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Flashcards in Skeletal System Deck (25):

describe the following:
1. diaphysis
2. epiphysis
3. metaphysis
4. Articular cartilage
5. periosteum
6. medullary cavity
7. endosteum
8. physis

1. shaft of the bone. tubular. compact bone
2. ends of bone. formed of cancellous bone
3. region between epiphysis and diaphysis. transitional region between cancellous and compact bone
4. thin layer of hyaline cartilage covering part of the epiphysis where a bone forms an articulation
5. tough connective tissue layer and associated blood supply that surrounds the bone surface. Osteoblasts are found in the deeper layer
6. hollow space within the diaphysis; contains yellow bone marrow in adults
7. highly vascular membrane that lines the medullary cavity
8. layer of cartilage that separates the epiphysis and metaphysis. Responsible for longitudinal growth


Compact Bone Structure
1. what are concentric lamellae?
2. how are the concentric lamellae arranged?
3. what are osteons and how are they arranged?
4. what are the spaces between concentric lamellae called and what do they contain?
5. what are canaliculi filled with?
6. how do neighbouring osteocytes communicate?

1. circularised plates of mineralised ECM of increasing diameter
2. they are arranged around a central canal (network of nerves and vessels)
3. the functional unit of compact bone; formed of concentric lamellae. Arranged in parallel to the long axis of the bone
4. lacunae. Contain osteocytes
5. ECF and the processes of osteocytes
6. via gap junctions


Cancellous Bone Structure
1. how does cancellous bone differ from compact bone?
2. where is cancellous bone found?
3. what does cancellous bone consist of?
4. what are the spaces filled with?

1. does not contain osteons
2. interior of bones, protected by a covering of compact bone. e.g. interior of short, flat, irregular bones and the core of epiphyses of long bones
3. lamellae, arranged in an irregular pattern of thin struts called trabeculae
4. bone marrow


1. what does bone ECM consist of?
2. what does ground substance consist of? Why are these components important?

3. Describe the function of the following cells:
a) osteoprogenitor cells
b) osteoblasts
c) osteocytes
d) osteoclasts

1. collagen fibres, ground substsance, water and mineral salts
2. glycoproteins and proteoglycans. They have a high ion binding capacity therefore are important in calcification

3a) mesenchymal derived bone stem cells. undergo cell division to form osteoblasts
3b) bone building cells. Secrete collagen to build ECM and initiate calcification. As they become surrounded and thus trapped by ECM, they become osteocytes
3c) mature bone cells. Maintain bone metabolism
3d) derived from monocytes. Have a deeply ruffled border from which it releases lysosomal enzymes and HCl to digest bone


Name 6 functions of bone

1. support
2. protection of internal organs
3. assistance in movement
4. mineral homeostasis - phosphate and calcium
5. haematopoeisis
6. triglyceride storage - yellow bone marrow


1. from which embryological structures is the skeleton derived from?
2. which structures give rise to the head?
3. which structures give rise to the axial and appendicular skeletons?
4. by which process does the skull develop?
5. by which process do the limbs develop?
6. which genes are involved in patterning the vertebrae? What are their gene products? What is their expression guided by?

1. mesenchyme of the neural crest and mesoderm
2. neural crest
3. somites and lateral plate mesoderm
4. intramembranous ossification
5. endochondrial ossification
6. Hox genes


1. what is the basis of endochondrial ossification?

2. describe the development of the cartilage model
3. describe the growth of the cartilage model
4. describe how the primary ossification centre develops
5. describe the development of the medullary cavity
6. describe the development of the secondary ossification centres

1. replacement of cartilage with bone

2. mesenchymal cells condense in the general shape of the future bone and develop into chondroblasts. Chondroblasts secrete ECM forming a hyaline cartilage model

3. chondroblasts become surrounded by ECM, thus becoming chondrocytes. Continuous cell division causes the cartilage model to grow in length, accompanied by further secretion of ECM. Chondrocytes within calcifying ECM die; spaces left behind form lacunae

4. nutrient artery penetrates calcifying cartilage model. Stimulates osteoprogenitor cells in perichondrium to differentiate into osteoblasts.
Periosteal capillaries grow into disintegrating calcified cartilage in moddle of model, inducing formation of primary ossification centre. Osteoblasts deposit bone ECM over remnants of calcified cartilage. Primary ossification spreads from centre outwards

5. osteoclasts begin to break down newly formed trabeculae, leaving a cavity

6. branches of epiphyseal artery enter epiphyses and develop secondary ossification centres.


describe the stages of intramembranous ossification

1. mesenchymal cells cluster together and differentiate into ostroprogenitor cells and osteoblasts, forming an ossification centre
2. osteoblasts secrete EXM until they are surrounded by it
3. osteocytes extend cytoplasmic processes into canaliculi
4. mineral salts and calcium are deposited.


1. where does growth of long bones occur from?
2. Describe the following structures of the growth plate:
a) zone of resting cartilage
b) zone of proliferating cartilage
c) zone of hypertrophic cartilahe
d) zone of calcified cartilage
3. On which side of the growth plate is cartilage replaced with bone?

1. epiphyseal growth plate
2a) nearest to epiphysis. acts to anchor the growth plate to the epiphysis
b) chondrocytes are arranged in stacks
c) large chondrocytes arranged in collumns
d) dead chondrocytes. Site of endochondrial ossification
3. diaphyseal side.


Describe and give examples of the following joints:
1. fibrous
2. cartilagenous
3. synovial

4. hinge
5. pivot
6. bicondylar
7. condylar
8. saddle
9. pivot

1. solid joint. Bones held together with connective tissue. E.g. sutures
2. solid joint. Bones held together with cartilage. E.g. symphyses
3. flexible joint. Bones involved are separated by articular cavity, and a layer of hyaline cartilage covers the articulating surfaces. Joint capsule consists of inner synovial membrane and outer fibrous membrane.

4. movement (flexion and extension) around 1 axis (e.g. elbow)
5. movement (rotation) around one axis (e.g. antaloaxial)
6. movement mostly in one axis, with limited movement in a second (e.g. knee)
7. movement in 2 axes at right angles to one another (e.g. wrist)
8. movement in 2 axes at right angles to one another. Articulating surfaces are saddle shaped (e.g. thumb)
9. movement in multiple axes (e.g. shoulder, hip)


Name and describe the 3 stages of fracture healing

1. reactive phase - early inflammatory phase; fracture haematoma forms at the site of fracture; nearby bone cells die due to lack of blood flow. Phagocytes and osteoclasts remove dead and damaged tissue

2. reparative phase - formation of fibrocartilaginous callus as fibroblasts grow into fracture haematoma and produce collagen. Cells from periosteum develop into chondroblasts which form fibrocartilage. Osteoprogenitor cells develop into osteoblasts which produce trabeculae and the fibrocartilage is converted to cancellous bone

3. bone remodelling - remodelling of bony callous by osteoclasts


1. describe the production of vitamin D3
2. describe the negative feedback mechanism that prevents against vitamin D3 toxicity

3. name 3 factors that regulate calcium homeostasis
4. what occurs under levels of decreased calcium?
5. what occurs under levels of increased calcium

6. what do high levels of PTH stimulate?
7. what do intermittent low levels of PTH stimulate?

8. what is the major mediator of hypercalcemia in malignancy?
9. what is calcitonin released by and how does it act?

1. vitamin D3/cholecalciferol is produced from 7-dehydroxycholestrol in the skin by UV light
in the liver, it undergoes hydroxylation, forming 25 (OH) Vitamin D3
Further hydroxylation occurs in the kidney, forming 1,25 (OH) vit D3. This is metabolically active.

2. Further hydroxylation to produce 24,35 (OH) vit D3 or 1,24,25 (OH) vit D3. These prodices are not metabolically active.

3. vitamin D3, parathyroid hormone and calcitonin
4. PTH is secreted. This acts to increase renal Vit D3 hydroxylation; vit D3 acts to increase intestinal absorption and decrease renal excretion of Vit D3. PTH also stimulates osteoblasts, which stimulate osteoclasts to resorb bone.
5. Decreased VitD3 production. Increased calcitonin secretion. Calcitonin inhibits osteoclasts.

6. osteoclastic bone resorption (and vitD3 production)
7. osteoblastic bone formation

8. Parathyroid related protein. It is secreted by most malignant tumours and promotes hypercalcemia by activating the PTH receptor
9. released by parafollicular cells of the thyroid in response to high plasma calcium. It acts to inhbit osteoclastic bone resorption.


1. How to oestrogens act to maintain bone?
2. how do androgens act to maintain bone?

1. they maintain bone mass by inhibiting resorption
2. they maintain bone mass by inhibiting resorption


1. Name 5 causes of hypercalcemia
2. name 4 causes of hypocalcemia

1. primary hyperparathyroidism; malignancy; hyperthyroidism; immobilisation; vitamin D toxicity
2. renal failure; vitamin D deficiency; prematurity; secondary hyperparathyroidsm (a physiological response to hypocalcemia)


1. what is osteomalacia and rickets?
2. name 6 features
3. name 6 causes

4. what is osteoporosis?
5. Name 6 causes
6. name 5 treatments of osteoporosis

1. softening of the bones
2. diffuse bone pain; localised bone pain around hips; muscle weakness; elevated alkaline phosphatase levels; decreased mineralisation; bowing deformity of weight bearing long bones
3. vitamin D deficiency; malabsorption; renal disease; lack of sunlight; anticonvulsants; inherited

4. decreased bone density due to uncoupled bone remodelling. Deterioration of bone microarchitecture increases susceptibility to fracture
5. lack of sex hormones. calcium deficiency. vitamin D deficiency. lack of weight bearing exercise; overuse of corticosteroids; thyroid problems
6. calcium supplimentation; HRT; bisphosphonates; calcitonin; selective oestrogen receptor modulators


1. what is the human gait cycle?
2. what is the stance phase?
3. what is the swing phase?

4. how are the gait cycles of running and walking different?
5. how are tendons involved in running?

1. period of heel strike of one limb to the next time the same heel hits the ground
2. from heel strike to toe lift
3. where limb has lost contact with ground, until heel strike

4. during walking, there is always one foot on the ground. During running, at one point, both feet are off the ground simultaneously
5. tendons absorb and release energy to make running a series of controlled leaps.


Name the 6 muscle groups involved in the human gait cycle and describe what they do

1. gluteals. Act to abduct and extend the hip
2. quadriceps - anterior and lateral thigh. Act to extend the knee
3. hamstrings - posterior thigh. Act to flex the knee and extend the hip
4. calf muscles - gastrocnemius and soleus. Flex the knee and plantarflex the foot
5. tibial muscles - assist in plantar flexion
6. adductors - medial thigh. act to addict the leg.


1. where is the body's centre of mass positioned?
2. what is the base of support?
3. what is the ankle strategy?
4. what is the hip strategy?
5. what do the ankle and hip strategies act to do?

1. within the pelvis, in the midline, anterior to the second sacral vertebrae
2. the area between the feet
3. movements of the ankle joints counteract small perturbations in centre of mass
4. swaying of the hips to counteract larger perturbations of centre of mass
5. act like a pendulum to maintain posture and stability, with very little energy expenditure


Describe the role of the gluteals during the stance phase

they act as abductors to stabilise the pelvis. Contraction prevents the pelvic tilt that would occur under gravity as we put our weight on one foot


Describe the following gaits
1. Antalgic
2. Ataxic
3. Parkinsonian
4. Myopathic
5. Neuropathic

1. gait that reduces loading on affected extremity by decreasing stance phase (limping)
2. unsteady, unco-ordinated walk
3. short, accelerating steps, often on tiptoe. trunk flexed forward, legs flexed stiffly
4. waddling gait
5. high stepping gait to avoid dragging the toe.


1. How are the pelvis and hip evolved for bipedalism
2. how is the femur evolved for bipedalism?
3. how is the knee evolved for bipedalism?
4. how is the foot evolved for bipedalism?

1. shortened vertically and expanded laterally and anteroposteriorly. This brings hip closer to sacroiliac joint to reduce stress on ilium
Iliac blade is curved and medially orientated. This brings the gluteal muscles into a position where they can act as thigh abductors

2. femoral head is larger to assist with load bearing. Its diagonal disposition also redirects support directly inferior to the leg.

3. has a locking mechanism, enabling it to stabilise in a fully extended position.

4. foot arches act as shock absorbers, distribute body weight over sole of foot permit medial weight transfer during midstance


1. how many segments are there in each part of the spine?:
a) cervical
b) thoracic
c) lumbar
d) saccral

2. what type of bone are vertebral bodies formed of?
3. which structures form the vertebral foramen?
4. collectively, what do the vertebral foramina form?
5. what are the vertebral pedicles?
6. what are the vertebral laminae?
7. where do spinal nerves exit by? What are these structures formed by?

1a) 7
b) 12
c) 5
d) 2

2. cancellous bone surrounded by a thin coating of compact bone
3. vertebral arch (formed by laminae and peduncles) and vertebral body
4. vertebral canal
5. structures that connect the vertebral arch to the vertebral body
6. flat sheets of bone that meet in the midline and form the roof of the vertebral arch
7. intervertebral foramen. They are created by the vertebral notches when adjacent vertebrae articulate.


1a) what is the shape of cervical vertebrae
1b) what is the shape of the cervical vertebral foramen?
1c) what is the shape of the cervical spinous process?

2a) what is the name of the sites of articulation for ribs on thoracic vertebrae?
2b) how does the body of thoracic vertebrae compare to that of cervical?
2c) what is the shape of thoracic spinous processes?
2d) how are the facet joints arranged?

3a) what is the shape of lumbar vertebral bodies?
3b) what is the size of the lumbar arches?
3c) what is the size of the lumbar spinous processes?
3d) how are the facet joints arranged?

1a) square shaped
1b) triangular and large
1c) short and bifid

2a) costal facets
2b) body is bigger
2c) long
2d) vertically arranged

3a) kidney shaped
3b) small
3c) large
3d) vertically arranged


1. what is cauda equina syndrome?
2. name 4 presentations of cauda equina syndrome
3. what is cauda equina syndrome considered as?

4. what does the intervertebral disc consist of (outer and inner)

1. central herniation of the intervertebral disc that compresses the cauda equina
2. bladder and bowel dysfunction; perineal numbness; new sexual dysfunction; progressive bilateral leg weakness
3. surgical emergency

4. outer - fibrous ring made of fibrocartilage; called annulous fibrosus
inner - soft pulpy elastic substance called nucelus pulpus


1. what is lordosis?
2. what is kyphosis?
3. what is scoliosis?

4. where are kyphosis and lordosis normally seen?

1. inward curve
2. outward curve
3. lateral curvature

4. cervical lordosis
thoracic kyphosis
lumbar lordosis