ASFYT Part I: The Skeletal System Module S4 (Leg Ankle and Foot)

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Mary McKenzie
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1 Mdule S4 (Leg Ankle and Ft) (1) OVERVIEW In this mdule, we ll explre the: Features f the leg & ft bnes Anatmy f the ankle & ft jints Mvements pssible at the ankle & ft Imprtant ligaments f the ankle & ft (2) BONES OF THE LEG Tw parallel lng bnes, the tibia and fibula, frm the regin f the lwer limb between the knee and the ankle (the tibia is medial, and the fibula is lateral) The tibia and fibula are cnnected by an intersseus membrane and articulate with each ther via the prximal, middle and distal tibifibular jints They frm a strnger and mre stable limb than thse f the frearm, but their jint structure allws less mvement The tibia articulates prximally with the femur t frm the mdified hinge jint f the knee, and distally with the talus bne f the ft t frm the hinge jint f the ankle The fibula des nt cntribute t the knee jint and merely helps stabilize the ankle jint Page 1 f 13 Jasn R. Brwn 2006

2 Mdule S4 (Leg Ankle and Ft) (3) FEATURES OF THE TIBIA The tibia receives the weight f the bdy frm the femur and transmits it t the ft It is secnd nly t the femur in size and strength At its brad prximal end are the cncave medial and lateral cndyles, which are separated by an irregular prjectin called the intercndylar eminence The tibial cndyles articulate with the crrespnding cndyles f the femur t frm the knee jint The inferir regin f the lateral tibial cndyle bears a facet that indicates the site f the prximal tibifibular jint Just inferir t the cndyles, the tibia's anterir surface displays the rugh tibial tubersity, where the patellar ligament attaches The anterir edge f the tibial shaft, which is triangular in crss sectin, is called the anterir crest Neither this crest nr the tibia's medial surface is cvered by muscles, s they can be felt just deep t the skin alng their entire length (the anguish f a "bumped" shin is an experience familiar t nearly everyne) Distally the tibia is flat where it articulates with the talus bne f the ft. Medial t that jint surface is an inferir prjectin, the medial mallelus ("little hammer"), which frms the medial bulge f the ankle The fibular ntch, n the lateral surface f the tibia, is part f the distal tibifibular jint Page 2 f 13 Jasn R. Brwn 2006

3 Mdule S4 (Leg Ankle and Ft) (4) FEATURES OF THE FIBULA The fibula ("pin") is a stick-like bne that des nt bear weight -- its shaft is heavily ridged and serves mainly as a site fr muscle attachment The prximal end f the fibula is called the head, which articulates with the lateral aspect f the tibia, and the distal end is the lateral mallelus, which articulates with the talus and frms the bvius bulge f the lateral ankle jint Hmestatic Imbalance A Ptt's fracture is a break that ccurs at the distal end f the fibula, the tibia, r bth, and is a cmmn sprts injury (5) BONES OF THE FOOT The ft has tw imprtant functins: 1. It supprts ur bdy weight, and 2. It acts as a lever t prpel the bdy frward when we walk and run A single bne culd serve bth purpses, but it wuld adapt prly t uneven grund -- segmentatin makes the ft mre pliable The ft includes the tarsal bnes, the metatarsal bnes, and the phalangeal bnes (r te bnes) Page 3 f 13 Jasn R. Brwn 2006

4 Mdule S4 (Leg Ankle and Ft) (6) TARSAL BONES The seven tarsal bnes frm the psterir half f the ft, and crrespnd t the carpal bnes f the hand Bdy weight is carried primarily by the tw largest, mst psterir tarsals: 1. the talus (ankle), which articulates with the tibia and fibula superirly, and 2. the calcaneus (heel bne), which frms the heel f the ft and carries the talus n its superir surface (the calcaneal tubersity is the part f the calcaneus that tuches the grund) The remaining tarsals, frm medial t lateral, are the: 3. Navicular (medial) 4. Medial cuneifrm 5. Intermediate cuneifrm 6. Lateral cuneifrm 7. Cubid (lateral) (7) METATARSAL BONES The metatarsal bnes are five small lng bnes that are numbered 1 t 5, beginning n the medial side f the ft (the great te side) The base f each metatarsal is prximal, while the head is distal Distally, where the metatarsals articulate with the prximal phalanges f the tes, the enlarged head f the first metatarsal frms the ball f the ft Page 4 f 13 Jasn R. Brwn 2006

5 Mdule S4 (Leg Ankle and Ft) The first metatarsal is shrt and thick, and its plantar surface rests n paired sesamid bnes (which play an imprtant rle in supprting bdy weight) (8) PHALANGES The 14 phalanges f the ft (tes) are a gd deal smaller than thse f the fingers and thus are less nimble, but their general structure and arrangement are the same Except fr the great te, there are three phalanges in each digit, which are identified as the prximal phalanx, the middle phalanx and the distal phalanx (the great te, r hallux, has nly prximal and distal phalanges) Phalanx is the singular; phalanges is plural As with the metatarsals, the base f each phalanx is prximal, while the head is distal (9) ARCHES OF THE FOOT The ft has three arches: 1. The medial lngitudinal arch curves well abve the grund; it riginates at the calcaneus, rises t the talus (the keystne f the arch), and then descends t the three medial metatarsals 2. The lateral lngitudinal arch is very lw; it elevates the lateral part f the ft just enugh t redistribute sme f the weight between the tw ends f the arch -- the calcaneus and the head f the fifth metatarsal (the cubid is the keystne bne f this arch) Page 5 f 13 Jasn R. Brwn 2006

6 Mdule S4 (Leg Ankle and Ft) 3. the transverse arch runs bliquely frm ne side f the ft t the ther, fllwing the line f the jints between the tarsals and metatarsals; the tw lngitudinal arches serve as pillars fr the transverse arch Tgether, the arches f the ft frm a half-dme that distributes abut half ur standing and walking weight t the heel bnes and half t the heads f the metatarsals, which accunts fr the ft s ability t bear the weight f the bdy The arches are maintained by the interlcking shapes f the ft bnes, by strng ligaments, and by the pull f sme tendns during muscle activity The ligaments and muscle tendns prvide a certain amunt f springiness, allwing the arches t give" r stretch slightly when weight is applied t the ft and spring back when the weight is remved (this makes walking and running mre ecnmical in terms f energy use than wuld therwise be the case) (10) HOMEOSTATIC IMBALANCE: FALLEN ARCHES Fallen arches (r flatfeet ) is a cnditin that ccurs when the arch r instep f the ft cllapses r tuches the standing surface. Can be structural (yu re brn with it) r functinal (yu ve lst it) Functinal flatfeet may result frm: prlnged standing (esp. if verweight) running n hard surfaces withut prper arch supprt temprary increase in elastin due t pregnancy Page 6 f 13 Jasn R. Brwn 2006

7 Mdule S4 (Leg Ankle and Ft) (11) PLANTAR FASCIA The plantar fascia is a dense layer f fibrus tissue n the plantar surface f the ft, which maintains and stabilizes the lngitudinal arches f the ft The plantar fascia attaches psterirly t the calcaneal tubersity and anterirly t the plantar plates f the metatarsphalangeal (MTP) jints and adjacent flexr tendns f the tes (12) WINDLASS MECHANISM The plantar fascia inserts int the flexr tendns, and gets pulled taut when the te jints are extended (as when rising nt the balls f the feet) As the plantar fascia becmes mre taut, the height f the arch increases and creates a mre rigid ft (13) HOMESTATIC IMBALANCE: PLANTAR FASCIITIS Plantar fasciitis is inflammatin f the plantar fascia, which usually results in lcalized pain under the calcaneus (the heel) Often the pain frm plantar fasciitis is mst severe in the mrning, when first standing, then subsides a bit, but then returns after prlnged standing r walking Plantar fasciitis is smetimes assciated with a rapid gain f weight, but is als seen in recreatinal athletes (especially runners); in these athletes, it is thught that the repetitive nature f the sprts causes the damage t the fibrus tissue that frms the arch f the ft Page 7 f 13 Jasn R. Brwn 2006

8 Mdule S4 (Leg Ankle and Ft) Treatment: Rest, Ice (use frzen water bttles), stretching the calf muscles, rthtics (14) TIBIOFIBULAR JOINTS Three tibifibular jints exist between the tibia and fibula The prximal tibifibular jint is lcated between the lateral cndyle f the tibia and the head f the fibula Classificatin: gliding synvial jint The middle tibifibular jint is created by the intersseus membrane uniting the shafts f the tibia and fibula Classificatin: slightly mvable fibrus jint the intersseus membrane hlds the tibia and fibula tgether s that they can grasp the talus between them at the ankle jint, as well as allw the frce f all muscle attachments that pull n the fibula t be transferred t the tibia t mve the leg at the knee jint The distal tibifibular jint is lcated between the medial side f the lateral mallelus f the fibula and the fibular ntch f the distal tibia Classificatin: slightly mvable fibrus jint The tibifibular jints allw superir and inferir glide f the fibula relative t the tibia (15) THE ANKLE JOINT The ankle jint is lcated between the trchlear surface f the dme f the talus and the rectangular cavity frmed by the distal end f the tibia and the malleli f the tibia and fibula Page 8 f 13 Jasn R. Brwn 2006

9 Mdule S4 (Leg Ankle and Ft) It resembles a mrtise jint (culd als be visualized as a nut within a wrench) It is classified as a freely mvable, synvial hinge jint (uniaxial) (16) MOTIONS ALLOWED AT THE ANKLE Drsiflexin (20 O ) and plantarflexin (50 O ) f the ft at the ankle jint within the sagittal plane arund a medilateral axis Reverse actin wuld be drsiflexin/plantarflexin f the leg at the ankle jint (ft fixed) (17) DELTOID LIGAMENT The deltid ligament is actually a set f several ligaments that fan ut frm the medial mallelus f the tibia t the medial side f the talus, calcaneus and navicular bnes; it limits eversin f the ft at the ankle jint Nte: the lateral mallelus f the fibula extends mre distally than the medial mallelus f the tibia, which helps limit excessive eversin f the ankle jint; this fact, in cnjunctin with the presence f the strng deltid ligament, makes eversin ankle sprains very uncmmn (18) LATERAL COLLATERAL LIGAMENT COMPLEX A cmplex f three ligaments that branch ut frm the lateral mallelus f the fibula and cllectively help t limit excessive inversin f the ankle Page 9 f 13 Jasn R. Brwn 2006

10 Mdule S4 (Leg Ankle and Ft) the anterir talfibular ligament attaches t the anterir talus, and is the mst cmmnly sprained ligament f the human bdy the psterir talfibular ligament attaches t the psterir talus the calcanefibular ligament attaches t the lateral surface f the calcaneus Nte: the medial mallelus f the tibia des nt extend distally enugh t prvide stability t the uter ankle, and therefre the lateral cllateral ligaments are the nly line f defense against inversin sprains f the ankle (19) OTHER STRUCTURES OF THE ANKLE Bursae (singular, bursa) and tendn sheaths, which help minimize frictin between the tendns and underlying bny structures, are prevalent thrughut the ankle jint Retinacula (singular, retinaculum) help t hld dwn the tendns that crss the ankle jint, preventing bwstringing f these tendns (20) SUBTALAR TARSAL JOINT The subtalar tarsal jint is the main tarsal jint f the ft, and is lcated between the talus and the calcaneus It is classified as a freely mvable, synvial gliding jint (uniaxial) (21) MOTIONS OF SUBTALAR TARSAL JOINTS Prnatin, which cnsists f: Eversin Page 10 f 13 Jasn R. Brwn 2006

11 Mdule S4 (Leg Ankle and Ft) Drsiflexin Abductin Supinatin, which cnsists f: Inversin Plantarflexin Adductin Nte: when weight-bearing, prnatin f the fts results in a visible drp in the arch (22) TRANSVERSE TARSAL JOINT The transverse tarsal jint is a cmpund jint cnsisting f: the talnavicular jint, between the talus and navicular bne the calcanecubid jint, between the calcaneus and cubid It is classified as a freely mvable, synvial gliding jint Mvements available at this jint include prnatin and supinatin (in cnjunctin with the subtalar jint) (23) TARSOMETATARSAL JOINTS There are five tarsmetatarsal (TMT) jints, which are lcated between the distal rw f tarsal bnes and the metatarsal bnes The 1 st thru 3 rd TMT jints are lcated between the 1-3 cuneifrms and the base f the 1 st thru 3 rd metatarsals The 4 th and 5 th TMT jints are lcated between the cubid and the base f the 4 th and 5 th metatarsals Page 11 f 13 Jasn R. Brwn 2006

12 Mdule S4 (Leg Ankle and Ft) They are all classified as freely mvable synvial, gliding jints The base f the 2nd metatarsal is set back further psterirly than the ther metatarsal bnes, causing it t be wedged between the 1st and 3rd cuneifrms; it is therefre the mst stable f the five TMT jints, and an imaginary line thrugh its crrespnding ray is knwn as the central stable pillar f the ft (24) INTERMETATARSAL JOINTS All five metatarsal bnes articulate with each ther prximally (at their bases) and distally (at their heads) All are freely mvable, gliding synvial jints Allw nn-axial gliding mtin f ne metatarsal relative t the adjacent metatarsal (25) METATARSOPHALANGEAL JOINTS The metatarsphalangeal (MTP) jints are lcated between the heads f the metatarsals and the bases f the prximal phalanges f the tes They are classified as freely mvable, synvial cndylid jints (biaxial) (26) The majr mtins allwed are: Flexin/Extensin within the sagittal plane arund a medilateral axis Abductin/Adductin within the transverse plane arund a vertical axis Page 12 f 13 Jasn R. Brwn 2006

13 Mdule S4 (Leg Ankle and Ft) Nte: the reference fr abductin/adductin is an imaginary line drawn thrugh the 2 nd te when it is in anatmic psitin Average Range f Mtin f MTP Jints Tes #2-5: Extensin (60 O ) / Flexin (40 O ) Big Te: Extensin (80 O ) / Flexin (40 O ) (27) INTERPHALANGEAL JOINTS The interphalangeal (IP) jints f the ft are lcated between the head f the mre prximal phalanx and the base f the mre distal phalanx The big te has ne IP jint between the prximal and distal phalanges f the big te Tes #2-5 have tw IP jints a prximal IP jint (PIP) between the prximal and middle phalanges, and a distal IP jint (DIP) between the middle and distal phalanges These jints are freely mvable, synvial hinge jints (uniaxial), allwing flexin and extensin within the sagittal plane arund a medilateral axis Page 13 f 13 Jasn R. Brwn 2006

ASFYT Part I: The Skeletal System S1: Intro to Kinesiology

ASFYT Part I: The Skeletal System S1: Intro to Kinesiology S1: Intr t Kinesilgy (1) Intr t Kinesilgy Majr Divisins f the Human Bdy Jints Between Majr Bdy Parts Describing Mvement in the Bdy True Mvement vs. Ging Alng fr the Ride Anatmic Psitin Directinal Terms