Since ancient times, asymptomatic bone variations have been studied in many different disciplines. In radiology, for example, they enable the differentiation of the typical from the anomalous, but in biological anthropology they are especially useful in answering questions about humans and their diachronic and synchronic variability.
This book provides an easily accessible presentation of the osseous variations of the postcranial skeleton (from the spine to the feet), which are sometimes poorly understood by the scientific community. These variations are examined one by one, with definitions, population frequencies and complete illustrations given for each.
Asymptomatic Osseous Variations of the Postcranial Human Skeleton is intended as a comprehensive reference manual for further research on these types of skeletal variations.
Table of Contents
Foreword ix
Preface xi
Acknowledgments xiii
Introduction xv
Chapter 1 The Upper Limb 1
1.1 Clavicle 2
1.1.1 Perforation of the clavicle 2
1.1.2 Coracoclavicular joint 4
1.1.3 Duplication of the acromial extremity 6
1.1.4 Costoclavicular sulcus 7
1.2 Scapula 9
1.2.1 Coracoclavicular joint 9
1.2.2 Suprascapular foramen 11
1.2.3 Suprascapular notch 13
1.2.4 Unfused acromial epiphysis 15
1.2.5 Circumflex sulcus 17
1.2.6 Acromial articular facet 19
1.3 Humerus 21
1.3.1 Septal aperture 21
1.3.2 Supracondyloid process 24
1.3.3 Supracondyloid tunnel 25
1.3.4 Translucency of the septum 27
1.4 Radius 28
1.4.1 Radial tuberosity orientation 28
1.4.2 Double distal radial articular facet 30
1.5 Ulna 31
1.5.1 Medial trochlear notch 32
1.5.2 Lateral trochlear notch 33
1.5.3 Trochlear groove 35
Chapter 2 The Thorax 37
2.1 Sternum 38
2.1.1 Sternal cleft 38
2.1.2 Non-fusion of sternebrae 40
2.1.3 Misplaced manubrium-mesosternal joint 42
2.1.4 Sternal foramen 43
2.1.5 Manubriosternal fusion 45
2.1.6 Manubrium foramen 47
2.1.7 Xiphoid foramen 48
2.1.8 Single xiphoid process 50
2.1.9 Bifurcated xiphoid process 51
2.1.10 Triple xiphoid process 53
2.1.11 Absence of the xiphoid process 54
2.1.12 Suprasternal bones 55
2.2 Ribs 56
2.2.1 Cervical rib 56
2.2.2 Lumbar rib 58
2.2.3 Bifid rib 60
2.2.4 Costal fusion 62
2.2.5 Sacral rib 64
2.2.6 Intrathoracic rib 65
2.2.7 Absence of the 12th rib 67
Chapter 3 The Vertebral Column 69
3.1 First cervical vertebra (atlas) 70
3.1.1 Posterior atlas bridge 70
3.1.2 Lateral atlas bridge 72
3.1.3 Retroarticular bridge 73
3.1.4 Occipitalization 75
3.1.5 Anterior atlas arch deficiency 76
3.1.6 Posterior atlas arch deficiency 77
3.1.7 Double condylar facet 79
3.1.8 Spina bifida occulta 80
3.2 Second cervical vertebra (axis) 82
3.2.1 Os odontoideum 82
3.3 Cervical vertebra 84
3.3.1 Open transverse foramen 84
3.3.2 Double transverse foramen 86
3.3.3 Bifid spinous process 88
3.4 Spine 90
3.4.1 Spina bifida occulta 90
3.4.2 Butterfly vertebra 91
3.4.3 Spondylolysis 93
3.4.4 Transitional vertebra 95
3.4.5 Sacralization 96
Chapter 4 The Pelvic Girdle 99
4.1 Sacrum 100
4.1.1 Lumbarization 100
4.1.2 Spina bifida occulta 102
4.1.3 Butterfly vertebra 103
4.1.4 Accessory hip facet 105
4.2 Coxal bone 106
4.2.1 Accessory hip facet 107
4.2.2 Pubic spine 108
4.2.3 Acetabular mark 109
Chapter 5 The Lower Limb 113
5.1 Femur 114
5.1.1 Supracondylar apophysis 114
5.1.2 Fabella 115
5.1.3 Third trochanter 117
5.1.4 Hypotrochanteric fossa 119
5.1.5 Allen’s fossa 120
5.1.6 Posterior cervical (acetabular) imprint 122
5.1.7 Poirier’s facet 124
5.2 Patella 125
5.2.1 Dorsal defect 126
5.2.2 Bipartite patella 127
5.2.3 Vastus notch 129
5.3 Tibia 131
5.3.1 Lateral squatting facet 131
5.3.2 Medial squatting facet 132
5.4 Talus 134
5.4.1 Lateral squatting facet 134
5.4.2 Medial squatting facet 136
5.4.3 Os trigonum 138
5.4.4 Bifid inferior articular facet 139
5.5 Calcaneus 141
5.5.1 Calcaneus secondarius 141
5.5.2 Absence of the anterior articular surface of the talus 143
5.5.3 Bipartite anterior facet 144
5.5.4 Extension of the posterior articular facet 146
5.5.5 Peroneal trochlea 148
5.5.6 Retrotrochlear eminence 149
5.6 The foot 151
5.6.1 Os tibiale 151
5.6.2 Os peroneum 153
Appendix AOVs versus Pathologies 155
References 159
Index 171
