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Anatomy of the Individual > Skeletal Variation > Flashcards

Skeletal Variation Flashcards

1
Q

How can bone remodelling be described generally?

A

Bone formation and degradation as an ongoing process throughout life

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2
Q

Where is bone created?

A

In skeletal tissues that are supposed to ossify

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3
Q

What condition is the formation of bony in tissues that are not normally bony?

A

Myositis ossificans circumscripta:

- Traumatica

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4
Q

Give examples of studies into formation of bone in non-bony tissues?

A

Sodl et al., (2008):
- Repeated trauma to quadriceps during college hazing resulted in myositis ossificans circumscripta
Salter, (1999)

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5
Q

How can myositis ossificans circumscripta appear on imaging?

A

Opacity on x-ray

Oedema on MRI

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6
Q

What type of bone is formed following trauma?

A

Woven

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7
Q

Give examples of studies that show the difference between bony variation and bony pathology?

A

Chakraborty and Bhattacharya, (2012):
- Describe brachydactyly of 3rd and 4th digits in right foot
- VARIATION
Singh and Downing, (2005):
- ‘Empty’ toe
- Closed degloving injury displacing 5th toe medially
- NOT variation

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8
Q

How do sternal foramina arise?

A

Incomplete fusion of multiple ossification centres

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9
Q

What risks do sternal foramina pose?

A

Risk of injury to deep structures during:

  • Bone marrow aspiration
  • Acupuncture
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10
Q

Describe the study on sternal foramina by Lloret, (2004)?

A

Anthropological study
Two holes in sternum:
- One with irregular edged and fracture lines = Gunshot wound
- One with smooth, rounded edges (sternal foramen)

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11
Q

What potential reason do Kumarasamy and Agrawal, (2011) give for a large sternal foramen?

A

Two failed ossification centres

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12
Q

Os odontoideum is an area of debate as to whether or not its variation or traumatic. What is the reasoning behind both?

A

Variation:
- Congenital condition representing centrum of pro-atlas or atlas
OR
Trauma:
- Chronic non-united fracture of odontoid

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13
Q

What can os odontoideum result in according to 3 case studies by Limo et al., (2008)?

A

Flexion-extension may cause ossicle and C1 movement relative to C2:
- Results in atlantoaxial instability

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14
Q

What was measured to quantify the instability in the case studies by Limo et al., (2008)?

A

Interval between:
- Posterior margin of anterior tubercle of C1
AND
- Anterior margin of base of dens and body of C2
This interval is then compared to neutral

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15
Q

What does the study by Candan et al., (2014) describe?

A

Traumatic os odontoideum in a 3 year old boy

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16
Q

What do non-metric traits result from?

A

Genetic factors

Environmental factors

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17
Q

What are non-metric traits?

A

Traits that are either present or not

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18
Q

Regarding the uses for skeletal variation, what did Eroglu, (2008) use?

A

Used frequency of metopism to obtain information about gene flow in Anatolian populations

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19
Q

What is metopism?

A

Presence of a persistent frontal suture = A metopic suture

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20
Q

What did Ajmani et al., (1983) study?

A

Incidence of metopic suture in adult Nigerian skulls

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21
Q

What did Dodo, (1974) study?

A

Hyperostotic features more common in AInu than Japanese population

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22
Q

What supernumerary ossicle variations of the skull were described by Hanihara and Ishida, (2001a)?

A

Ossicle at the lambda
Parietal bone notch
Asterionic bone
Occipitomastoid bone

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23
Q

What hypostotic variations of the skull were described by Hanihara and Ishida, (2001b)?

A 
Tympanic dehiscence
Ovale-spinosum confluence
Metopism
Transverse zygomatic suture vestige
Biasteronic suture
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24
Q

What variations in the bony structure of the skull did Seema and Mahajan, (2014) find?

A 
Metopism
Multiple Wormian (intrasutral) bones at lambda
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25
Q

What variation do Udupi and Srinivasan, (2011) describe?

A

Large interparietal bone

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26
Q

What did Karau et al., (2010) investigate?

A

Prevalence of atlas vertebral bridges in Kenyans:

- Bony outgrowths over V3 segment of vertebral artery

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27
Q

What were the results of the Karau et al., (2010) study?

A

Complete atlas vertebral bridges more common in females:

Atlas vertebral bridges predispose to vertebrobasilar insufficiency

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28
Q

What did Nambiar et al., (1999) study?

A

Variation in frontal sinuses for forensic indentification

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29
Q

What is the postcranial axial skeleton formed from?

A

Somites:

- Mesenchyme = Mesenchymal origin

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30
Q

What part of the somite does connective tissue of the skin form from?

A

Lateral and superficial dermatome

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31
Q

What part of the somite does muscle form from?

A

Myotome

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32
Q

What part of the somite does the axial skeleton (including vertebrae and ribs) form from?

A

Medial and ventral sclerotome

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33
Q

What does sclerotome growth towards midline form?

A

Vertebral body

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34
Q

What does dorsal sclerotome growth do?

A

Encloses neural tube

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35
Q

What does ventrolateral sclerotome growth form?

A

Costal processes

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36
Q

What do the costal processes form in the cervical region?

A

Fuse with transverse process and vertebral body = Foramen transversarium

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37
Q

What do the costal processes form in the thoracic region?

A

Ribs

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38
Q

What do the costal processes form in the lumbar region?

A

Fuse with transverse processes

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39
Q

What do the costal processes form in the sacral region?

A

Pars lateralis (flat plates)

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40
Q

What genes regulate what the costal processes form in each region?

A

Hox genes

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41
Q

What study investigated the fates of costal processes depending on location?

A

Chernoff and Rogers, (2004)

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42
Q

Regarding the cervical prevalence of supernumerary ribs, what are the results of a study by Kurihara et al., (1999)?

A

Cervical (C7) rib in 0.5% of population

C7 rib more common in females

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43
Q

Regarding the prevalence of cervical supernumerary ribs, what are the results of a study by Viertal et al., (2012)?

A

Cervical ribs in 2% of population
Twice as common in females
40.3% bilateral
Higher incidence in African American population

44
Q

How do cervical supernumerary ribs present according to the study by Viertal et al., (2012)?

A 
Often asymptomatic
Brachial plexus/Subclavian vessel compression:
- Thoracic outlet syndrome
- In 8.3% of cervical rib patients
Underreported on CT
45
Q

What are the types of intrathoracic ribs? (Reference?)

A

Type I = Supernumerary intrathoracic rib arising from:
- Ia = Vertebral body
- Ib = Part of rib close to vertebral body
Type II = Bifid intrathoracic rib
Type III = Rib locally depressed into thoracic cavity
(Kamano et al., 2006)

46
Q

How do intrathoracic ribs present?

A

Often asymptomatic

Pain if attached to diaphragmatic pleura

47
Q

How many cases of intrathoracic rib have been reported?

A

40 cases in literature since 1947

48
Q

What might an intrathoracic rib be mistaken for?

A

A bone tumour
Pleural calcified plaque
Pulmonary vein variant

49
Q

What is the prevalence of lumbar ribs?

A

0.04-2.0%

50
Q

Describe sacral/pelvic ribs

A

Sacral/Pelvic ribs develop bone (with cortex) in soft tissues adjacent to sacrum which may pseudoarticulate

51
Q

In what state might sacral or pelvic ribs cause issues?

A

Pregnancy

52
Q

What does the Schumacher et al., (1992) study show is linked to rub anomalies?

A

Rib anomalies associated with malignancy:

  • 242 rib anomalies in 218/1000 kids with tumours (21.8%)
  • Only 11/200 kids without malignancy had rib anomalies (5.5%)
53
Q

What are cervical ribs associated with according to the Schumacher et al., (1992) study?

A 
Brain tumours (27.4%)
Leukaemia (26.8%)
54
Q

How did the patient of a Kazanci et al., (2012) study present?

A

No functional issues

Presented following injury

55
Q

What was the variation seen in the Kazanci et al., (2012) case study?

A

Unilateral C6 hyperplasia of lamina
Schisis of spinal process:
- Gap between 2 parts of process
Spinous process 15cm long (when removed)

56
Q

How could the case seen in the Kazanci et al., (2012) study be differentiated from trauma by imaging?

A

CT would show:
- No pseudoarthritis
- No ossifying haematoma
MRI would show no ossifying haematoma

57
Q

What is the average length of the styloid process and where does the tip lie?

A

2.5cm long

Tip between ECA and ICA

58
Q

Regarding a styloid process, what did the case study by Kolagi et al., (2010) describe?

A

8cm long styloid process:

  • 5cm bone
  • 3cm ossified stylohyoid ligament
59
Q

What implications can styloid processes longer than 3cm have?

A

Difficulty swallowing
Carotid artery compression
Foreign body sensation

60
Q

What features of a long styloid process are important regarding whether or not it will result in signs/symptoms?

A

Direction

Curvature

61
Q

What are the epidemiological stats for hyperplasia of the styloid process (Kolagi et al., 2010)?

A

Prevalence = 4-7%
4x more common in males
75% of cases are bilateral

62
Q

What are the types of upper limb dysplasias?

A

Osseous
Musculotendinous
Neuromuscular

63
Q

What does radial deficiency result in?

A

Longitudinal deficiency in embryonic limb bun leading to defects of:

  • Radius
  • Carpals
  • Radial rays (especially thumb)
64
Q

What does ulnar deficiency result in?

A

Longitudinal deficiency in embryonic limb bun leading to defects of:

  • Ulna
  • Carpals
65
Q

What other systems may be affected in radial and ulnar deficiency?

A

Renal
Cardiac
GI

66
Q

Regarding radial and ulnar deficiency, what did radiographs in a study by Manske, (1996) show?

A 
Radiograph of ulnar deficiency:
- Abnormal radius
- Absent carpals
Radiograph of radial absence:
- Centralised ulna (surgically) = More stable wrist
67
Q

What ribs are usually affected as shortened midthoracic ribs?

A

6, 7 or 8

68
Q

What is the prevalence of shortened midthoracic ribs?

A

16%
Right side = 8%
Left side = 1%
Bilateral = 7%

69
Q

What is the reference for shortened midthoracic ribs?

A

Kurihara et al., (1999)

70
Q

What is the embryological origin of shortened midthoracic ribs?

A

Early fusion of epiphyseal centre

71
Q

What are the clinical issues associated with shortened midthoracic ribs?

A

There are none

72
Q

What are the functions of bone?

A

Protection/Support
Muscle attachment
Movements (joints

73
Q

What are the surgical implications of bony variation?

A

Transplantation issues

Implantation of prostheses/Fixation

74
Q

What variation is described in a case study by Varrichio et al., (2013)?

A

Obturator nerve running in osseous tunnel from near ischial spine to normal pelvic aspect of the obturator canal

75
Q

What are the implications of the variation described by Varrichio et al., (2013)?

A

None in this case

May result in issues if pelvic fracture

76
Q

What is the prevalence of bifid ribs?

A

0.15-3.4%

77
Q

What sort of defect is bifid ribs? What other defects may it be associated with because of this?

A

Mesenchymal
Other defects:
- Cardiac
- Renal

78
Q

What are the implications of bifid ribs?

A

Often asymptomatic

May affect NVB branching and rib counting

79
Q

What can syntosis (fusion) of ribs result in? (Reference?)

A

Compression of intercostal NVB
Reduced chest expansion = Respiratory issues
(Gupta et al., 2009)

80
Q

What does bony absence result in?

A

Leaves soft tissues vulnerable to damage

81
Q

How does spina bifida occulta arise?

A

Incomplete midline dorsal bony fusion

82
Q

What is a possible clinical implication of spina bifida occulta? (Reference?)

A

Unprotected spinal cord:
- Dural puncture if given epidural anaesthesia
(Senoglu et al., 2008)

83
Q

According to a study by Senoglu, (2007), how can a missing posterior arch of the atlas present?

A

Asymptomatic

Transient neurological symptoms

84
Q

Bony variation may also result in what issues?

A

Joint instability

Risk of injury during sport

85
Q

What variations may result in joint instability and how?

A

Aplasia = No bone to form joint

Malformations of articular surface

86
Q

What did Tubbs et al., (2005) study regarding bony variation and joint stability?

A

Duplication of occipital condyles

87
Q

What were the findings in the Tubbs et al., (2005) study?

A

Extra occipital condyles results in craniocervical instability
Additional bony prominences form in an attempt to stabilise

88
Q

What study disagrees with the Tubbs et al., (2005) study on atlanto-occipital joint stability in the presence of additional condyles?

A

Kunicki and Ciszek, (2005)

89
Q

What did Hemamalini, (2014) study?

A

Atlanto-occipital fusion

90
Q

What anomalies of the atlanto-occipital joint are major enough to affect movement at the joint according to the Hemamalini, (2014) study?

A

Assimilation of the atlas

Occipitalisation of the atlas

91
Q

What can atlanto-occipital fusion affect?

A 
Can alter course of or compress:
- Vertebral artery
- C1 nerve
(As both pass over C1 usually)
Cord compression (if affecting foramen magnum)
Flexion-extension of head
92
Q

What bony variations may compress neurovascular structures?

A

Foramina overgrowth
Bony tunnels
Bony spurs

93
Q

Apart from a variant bone itself compressing a neurovascular structure, what else may compress nerves/vessels? Examples?

A

Ligamentous material associated with it
Examples:
- Supracondylar spur of humerus and ligament of Struthers (Krishnamurthy and Lakshmiminarayan, 2013)
- Compression of median nerve by ligament of Struthers (Suranyi, 1983)

94
Q

What can additional bones be mistaken for?

A

Avulsion fracture

Disease pathology

95
Q

What ‘normal’ anatomy may be mistaken for variation?

A

Accessory ossicles
Sesamoid bones in:
- Hands
- Feet

96
Q

In a study of 984 feet by Coskun et al., (2009), what did they find?

A

209 accessory ossicles:

  • 10.9% of females
  • 10.2% of males
97
Q

What are the implications of an interphalangeal sesamoid bone according to Davies et al., (2003)?

A

Painful calluses

Migrations into a dislocated joint

98
Q

How can bony variation affect dental procedures?

A

Bony landmarks

Foramina for neurovascular structures inside bone used for anaesthesia

99
Q

What did the Hasan et al., (2010) study find that may affect dental procedures?

A

Bilateral absence of mental foramen

100
Q

What racial differences are seen in the termination of mental canals?

A

Caucasians = More medial (1st/2nd premolar)
Mongoloid population = 2nd premolar
Black population = 2nd premolar/1st molar

101
Q

How can variation affect dental implants?

A

Osteotomy for implant may damage inferior alveolar or mental nerve resulting in altered lip sensation

102
Q

What are the 4 common forms of the pterion?

A

Sphenoparietal
Sphenoparietal plus Wormian bone
Frontotemporal
Epipteric

103
Q

What did Ma et al., (2012) investigate regarding the pterion?

A

Its relation to the middle meningeal artery

104
Q

What did Ma et al., (2012) find regarding the thickness of the skull at the pterion?

A

Not always the thinnest part:
- Midpoint is 4.4mm thick vs thinnest part of squamous temporal bone which is 1.1mm on lateral wall of middle cranial fossa

105
Q

What did Ma et al., (2012) find regarding the pterion and the middle meningeal artery?

A

Anterior branch of MMA;

  • Overlies pterion in only 2/3
  • Is posterior to pterion in 1/3
  • Is enclosed by protective bony tunnel in 70%

Anatomy of the Individual (10 decks)

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