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The growing skull
The Growing Skull Leonard E. Swischuk,
T
HE MAJOR THRUST of this article is directed at the difficult problem of distinguishing fractures from sutures, fissures, and synchondroses. MATURATIONAL
CHANGES
As the neonate grows into childhood, the face becomes proportionately larger.The original 3 : 1 to 5: 1 calvarial to face ratio is progressively reduced (Fig. 1). The size of the cranium remains relatively unchanged, but the facial structures and paranasal sinuses become larger, more prominent, and more sharply outlined. At the same time, inner table convolutions become more prominent, and the individual calvarial bones thicker. A true diploic space begins to develop during the first year or two of life. After about 1 mo of age, the sutures rapidly lose their neonatal prominence, and become narrower (Fig. 1). Sutural interdigitations are usually present to one degree or another. On the outer table, the suture is usually markedly interdigitated and presents a zigzag pattern, while on the inner table interdigitations are sparser and the suture often appears straighter.6 The sutures become more closely knit and less prominent as the child grows older. Obliteration of the various fontanelles and synchondroses and maturation of the sella also occur. The sella becomes wider and deeper and the dorsum and posterior clinoids larger and taller (Fig. 1). The posterior fontanelle, often difficult to identify even at birth, is seldom seen as a distinct opening after 6 mo. The anterior fontanelle may remain open up to 24 mo,1,2,5 but often closes earlier (rarely under 12 mo). The anterior and posterior lateral fontanelles are obliterated early, and are usually difficult to see as definite defects after 6 mo. The various sutures leading to these fontanelles are still visible after the fontanelles are closed. The frontosphenoid and intersphenoid synchondroses are usually obliterated by 2 yr of age, if not earlier,59’4 but the spheno-occipital synchondrosis Leonard E. Swischuk, M.D.: Professor of Radiology and Pediatrics, University of Texas Medical Branch, Galveston, Tex. 77550. 0 1974 by Grune & Stratton, Inc. Seminars in Roentgenology,
Vol.
IX, No. 2 (April),
1974
M.D.
remains open into the late teens or even the early twenties. lo The innominate synchondrosis rapidly narrows after birth, but a suture line in this area is often visible well into childhood. SUTURE
VS. FRACTURE
I am sure that almost every suture, common or accessory, has been called a fracture by someone somewhere. Certain of these structures are more prone to misinterpretation than others. Some, because of their relative rarity, are almost routinely called fractures. Even common sutures can be so projected on rotated films that a fracture is suggested even to the experienced. The sutures are illustrated in Figs. 1-7. The intraparietal suture is an accessory suture that can present a most bizarre and variable configuration (Fig. 2). It may divide the parietal bones so as to render them bipartite.13 When bilateral, as they often tend to be, differentiation from fracture is easier. Absence of swelling over the area makes fracture unlikely. If the suture has a peculiar course, fracture is also less likely. Fractures tend to be straight, or gently curving, while the intraparietal suture is often more tortuous (Fig. 2). Unfortunately none of these points of differentiation are foolproof, and there are times when one simply cannot resolve the problem. There are even those who feel that most of these sutures are unrecognized fractures. The metopic suture is less bizarre, but certainly not without its own problems.” On properly positioned films, it is seen as a midline fissure in the frontal bone. Unfortunately, its edges are frequently extremely straight and sharp, so that it is tempting to call it a fracture. This is especially true if there is some rotation of the skull (Fig. 3). On a Towne’s projection, a clue to the fact that a line represents a metopic suture, rather than an occipital fracture, is that it frequently extends into or across the shadow of the foramen magnum. The squamosal, parietomastoid, and occipitomastoid sutures are other common sources of erroneous interpretation, especially on films obtained with the skull rotated. The occipital bone proper is literally loaded with sutures. They are best seen on lateral and Towne projections, and 115
116
LEONARD
E. SWISCHUK
Fig. 1. The maturing skull. (A) Three-month-old infant. (3) Three-year-old child. (Cl Ten-year-old child. Note the absolute and relative increase in size of the face as maturation occurs. A true diploic space is noted in B and C and diploic vascularity is also more prominent in the older child. In A the sutures are still quite prominent and the anterior fontanelle widely patent. In the two older children, the coronal suture becomes progressively more difficult to visualize. However, the lambdoid and other occipital sutures remain prominent. Also note how in C, there is characteristic early pneumatization of the sphenoid sinus anteriorly (S) and other signs of sphenoid maturation. 1, Remnant of intersphenoid synchondrosis; 2, spheno-occipital synchondrosis; 3, coronal suture; 4, squamosal suture; 5, lambdoid suture.
Fig. 2. lntraparietal sutures. Bilateral intraparietal sutures (arrows). The hump in the middle is an un(Courtesy of Dr. usual configuration for a fracture. H. Weens, Atlanta, Ga.)
THE GROWING
SKULL
Fig. 3. Metopic suture. causes it to be offset from
Slight rotation the midline.
of the skull
are an unending source of trouble for the uninitiated. Most of these sutures are shown in Figs. 4 and 5. The occipitomastoid suture is also well illustrated in Fig. 12. The problem of distinguishing between the cerebellar synchondrosis and a midoccipital fracture is a frequent one. A sharp line runs from the posterior lip of the foramen magnum upward throughout the length of the occipital bone, dividing it in two (Fig. 6). It is frequently interpreted as but recently the cerebellar synchondrosis,’ Franken has pointed out that this synchondrosis extends for only a centimeter or two above the posterior lip of the foramen magnum.’ Thus, the radiolucent line in Fig. 6 most likely represents an occipital fracture. Occasionally, accessory sutures occur in totally unexpected places. These are often difficult to explain embryologically, and yet their features suggest accessory suture rather than fracture. Two of these are illustrated in Fig. 7. In Fig. 7A, an accessory suture was noted in the left frontal bone, in this patient with Greig’s syndrome (ocular hypertelorism syndrome). There was no history of trauma, and the appearance of the radiolucent line was that of a suture. In Fig. 7B, an accessory occipital suture is demonstrated. The small fontanelle-
like structure at the lower end of the suture supports the diagnosis of accessory suture. NORMAL
SUTURE
VS. SPREAD
SUTURE
The only suture to which this problem applies is the coronal. Spreading is especially difficult to assessin infants from l-3 yr of age, for in this age group normal brain growth is rather exuberant, and I believe this sometimes causes the coronal suture to undergo physiologic splitting (Fig. 8).16 It is difficult to come up with a specific rule for pathologic separation. Segal et al. have suggested that in the first year of life if the upper aspect of the coronal suture measures 3 mm or more, it is likely to be spread.12 However, even with these criteria, I believe you must see a number of clinically correlated cases before adequate confidence can be attained. VASCULAR
GROOVES
The grooves for the numerous diploic vessels in the parietal bone, the middle meningeal artery, and the various dural sinuses are readily identified. They are not routinely seen in infants, but become more apparent in older children. They appear no different than in adults, and thus will not be covered here in detail. However, I would like to
LEONARD
118
draw attention to the frontal bone. Children are always falling on their foreheads, and one is often tempted to call a frontal vascular groove a fracture, especially if it is unilateral and straight16 (Fig. 9).
CONVOLUTIONAL
E. SWISCHUK
MARKINGS
Convolutional markings are only a problem when they are overly prominent.” If the sella is normal, one should discount the possibility of chronically
THE GROWING
SKULL
increased intracranial pressure (Fig. 10). Further, even in the older child, the coronal and other sutures are likely to be split by the time increased convolutional markings become apparent. OTHER
NORMAL
VARIATIONS
Posterior Parietal Foramina Posterior parietal foramina are seen in children. They are of variable size and no different in configuration from those in adults. They may be related to the posterior parietal fissures commonly encountered in neonates (see Fig. 6E in “The Newborn Skull” in this Seminar).
Anterior Fontanelle Bone The anterior fontanelle bone is generally presumed to be a normal variation.4Y9 It is not common, but can be encountered in perfectly normal children. It does not alter calvarial growth.’ Little more need be said about it, for once recognized (Fig. 11) it poses no further problem. The Sella Only a few general comments regarding the maturing sella are in order. The sella becomes deeper, wider, and more sharply outlined by the
LEONARD
E. SWISCHUK
Fig. 5. (Cj Towne projection. Note the fracture-like appearance of the lower aspect of the left lambdoid suture as it joins the parietomastoid suture. \n other cases, the parietomastoid suture runs a more horizontal course. Also note innominate synchondrosis on the right. (D) Towne projection in another child. The inferior extent of the lambdoid suture, the parietomastoid suture, and the occipitomastoid suture are shown. Note the characteristic obliquity of the occipitomastoid suture on the Towne projection.
surrounding sphenoid bone. The anterior clinoid processes become more prominent, the chiasmatic groove deeper, and the dorsum sella and posterior clinoid processes larger and more ossified (Fig. 1). For more details regarding sellar size in childhood, read Silverman’s article on the subject.16 Sinuses and Mastoids The development of the paranasal sinuses has been discussed in an earlier Seminar (April 1968) and by Vidic,” and will not be repeated here. The mastoid antrum is often visible at birth, but air cell formation does not usually become noticeable for 2-3 mo. Thereafter the air cells progressively develop and extend as the infant grows.
Condylar Fossa and Canal Not infrequently, a unilateral or bilateral radiolucent defect, measuring approximately 1 cm in diameter is discovered just to the side of the foramen magnum (Fig. 12). It probably represents an area of thinning in the occipital bone posterior to the occipital condyle. It has been termed the condylar fossa. In some instances, the fossa is perforated by the condylar canal, a smaller radiolucency, measuring l-3 mm, through which an emissary vein travels. In still other cases, only the canal is seen.3y8 Both the fossae and canals are usually best visualized on steep Towne’s projection. Actually, there is some disagreement as to the
THE GROWING
SKULL
Thin, Fig. 6. Occipital fracture. the midoccipital bone (arrows).
sharp-edged
fracture
true nature of the radiolucent defect. Some attribute it to a condylar canal that is displaced medially by medial extension of the sigmoid sinus.8 I favor the condyloid fossa version, since you can see such depressions on dried skull specimens. From a practical standpoint, however, I have
in
found it best to remember that almost any radiolucency noted in this area will turn out to be a normal variation. I would imagine that this sort of attitude might give the purist a little indigestion, but in day-to-day living, it’s not too bad an approach.
Fig. 7. Unusual accessory sutures. (A) Note the vertical accessory suture in the left frontal bone (arrows). Its upper end joins the almost horizontal coronal suture (upper arrow), which then joins the sagittal suture. The suture is of uniform width, and somewhat wider than the usual nondiastatic linear skull fracture. This patient had Greig’s syndrome and the frequently associated vertical bony strut, located just behind the nasion, is projected over the foramen magnum. (6) Younger child with an accessory suture in the left occipital bone. A small triangular fontanelle-like structure is seen et its inferior end. The suture is wider and much more irregular than the usual occipital bone fracture (compare with Fig. 6).
LEONARD
E. SWISCHUK
Fig. 8. Upper coronal suture-is it spread? These three examples represent normal coronal sutures with varying degrees of physiologic spread. (A) Twenty-month-old infant. (6) Three-year-old. (Cl Five-year-old. The degree of coronal suture prominence, or pseudospread, decreases with age.
Fig. 9. Frontal fracture (arrows). In addition a sharp with permission of
vascular grooves vs. fracture. (A and B) Two normal frontal vascular grooves (arrows). (C) Frontal bone Note that the radiolucent line is somewhat sharper, and some diastasis is suggested along its lower aspect. angle is present at the inferior extenti13ren so, some cases are virtually indistinguishable. (a reproduced ) Radiologic Clinics of North America.
THE GROWING
Fig. 10. proximately spread.
123
SKULL
Normal 2 yr
prominent inner of age. The sella
table convolutions in a child apis normal and there is no suture
Fig. 11. Anterior fontanelle bone. Note the calvarial bone in the anterior fontanelle (arrows). considered a large wormian or sutural bone.
extra It is
fossa. Symmetrical condylar fossae are located Fig. 12. Condylar just to either side of the foramen magnum (FM) (arrows). These fossae probably represent areas of thinning just posterior to the occipital condylr. Bilateral occipitomastoid sutures are also present. Note their characteristic obliquity.
REFERENCES 1. Acheson RM, Jefferson E: Some observations on the closure of the anterior fontanel. Arch Dis Child 29:196198,1954 2. Aisenson MR: Pediatrics 6:223-226,
Closing 1950
of
the anterior
fontanel.
3. Bories J, Zalzaf P, Levesque M: Occipital lacunae and condyloid fossa. Ann Radio1 15~757-766, 1972
4. Brown WH: Anterior fontanel bone. J Pediatr 58:800-802,196l 5. Caffey 3: Pediatric X-Ray Diagnosis (ed 6). Chicago, Year Book, 1973, pp 3-35 6. Danelius G: The occasional appearance of both inner and outer suture lines in roentgenograms of the skull simulating fissure fracture. Am J Roentgen01 55: 3 15-3 18, 1946
124
7. Franken EA Jr: The midline occipital fissure: diagnosis of a fracture versus anatomic variants. Radiology 93:1043-1046,1969 8. Gathier JC, Bruyn GW: The so-called condyloid foramen in the half axial view. Am J Roentgen01 107: 515-519,1969 9. Girdany BR, Blank E: Anterior fontanel bones. Am J Roentgen01 95:148-153, 1965 10. Irwin GL: Roentgen demonstration of the time of closure of the spheno-occipital synchondrosis. Radiology 75:450-453,1960 11. Macaulay D: Digital markings in the radiographs of the skull in children. Br J Radio1 24:647-652, 1951 12. Segal HD, Mikity VG, Rumbaugh CL, et al: Cranial sutures in the fist year of life: limits of normal and the “sprung suture.” Presented at the 57th annual meeting of the R.S.N.A., Chicago, 1971
LEONARD
E. SWISCHUK
13. Shapiro R: Anomalous parietal sutures and the bipartite parietal bone. Am J Roentgen01 115:569-577, 1972 14. Shopfner CE, Wolfe TW, O’Kell RT: The intersphenoid synchondrosis. Am J Roentgen01 104:184-193, 1968 15. Silverman FN: Roentgen standards for size of the pituitary fossa from infancy through adolescence. Am J Roentgen01 78:451460,1957 16. Swischuk LE: The normal pediatric skull: variations and artefacts. Radio1 Clin North Am 10: 277-290, 1972 17. Torgerson J: A roentgenologic study of the metopic suture. Acta Radio1 33: l-l 1, 1950 18. Vidic B: The postnatal development of the sphenoidal sinus and its spread into the dorsum sellae and posterior clinoid processes. Am J Roentgen01 104:177183,1968
T
HE MAJOR THRUST of this article is directed at the difficult problem of distinguishing fractures from sutures, fissures, and synchondroses. MATURATIONAL
CHANGES
As the neonate grows into childhood, the face becomes proportionately larger.The original 3 : 1 to 5: 1 calvarial to face ratio is progressively reduced (Fig. 1). The size of the cranium remains relatively unchanged, but the facial structures and paranasal sinuses become larger, more prominent, and more sharply outlined. At the same time, inner table convolutions become more prominent, and the individual calvarial bones thicker. A true diploic space begins to develop during the first year or two of life. After about 1 mo of age, the sutures rapidly lose their neonatal prominence, and become narrower (Fig. 1). Sutural interdigitations are usually present to one degree or another. On the outer table, the suture is usually markedly interdigitated and presents a zigzag pattern, while on the inner table interdigitations are sparser and the suture often appears straighter.6 The sutures become more closely knit and less prominent as the child grows older. Obliteration of the various fontanelles and synchondroses and maturation of the sella also occur. The sella becomes wider and deeper and the dorsum and posterior clinoids larger and taller (Fig. 1). The posterior fontanelle, often difficult to identify even at birth, is seldom seen as a distinct opening after 6 mo. The anterior fontanelle may remain open up to 24 mo,1,2,5 but often closes earlier (rarely under 12 mo). The anterior and posterior lateral fontanelles are obliterated early, and are usually difficult to see as definite defects after 6 mo. The various sutures leading to these fontanelles are still visible after the fontanelles are closed. The frontosphenoid and intersphenoid synchondroses are usually obliterated by 2 yr of age, if not earlier,59’4 but the spheno-occipital synchondrosis Leonard E. Swischuk, M.D.: Professor of Radiology and Pediatrics, University of Texas Medical Branch, Galveston, Tex. 77550. 0 1974 by Grune & Stratton, Inc. Seminars in Roentgenology,
Vol.
IX, No. 2 (April),
1974
M.D.
remains open into the late teens or even the early twenties. lo The innominate synchondrosis rapidly narrows after birth, but a suture line in this area is often visible well into childhood. SUTURE
VS. FRACTURE
I am sure that almost every suture, common or accessory, has been called a fracture by someone somewhere. Certain of these structures are more prone to misinterpretation than others. Some, because of their relative rarity, are almost routinely called fractures. Even common sutures can be so projected on rotated films that a fracture is suggested even to the experienced. The sutures are illustrated in Figs. 1-7. The intraparietal suture is an accessory suture that can present a most bizarre and variable configuration (Fig. 2). It may divide the parietal bones so as to render them bipartite.13 When bilateral, as they often tend to be, differentiation from fracture is easier. Absence of swelling over the area makes fracture unlikely. If the suture has a peculiar course, fracture is also less likely. Fractures tend to be straight, or gently curving, while the intraparietal suture is often more tortuous (Fig. 2). Unfortunately none of these points of differentiation are foolproof, and there are times when one simply cannot resolve the problem. There are even those who feel that most of these sutures are unrecognized fractures. The metopic suture is less bizarre, but certainly not without its own problems.” On properly positioned films, it is seen as a midline fissure in the frontal bone. Unfortunately, its edges are frequently extremely straight and sharp, so that it is tempting to call it a fracture. This is especially true if there is some rotation of the skull (Fig. 3). On a Towne’s projection, a clue to the fact that a line represents a metopic suture, rather than an occipital fracture, is that it frequently extends into or across the shadow of the foramen magnum. The squamosal, parietomastoid, and occipitomastoid sutures are other common sources of erroneous interpretation, especially on films obtained with the skull rotated. The occipital bone proper is literally loaded with sutures. They are best seen on lateral and Towne projections, and 115
116
LEONARD
E. SWISCHUK
Fig. 1. The maturing skull. (A) Three-month-old infant. (3) Three-year-old child. (Cl Ten-year-old child. Note the absolute and relative increase in size of the face as maturation occurs. A true diploic space is noted in B and C and diploic vascularity is also more prominent in the older child. In A the sutures are still quite prominent and the anterior fontanelle widely patent. In the two older children, the coronal suture becomes progressively more difficult to visualize. However, the lambdoid and other occipital sutures remain prominent. Also note how in C, there is characteristic early pneumatization of the sphenoid sinus anteriorly (S) and other signs of sphenoid maturation. 1, Remnant of intersphenoid synchondrosis; 2, spheno-occipital synchondrosis; 3, coronal suture; 4, squamosal suture; 5, lambdoid suture.
Fig. 2. lntraparietal sutures. Bilateral intraparietal sutures (arrows). The hump in the middle is an un(Courtesy of Dr. usual configuration for a fracture. H. Weens, Atlanta, Ga.)
THE GROWING
SKULL
Fig. 3. Metopic suture. causes it to be offset from
Slight rotation the midline.
of the skull
are an unending source of trouble for the uninitiated. Most of these sutures are shown in Figs. 4 and 5. The occipitomastoid suture is also well illustrated in Fig. 12. The problem of distinguishing between the cerebellar synchondrosis and a midoccipital fracture is a frequent one. A sharp line runs from the posterior lip of the foramen magnum upward throughout the length of the occipital bone, dividing it in two (Fig. 6). It is frequently interpreted as but recently the cerebellar synchondrosis,’ Franken has pointed out that this synchondrosis extends for only a centimeter or two above the posterior lip of the foramen magnum.’ Thus, the radiolucent line in Fig. 6 most likely represents an occipital fracture. Occasionally, accessory sutures occur in totally unexpected places. These are often difficult to explain embryologically, and yet their features suggest accessory suture rather than fracture. Two of these are illustrated in Fig. 7. In Fig. 7A, an accessory suture was noted in the left frontal bone, in this patient with Greig’s syndrome (ocular hypertelorism syndrome). There was no history of trauma, and the appearance of the radiolucent line was that of a suture. In Fig. 7B, an accessory occipital suture is demonstrated. The small fontanelle-
like structure at the lower end of the suture supports the diagnosis of accessory suture. NORMAL
SUTURE
VS. SPREAD
SUTURE
The only suture to which this problem applies is the coronal. Spreading is especially difficult to assessin infants from l-3 yr of age, for in this age group normal brain growth is rather exuberant, and I believe this sometimes causes the coronal suture to undergo physiologic splitting (Fig. 8).16 It is difficult to come up with a specific rule for pathologic separation. Segal et al. have suggested that in the first year of life if the upper aspect of the coronal suture measures 3 mm or more, it is likely to be spread.12 However, even with these criteria, I believe you must see a number of clinically correlated cases before adequate confidence can be attained. VASCULAR
GROOVES
The grooves for the numerous diploic vessels in the parietal bone, the middle meningeal artery, and the various dural sinuses are readily identified. They are not routinely seen in infants, but become more apparent in older children. They appear no different than in adults, and thus will not be covered here in detail. However, I would like to
LEONARD
118
draw attention to the frontal bone. Children are always falling on their foreheads, and one is often tempted to call a frontal vascular groove a fracture, especially if it is unilateral and straight16 (Fig. 9).
CONVOLUTIONAL
E. SWISCHUK
MARKINGS
Convolutional markings are only a problem when they are overly prominent.” If the sella is normal, one should discount the possibility of chronically
THE GROWING
SKULL
increased intracranial pressure (Fig. 10). Further, even in the older child, the coronal and other sutures are likely to be split by the time increased convolutional markings become apparent. OTHER
NORMAL
VARIATIONS
Posterior Parietal Foramina Posterior parietal foramina are seen in children. They are of variable size and no different in configuration from those in adults. They may be related to the posterior parietal fissures commonly encountered in neonates (see Fig. 6E in “The Newborn Skull” in this Seminar).
Anterior Fontanelle Bone The anterior fontanelle bone is generally presumed to be a normal variation.4Y9 It is not common, but can be encountered in perfectly normal children. It does not alter calvarial growth.’ Little more need be said about it, for once recognized (Fig. 11) it poses no further problem. The Sella Only a few general comments regarding the maturing sella are in order. The sella becomes deeper, wider, and more sharply outlined by the
LEONARD
E. SWISCHUK
Fig. 5. (Cj Towne projection. Note the fracture-like appearance of the lower aspect of the left lambdoid suture as it joins the parietomastoid suture. \n other cases, the parietomastoid suture runs a more horizontal course. Also note innominate synchondrosis on the right. (D) Towne projection in another child. The inferior extent of the lambdoid suture, the parietomastoid suture, and the occipitomastoid suture are shown. Note the characteristic obliquity of the occipitomastoid suture on the Towne projection.
surrounding sphenoid bone. The anterior clinoid processes become more prominent, the chiasmatic groove deeper, and the dorsum sella and posterior clinoid processes larger and more ossified (Fig. 1). For more details regarding sellar size in childhood, read Silverman’s article on the subject.16 Sinuses and Mastoids The development of the paranasal sinuses has been discussed in an earlier Seminar (April 1968) and by Vidic,” and will not be repeated here. The mastoid antrum is often visible at birth, but air cell formation does not usually become noticeable for 2-3 mo. Thereafter the air cells progressively develop and extend as the infant grows.
Condylar Fossa and Canal Not infrequently, a unilateral or bilateral radiolucent defect, measuring approximately 1 cm in diameter is discovered just to the side of the foramen magnum (Fig. 12). It probably represents an area of thinning in the occipital bone posterior to the occipital condyle. It has been termed the condylar fossa. In some instances, the fossa is perforated by the condylar canal, a smaller radiolucency, measuring l-3 mm, through which an emissary vein travels. In still other cases, only the canal is seen.3y8 Both the fossae and canals are usually best visualized on steep Towne’s projection. Actually, there is some disagreement as to the
THE GROWING
SKULL
Thin, Fig. 6. Occipital fracture. the midoccipital bone (arrows).
sharp-edged
fracture
true nature of the radiolucent defect. Some attribute it to a condylar canal that is displaced medially by medial extension of the sigmoid sinus.8 I favor the condyloid fossa version, since you can see such depressions on dried skull specimens. From a practical standpoint, however, I have
in
found it best to remember that almost any radiolucency noted in this area will turn out to be a normal variation. I would imagine that this sort of attitude might give the purist a little indigestion, but in day-to-day living, it’s not too bad an approach.
Fig. 7. Unusual accessory sutures. (A) Note the vertical accessory suture in the left frontal bone (arrows). Its upper end joins the almost horizontal coronal suture (upper arrow), which then joins the sagittal suture. The suture is of uniform width, and somewhat wider than the usual nondiastatic linear skull fracture. This patient had Greig’s syndrome and the frequently associated vertical bony strut, located just behind the nasion, is projected over the foramen magnum. (6) Younger child with an accessory suture in the left occipital bone. A small triangular fontanelle-like structure is seen et its inferior end. The suture is wider and much more irregular than the usual occipital bone fracture (compare with Fig. 6).
LEONARD
E. SWISCHUK
Fig. 8. Upper coronal suture-is it spread? These three examples represent normal coronal sutures with varying degrees of physiologic spread. (A) Twenty-month-old infant. (6) Three-year-old. (Cl Five-year-old. The degree of coronal suture prominence, or pseudospread, decreases with age.
Fig. 9. Frontal fracture (arrows). In addition a sharp with permission of
vascular grooves vs. fracture. (A and B) Two normal frontal vascular grooves (arrows). (C) Frontal bone Note that the radiolucent line is somewhat sharper, and some diastasis is suggested along its lower aspect. angle is present at the inferior extenti13ren so, some cases are virtually indistinguishable. (a reproduced ) Radiologic Clinics of North America.
THE GROWING
Fig. 10. proximately spread.
123
SKULL
Normal 2 yr
prominent inner of age. The sella
table convolutions in a child apis normal and there is no suture
Fig. 11. Anterior fontanelle bone. Note the calvarial bone in the anterior fontanelle (arrows). considered a large wormian or sutural bone.
extra It is
fossa. Symmetrical condylar fossae are located Fig. 12. Condylar just to either side of the foramen magnum (FM) (arrows). These fossae probably represent areas of thinning just posterior to the occipital condylr. Bilateral occipitomastoid sutures are also present. Note their characteristic obliquity.
REFERENCES 1. Acheson RM, Jefferson E: Some observations on the closure of the anterior fontanel. Arch Dis Child 29:196198,1954 2. Aisenson MR: Pediatrics 6:223-226,
Closing 1950
of
the anterior
fontanel.
3. Bories J, Zalzaf P, Levesque M: Occipital lacunae and condyloid fossa. Ann Radio1 15~757-766, 1972
4. Brown WH: Anterior fontanel bone. J Pediatr 58:800-802,196l 5. Caffey 3: Pediatric X-Ray Diagnosis (ed 6). Chicago, Year Book, 1973, pp 3-35 6. Danelius G: The occasional appearance of both inner and outer suture lines in roentgenograms of the skull simulating fissure fracture. Am J Roentgen01 55: 3 15-3 18, 1946
124
7. Franken EA Jr: The midline occipital fissure: diagnosis of a fracture versus anatomic variants. Radiology 93:1043-1046,1969 8. Gathier JC, Bruyn GW: The so-called condyloid foramen in the half axial view. Am J Roentgen01 107: 515-519,1969 9. Girdany BR, Blank E: Anterior fontanel bones. Am J Roentgen01 95:148-153, 1965 10. Irwin GL: Roentgen demonstration of the time of closure of the spheno-occipital synchondrosis. Radiology 75:450-453,1960 11. Macaulay D: Digital markings in the radiographs of the skull in children. Br J Radio1 24:647-652, 1951 12. Segal HD, Mikity VG, Rumbaugh CL, et al: Cranial sutures in the fist year of life: limits of normal and the “sprung suture.” Presented at the 57th annual meeting of the R.S.N.A., Chicago, 1971
LEONARD
E. SWISCHUK
13. Shapiro R: Anomalous parietal sutures and the bipartite parietal bone. Am J Roentgen01 115:569-577, 1972 14. Shopfner CE, Wolfe TW, O’Kell RT: The intersphenoid synchondrosis. Am J Roentgen01 104:184-193, 1968 15. Silverman FN: Roentgen standards for size of the pituitary fossa from infancy through adolescence. Am J Roentgen01 78:451460,1957 16. Swischuk LE: The normal pediatric skull: variations and artefacts. Radio1 Clin North Am 10: 277-290, 1972 17. Torgerson J: A roentgenologic study of the metopic suture. Acta Radio1 33: l-l 1, 1950 18. Vidic B: The postnatal development of the sphenoidal sinus and its spread into the dorsum sellae and posterior clinoid processes. Am J Roentgen01 104:177183,1968