is endochondral ossification simply?

A

Formation of bone in hyaline cartilage, -mesenchyme is transformed into chondroblasts (responsible for cartilage formation)– produce a hyaline matrix that is gradually replaced by bone.

15
Q

What intramembranous ossification has occurred on the left but not the right?

A

The fontanel has ossified and formed the sagittal suture

16
Q

What is the benefit of a baby having a fontanel?

A

Membrane between bones – enables baby to pass along the birth canal, skull is incompletely ossified

17
Q

When does the capitate start to ossify?

A

3 months

18
Q

Explain the first step of intramembranous ossification?

A
  1. Development of the ossification centre: At the site where the bone will develop specific chemical messages cause the cells of the mesenchyme to cluster together and differentiate, first into osteo progenitor cells is then into osteoblasts. The sight of such a cluster is call and ossification centre. Osteoblasts secretes the organic extracellular matrix of bone until they are surrounded by it.
19
Q

Explain the second step of intramembranous ossification?

A
  1. Calcification: the secretion of extracellular matrix stops, in the cells, now called osteocytes, lie in lacunae and extend their narrow cytoplasmic processes into canaliculi that radiates in all directions. Within a few days, calcium and other mineral salts are deposited and the extracellular matrix hardens or calcifies (calcification).
20
Q

Explained the third step of intramembranous ossification?

A
  1. Formation of trabeculae: as the bone extracellular matrix forms it develops into trabeculae but use with one another to form spongy bone around network of blood vessels in the tissue. Connective tissue associated with the blood vessels in the trabeculae differentiates into red bone marrow.
21
Q

Explain the fourth step of intramembranous ossification?

A
  1. Development of the periosteum: in conjunction with the formation of trabeculae, the mesenchyme condenses at the periphery of the bone and develops into the periosteum. Eventually a thin layer of compact bone replaces the surface layers of the spongy bone but spongy bone remains in the centre. Much of the newly formed bone is remodelled (destroyed and reformed) as the bone is transformed into its adult size and shape.
22
Q

When does the hamate start to ossify?

A

2 months

23
Q

When does the triquetrum start to ossify?

A

3 years

24
Q

When does the lunate start to ossify?

A

4 years

25
Q

When does the trapezium start to ossify?

A

4-5 years

26
Q

When does the trapezoid start to ossify?

A

4-5 years

27
Q

When does the scaphoid start to ossify?

A

4-5 years

28
Q

When does the pisiform start to ossify?

A

8-12 years

29
Q

What is a sesamoid bone?

A

They are bones that are embedded within a tendon, and are typically found in locations where a tendon passes over a joint.

30
Q

What are some likely places to find sesamoid bones?

What is the purpose of a sesamoid bone?

A
  • Sesamoid bones can be found in the hand, knee, and foot, and their unique structure works to protect the tendon, and to increase its mechanical effect.
  • The presence of a bone embedded in the tendon serves to hold the tendon slightly further away from the centre of the joint this increases its movement, and stops the tendon from flattening into the joint as tension increases
31
Q

Label the epiphyseal plate

A
32
Q

Epiphyseal plate

What does the zone of resting cartilage do?

What is it made of?

A

Anchors epiphyseal plate to epiphysis due to infiltration of capill’s

Consists of small scattered chondrocytes –cells do not function in bone growth

33
Q

Epiphyseal plate

What does the zone of proliferating cartilage do?

What is it made of?

A

Produces chondrocytes

Consists of slightly larger chondrocytes (than resting zone) arranged in columns – chodrocytes divide to replace those that die at the diaphyseal surface of the epiphyseal plate.

34
Q

Epiphyseal plate

What does the zone of hypertrophic (maturing) cartilage do?

What is it made of?

A

Chondrocytes mature, lacunae form

Even larger chondrocytes arranged in columns

Movement of ephiphisis farther from the diaphysis is the result of cell divisions in the zone of the proliferating cartilage and maturation of cells in the zone of hypertrophic cartilage.

35
Q

Epiphyseal plate

What does the zone of calcified cartilage do?

A

The cartilage matrix calcifies

Osteoblasts and osteoclasts infiltrate remodel the calcified cartilage into bone

Capillaries from the diaphysis also infiltrate anchoring the plate to the diaphysis.

36
Q

What is the ossification age for the base of the 1st metacarpal?

A

2-3 years

37
Q

What is the ossification age for the heads of 2-5th metacarpals?

A

2 years

38
Q

At what age does the lumbar spine curve appear?

A

Curve of lumbar spine appears when child walks 12-18 months (secondary curve)

39
Q

What is the Mneumonic CRITOL for?

A

Elbow

40
Q

What does CRITOL stand for?

A

Capitulum- 2 years

Radius- 4 years

Internal epicondyle- 5 years

Trochlea- 9 years

Olecranon- 9 years

Lateral epicondyle- 11 years

41
Q

What are the ossification centres for the elbow?

A

C-2 years

R- 4 years

I- 5 years

T- 9 years

O- 9 years

L- 11 years

42
Q

What’s wrong here?

A

Nothing, it’s an infant’s pelvis

43
Q

At what age does the greater trochanter appear?

A

Age 4

44
Q

At what age does the lesser trochanter appear?

A

Age 13

45
Q

At what age does the head of the femur fuse with the shaft?

A

Age 16-18

46
Q

When does the iliac crest appear?

A

Puberty

47
Q

What is the ossification centre for the ilium?

A

8th week in utero

48
Q

What is the ossification centre for the ischium?

A

4-6 months in utero

49
Q

What is the ossification centre for the pubis?

A

4-6 months in utero

50
Q

What is the ossification centre for the acetabulum?

A

(2 centres) puberty

51
Q

What is the ossification centre for the shaft of femur?

A

7 weeks in utero

52
Q

What is the ossification centre for the femoral head?

A

4-6 months

53
Q

At what age does the pelvis fuse?

A

7-9 years

54
Q

Whats up with this image?

A

Secondary centre for ossification

Posterior aspect appears age 6-8, fuses at puberty.

55
Q

What is an avulsion fracture?

A

Fracture at point of insertion of tendon & ligament

56
Q

What can be confused with an avulsion fracture?

A

Can be confused with epiphyses or sesamoid bones

57
Q

What sesamoid bone is shown here?

A

Fabella

58
Q

What sesamoid bone is shown here?

Where are they usually found?

A

Bipartite sesamoids

Normally found in the thumb or great toe

59
Q

What sesamoid bone is shown here?

A

Os Navicular

60
Q

What sesamoid bone is shown here?

A

Os peroneum

61
Q

What is shown here?

A

Normal variant

Bipartite patella

62
Q

What is shown here?

What causes it?

A

Bipartite patella

Failure of secondary ossification centre to fuse fully

63
Q

What are the signs of an abnormality being a fracture over a normal variant?

A
  • Roughened edge
  • Discontinuous periosteum
64
Q

What are the signs of an abnormality being a normal variant over a fracture?

A
  • Smooth
  • Continuous edge
  • Increased density around edge (cortical bone)
65
Q

What is spina bifida occulta?

A
  • Neural arch defect
  • Without protusion of spinal cord and nerves
  • Less serious than spina bifida, (where spinal cord and meninges protrude through defect)
  • Common condition, occurring in 10% - 20% of otherwise healthy people; it is often found incidentally during a radiograph.
66
Q

At what ages are the different sexes more likely to get idiopathic scoliosis?

A

Infantile

  • Under 3 years old
  • Male > female
  • May resolve spontaneously

Juvenile

  • 4 – 10 years
  • Male = female
  • Progresses with growth

Adolescent

  • 10 years +
  • Male < female
  • Progresses rapidly during growth spurt
67
Q

What does this image show?

A

Scoliosis

68
Q

What are the 2 forms of structural scoliosis?

A

Congenital

Acquired

69
Q

What causes congenital scoliosis?

A

Congenital scoliosis happens when the spine doesn’t develop as it should while a baby is in the womb.

For example, the bones that make up the spine (vertebrae) may grow more on one side compared with the other, resulting in curvature.

This type of scoliosis can get worse over time, but the severity depends on how the spine has formed.

70
Q

What causes acquired scoliosis?

A

Neuromuscular scoliosis- due to a condition that affects the nerves or muscles of the back, such as cerebral palsy or muscular dystrophy

Metabolic scoliosis is associated with disorders of metabolism (the production and breakdown of chemicals in the body) - this includes osteoporosis which is a loss of bone density

Trauma - scoliosis can develop after an accident that damaged the spine

Cancer - some types of bone cancer or cancer treatments can cause scoliosis