The Anatomy of Sea Turtles

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1 Close this window to return to the previous pge or go to The Antomy of Se Turtles Jenette Wyneken, Ph.D. Illustrted y Dwn Witherington Close this window to return to the previous pge or go to

2 Muscle Antomy The s re responsile for moving structures, modifying the function of other s, nd stilizing joints. Muscles originte nd insert vi tendons. The origin of is its fixed point while the insertion is typiclly the point tht it moves. Muscles cn ttch vi their tendons to ones, s, skin or eyes. Where known, the innervtions of the s re reported. For reding ese, the designtion of M., prior to s nmes, hs een omitted. Nmes nd key concepts re given in old the first time the is discussed. Muscle functions re descried with ech figure. As they pply to se turtles, these functions re s follows. Flexion ends one prt reltive to nother t joint; extension strightens those prts. Protrction moves one prt (usully lim) out nd forwrd; retrction moves tht prt in nd ck. Aduction moves prt wy from the ventrl surfce; dduction rings the prt towrd the ody's ventrl surfce. Rottion turns structure. Depressor s open ( specil form of duction) structure, jws in this cse, while levtors close jws ( kind of dduction). Muscle groups. The s descried here re the mjor or lrge s (detiled discussion of most s cn e found in the primry literture). For convenience, s re grouped y region; xil s, include the hed s; ventrl s include oth proximl pectorl nd pelvic s tht re ssocited with the plstron; forelim nd respirtory s re those found on the flippers, crpce, nd scpul involved in flipper movements nd rething. Posterior s re the lrge s of the hip, thigh, nd lower leg. Muscles of the flipper lde nd hind foot re not discussed or illustrted in detil here ecuse they re oscured y extensive connective tissue nd re difficult for most to identify, even with specil dissection equipment nd techniques. Ventrl Muscles. The mssive ventrl musculture is found fter removing the plstron (Fig. 111). This musculture is dominted y superficil, the pectorlis mjor, which origintes on the plstron nd inserts on the lterl process nd shft of the humerus. Anterior to the pectorlis nd ventrl to the cromion processes re two s: the deltoideus (ventrl prt), which origintes on the ventrl scpul, cromion, nd nterior plstron ones nd the suprcorcoideus, which hs severl sudivisions. Its nterior prt origintes on the cromion (Figs ). Both the deltoideus nd the nterior prt of the suprcorcoideus insert on the lterl process of the humerus. These 3 ventrl s function in swimming nd respirtion (y movement of the shoulders nd plstron). Their innervtions re vi the suprcorcoid nerve from the ventrl portion of the rchil plexus (see Nervous System, Figs ). After removing the pectorlis mjor, deep locomotor s re found ssocited with the pectorl girdle (Figs ). The rchii hs severl sudivisions, or heds, in se turtles. The superficil hed (Figs ) origintes on the corcoid nd extends vi long tendon to insert on the rdius nd uln; the profundus hed inserts on the humerus nd rdius. Innervtion is vi the inferior rchil flexor nd medin nerves. The corcorchilis mgnus origintes on the dorsl side of corcoid process nd inserts on the medil process of the humerus. The posterior prt of the suprcorcoideus (Fig. 112) origintes on the corcoid nd its crtilge nd inserts in the lterl process of the humerus. These s re innervted y the suprcorcoid nerve. There is n extensive series of rteries nd veins running within nd etween these very ctive s (Fig. 114). A pir of superficil posterior s, the left nd right rectus dominis (Fig. 111) re found ventrlly. Ech origintes on the lterl puis nd inserts on the plstron. They stilize the pelvis nd my function in compressing the plstron during rething. The Antomy of Se Turtles 59

3 deltoideus suprcorcoideus pectorlis mjor rectus dominus Figs. 111 nd 111. Superficil ventrl s of the pectorl nd pelvic girdles. The lrge pectorlis mjor is forelim retrctor nd dductor. Both the deltoideus nd the suprcorcoideus protrct nd duct the humerus. The rectus dominus is pelvic stilizer. Anterior is towrd the top of the picture. 60 The Antomy of Se Turtles

4 supr corcoideus (nterior prt) deltoideus hed cromion process rchii superficilis supr corcoideus (posterior prt) cromil corcoid ligment pectorlis mjor (cut wy medilly) corcoid process corcorchilis mgnus Figs. 112 nd 112. The deep pectorl s re exposed fter removl of the pectorlis mjor. These forelim retrctors, seprted on the niml's left (right in picture), re the rchii superficilis nd corcorchilis mgnus. The posterior prt of the suprcorcoideus oth dducts nd retrcts the flipper. The Antomy of Se Turtles 61

5 ext. digitorum ext. rdilis interm. trctor rdii humerl h. cromion deltoideus ventrl prt testoscpulris testocorcoideus crpce ltissimus dorsi teres mjor humerl h. rchilis inf. suscpulris scpulr h. scpulr h. cromilcorcoid ligment pectorlis mjor suprcorcoideus nterior prt corcorchilis profundus superficilis flexor crpi ulnris ext. rdilis interm. extensor digitorum trctor rdii rchilis inf. humerl h. suprcorcoideus nterior prt testoscpulris testocorcoideus ltissimus dorsi teres mjor scpulr h. suscpulris humerl h. deltoideus corcorchilis scpulr h. profundus superficilis suprcorcoideus posterior prt cromilcorcoid ligment corcoid crtilge superficilis profundus flexor crpi ulnris extensor rdilis interm. extensor digitorum revis Fig Digrms of cheloniid right shoulder s including locomotor nd respirtory s. Superficil ventrl s (top left), deep ventrl s (ottom left), posterior s (ottom right), nd lterl s (top right). The extensor digitorum, extensor rdilis intermedius, trctor rdii, nd flexor crpi ll control the extension nd flexion of the flipper lde. Ext.= extensor, h.= hed, Inf.= inferior, Interm.= intermedilis. (After Wyneken, 1988) 62 The Antomy of Se Turtles

6 suprcorcoideus (nterior prt) pectorl rteries nd veins cromion process cut cromil corcoid ligment pericrdium superficilis corcoid process suprcorcoideus (posterior prt) Figs. 114 nd 114. The deep pectorl s of the niml's right side re shown in detil. The suprcorcoideus hs two prts: posterior, which protrcts nd nterior, which retrcts the forelim. The Antomy of Se Turtles 63

7 Forelim nd Respirtory Muscles. The ltissimus dorsi/teres mjor complex, the scpulr hed of the deltoideus, nd the suscpulris originte on the crpce nd/or shoulder girdle nd insert on the proximl humerus (Fig. 113). The ltissimus dorsi nd teres mjor together originte on the scpul nd the crpce from the ttchment point of the scpul, long the first pleurl one to the nterior peripherl ones. They insert vi common tendon just distl to the hed of the humerus. The scpulr hed of the deltoideus rises from the nterior scpul nd inserts on the lterl process nd shft of the humerus. The suscpulris is very lrge, origintes on the medil nd posterior scpul, nd inserts on the lrge medil process nd the shft of the humerus. These s re innervted y the deltoid nerve ( rnch of the rchil plexus). There re two sheet-like respirtory s locted dorslly, which re often destroyed when removing the pectorl girdles (Figs. 113 nd 115). These re the testocorcoideus (origin: crpce ner the nterior infrmrginls; insertion: dorsl corcoid) nd testoscpulris (origin: crpce posterior to the ltissimus dorsi; insertion: dorsl scpul nd the scpulr ttchment to the crpce). They re innervted y cervicl spinl nerves. The remining dorsl shoulder, the rchii (= superficilis) hs two heds in cheloniid se turtles (Figs ). The humerl hed rises from the humerus, nd the scpulr hed rises from the scpul. Both converge to form common tendon inserting on the proximl uln. This my hve only humerl hed in Dermochelys. The is innervted y the superficil rdil nerve ( rnch from the superior rchil nerve of the rchil plexus). testoscpulris Fig Ventrl pectorl s with rteries nd veins. The pectorl rtery is found running long the deep s of the shoulder. The testoscpulris, respirtory, is deep to the pectorlis. Other pectorl s originting on the corcoid re reflected medilly (to the right) in this picture. 64 The Antomy of Se Turtles

8 Fig Superficil dorsl forelim s (right). The two heds of the rchii, ( scpulr hed nd humerl hed) re forelim dductors, which twist the flipper. The more medil nd flexor crpi ulnris s flex the flipper lde. The extensor digitorum ecomes diffuse in dults s firous connective tissue stiffens the flipper lde. Young turtles cn extend the digits, somewht mture turtles cnnot. scpulr hed extensor digitorum humerl hed flexor crpi ulnris superficilis nd profundus extensor rdilis intermedis rchilis inferior scpulr hed humerl hed scpulr hed extensor crpi ulnus extensor digitorum revis & longus I II numerl trctor hed rdii tendon Fig Ventrl forelim s (right). Most of the ventrl s flex the flipper lde reltive to the upper rm. The extensor rdilis extends the flipper. The scpulr hed of the my twist the flipper lde long its xis, or duct the forerm. superficilis profundus V flexor crpi ulnris IV IV Fig Dorsl forelim s of n immture hwksill. In young nimls, the divisions of the forerm nd the flipper, prticulrly, re more ovious thn in older nimls. Less connective tissue is present nd the digits cn flex nd extend to limited extent. III The Antomy of Se Turtles 65

9 rchii humerl hed rchii scpulr hed hed ltissimus dorsi teres mjor ltissimus dorsi suscpulris cervicl verter corcorchilis mgnus scpul Figs. 119 nd 119. Dorsl view of the pectorl musculture. The crpce, skin nd ft hve een removed (from left). The hed, cut cervicl verter, nd scpulr ends provide lndmrks for orienttion. The ltissimus dorsi, lrge sheet-like, is shown intct (niml's right) nd cut (niml's left). It, plus the teres mjor nd deltoideus (scpulr hed, not shown), duct nd sometimes protrct the flipper. The lrge suscpulris is strong flipper protrctor. The corcorchilis, ventrl, is seen extending from the shoulder posteriorly, towrd its origin, the corcoid. 66 The Antomy of Se Turtles

10 The my hve one or two prts (Figs. 112 nd 114). When two heds re present, the superficilis rises from the corcoid nd inserts on the pisiform of the wrist. The hs two ellies in series, with short tendon in the middle. The second nd most prominent hed, the profundus, lso origintes on the posterior corcoid, ut ventrl to the superficilis nd inserts vi tendon with the rchilis on the uln (Fig. 114). In Dermochelys nd Lepidochelys, often there is just single hed inserting on the rdius nd uln. left flipper crpl extensors distl humerus rchii ltissimus dorsi scpul suscpulris teres mjor Figs. 120 nd 120. The pectorl s of the left shoulder, rm nd flipper. The lrge suscpulris covers most of the scpul. The lrge corcorchilis is seen ventrlly, covering much of the corcoid. The hs one or two heds (vrying mong species nd mong individuls). The superficilis extends from the shoulder (mostly the corcoid) to the pisiform one of the wrist, nd proly helps control the twist or rottion of the flipper lde. The profundus (seen only s prtil seprtion here) cts s flipper retrctor nd flexor of the flipper lde t the elow. superficilis profundus corcorchilis The Antomy of Se Turtles 67

11 Axil Muscles. Most xil s re ssocited with the neck nd til of se turtles. The mjority of the neck s re illustrted with the neck circultion (Figs. 131, 141, ). These include the trnsverse cervicl s, nd the iventer cervicl. Here, the superficil s of the throt nd the jw s re descried. The til musculture is not discussed ecuse it hs not een studied in ny detil. The mjor deep s of the neck re the longus colli nd retrhens colli. The longus colli s re short, segmentlly rrnged, nd trvel oliquely etween successive cervicl vertere; they serve to extend the neck. The retrhens colli originte on the cervicl vertere nd extend posteriorly to insert on the dorsl verterl elements of the crpce. They re neck flexors nd retrctors, to the extent tht mrine turtles extend nd retrct the neck. Hed Muscles. Just eneth the skin of the throt is thin lyer of, the intermndiulris, intermndiulris constrictor colli rphe depressor mndiule which hs fiers running etween the two dentry ones. It inserts on flt midline tendon (rphe) tht runs the length of the throt (Fig. 121). The intermndiulris ecomes the constrictor colli posterior to the jw joint (Fig. 121), originting on dorsolterl cervicl tendon. Just deep to the intermndiulris re s running oliquely etween the jws nd inserting on the hyoid, the geniohyoideus. Posterior to the geniohyoideus is pir of strp-like s, the corcohyoideus tht extend to the hyoid pprtus from the corcoid (Figs ). These s ssist in depressing the jw, swllowing, nd pumping the throt (gulr flutter). They re innervted y the fcil nerve. Muscles of the tongue, innervted y the hypoglossl nerve, nd the glossophryngel nerve re not descried here. The jw s of turtles re mostly locted inside the skull. Becuse of these deep positions, most re descried ut not illustrted. Unlike mmmls, turtles lck mndiulris ; insted they hve n dductor mndiule with severl heds. The heds originte on the prietl, suproccipitl, qudrte, prootic, nd opisthotic ones (Fig. 31) nd converge on tendon tht inserts primrily on the lower jw (dentry, with smll insertions on the squmosl one posterior to the jw joint). Medil to the dductor mndiule complex is pir of connected s. The intermndiulris runs from the lower jw to the tendon of the pseudotemporlis which itself continues to the prietl one. These jw closing s re ll innervted y the trigeminl nerve. The jws Fig Ventrl nd superficil neck s. The constrictor colli of the ventrl neck is exposed lterl to nd overlying the trche. Connective tissue tht loosely ttched the to the skin is still present on the turtle s nterior neck. The midline rphe (tendon) is visile long the nterior hlf of the. 68 The Antomy of Se Turtles

12 re opened y the depressor mndiule, which hs severl prts. The depressor mndiule rises from the qudrte, qudrtojugl, nd squmosl ones nd inserts on the rticulr of the lower jw; in Dermochelys portion lso inserts on the uditory tue. These prts re innervted y the fcil nerve. hyoid ody constrictor colli rnchiohyoideus cut nd reflected nteriorly process lterlis posterior esophgus trche corcohyoideus crotid rtery Figs. 122 nd 122. Dissection of the ventrl neck s, showing the deep s (right in picture) nd superficil s (left). The prllel fiers of the intermndiulris rise from the lower jw, nd terminte in the cut rphe (found overlying the hyoid ody nd nterior trche). The rnchiohyoideus is cut etween the hyoid ody nd the hyoid process (process lterlis posterior) on the turtle s left. The corcohyoideus trvels long the trche to the hyoid. The crotid rtery lies deep to these s. The Antomy of Se Turtles 69

13 dductor mndiule otic cvity siocciptl exoccipitl splenius cpitus suprficil dductor mndiule trnsverse cervicl spinl cnl qudrte rticulr process externl jugulr vein pterygoideus (ventrl prt) esophgus (collpsed) depressor mndiule crotid rtery trche longus colli geniohyoideus hyoid element corcohyoideus constrictor colli Figs. 123 nd 123. This olique xil section through the neck of hwksill, is just posterior to the jw joint ventrlly nd suproccipitl crest dorslly. The s, mjor lood vessels, trche, nd esophgus cn e identified. Their reltive positions nd extent re seen in this dissection. 70 The Antomy of Se Turtles

14 Posterior Muscles. The mjor posterior s cn e identified fter removing the rectus dominus nd the skin covering the hind legs nd til. Ventrlly, these re the puoischiofemorlis externus nd internus, the puotiilis, the flexor tiilis complex nd the miens (Figs ; see lso Nervous System). These ventrl hip s re innervted y the oturtor nd tiil nerves of the scrl (=lumoscrl) plexus. The puoischiofemorlis externus, thigh dductor, covers much of the ventrl pelvis, nd rises from the ventrl puis, ischium, nd memrne covering the thyroid fenestre (Fig. 106); it inserts on the femur s minor trochntor. Different prts of this cn either protrct or retrct the leg. The puoishiofemorlis internus is lrge in cheloniids nd hs oth superficil nd deep components. It my e sent in Dermochelys nd replced in function nd position y the iliofemorlis. When present, it origintes on the dorsolterl puis, ilium, nd the scrl vertere. It inserts on the femur's mjor trochnter. femur. The dorsl hip nd thigh s (illustrted in Circultory Antomy; Figs nd Nervous System; Fig. 207), include the hip ductors: iliotiilis, femorotiilis, nd miens. The ventrlly positioned miens (Fig. 125) origintes on the puioischidic ligment, nd inserts on the "ptellr" tendon cross the knee to the nterior tii. The iliotiilis origintes on the dorsl ilium nd inserts with the miens on the ptellr tendon. Deep to these two s, the femorotiilis (see Nervous System, Fig. 207), rises from the dorsl nd nteroventrl surfces of the femur, nd inserts with the iliotiilis nd miens. The peronel nd femorl nerves of the scrl plexus innervte most of these dorsl hip s. The hind foot extensors (Fig. 124) re lrge sheet-like s originting on the dorsl nd lterl femur nd inserting on the dorsl nd nterior fiul nd digits. They flex the lower leg or extend the digits. The puotiilis, prt of the flexor tiilis complex, is found in cheloniids ut is sent in Dermochelys. This origintes on the puic symphysis nd lterl puis; it inserts on the tii with the flexor tiilis internus. The flexor tiilis internus, Y- shped, origintes on the scrl nd postscrl vertere dorslly, nd ventrlly on the pelvic symphysis nd lterl puis. It psses distlly nd wrps round the gstrocnemius to insert on the tii. The flexor tiilis externus hs two heds (Figs ) nd is somewht medil to the internus. The dorsl hed rises from the ilium nd the ventrl hed from the posterior ischium. Both converge to insert, vi single tendon, on the tii nd the gstrocnemius of the shnk; some fiers insert on the skin nd connective tissues of the shnk. knee extensor digitorum foot left thigh (medil) The dductor femoris (Fig. 126) origintes on the lterl ischium nd inserts on the posterior femorl shft. The ischiotrochntericus (not shown), leg retrctor, origintes on the nterior puis nd puic symphysis. It inserts on the mjor trochnter of the Fig Anterior nd dorsl foot extensors of loggerhed right hind lim. The leg is ducted nd flexed t the knee. The foot extensors flex the lower leg or extend nd spred the digits. The Antomy of Se Turtles 71

15 puoischiofemorlis externus dominl vein puoischiofemorlis internus miens puoischiotiilis flexor tiilis til Figs. 125 nd 125. The superficil ventrl hip s. The puoischiofemorlis externus is n dductor of the leg. The puoishiofemorlis internus (the nterior ventrl portion is seen here) is protrctor nd ductor of the leg. The flexor tiilis complex, including the puotiilis, flexes nd retrcts the leg nd controls the shpe of the triling edge of the foot, perhps during steering. More nteriorly, the miens is wek dductor nd protrctor of the hind leg nd cn extend the shnk. 72 The Antomy of Se Turtles

16 flexor tiilis puotiilis dductor femoris puoischiofemorlis internus ischil tuerosity scitic nerve nd peronel nerves flexor tiilis til Figs. 126 nd 126. The deeper ventrl hip s re shown fter removing the superficil lim retrctors. The dductor femoris nd puoishiofemorlis internus re ntgonistic s, with the former dducting the thigh nd the lter ducting it. The Antomy of Se Turtles 73