NUVASIVE - EXHIBIT 2001
`Alphatec Holdings Inc. et al. v. NuVasive, Inc. - IPR2019-00362
`
`

`

`si.'i-E!c/.
`~ T~
`~ EDITION ~
`
`THE ANATOJ\JIICAL BASIS OF iVIED I CINE AND SURGERY
`
`CHAIRMAN OF THE EDITORIAL BOARD
`The late Peter L. Williams DSc (Land) MA MB BChir (Cantab) FRCS (Eng)
`Emeritus Professor, University of London
`Formerly Professor of Anatomy, Guy's Hospital Medical School, London
`
`EDITORIAL BOARD
`
`Lawrence H. Bannister
`Martin M. Berry
`Patricia Collins
`Mary Dyson
`Julian E. Dussek
`Mark W. J. Ferguson
`
`&1
`CHURCHILL LIVINGSTONE
`EDINBURGH LONDON NEW YORK PHILADELPHIA SYDNEY TORONTO 1995
`
`HIGHlAND PARK PUBllC t IBRARY
`494 lAURrt AVE
`HIGHlAND PARK. ll 6003~·2690
`841-432-{)?16
`
`

`

`&!!
`617Cfb
`
`CHURCHILL LIVINGSTONE
`An imprint of Harcourt Brace and Company Limited
`
`© Pearson Professional Limited 1995
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`For Churchill Livingstone
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`Commissioning Editor: Timothy Horne
`Project Editors: Julia Merrick, Dilys Jones
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`Illustrators who have contributed new artwork
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`Thirty-eighth edition first published 1995
`Reprinted 1999
`
`Standard edition ISBN 0 443 04560 7
`
`international edition ISBN 0 443 05717 6
`
`British Library Cataloguing In Publication Data
`A catalogue record for this book is available from the British Library.
`
`Library of Congress Cataloging In Publication Data
`A catalog record for this book is available from the Library of Congress.
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`The Publishers have made every effort to trace holders of copyright in
`original material and to seek permission for its use in Grays Anatomy.
`Should this have proved impossible then copyright holders are asked to
`contact the Publishers so that suitable acknowledgement can be made at
`the first opportunity.
`
`Andrew Bezear
`Robert Britton
`Peter Cox
`Marks Creative
`Patrick Ellion
`Jenny Halstead
`Dr A. A. van Horssen
`Peter Jack
`Peter Lamb
`Gillian Lee
`Paul Richardson
`Lesley J. Skeates
`Denise Smith
`Philip Wilson
`
`Photographers
`
`Sarah-Jane Smith
`Kevin Fitzpatrick
`
`Printed in Great Britain
`
`

`

`CONTENTS
`
`PREFACE
`
`ix
`
`CONTRIBUTORS xi
`
`HISTORICAL ACCOUNT xv
`Biography of Henry Gray xv
`Brief history of Gray's Anatomy xvii
`
`1
`INTRODUCTION TO HUMAN ANATOMY 1
`Edited by Lawrence H. Bannister
`What is anatomy? 2
`Origin of life on Earth 3
`Evolution of life on Earth 3
`Primate and human evolution 7
`Anatomical nomenclature 13
`
`2
`CELLS AND TISSUES 17
`Edited by Lawrence H. Bannister
`Cell structure 21
`Cytoplasm 23
`Cytoskeleton 36
`Nucleus 46
`Reproduction of cells 56
`Tissues 67
`Epithelium 67
`Unilaminar epithelia 67
`Multilaminar epithelia 71
`Glands 73
`Connective tissues 75
`
`5
`INTEGUMENTAL SYSTEM 375
`Edited by Lawrence H. Bannister
`Skin 376
`Introduction 376
`Epidermis 381
`Dermis 395
`Nerves 399
`Blood vessels 398
`Age-related changes 411
`Repair 412
`Breasts {mammae) 417
`Female breasts 418
`Male breasts 424
`
`6
`SKELETAL SYSTEM 425
`Edited by Roger W. Soames
`Morphology of the human skeleton 426
`Skeletal connective tissues 443
`The scope of arthrology 484
`Axial skeleton 510
`Vertebral column 511
`Ribs 539
`Thorax 545
`Skull 547
`Appendicular skeleton 613
`Upper limb 615
`Wrist and hand 646
`Lower limb 662
`Ankle and foot 712
`
`3
`EMBRYOLOGY AND DEVELOPMENT 91
`Edited by Patricia Collins
`Developmental biology 1 02
`Early human development 121
`Development of individual systems 173
`Respiratory and gastrointestinal systems 17 4
`Urinary and reproductive systems 199
`Nervous system and special sense organs 217
`Musculoskeletal system 264
`Cardiovascular system 298
`Prenatal growth in form and size 328
`
`4
`NEONATAL ANATOMY AND GROWTH 343
`Edited by Patricia Collins
`Neonatal anatomy 344
`Individual systems in the neonate 346
`Growth 365
`
`7
`MUSCLE 737
`Edited by Stanley Salmons
`Introduction 738
`Brief survey of the major types of muscle 738
`Skeletal muscle 738
`Cardiac muscle 764
`Smooth muscle 771
`Attachments of skeletal muscles 781
`Form and function in skeletal muscles 783
`Form and fibre architecture 783
`Functional implications of form 783
`Muscles and movement 785
`Muscles and fasciae of the head 789
`Craniofacial muscles 789
`Masticatory muscles 799
`Anterolateral muscles and fasciae of the neck 802
`Superficial and lateral cervical muscles 804
`Suprahyoid muscles 806
`lnfrahyoid muscles 807
`
`v
`
`

`

`CONTENTS
`
`Anterior vertebral muscles 807
`Lateral vertebral muscles 808
`Muscles and fasciae of the trunk 809
`Deep muscles of the back 809
`Suboccipital muscles 813
`Muscles of the thorax 813
`Muscles of the abdomen 819
`Muscles and fasciae of the pelvis 829
`Muscles and fasciae of the perineum 832
`Muscles and fasciae of the upper limb 835
`Muscles connecting
`the upper
`limb with
`column 835
`Muscles connecting the upper limb with the thoracic wall 838
`Muscles of the scapula 840
`Muscles of the upper arm 842
`Muscles of the forearm 844
`Muscles of the hand 858
`Muscle and fasciae of the lower limb 868
`Muscles of the iliac region 868
`Muscles of the thigh and gluteal region 870
`Muscles of the leg 881
`Muscles of the foot 889
`
`the vertebral
`
`8
`NERVOUS SYSTEM 901
`Edited by Martin M. Berry, Susan M. Standring,
`Lawrence H. Bannister
`Introduction to the nervous system 902
`Cy1ology of the nervous system 921
`Regional organization of the central nervous system 974
`Spinal medulla or cord 975
`Rhombencephalon 1011
`Mesencephalon 1 066
`Diencephalon 1 079
`Telencephalon 1107
`Basal nuclei 1186
`Fluid compartments and fluid balance in the central nervous
`system 1202
`Peripheral nervous system 1224
`Cranial nerves 1225
`Spinal nerves 1258
`Autonomic nervous system 1292
`Peripheral apparatus of the special senses 1312
`Gustatory apparatus 131 2
`Olfactory apparatus 1315
`Peripheral visual apparatus 1321
`Accessory visual apparatus 1353
`Auditory and vestibular apparatus 1367
`
`Arteries of the lower limbs 1564
`Venous system 1574
`Cardiac veins 1575
`Veins of the head and neck 1576
`Veins of the upper limbs 1589
`Veins of the thorax 1591
`Veins of the lower limbs 1595
`Veins of the abdomen and pelvis 1598
`Lymphatic system 1605
`
`11
`RESPIRATORY SYSTEM 1627
`Edited by Lawrence H. Bannister
`Introduction 1628
`Nose and paranasal sinuses 1631
`Larynx 1637
`Trachea and bronchi 1653
`Lungs 1657
`Pleurae 1662
`Mediastinum 1676
`
`12
`ALIMENTARY SYSTEM 1683
`Edited by Lawrence H. Bannister
`Introduction 1684
`Oral cavity and related structure 1686
`Palate 1688
`Salivary glands 1691
`Teeth 1699
`Tongue 1721
`Pharynx 1725
`Abdomen 1733
`Peritoneum 1734
`Oesophagus to anus 17 46
`Introduction 17 46
`Enteric nervous system 1749
`Oesophagus 1751
`Stomach 1753
`Small intestine 1763
`Large intestine 1774
`Gastro-entero-pancreatic endocrine system 1787
`Hernia 1788
`Pancreas 1790
`Liver 1795
`Liver transplantation 1808
`Biliary ducts and gallbladder 1809
`
`9
`HAEMOLYMPHOID SYSTEM 1399
`Edited by Lawrence H. Bannister
`Haemal cells and tissue 1400
`Haemopoiesis 1407
`Lymphoid cells and tissues 1417
`Lymphocytes 1417
`Thymus 1423
`Lymph nodes 1431
`Spleen 1437
`Mucosa-associated lymphoid tissue 1442
`
`10
`CARDIOVASCULAR SYSTEM 1451
`Edited by Giorgio Gabella
`Blood vessels 1452
`Thoracic cavity and heart 1470
`Arterial system 1504
`Aorta 1505
`Carotid system of arteries 1513
`Subclavian system of arteries 1529
`Arteries of the trunk 1545
`
`vi
`
`13
`URINARY SYSTEM 1813
`Edited by Mary Dyson
`Kidneys 1815
`Renal microstructure 1819
`Juxtaglomerular apparatus 1824
`Renal vessels and nerves 1826
`Renal blood vessels 1826
`Upper urinary tract 1827
`Ureters 1828
`Kidney transplantation 1834
`Urinary bladder 1837
`Male urethra 1842
`Female urethra 1843
`
`14
`REPRODUCTIVE SYSTEM 1847
`Edited by Lawrence H. Bannister and Mary Dyson
`Reproductive organs of the male 1848
`Testes and epididymes 1848
`Ductus deferens (vas deferens) 1855
`Spermatic cord 1856
`
`

`

`Scrotum 1856
`Penis 1857
`Prostate 1859
`Reproductive organs of the female 1861
`Ovaries 1861
`Uterine tubes 1867
`Uterus 1869
`Vagina 1875
`Female external organs 1876
`
`15
`ENDOCRINE SYSTEM 1881
`Edited by Mary Dyson
`Adenohypophysis 1883
`Neurohypophysis 1886
`Pineal gland 1888
`Thyroid gland 1891
`Parathyroid glands 1897
`Chromaffin system 1898
`Diffuse neuroendocrine system 1898
`Suprarenal (adrenal) glands 1900
`
`Paraganglia 1905
`Para-aortic bodies 1906
`Tympanic body 1906
`Coccygeal body 1906
`
`16
`SURFACE ANATOMY 1909
`Edited by Harold Ellis and Julian E. Dussek
`Head 1911
`Neck 1914
`Thorax 1915
`Abdomen 1918
`Perineum 1920
`Back 1921
`Upper limb 1923
`Lower limb 1929
`
`BIBLIOGRAPHY 1937
`
`INDEX 2045
`
`CONTENTS
`
`vii
`
`

`

`SKELETAL SYSTEM
`
`but all movements, active or not, can be made passively when the
`muscles concerned are relaxed; the term 'accessory' will be used for
`all movements impossible in the absence of resistance (Salter 1955).
`Limitation of moveme nts. This is due to several factors, of
`which tension in ligaments is prominent, as is obvious in aHempted
`hyperextension of the unfixed cadaveric knee or hip. I ncreasing
`ligamentous tension, balanced by increased compression between
`opposed articular surfaces, are integral factors in producing close(cid:173)
`packing, limiting most habitual movements. But tension of antag(cid:173)
`onistic muscles is equally important, involving both passive elastic
`components of muscles (and other structures around the joint) and
`reflex contraction when stimulation of mechanoreceptors in articular
`and periarticular tissues reaches a critical level. M uscles as limiting
`factors are exemplified in flexion at the hip; with the knee extended
`it is much more limited in range; with the knee flexed the hamstring
`muscles are relaxed allowing flexion of the thigh to the abdominal
`wall, such approximation of the soji parts being a third factor in
`some movements, for example flexion at the elbow and knee. Contact
`(occlusion) of teeth obviously limits mandibular elevation.
`In synovial joints, where bones are connected only by ligaments
`and muscles, parts of articular surfaces are in constant apposition
`in all positions. (Some maintain that 'apposition' implies a fine film
`of synovial fluid, of I 0 J.!ID or less, between adjacent surfaces.)
`Apposition is assisted by atmospheric pressure and cohesion between
`surfaces, but these are subsidiary to balanced contraction of muscle
`groups around the joint. When these contract, the force generated
`is vectorially resolvable into components (p. 787). Some maintain or
`alter positions of bones ('swing' and 'spin' components) and oppose
`internal and external resistances, including gravity. Another com(cid:173)
`ponent is transarticular ('shunt' component), which increases com(cid:173)
`pression between articular surfaces and helps apposition in various
`postures and movements (p. 786). Effects of external compressive or
`tensile forces, including gravity, vary with body posture and the
`direction of applied force. Thus gravity or load-bearing may some(cid:173)
`times provide a distractive force, tending to separate conarticular
`surfaces, or may exert a largely translatory/swing force between them.
`They often exert a considerable compressive force at surfaces.
`Summary. The preceding remarks are merely an introduction to
`the main concepts of kinesiology. Brief references to myokinetics are
`on p. 785. For further analyses the references given should be
`consulted. (Readers with greater faci lity in mathematics and physics
`may be interested i.n attempts to present a 'generalized mechanics of
`articular swing', ranging from Aristotelian and Newtonian physics to
`the relativity theory and quantum mechanics; MacConaill 1978a,b,c.)
`
`Blood supply and lymphatics of joints
`Joints receive blood from periarticular arterial plexuses whose numer(cid:173)
`ous rami pierce capsules to form subsynovial vascular plexuses. Some
`synovial vessels end near articular margins in an anastomotic fringe,
`the circulus articular is vasculosus (p. 470). A lymphatic plexus in the
`synovial subintin1a drains along blood vessels to the regional deep
`lymph nodes.
`
`Nerve supply of joints
`Movable joints are innervated in general by nerves supplying their
`muscles, probably establishing local reflex loops involved in move.
`ment and posture. Although the branches concerned vary, each
`innervates a specific capsular region but their territories freely
`overlap. The region made taut by muscular contraction is usually
`innervated by nerves supplying antagonists (Gardner 1948a,b). For
`example, the hip joint's capsule, on stretch inferiorly in abduction,
`is here supplied by the obturator nerve, tension in it thus producing
`reflex contraction of the adductors, usually enough to prevent
`damage. However, this is not so at the shoulder, where the axillary
`nerve innervates the anteroinferior capsular region.
`Myelinated fibres in articular nerves have Ruffini endings, lam(cid:173)
`ellated articular corpuscles and some like the neurotendinous organs
`of Golgi. Simple endings are numerous at the attachments of capsule
`and ligaments; they are terminals of non-myelinated and finely
`myelinated fibres believed to mediate pain (Gardner 1950). Ruffini
`end organs are variably orientated in the knee joint's capsule,
`principally in its flexor region, responding to stretch and adapting
`slowly. Lamellated corpuscles, less nwnerous than Ruffini endings,
`are sited laterally and adapt rapidly since they respond to rapid
`movement and vibration; both register speed and direction of move(cid:173)
`ment. Golgi end organs, with the largest myelinated nerve fibres (10-
`15 J.!m diameter), are like those at neuromuscular junctions and s.low
`to adapt (Boyd & Roberts 1953: Boyd \954; Skoglund 1956);
`they mediate position sense (Stopford 1921: Mountcastle & Powell
`1959a,b; Gardner 1967) and are concerned in stereognosis, i.e.
`recognition of shape in objects held (Renfrew & Melville 1960).
`Many non-myelinated fibres are sympathetic, ending near vascular
`non-striated muscle and believed to be vasomotor or vasosensory,
`although evidence is sparse. In synovial membrane no special end
`organs or even simple endings occur, except near blood vessels, the
`membrane being relatively insensitive to pain (Kellgren & Samuel
`1950; Barnett et all961). For a review concerned with receptors and
`sensation see Wyke (1981); for histological and functional details
`and classification of articular nerve endings see page 969.
`
`AXIAL SKELETON
`
`INTRODUCTION
`
`Dividing the skeleton into axial and appendicular sections is not
`merely a convention. The axial stmctures, cranium and vertebral
`column and associated ribs and sternum, are primary; the appen(cid:173)
`dicular elements in fins, limbs or wings were subsequent though early
`additions. Both primary and secondary elements are concerned in
`elaboration of locomotion. An axial endoskeleton, first a notochord
`and then a vertebral column, is the basic feature of Chordata and
`their subphylum, the Vertebrata, including mankind. A stiff but
`flexible axis, in bilaterally symmetrical animals that show an early
`tendency to elongation, prevents telescoping of the body. during
`waves of contraction in successive segmental muscles to produce the
`sinuous movements, especially in the tail, which are the basic mode
`of locomotion in aquatic vertebrates. A chain of bones, connected
`by discs of defonuable substance, developed around and largely
`replaced the notochord. However, notochordal vestiges occur in
`vertebrae of many fish, amphibians and reptiles, and centrally in
`mammalian intervertebral discs. This replacement is repeated in
`every vertebrate embryo. These new vertebral elements are complex
`and variable in pattern in earlier vertebrates but from reptiles
`onwards the most basic part is the centrum, forming most of the
`
`vertebral body, ventral to the spinal cord (spinal medulla). ln a
`typical vertebra a neural arch, encircling the spinal cord, fuses
`ventrally with the centrum and usually bears a median dorsal spinous
`process and paired lateral transverse processes just dorsal to the
`neurocentra! junctions. This enclosure isolates the spinal cord from
`the axial musculature and protects it from external forces, thus
`insulating its vessels from extraneous compression.
`T he centrum and each half neural arch ossify from separate
`centres; when these extend through cartilaginous precursors to meet
`and fuse, the dorsolateral parts of the vertebral body are formed
`from the ventral ends of the neural arch. Centrum and body are
`therefore not synonyms, nor is the vertebral arch exactly equal to a
`neural arch. A centrum is somewhat less than a vertebral body, a
`neural somewhat more than a vertebral arch (p. 532).
`Segmental muscles flexing the vertebral axis are only in part
`attached to vertebrae; in connective tissue septa (myocommata)
`between adjacent myotomes ribs evolve as levers for such attach(cid:173)
`ments. Such costal struts first appeared dorsally in the axial muscu(cid:173)
`lature and extended ventrally into the body wall in early vertebrates.
`In fish ventral ribs also appeared, which enclosed caudal vessels in
`the tail. It is generally agreed that ribs of land tetrapods correspond
`to the dorsal piscine series (Romer 1970).
`
`510
`
`

`

`VERTEBRAL COLUMN
`
`SKELETAL SYSTEM
`
`Ribs are thus intersegmental, and segmental muscles, derived
`basically from myotomes, bend the vertebral co lumn; vertebrae also
`become intersegmental, though their embryonic pa ttern (p. 265) is
`primarily segmental. ln early vertebrates dorsal ribs adjoin most
`vertebrae, showing little regional adaptation except in the postnatal
`tail. ln la nd vertebrates, with the elaboration of appendages for
`locomotion, the vertebral column is ada pted to new patterns of force
`in the distribution of weight and muscular tensions.
`In hindlimbs the pelvic girdle articulates with several vertebrae,
`which fuse with each other and with costal elements to form a
`sacrum. Sacral vertebrae lose individual movement; in mammals there
`are three to five fused sacral vertebrae, and distal to these a varia ble
`number of caudal vertebrae, reduced to fo ur degenerate elements.
`fused into a coccyx in adult humans. Some movement persists,
`however, between the fused sacral mass and neighbouring vertebrae,
`as well as between the sacrum and pelvic girdle.
`Mammalian presacral vertebrae vary in number and differentia tion
`but can be grouped into cervical (neck), thoracic (where ribs persist)
`and lumbar vertebrae (devoid of mobile ribs) by distinguishing
`features. Cervical ribs are small or ' absent' (but see below); their
`disappearance in cervical and lumba r regions is linked to the change
`from breathing by gills to lungs, and to development of independent
`movements of the head. There is no neck in fish, the postcranial
`region being occupied by the branchial apparatus. Ca udal shift of
`the respiratory a pparatus in land vertebrates necessarily preceded
`development of a neck. Cervical vertebrae were early sta bilized to
`seven in mammals (except tree sloths and manatees), even in such
`extremes as wha les and giraffes. With respirato ry adaptation of ribs
`in land a nimals and develo pment o f a diaphragm in mammals, well(cid:173)
`formed ribs, articulating with but separate from vertebrae, are limited
`to thoracic levels. But ribs do not disappear completely in cer vical
`and post-thoracic regions: vestigial costal elements a re combined
`with transverse processes of all such vertebrae (see 3.134, 6.89).
`·
`The total number of vertebrae, excluding the tail, is reduced from
`the lemuroid and tarslo id to the a nthropoid primates. Monkeys,
`apes and hominids (extinct and extant) show some uniformity. The
`cervical, thoracic, lumba r and sacral vertebrae number respectively
`7, 11- 15, 4 to 7, a nd 3- 6, human values being 7, 12, 5 and 5. Caudal
`vertebrae va ry much in number.
`
`VERTEBRAL COLUMN
`GENERAL VERTEBRAL FEATURES
`A vertebra (6.87) essentia lly has a ventral body a nd a dorsal vertebral
`(neural) arch, extended by lever-like processes, together enclosing a
`vertebral foramen , occupied by the spinal cord, meninges a nd their
`vessels. Opposed surfaces of adjacent bodies are bound together by
`intervertebral discs of fibrocartilage. T he complete column of bodies
`and discs forms a strong but flexible central axis of the body
`
`supporting, in bipeds, the full weight of the head a nd trunk . lt also
`transmits even greater forces due to muscles attached to it directly
`and indirectly. The foramina form a vertebral canal for the spinal
`cord, and between adjo ining neural arches, nea r their junctions with
`vertebral bodies, interve..rtebralforamina transmit m ixed spinal nerves,
`smaller recurrent nerves and blood and lymphatic vessels (see also
`p. 1258).
`The cylindroid vertebral body varies in size, shape and proportions
`in different regions a nd more so in different species. lts junctional
`aspects vary from approximately flat (but not pa rallel) to sellar, with
`a raised peripheral smooth zone formed from the 'annular' epiphyseal
`disc (p. 532), within which the surface is rough. These differences in
`texture are due to variations in early structure of intervertebral discs
`(p. 265). In the horizontal plane the profiles of most bodies a re
`convex anteriorly, but concave posterio rly where they complete the
`vertebral foramen.' Most vertical profiles are concave anteriorly but
`flat posteriorly. Small vascular foramina appear on the front a nd
`sides, but posteriorly there a re small arterial foramina (Willis 1949)
`and a large irregular orifice (sometimes double) for the exit o f
`basivertebral veins (6.88). The adult vertebral body is not coextensive
`the developmental centrum (p. 532) but
`includes, post(cid:173)
`with
`erolaterally, pa rts of the neural arch, as already noted.
`The vertebral arch has on each side a vertically narrower ventral
`pa rt, the pedicle, a nd dorsally a broader lam ina. Projecting from
`their junctions are paired transverse, superior and inferior articular
`processes; dorsally is a median spinous process.
`Pedic/es are short, thick, rounded dorsal projections from the
`superior part of the body a t the junction of its lateral and dorsal
`surfaces, so that the concavity formed by its curved superior border
`is shallower than the inferior one (6.84). Adjacent vertebral notches
`contribute to an intervertebral foramen when vertebrae articulate
`by the intervertebral disc a nd zygapophyseal joints. The complete
`perimeter of an intervertebral fora men consists, therefore, of the
`notches, the dorsolateral aspects of parts of adjacent vertebral bodies
`and intervening disc, and the capsule of the synovial zygapophyseal
`joint.
`Laminae, directly continuous with pedicles, are vertically flattened
`a nd curve dorsomedially to complete, with the base of the spinous
`process, a vertebral foramen.
`,
`The spinous process (spi11e) projects dorsally and often caudally
`from the junction of the laminae. Spines vary much in size, shape
`and direction. They act as levers for muscles which control posture
`and active movements (flexion/extension, lateral flexion and rota tion)
`of the vertebral column.
`The paired superior and inferior articular processes (zygapophyses)
`a rise from the vertebral arch at the pediculolaminar junctions. T he
`superior processes project cranially, bearing dorsal facets which may
`also have a lateral or medial inclination, depending on level. Inferior
`processes bulge caudally with articular facets directed ventrally, again
`with medial or lateral inclination depending on vertebral level.
`Articular processes of adjoining vertebrae thus form small synovial
`
`Bo"e derived
`from annular
`epiphysis
`
`' Costal
`
`Superior vertebral notch
`
`Spi11ous
`process
`
`6.87 Typical thoracic vertebra: superior aspect.
`
`6.88 Median sagittal section through a lumbar vertebra.
`
`511
`
`

`

`SKELETAL SYSTEM
`
`zygapophyseal joints (p. 514), forn1ing the posterior aspect of the
`intervertebral foramina;
`these joints permit limited movement
`between vertebrae: mobility varying considerably with vertebral level.
`Trans~erse processes project laterally from the pediculolaminar
`junctions as levers for muscles and Ligaments particularly concerned
`in rotation and Lateral flexion. (The preceding comment is a sim(cid:173)
`pliJication. In practice the activities of spinal musculature must be
`considered in terms of bilateral and surrounding muscle groups;
`weight-bearing and initial posture are also crucial.) The thoracic
`transverse processes articulate with ribs. At other levels the mature
`transverse process is a composite of 'true' transverse process
`(diapophysis) and an incorporated costal clement.
`Costal elements (pleurapophyses) develop as basic parts of neural
`arches in mammalian embryos, but become independent only as
`thoracic ribs. Elsewhere they remain less developed and fuse with
`the 'transverse process' of descriptive anatomy (6.89).
`Vertebrae are internally trabecular (6.88), with an external shell
`of compact bone perforated by vascular foramina. The shell is thin
`on discal surfaces but thicker in the arch and its processes. The
`trabecular interior contains red bone marrow and one or two large
`ventrodorsal canals for the basivertebral veins.
`A technique involving the analysis of nine dimensions of vertebral
`bodies and spines. from which exact anthropometric vertebral dimen(cid:173)
`sions can be determined from radiographs, has been developed by
`Gilad and Nissan (1985).
`The arterial patterns in bodies of thoracic vertebrae between ages
`29th prenatal week to adulthood has been described by Ratcliffe
`(1980, 198 1).
`All vertebrae, from second cervical to first sacral, articulate by
`cartilaginous joints between their bodies, synovial joints between
`their articular processes (zygapophyses) and fibrous joints between
`their laminae and also between their transverse and spinous processes.
`
`JOINTS OF VERTEBRAL BODIES
`Vertebral bodies are united by anterior and posterior longitudinal
`ligaments and by fibrocartilaginous intervertebral discs between
`laminae of hyaline cartilage, together forming symphyses.
`
`The anterior longitudinal lig.ament
`The anterior longitudinal ligament (6.90) is a strong band extending
`along the anterior surfaces of the vertebral bodies, broader caudally,
`being thicker and narrower in thoracic than in cervical and lumbar
`regions. It is also relatively thicker and narrower opposite vertebral
`bodies than at the levels of intervertebral symphyses. Attached to
`the basilar occipital bone, it extends to the anterior tubercle of Cl
`(atlas), the front of the body of C2 (axis), continuing caudally to the
`
`front of the upper sacrum. !ls longitudinal fibres, strongly adherent
`to the intervertebral discs, hyaline cartilage laminae and margins of
`adjacent vertebral bodies, are loosely attached at intermediate levels
`of the bodies. where the ligament fills their anterior concavities
`flattening the vertebral profile (6.90). At these various levels liga:
`mentous fibres blend with the subjacent periosteum, perichondrium
`and periphery of the annulus fibrosus. It has several layers, the most
`superficial fibres being longest extending over three or four vertebrae
`intermediate between two or three, the deepest from one body t~
`the next: laterally short fibres connect adjacent vertebrae.
`
`The posterior longitudinal ligament
`The posterior longitudinal ligament (6.91) on the posterior surfaces
`of the vertebral bodies lies in the vertebral canal, attached to the
`body of C2 (axis) and the sacrum; above it is continuous with the
`membrana tectoria (p. 522). Its smooth glistening fibres, attached to
`intervertebral discs, laminae of hyaline cartilage and adjacent margins
`of vertebral bodies, are separated between attachments by basi(cid:173)
`vertebral veins and the venous rami draining them into anterior
`internal vertebral plexuses. At cervical and upper thoracic levels the
`ligament is broad and of uniform width, but in lower thoracic and
`lumbar regions it is denticulated. narrow over vertebral bodies and
`broad over discs (strictly symphyses). Its superficial fibres bridge
`three or four vertebrae, while deeper fibres extend between adjacent
`vertebrae as perivertebral ligame111s close to and. in adults, fused
`with the annulus fibrosus of the intervertebral disc. The layers are
`more distinct in the immediate postnatal years.
`
`Intervertebral discs
`Intervertebral discs (6.90, 92). between adjacent surfaces of vertebral
`bodies from C2 (axis) to the sacrum, are the chief bonds between
`them. Disc outlines correspond with the adjacent bodies, thickness
`varying in different regions and parts of the same disc. In cervical
`and lumbar regions they are thicker anteriorly, contributing to the
`anterior convexity: in the thoracic region they are nearly uniform,
`the anterior concavity being largely due to the vertebral bodies.
`Discs are thinnest in the upper thoracic region and thickest in the
`lumbar regions, being adherenl to thin layers of hyaline carti.lage on
`the superior and inferior vertebral surfaces (p. 51 1 ); together the disc
`and hyaline cartilages form an intervertebral symphysis. Except for
`their peripheries, supplied from adjacent blood vessels, discs arc
`avascular and supported by diffusion through the trabecular bone
`of adjacent vertebrae. Vascular and avascular parts differ in reaction
`to injury (Smith & Walmsley 1951). Connected to anterior and
`posterior longitudinal ligaments discs in the thoracic region are
`additionally tied laterally, by intra-articular ligaments, to the beads
`
`Neuroc<!lllral lip
`Capimlar process
`
`Apophysis IICUTOCCIIIra/is
`Parapophysis
`
`COSTAL ELEMENT
`Amerior costal ba r - - - - - - - - ,
`
`PLEURAPOPHYSIS
`
`TratiSfJase process --'----./
`
`Prcsmre facet - -- - --"
`
`Superior articular - - - - - - - /
`process
`
`# =1--------Capm costae
`_.-- ---Foramen vercebrarrcrialis
`~-~-Collum costae
`
`'----
`
`--Diapophysis
`
`"--- -- - Paraprezygapophysis
`
`" - - - - - - Pre:::ygapophysis
`
`6.89 The morphology of a generalized cervical vertebra, with particular
`reference to the pleurapophyses. On the left the terms are zoological, on
`the right are alternatives for human anatomy suggested by Cave (1975).
`
`512
`
`(Reproduced with permission from the author, the Journal of Zoology and
`Cambridge University Press.)
`
`

`

`IERTEBRAL COLUMN
`
`SKELETAL SYSTEM
`
`Pedicle
`
`lnttr'lltrttbrolforamm
`
`lnttr'IJtrtebra/
`disc
`
`}
`
`6.90 Median sagittal section through part of the lumbar region of the
`vertebral column. Note the boundaries of intervertebral foramina. For con-
`
`trasting details concerning the direction of fibre bundles in the Interspinous
`ligaments see text and Heylings (1978).
`
`of ribs articulating with adjacent vertebrae. Intervertebral discs
`(excluding the first two vertebrae) form a fifth of the postaxial
`vertebral column, cervical and lumbar regions having, in proportion
`to length, a greater contribution than the thoracic and thus being
`more pliant (Harris 1939). Each disc consists of an outer laminated
`annulus fibrosus and an inner nucleus pulposus (6.90, 92).
`Annulus fibrosus . This has a narrow outer collagenous zone and
`a wider inner fibrocartilaginous zone. Its laminae, convex peripheraiJy
`seen in vertical section, are incomplete coiJars connected by fibrous
`bands overlapping one another. (The internal vertical concavity of
`the laminae conforms to the surface profile of the nucleus pulposus.)
`Posteriorly, laminae join in a complex manner; fibres in the rest of
`each lamina are paraiJel and run obliquely between vertebrae; fibres
`in contiguous laminae criss-cross (6.92), thus limiting rotation in
`both directions. Predominantly vertical