bone anatomy and physiology

Question 1

how many bones in axial skeleton

Answer 1

• vertebral column, ribs, skull

- 80 bones (protection of main organs)

Question 2

how many bones in appendicular skeleton

Answer 2

• pelvis / shoulder girdles, upper and lower limbs (weight bearers)
• 126 bones

Question 3

what is the function of bone

Answer 3

• support: structural framework of body
• protection: many major organs (axial)
• assist in movement: contraction of muscles with bones
• mineral homeostasis: store and release minerals (Ca and P)
• hematopoiesis: blood cell production, red bone marrow
• fat storage: triglyceride

Question 4

what are the classification of bones

Answer 4

• long: axis longer than width, weight bearing, strong (humerus / femur)
• short: wrist and ankle
• flat: provide protection, production of blood cells (sternum)
• irregular: vertebra
• sesamoid: develop in tendon, compression between bone and tendon, stabilise (patella)
• sutural: small flat irregular bones of the skull

Question 5

describe the sutural bones of the skull

Answer 5

• wormian, small extra bone plates
• within sutures of cranial bones
• coronal, lambdoid, sagital, squamous

Question 6

identifying markings of bones

Answer 6

• tuberosity: rounded projection
• crest: narrow, prominent ridge
• trochanter: large blunt irregular surface
• epicondyle: raised area above condyle
• process: bony prominence
• tubercle: small rounded projection

Question 7

summary of depressions and openings of bones

Answer 7

• fissure: narrow opening
• foramen: round / oval opening through bone
• fossa: shallow, basin like depression

Question 8

what is the general anatomy of bones

Answer 8

• external: compact
• internal: spongey / trabecular and marrow
• marrow: fills spaces between trabeculae, yellow (fat) or red (RBC prod.)
• periosteum: connective tissue covers bones
• endosteum: covers internal surface
• short / irregular / flat: thin layer of spongey, covered by compact, covered by periosteum

Question 9

what is the anatomy of a long bone (whole bone)

Answer 9

• diaphysis: shaft of bone
• epiphysis: ends of bone (enlarged)
• epiphyseal line: allows growth of diaphysis in length, cartilage (young), bone tissue (older)
• metaphysis: diaphysis joins epiphysis
• articular cartilage: covers epiphysis and reduces shock and friction
• periosteum: tough sheath of connective tissue, surrounds bone, allow growth in diameter, increased nerve fibres and blood vessels
• nutrient foramen: allows artery and veins to enter bone
• medullary cavity: bone marrow

Question 10

what is the microscopic anatomy of bone cells

Answer 10

• osteogenic: stem cells in periosteum and endosteum, growth of bone
• osteoblast: form bone become osteocytes
• osteocytes: mature, maintain structure of bone
• osteoclasts: break down (resorb) bone matrix / tissue

Question 11

compact vs spongey bone

Answer 11

• compact: no visible spaces in matrix, thick-celled diaphysis, tough, strength
• spongey: delicate sheets of bone, ends of long bones

Question 12

microscopic anatomy of compact bone

Answer 12

• haversian system / osteon: structural unit, ring, lamellae (weight bearing), central canal
• perforating / volkmanns canal: connect blood supply of periosteum, central canals and medullary cavity, nourishment, horizontal
• lacunae: small cavities, contain osteocytes
• canaliculi: hair like canals that connect lacunae to each other and central canal

Question 13

microscopic anatomy of spongey bone

Answer 13

• consists of trabeculae but no osteons
• irregularly arranged lamellae, osteocytes and canaliculi
• red bone marrow often fills spaces between trabeculae

Question 14

how are bones formed (intra-membranous ossification)

Answer 14

• mesenchyme (embryonic tissue) develops into connective tissue and musculoskeletal systems
• bone forms directly with mesenchyme within fibrous tissues
• flat bones of skull, mandible

Question 15

growth of bones

Answer 15

• bone collar forms around hyaline cartilage model
• cartilage in centre of diaphysis calcifies and develops cavities
• the periosteal bud invades the internal cavities and spongey bone forms
• diaphysis elongates and medullary cavity forms, ossification continues
• secondary ossification centre appears in epiphysis
• epiphysis ossify, hyaline cartilage remains only in epiphyseal plate and articular cartilage

Question 16

how is bone growth regulated

Answer 16

• growth hormone: stimulates epiphyseal plate activity
• thyroid hormone / TSH: modulates activity of GH, lack of TSH = short stature
• testosterone / oestrogen: puberty, promote adolescent growth spurts
• frequent exercise: mechanical stimuli promotes bone growth

Question 17

what is osteoporosis

Answer 17

• loss of bone mass, resorption occurs faster than bone production
• spongey bone of spine and neck of femur (most susceptible to fracture)
• risk factors: lack of oestrogen (menopause), calcium of vitamin D deficiency, petite body, immobility, low TSH, diabetes
• treatment: calcium / vitamin D supplements, increase weight bearing exercise, hormones, replacement therapy slows bone loss, medicines (increase mineral density)

Question 18

bones involvement in regulation of body calcium levels

Answer 18

• important during osteoporosis
• calcitonin: increases Ca intake by bone, decreases renal Ca reabsorption
• calcitrol: active ingredient in vitamin D, increases plasma Ca by stimulating Ca absorption in digestive tract and releasing Ca from bone
• PTH: stimulates calcium reabsorption in renal tubules, bone resorption and calcitrol activation

Question 19

two types of bones growth

Answer 19

• interstitial: length of bones, from epiphyseal cartilage

- appositional: increased thickness, remodelling of all bones by osteoblasts / clasts very dynamic

Question 20

bone repair of fractures

Answer 20

• closed: bones remain inside
• open: breaking of skin, bone outside body, increased infection rate
• hematoma forms, fibrocartilage callus forms, bony callus forms, bone remodelling