BACKGROUND OF THE INVENTION 
     This invention relates to backboards for supporting, carrying and transporting patients for emergency medical treatment and, more particularly, to an improved, lightweight, durable, degradation resistant backboard which enables transportation of a patient while minimizing risk of further injury. 
     Emergency medical treatment often requires the transportation of a patient from an accident site to a hospital or other location where more complete and extensive medical treatment can be performed. The common method for such transportation is on a stretcher or rigid backboard to which the patient is secured using straps or the like. Such backboards are common place in ambulances, emergency medical vehicles, swimming pools, athletic arenas and the like. Such backboards are often improperly stored, mishandled, and/or generally given insufficient care and maintenance. In the past, several different varieties of backboards have been used including solid or laminated wood boards, glass fiber reinforced resinous plastic boards, aluminum or other metallic boards, or composition or pressed boards. Each of these varieties has its own problems and drawbacks. 
     In the case of backboards made from solid or laminated wood, such as plywood, since such boards are often subjected to the weather by being stored outside at swimming pools, ski areas or the like, they are subject to splintering, rot and other degradation from the elements. Such boards also tend to absorb and/or retain fluids or other foreign matter, and can cause infection given the circumstances in which they are used. Further, it is not uncommon that wooden boards, because of deterioration, break during use causing further aggrevation to the injuries of the transported patient or even injury to the rescuer. Wooden boards have also suffered from a limitation in the number of handholds included thereon and have thus been less than adequate in allowing carrying in many situations. 
     Glass fiber reinforced resinous plastic backboards have also been used but such boards have also been subject to splintering, chipping and/or the loss of glass fiber particles which can cause a rash on the skin of the patient being transported. Such rash has, in the past, led to an improper diagnosis of the injuries to the patient. Further, glass fiber reinforced resinous plastic boards tend to absorb moisture and thus can freeze when used in cold environments and/or cause infection of the patient being carried much like wooden boards. 
     Metallic boards, such as those made from aluminum, have also been tried but, because of their temperature conduction characteristics, have caused discomfort in use in cold or extremely warm climates. Such metallic boards also tend to freeze more readily and have little or no buoyancy which makes them unsuitable for use in transferring patients having back or spinal injuries from swimming pools or lakes. In addition, many of the prior known metallic backboards required the use of numerous parts which could disassemble in use and cause premature failure of the board. 
     A fourth type of board is that made from composition or particle board. These tend to be very heavy, difficult to use, and also suffer from many of the same drawbacks as the wooden boards. 
     In view of the above problems, a need was recognized for an improved backboard which could overcome the above problems and provide a light-weight, easy to use, strong, durable and degradation resistant device suitable for all types of situations encountered in emergency medical treatment. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a patient supporting and transporting backboard which overcomes the above problems by providing a pair of cooperating, substantially rigid panels, one panel fitted over top the other and adapted to carry a patient, the other panel being fitted under the top panel and engaging, supporting and being secured to the top panel to rigidify and stabilize the same. Preferably, each panel is molded from a resinous plastic material such as polycarbonate or modified phenylene oxide and includes a downturned, peripheral flange for securing the panels together and forming a peripheral handhold around the entire backboard. The bottom panel peripheral flange is nested within and secured to the top panel peripheral flange. The panels are secured together to form a rigid backboard unit. 
     Preferably, the panels forming the present backboard also include a series of ribs in at least one of the panels for reenforcing, stabilizing and rigidifying the other panel, as well as an edge strip extending along the combining panel flanges for attaching the top panel flange to the bottom panel flange. Together, the flanges and edge strip are adapted to receive and removeably attach securing clip members on various backboard accessories including tie-down straps, supplemental carrying handles, and/or head restraints at numerous and varied positions as desired on the board. 
     In one preferred form, the edge strip extending along the peripheral flanges is an extruded, resinous plastic, contoured strip fitted over and secured to the flanges. In another form, the flanges are themselves contoured or molded into a bulbous shape and secured together using an edge strip having opposing slots therein for receiving the aligned edges of the flanges. In either form, a continuous notch or recess on the inside surface of at least one of the flange or edge strip provides a securing area for further securing the clip means on the accessories mentioned above. 
     The accessories themselves may include a head restraint assembly for substantially immobilizing the head of a patient and/or applying cervical traction when secured and arranged on the backboard, a plurality of adjustable tie-down straps which may be clipped anywhere along the periphery of the board, as well as supplemental carrying handles including securing clips enabling them to be clipped on the periphery of the board at desired locations. In addition, the backboard may include handhold apertures which allow use of conventional straps and/or provide additional handholds for rescurers using the board. 
     When used in the above forms, the present invention provides a lightweight, strong, durable, corrosive resistant backboard which will stand up to rough handling, storage in and exposure to the elements without deterioration. The backboard assembly resists rot, splintering, chipping, the shedding of particles and the absorption or retention of fluids or foreign matter, thus being stain and infection resistant. The board may be sterilized for use in hospital environments, and allows x-rays to be taken of a patient carried on the board without further transfer of the patient to another support. Since the backboard assembly is at least partially hollow and the preferred material has its own natural buoyancy, the backboard is especially useful for emergency medical treatment of swimming injuries. Further, the board resists freezing, provides a unitary structure which is unlikely to disassemble, and is resistant to extreme heat for short periods of time making it especially useful for rescues from fires or burning buildings. When formed from the preferred polycarbonate material, even if the board is burned, it is reduced to carbon dioxide and water which are not toxic to humans. In addition, the present backboard is easier to carry by a larger number of rescuers than are prior known boards due to the provision of the handhold around the entire perimeter thereof, in addition to allowing use of extra carrying handles. The present backboard encourages the use of tie-down straps for the immobilization of the transported patient and provides a unique assembly for immobilization of the head and neck of an injured patient which can also be utilized to provide cervical traction during transportation to a hospital. 
     These and other objects, advantages, purposes and features of the invention will become more apparent from a study of the following description taken in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the backboard assembly of the present invention illustrating the tie-down strap, supplemental carrying handle and head restraint accessories secured thereto; 
     FIG. 2 is an exploded, perspective view of the various panel, edge strip and accessory portions of the backboard of the present invention; 
     FIG. 3 is a fragmentary, sectional view taken along line III--III of FIG. 1 illustrating the edge structure of a first embodiment of the backboard assembly, the edge structure receiving the resilient body of an supplemental carrying handle secured therearound. 
     FIG. 4 is a broken, sectional view of the first form of the backboard assembly taken along line IV--IV of FIG. 1 and illustrating the interior structure thereof; 
     FIG. 5 is a perspective view of a first form of the head restraint assembly with portions of its securing straps broken away; 
     FIG. 6 is a side elevation of the head restraint shown in FIG. 5; 
     FIG. 7 is a sectional view of the head restraint taken along line VII--VII of FIG. 6; 
     FIG. 8 is a fragmentary, perspective view of a second form of the head restraint including a substantially rigid base and a resilient foam liner received therein; 
     FIG. 9 is a fragmentary, sectional, perspective view of the head restraint shown in FIG. 8; 
     FIG. 10 is a side elevation of one of the supplemental carrying handles; 
     FIG. 11 is an end elevation of the carrying handle shown in FIG. 10; 
     FIG. 12 is a fragmentary, perspective view of one of the securing clips and attached webbing end of a tie-down strap used with the backboard assembly; 
     FIG. 13 is a fragmentary, exploded, sectional view of a second form of the backboard assembly illustrating the contoured flange portions thereon; 
     FIG. 14 is a fragmentary, sectional, assembled view of the backboard assembly embodiment shown in FIG. 13; 
     FIG. 15 is an enlarged view of the extruded edge strip used to secure the flanges of the second form of the backboard assembly shown in FIGS. 13 and 14; 
     FIG. 16 is a plan view of a suitable adjusting buckle used in the tie-down straps and securing straps for the head restraints; 
     FIG. 17 is a sectional view of the adjusting buckle taken along line XVII--XVII of FIG. 16; 
     FIG. 18 is a perspective view of the adjusting buckle shown in FIGS. 16 and 17 secured within one of the tie-down straps used with the backboard assembly of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in greater detail, FIGS. 1 and 2 illustrate a first embodiment 10 of the patient supporting and transporting backboard of the present invention. Backboard 10 is especially designed for use in emergency medical treatment situations such as the transfer of automobile accident victims, swimming injury victims, fire victims and the like. It provides a rigid, stable, substantially planar transporting surface to which a patient may be secured to prevent further injury through the use of tie-down straps 50 and one of head restraint assemblies 80 of 120. It may be easily carried by means of supplemental carrying handles 140. 
     With specific reference to FIGS. 1-4, backboard assembly 10 includes two generally rectangular, lightweight, substantially rigid panels preferably molded from a resinous plastic material such as polycarbonate or modified phenylene oxide. Both panels are approximately 18&#34;×72&#34; in a preferred form. The top or upper panel 12 includes a substantially planar, patient carrying area 14, a series of laterally aligned, rectangular handhold apertures 16 adjacent the lateral edges thereof, and an outwardly flared, downturned flange 18 extending continuously around the entire periphery of the panel. The lower or bottom panel 20 also has a generally rectangular shape but is slightly smaller than the top panel 12 so as to nest within top panel 12 therein when the panels are fitted together. 
     As shown in FIG. 2, bottom panel 20 includes a plurality of substantially planar areas 22 separated by upwardly and inwardly opening, integral, stiffening and stabilizing channels 24 extending parallel to one another along the longitudinal length of the backboard, as well as a series of equally spaced, upwardly and inwardly opening cross channels 26 which intersect the longitudinally extending channels 24, extend from side to side, and provide tranverse stability for the bottom panel. In addition, bottom panel 20 includes rectangular handhold apertures 28 positioned to be in alignment with handhold aperture 16 when panels 12 and 20 are fitted together as shown in FIG. 3. As shown in FIG. 4, longitudinal channels 24 are deeper than cross channels 26 and are substantially coterminous and coplanar so as to provide spaced supports for the backboard assembly 10 when placed on the ground or other support surface. Panel 20 further includes a peripheral edge flange 30 which is outwardly and downwardly flared and adapted to nest within and extend substantially parallel to edge flange 18 on panel 12 as shown in FIG. 3. 
     As is best illustrated in FIG. 3, panels 12 and 20 are designed to fit and nest together, one under and within the other, and to be secured together by an appropriate adhesive compatable with the resinous plastic material from which the panels are formed such as SUPERBONDER (Trademark), a cyanoacrylate adhesive manufactured by Loctite Corporation, Newington, Conn. The adhesive is applied both to the nesting flanges 18, 30 and to planar areas 22 which contact and support the underside of planar area 14 on the upper panel. In addition, edge flanges 18, 30 are substantially coterminous and adapted to receive an edge strip 32 to help secure them together and maintain the backboard 10 as an integral unit. The hollow areas within backboard 10 provide buoyancy allowing use of the board in pools or lakes. 
     As shown in FIGS. 2-4 edge strip 32 is a substantially rigid, generally cylindrical extrusion of synthetic, resinous plastic material such as nylon, polycarbonate or polyethylene. Edge strip 32 includes a generally cylindrical body and extends around the entire periphery of the backboard. It is fitted over the combined edge flanges 18, 30 after initial assembly of panels 12, 20 by means of a slot 34 formed at an angle therein to receive the downwardly and outwardly flared combined flanges. Suitable adhesive is also used in slot 34 to secure strip 32 to the combined flanges. Strip 32 also includes a continuous, interior, V-shaped notch 36 which receives and helps secure the securing clips from the tie-down straps, supplemental carrying handles and head restraint straps in a manner more fully described hereinafter. 
     As shown in FIG. 2, edge extrusion 32 may be formed in an overall rectangular shape. Alternately, the lateral side and end portions may be formed in rectilinear lengths with the four corners provided in sections and fitted separately to the corners of the combined flanges. As shown in FIG. 3, the extruded edge strip 32, together with the flanges 18, 30, when assembled as set forth above, form an edge structure which provides a convenient and secure handhold for carrying the entire backboard from any position around the periphery of the backboard. A number of persons or rescuers can thus grab the flange-strip structure simultaneously. In addition, the edge structure provides an appropriate securement for the securing clips from the accessories as will be described below. 
     An alternate form 40 of the patient transporting backboard assembly is shown in FIGS. 13-15. In this form, top panel 12&#39; includes a substantially planar patient supporting area 14&#39; and a contoured, outwardly curved, downwardly and outwardly flared flange 18&#39;. The outwardly curved section of flange 18&#39; has the sectional shape of a semi-circle. Likewise, bottom panel 20&#39; includes planar area and integral rib channels in a manner similar to that described above for panel 20, but includes an outwardly and downwardly flared contoured flange 30&#39; having an area 31&#39; in the shape of a quarter circle and indented, continuous, V-shaped notch 36&#39; in the same, inner location as notch 36 in embodiment 10. Preferably, panels 12&#39; and 20&#39;, like panels 12 and 20, are molded from polycarbonate sheet material or modified phenylene oxide sheet into the shapes shown in FIG. 13. 
     As shown in FIGS. 14 and 15, panels 12&#39; and 20&#39; are combined and secured in much the same manner as are panels 12 and 20 with panel 20&#39; being nested within upper panel 12&#39;. However, end edges 19&#39; and 33&#39; of flanges 18&#39;, 36&#39; are aligned when the panels are nested together. Edges 19&#39;, 33&#39; are secured together and sealed off by an extruded edge strip 38 which, as shown in FIG. 15, includes aligned, opposing slots 39, 41 which receive flange end edges 19&#39; 33&#39; respectively. Extruded edge strip 38, which has the cross sectional shape of an H, may be formed from polycarbonate, phenylene oxide or another resinous plastic material such as nylon. Preferably, end edges 19&#39;, 33&#39; are adhered within slots 39, 41 by a suitable adhesive such as SUPERBONDER (Trademark), a cyanoacrylate adhesive manufactured by Loctite Corporation, Newington, Conn. Strip 38 thus seals off the interior of the combined flanges forming a hollow, bulbous portion around the entire periphery of the backboard. This hollow bulbous portion, together with the spaced interior of the center sections of the combined panels 12&#39;, 20&#39; provides a buoyancy for the backboard 40 making it especially useful in situations requiring the transfer of victims injured in swimming accidents since the backboard will float. Backboard 40 may include handhold apertures such as those shown at 16, 28 in embodiment 10 of the backboard in which case suitable adhesive is applied around the perimeter of that aperture to seal off and prevent the entry of water into the interior thus preserving the buoyant nature of the backboard 40. 
     In either of backboard assembly embodiments 10 or 40, the lower panel 20, 20&#39; rigidifies and stabilizes the upper panel 12, 12&#39;. Together with one of edge strips 32, 38, the entire composite backboard assembly provides a unitary structure which is light in weight and easily carried using the peripheral handhold edge structure, the additional handhold apertures 16, 28, or the supplemental carrying handles 140 described hereinafter. 
     Referring to FIGS. 1, 2, 12 and 16-18, either of the backboard embodiments 10 or 40 is designed for use with a patient tie-down and securing strap 50. Each tie-down strap includes two lengths of strong, non-stretchable, fabric or cloth webbing of the type commonly used in automobile seatbelts. Each webbing length 52 is combined with a securing clip 54 (FIG. 12) for attachment of the tie-down strap to the peripheral handhold flange structure on the backboard. Securing clip 54 includes a resilient body portion 56 and an extending, connection flange 58 offset from body 56 by shoulder 55 and having a rectangular aperture 60 adjacent the end of flange 58. Shoulder 55 allows flange 58 to extend above planar surface 14 of panel 12 when secured to the edge structure. One end of webbing length 52 is inserted through aperture 60 and sewn to itself to prevent removal from the securing clip. The remaining free ends of webbing length 52 are led toward one another and combined with a plastic or other securing buckle 62 (FIGS. 16-18) to enable adjustment of the length of the tie-down strap to adequately secure a patient on the backboard. 
     Buckle 62, which is but one suitable adjustment device useable with webbing lengths 52, includes a square or rectangular outer peripheral wall 64 having opposing end portions 65, 66. Spaced inwardly from end walls 65, 66, and from one another, are a pair of cross-ribs 68, 70 extending between side wall portions 64 and over which webbing 52 is looped upon itself as shown in phantom in FIG. 17. In this regard, the end of webbing 52 is passed upwardly through the space at the center of buckle 62 between ribs 68, 70, passed over one of the ribs 68 or 70 and returned downwardly through the space between that one rib 68 or 70 and the adjacent end wall 65 or 66 and doubled upon itself as shown in FIGS. 17 and 18. Thereafter, the free end of the webbing 52 is rolled and sewn to prevent withdrawal through the spaces in the buckle. After insertion and assembly of both webbing lengths 52 in buckle 62, the free ends of the webbing may be pulled away from one another to shorten the length of the overall tie-down strap. The edges of the buckle structure engaging the webbing to resist its withdrawal when tigthened in this manner. When loosening is desired, a thumb flange 72, formed integrally with end wall 66, may be pivoted upwardly to loosen and lengthen the webbing and release the patient from the backboard. Buckle 62 may be obtained from Indiana Mills and Manufacturing, Inc. of Carmel, Ind. 
     With reference again to FIGS. 3 and 12, the structure and operation of the securing clip 54 will be more fully understood. In addition to connection flange 58 mentioned above, resilient body portion 56 of clip 54 is generally cylindrically shaped and has an inside diameter slightly larger than the outside diameter of extruded cylindrical strip 32 or the exterior surface of combined, contoured flange portions 18&#39;, 30&#39;. Adjacent the free end 59 of the body portion of clip 56 is a U-shaped, rounded, radially inwardly projecting protrusion 57 which is designed to engage notch 36 or 36&#39; in the edge flange structure to prevent rotation of the clip about the flange structure except when removal is desired. Preferably, securing clip 54 is formed from tempered sheet aluminum or stainless steel sheet material and stamped and/or rolled into the shape shown in FIGS. 3 and 12. 
     To insert the securing clip over the combined flange and edge strip structure at the edges of the backboard, it is merely necessary to grasp the upwardly extending free end 59 of body portion 56 adjacent inward protrusions 57 and flex it outwardly away from the remainder of the body portion while passing the body portion of the clip over the combined flange and edge strip structure. Upon release, inward protrusion 57 engages notch 36 or 36&#39; and seats the clip properly in place and prevents its removal. As will be understood, since the entire length of the flange and edge strip structure has this external, cylindrical shape, securing clips 54 may be attached at virtually any place along its length except for the corners of the backboard. 
     Referring now to FIGS. 5-7, a first embodiment 80 of a suitable head restraint for use with backboard assembly 10 or 40 is shown. Head restraint 80 is designed for attachment to the top surface of backboard 10 or 40, adjacent one end thereof, so as to immobilize the head and neck of an injured patient carried on the backboard. The head restraint includes a contoured head receptacle 82 preferably formed from elastomeric urethane foam which is preferably injection molded in a suitable mold and heated to form its own skin which resists soiling, staining and fluid absorption. Head receptacle 82 includes a base 84 and upwardly and outwardly extending side and end portions 86, 88 respectively which define a cranial depression receiving the back of the head of a patient being carried on the backboard. In order to properly locate the patient&#39;s head properly within the cranial depression, an additional shallow spherical depression 89 may be formed in the center of base 84 as shown in FIGS. 5-7. 
     At the corners of the head restraint 82, side and end walls 86, 88 curve upwardly to form four securing area 89 from which protrude securing straps 90, 92. Straps 90, 92 are designed to fit over and engage the chin and forehead areas of the patient&#39;s head. Strap 90 includes a chin cup 94 centered therein and extends downwardly through and is embedded in the molded foam of the head restraint 82 through the base 84 to the opposite securing area. Similarly, forehead strap 92 extends downwardly through the molded foam of the head restraint to the opposite securing area to thus securely embed the straps 90, 92 in place and prevent their removal. Each of the straps 90, 92 includes a strip of Velcro (trademark) material sewn thereto which engages a length of Velcro material secured by an appropriate adhesive or the like to the exterior of the opposite securing area as shown in FIGS. 5 and 6. Hence, when the back of a patient&#39;s head is resting in the spherical depression 89, strap 90 is placed over the chin of the patient with chin cup 94 engaging the patient&#39;s chin and the free end of the strap engaging Velcro strip 96. Similarly, forehead strap 92 is placed over the forehead of the victim and snugged around the skull and attached to Velcro strip 98. When both straps are secured in this fashion, the head is held immobile within the head restraint. As will be seen from FIG.&#39;S 6 and 7, the securing areas from which the securing straps 90, 92 protrude converge downwardly and inwardly preferably at an angle of approximately 20 degrees (FIG. 6) so as to apply restraining force to the chin and forehead areas urging the patient&#39;s head into the center of the cranial depression formed by the head restraint. 
     In order to position the head restraint 82 on the planar surface 14 of top panel 12 or 12&#39; of the backboard, a series of positioning and securing straps 100, 102 and 104 extend perpendicularly to one another as shown in FIGS. 1, 2 and 5. Positioning strap 100 includes a length 106 of nylon or other fabric webbing similar to that used for tie-down straps 50. Webbing length 106 passes beneath the center of spherical depression 89 and extends laterally out of either side of the base 84 of head restraint 82. Separate additional lengths 108, 110 of fabric webbing are coupled to buckles 62 along with the free ends of webbing length 106 to provide adjustment for the length of the positioning strap 100 on either side of the head restraint 82. The remaining outside free ends of lengths 108, 110 of webbing are secured to securing clips 54 for attachment to the combined flange-edge strip structure along the edge of the backboard in the manner described above in connection with tie-down straps 50. Positioning strap 100 thus allows movement of the head restraint 82 from side to side on the backboard to accommodate the lateral position of the patient&#39;s head. 
     In order to provide longitudinal positioning of the head restraint, and also to apply traction force to the cervical vertebrae of the patient carried on the backboard when desired, a pair of positioning and traction straps 102, 104 extend perpendicularly to the direction of extent of strap 100. Each of straps 102, 104 includes a length 112 of nylon or other fabric webbing which extends through base 84 under the spherical depression 89, intersects and is sewn to webbing 106 of strap 100 and is firmly embedded within the molded head restraint. The free end of each of strap 112 is secured to a buckle 62 along with the free one end of another length of webbing 114 having its free end attached to a securing clip 54 in the same manner as described above for straps 100 and 50. Clips 54 on positioning straps 102, 104 are fitted around the combined flange-edge strip structure at the end of the backboard adjacent which the head restraint is positioned. Straps 112, 114 are used to adjust the position of the head restraint longitudinally along the backboard and/or to apply traction to the patient&#39;s neck once his head is positioned in the head restraint and straps 90, 92 are secured. In such situation, the patient must first be secured atop the backboard using tie-down straps 50 in order to apply the proper traction force. 
     A second embodiment 120 of the head restraint is shown in FIGS. 8 and 9. In this form, head restraint 120 includes a two-piece head receptacle including a substantially rigid base portion 122 molded from high density polyethylene and including base 84&#39;, upstanding side and end walls 86&#39;, 88&#39;, embedded chin and forehead securing straps 90&#39;, 92&#39;, longitudinal and transverse positioning and securing straps 100&#39;, 102&#39; and 104&#39;, and Velcro securing strips 96&#39;, 98&#39; all similar to those included in embodiment 80 of the head restraint. In addition, head restraint 120 includes a molded foam liner 124 formed from elastomeric urethane foam and having a preferred wall thickess of approximately 3/8 inches. Liner 124 includes a base 125, side and end wall portions 126, 128, a shallow spherical depression 130 for centering the back of the patient&#39;s head, and upstanding corner portions 132 where the side and end wall portions merge, all of which provide a cradling effect for holding the patient&#39;s head in place when straps 90&#39;, 92&#39; are properly secured. As shown in FIG. 9, liner 124 fits snugly inside base 122 but can be easily removed for washing, cleaning or sterilization if necessary. Base 122 provides a stable, durable structure which can remain positioned on backboard 10 or 40 even while liner 124 is removed or replaced. 
     As shown in FIGS. 1, 2, 10 and 11, in addition to the peripheral flange structure providing a handhold and the through apertures 16, 28 which provide additional handholds, supplemental carrying handles 140 can be clipped to the edge structure to facilitate transportation of the backboard and patient. Each of the supplemental carrying handles 140 includes a securing clip member 142, a molded plastic or other closed-loop carrying handle 144, and a connecting length 146 of fabric webbing extending through handle 144, looped through aperture 148 in an extending flange 150 of securing clip member 142, and sewn to itself as shown in FIGS. 10 and 11. The main body of securing clip member 142 is a resilient, contoured, tempered aluminum or stainless steel member 152 having a cylindrical sectional shape or contour and an inwardly extending projection 154 substantially the same as that described above in connection with securing clip 54. Resilient body portion 152 may be expanded and fitted over the edge structure of backboard 10 or 40 in the same manner as securing clip 54 to position the carrying handles anywhere along the perhiphery of the backboard for supplemental carrying purposes. Inward protrusion 154 engages notch 36, 36&#39; to prevent removal of the carrying handle from the edge structure in either form of the backboard unless it is properly expanded by pulling the protrusion outwardly against the resistance of the resilient body portion. 
     Accordingly, the present invention provides a composite backboard assembly for emergency medical treatment purposes which is strong, light in weight, substantially rigid and sufficiently durable to endure the rough handling and exposure in many different types of medical treatment situations. It can be combined with various accessories to immobilize the head, neck, other extremities, and indeed the entire patient being carried, and provides a convenient method for carrying the backboard and patient without incurring further injury to either the patient or rescuer. 
     While several forms of the invention have been shown and described, other forms will now be apparent to those skilled in the art. Therefore, it will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention which is defined by the claims which follow.
A patient supporting and transporting backboard assembly formed from two cooperating, substantially rigid, lightweight panels which are corrosive, splinter, rot and stain resistant, can be sterilized for use in hospital environments, and allow patient x-rays without transferring the patient to another support. The panels are preferably formed from resinous plastic material such as polycarbonate and include integral, stabilizing ribs or channels and a peripheral edge structure providing a carrying handhold. Tie-down straps having resilient clips received on the edge structure can be positioned as desired along the length of the backboard. Supplemental carrying handles and head restraint assemblies for immobilizing a patient's head and/or applying cervical traction are also provided for attachment to the backboard.