Kinesiology of the Musculoskeletal System

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Kinesiology of the Musculoskeletal System

• Chapter 14
• Ankle and Foot

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Ankle and Foot Overview

• Primary function is to provide shock absorption
  and to impart thrust to the body during walking
  or ambulation
• Pliability to absorb force of body weight
• Rigidity to provide propulsive thrust
• Functions through an interaction of interrelated
  joints, connective tissues and muscles

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Osteology

• Ankle refers primarily to the talocrural joint,
  but includes proximal and distal tibiofibular
  joints
• Foot refers to all structures distal to the
  tibial and fibula
• Talus bone is included in the definition of both
  the ankle and foot

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Foot Anatomical Regions

• Rearfoot talus, calcaneus and subtalar joint
• Midfoot remaining tarsal bones, transverse
  tarsal joint and distal intertarsal joints
• Forefoot
• metatarsals
• and phalanges,
• tarsometatarsal
• joints

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Bones of the Lower Leg

• Fibula
• Transfers minority of weight bearing load
  through the leg
• Distal end is the lateral malleolus of the ankle
• 
  Tibia
• Distal end is the medial malleolus of the ankle
• Transfers majority of weight bearing load through
  the leg
• Torsion Angle of tibia is approximately 20-30
  degrees of intra-tibial external rotation

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Talocrural Joint
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Tarsal Bones

• Talus
• Articulates with the tibia and fibula at the
  talocrual joint, and with the navicular bone at
  the talonavicular joint
• Important kinesiological role in the foot/ankle
  and in the entire lower extremity
• Superior aspect covered with articular cartilage

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Tarsal Bones (cont.)

• Calcaneus
• Articulates with the talus superiorly at the
  subtalar joint and with the cuboid at the
  calcaneocuboid joint
• Largest tarsal bone built to absorb shock of
  heel strike
• Muscular attachments for achilles tendon,
  intrinsic foot musculature and plantar fascia
• Navicular
• Articulates with the talus at the talonavicular
  joint and with cuneiform bones
• Site of attachment for Tibialis Posterior

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Tarsal Bones (cont.)

• Cuneiforms
• Contribute to the transverse arch
• Articulations with cuboid, navicular and MTs
• Cuboid
• Articulates with calcaneus, lateral cuneiform,
  navicular and MTs
• Site of attachment of Peroneus Longus

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Metatarsals and Phalanges

• 5 MTs, 14 Phalanges
• Condylar joints
• Plantar surface of MTs are slightly concave
  longitudinally
• 1st MT is the shortest and thickest
• 2nd MT is the longest transfer of load travels
  through 1st and 2nd during gait

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Arthrology

• Major joints of the ankle and foot are the
  talocrural, subtalar, and transverse tarsal
  joints
• Talus mechanically involved in all 3 joints and
  is covered 70 by articular cartilage

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Motions at the Ankle Foot

• Motions about the foot and ankle are considered
• tri-planar but move through an oblique axis
• Pronation eversion/abduction/dorsiflexion
• Supination inversion/adduction/plantar flexion

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Tibiofibular Joints

• Proximal TFJ synovial joint with a joint
  capsule allows stresses put onto tibia to be
  transferred to the fibula
• Distal TFJ synarthrosis with very little motion
• Interosseous ligament
• Anterior Tibiofibular Ligament
• Posterior Tibiofibular Ligament

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Ankle Ligaments
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Ankle Ligaments
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High Ankle Sprain
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Talocrural Joint

• Aka Mortise Joint joint between tibia,
  fibular and talus
• Reinforced by medial and lateral collateral
  ligaments
• Primary motion at TC joint is dorsiflexion and
  plantarflexion
• ATFL Anterior Talofibular Ligament one
  component of the lateral collateral ligament
  most often injured in inversion sprain

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Subtalar Joint

• Tri-planar pronation/supination
• Pronation mostly eversion/abduction
• Supination mostly inversion/adduction
• During weight bearing activity, most of SJ motion
  occurs as the talus rotates and swan dives over
  a fixed calcaneus
• Ligaments of the STJ prevent extreme inversion
  and eversion
• Full supination increases rigidity of the midfoot
  and is the closed pack position
• Full pronation increases overall flexibility of
  the midfoot

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Subtalar Joint (cont.)
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Transverse Tarsal Joint

• Along with subtalar joint, TTJ controls most of
  pronation/supination
• Allows foot to accommodate different surfaces

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Joints of the Foot
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Medial Longitudinal Arch of the Foot

• Primary load bearing
• and shock-absorbing
• structure of the foot
• Height of arch is
• maintained by plantar
• fascia, intrinsic foot
• muscles, spring
• ligament and stability
• of midfoot joints

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Medial Longitudinal Arch (cont.)

• Pes Planus dropped MLA
• Flexible Pes Planus
• Rigid Pes Planus
• Pes Cavus raised MLA
• Less common than pes planus
• Poor shock absorption
• Possible association with stress fractures

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Clinical Considerations

• Patient/athlete with Pes Planus or Pronated
  feet often fitted with an orthotic and prescribed
  strengthening exercises to control pronation
• Strengthen tibialis posterior, intrinsic foot
  muscles, hip external rotators and abductors
  stretch hip adductors, TFL, hip flexors consider
  motion control athletic shoes
• Patient/athlete with Pes Cavus or Supinated
  feet often prescribed cushioning orthotics and/or
  athletic shoes

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Windlass Effect

• Mechanism through which intrinsic and extrinsic
  plantarflexors place tension on the medial
  longitudinal arch creating a rigid/stable mid
  and forefoot enabling the foot to accept the
  biomechanical stresses of push off during gait

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Windlass effect (cont.)
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References

• Neumann, D. Kinesiology of the Musculoskeletal
  System. 2002. Human Kinetics.