Download S4 Lecture Notes - Anatomy Studies for Yoga Teachers

ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
(1) Overview
In this module, we’ll explore the:
♦
The features of the leg & foot bones
♦
The anatomy of the ankle & foot joints
♦
The arches of the foot
♦
Structurally flat feet vs functionally flat feet
♦
The movements possible at the ankle & foot
♦
The important ligaments of the ankle & foot
(2) The Tibia & Fibula
♦
The tibia and fibula are two parallel long bones located in the leg
between the knee and the ankle joints (the tibia is medial to the
fibula)
♦
They are connected by an interosseous membrane and articulate
with each other at the proximal, middle and distal tibiofibular joints
♦
They form a stronger and more stable limb than those of the
forearm, but their joint structure allows less movement
♦
The tibia articulates proximally with the femur to form the knee
joint, and distally with the talus of the foot to form the ankle joint
♦
The fibula does not contribute to the knee joint and merely helps
stabilize the ankle joint
Page !1 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
(3) Features Of The Tibia
♦
The intercondylar eminence is a small crest-like feature located on
the proximal plateau of the tibia
♦
The medial and lateral condyles are located on the proximal
epiphysis of the tibia
♦
The tibial tuberosity is a large protuberance located proximally on
the anterior aspect of the tibia, where the patellar ligament attaches
♦
The anterior crest of the tibia is located along the anterior edge of
the shaft
♦
The soleal line is located posteriorly on the proximal aspect of the
tibia, and is a site of attachment for the soleus muscle
♦
The medial malleolus is located medially on the distal aspect of the
tibia, where it forms the medial bulge of the ankle joint
♦
The fibular notch is located on the lateral surface of the distal tibia,
where it articulates with the fibula to form the distal tibiofibular
joint
(4) Features Of The Fibula
♦
The fibula ("pin") is a stick-like bone that does not bear weight -- its
shaft is heavily ridged and serves mainly as a site for muscle
attachment
♦
The proximal end of the fibula is called the head, which articulates
with the lateral aspect of the tibia, and the distal end is the lateral
malleolus, which articulates with the talus and forms the obvious
bulge of the lateral ankle joint
Page !2 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
(5) Bones Of The Foot
♦
The foot supports our body weight and acts as a lever to propel the
body forward when we walk and run
♦
The tarsal bones are located in the hindfoot and midfoot, while
the metatarsals and phalanges are located in the forefoot
♦
Segmentation of the bones of the foot makes it more pliable, and
thus more capable of adapting to uneven surfaces
(6) Tarsal Bones
♦
The seven tarsal bones form the posterior half of the foot, and
correspond to the carpal bones of the hand
♦
Body weight is carried primarily by the talus (located between the
medial and lateral malleoli) and calcaneus (located immediately
distal to the talus)
♦
The remaining tarsals, from medial to lateral, are the navicular,
medial cuneiform, intermediate cuneiform, lateral cuneiform and
cuboid
(7) Metatarsal Bones
♦
The metatarsals are five small long bones that are numbered 1 to 5,
beginning on the medial side of the foot
♦
The base of each metatarsal is proximal, while the head is distal
♦
The enlarged head of the first metatarsal forms the ball of the foot
♦
Paired sesamoid bones can be found on ball of the foot, which play
an important role in weight-bearing and balance
Page !3 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
• sesamoid bones are small bones that develop within tendons
and give additional leverage to the muscle(s) that cross them
(8) Phalanges
♦
Except for the big toe, there are three phalanges in each digit,
which are identified as the proximal, the middle and distal
phalanges
♦
The big toe, or hallux, only has a proximal and distal phalange
♦
As with the metatarsals, the base of each phalanx is proximal, while
the head is distal
♦
The 14 phalanges of the foot (toes) are a good deal smaller than
those of the fingers, but their general structure and arrangement
are the same
(9) Arches Of The Feet
♦
The foot has three arches:
♦
The medial longitudinal arch originates at the calcaneus, rises to
the talus, and then descends to the three medial metatarsals
♦
The lateral longitudinal arch elevates the lateral part of the foot
just enough to redistribute some of the weight between the two
ends of the arch -- the calcaneus and the head of the fifth
metatarsal
♦
The transverse arch runs obliquely from one side of the foot to
the other, following the line of the joints between the tarsals and
metatarsals; the two longitudinal arches serve as pillars for the
transverse arch
Page !4 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
♦
Together, the arches of the foot form a half-dome that distributes
about half our standing and walking weight to the heel bones and
half to the heads of the metatarsals
(10) Arches Of The Feet (Cont’d)
♦
The arches are maintained by the interlocking shapes of the foot
bones, strong ligaments, and the pull of tendons during muscle
activity
♦
The arches give slightly when weight is applied to the foot and
spring back when the weight is removed, which makes makes
walking and running more economical in terms of energy use than
would otherwise be the case
(11) Plantar Fascia & Plantar Plates
♦
The plantar fascia is a dense layer of fibrous tissue on the plantar
surface of the foot, which maintains and stabilizes the longitudinal
arches of the foot; it attaches posteriorly to the calcaneal tuberosity
and anteriorly to the flexor tendons and plantar plates of the
metatarsophalangeal (MTP) joints
♦
The plantar plates are made of firm but flexible fibrocartilage and
can thus withstand compressive loads and act as a supportive
articular surface; most of its fibers are oriented longitudinally, in
the same direction as the plantar fascia, and the plates can thus
sustain substantial tensile loads in this direction
Page !5 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
(12) Windlass Mechanism
♦
The plantar fascia inserts into the flexor tendons, and gets pulled
taut when the toe joints are extended (as when rising onto the balls
of the feet)
♦
As the plantar fascia becomes more taut, the height of the arch
increases and creates a more “rigid” foot
(13) Homeostatic Imbalance: Fallen Arches
♦
Fallen arches (or “flatfeet”) is a condition that occurs when the arch
or instep of the foot collapses or touches the standing surface.
♦
It can be structural (you’re born with it) or functional (you’ve lost
it)
♦
With functionally low arches, rising onto the balls of the feet will
cause the arch to increase due to the windlass mechanism
♦
With structurally low arches, it will be difficult to rise onto the
balls of the feet because the feet are not capable of arching
♦
Functionally flat feet may result from increased weight gain,
prolonged standing, poor arch support, weakness in the muscles
that cross the arches and a temporary increase in elastin due to
pregnancy
♦
Strengthening the muscles that cross the arches (the “bootstrap”
muscles) and intrinsic flexor muscles on the plantar side of the foot
will increase their resting tone and help lift/maintain the arches
(14) Homestatic Imbalance: Plantar Fasciitis
♦
Plantar fasciitis is inflammation of the plantar fascia, which usually
results in localized pain under the calcaneus
Page !6 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
♦
Often the pain from plantar fasciitis is most severe in the morning,
when first standing, then subsides a bit, but then returns after
prolonged standing or walking
♦
Causes can include rapid weight, poor arch support, and repetitive
strain from running
♦
Treatment strategies usually include rest, ice (use frozen water
bottles), elevation, myofascial work and stretching of the posterior
thigh and leg, orthotics to maintain the arches during the day, using
a boot while sleeping to maintain dorsiflexion (which decreases pain
in the morning)
(15) Tibiofibular Joints
♦
♦
Three tibiofibular joints exist between the tibia and fibula:
♦
the proximal tibiofibular joint is located between the lateral
condyle of the tibia and the head of the fibula, and is classified
as a gliding synovial joint
♦
the middle tibiofibular joint is located between the shafts of
the tibia and fibula, which are united by the interosseus
membrane, and is classified as a slightly movable fibrous joint
♦
the distal tibiofibular joint is located between the lateral
malleolus of the fibula and the fibular notch of the distal tibia,
and is classified as a slightly movable fibrous joint
The tibiofibular joints allow superior and inferior glide of the fibula
relative to the tibia
Page !7 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
(16) The Ankle Joint
♦
The ankle joint (aka talocrural joint) is located between the
trochlear surface of the talus and the rectangular cavity formed by
the distal end of the tibia and the malleoli of the tibia and fibula
♦
It is classified as a freely movable, synovial hinge joint (uniaxial)
♦
It resembles a mortise joint, and could also be visualized as a nut
within a wrench
(17) Motions Allowed At The Ankle
♦
The ankle joint is capable of dorsiflexion and plantar flexion of the
foot at the ankle joint within the sagittal plane around a
mediolateral axis
♦
The reverse action would occur if the foot is fixed, and can be
referred to as dorsiflexion/plantarflexion of the leg at the ankle joint
♦
Ideal range of motion is 20O of dorsiflexion, and 50O of plantar
flexion
(18) Deltoid Ligament Of The Ankle
♦
Several ligaments fan out from the medial malleolus of the tibia to
the medial side of the talus, calcaneus and navicular bones
♦
Collectively referred to as the “Deltoid Ligament,” these ligaments
limit excessive eversion of the foot at the ankle joint
(19) Homeostatic Imbalance: Pott’s Fracture
♦
A Pott’s fracture is a term loosely applied to a variety of bimalleolar
ankle fractures
Page !8 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
♦
It is most often caused by a strong eversion force, which strains the
deltoid ligament of the ankle and tears off the medial malleolus due
to its strong attachment
♦
The talus then moves laterally, shearing off the lateral malleolus
and/or breaking the distal aspect of the fibula
♦
English physician Percivall Pott experienced this injury in 1765 and
described his clinical findings in a paper published in 1769
(20) Lateral Collateral Ligament Complex
♦
A complex of three ligaments that branch out from the lateral
malleolus of the fibula and collectively help to limit excessive
inversion of the ankle
♦
the anterior talofibular ligament attaches to the anterior talus,
and is the most commonly sprained ligament of the human body
♦
the posterior talofibular ligament attaches to the posterior talus
♦
the calcaneofibular ligament attaches to the lateral surface of
the calcaneous
♦
The lateral collateral ligaments are the main line of defense against
inversion sprains of the ankle
♦
In yoga asana practice, it is important not to stretch the ATL by
overly inverting the ankle during “lotus-like” postures
(21) Other Structures Of The Ankle
♦
Bursae (singular, bursa) and tendon sheaths, which help minimize
friction between the tendons and underlying bony structures, are
prevalent throughout the ankle joint
Page !9 of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
♦
Retinacula (singular, retinaculum) help to hold down the tendons
that cross the ankle joint, preventing bowstringing of these tendons
(22) Subtalar Tarsal Joint
♦
The subtalar tarsal joint is the main tarsal joint of the foot, and is
located between the talus and the calcaneus
♦
It is classified as a freely movable, synovial gliding joint (uniaxial)
(23) Motions Allowed At The Subtalar Tarsal Joint
♦
The subtalar tarsal joint is capable of pronation and supination of
the foot at the subtalar tarsal joint within an oblique plane around
an oblique axis
♦
Pronation consists of eversion, dorsiflexion and abduction
♦
Supination consists of inversion, plantarflexion and adduction
♦
When weight-bearing, pronation of the foots results in a visible drop
in the arch
(24) Transverse Tarsal Joint
♦
The transverse tarsal joint is a compound joint consisting of:
o the talonavicular joint, between the talus and navicular bone
o the calcaneocuboid joint, between the calcaneus and cuboid
♦
It is classified as a freely movable, synovial gliding joint
♦
Movements available at this joint include pronation and supination
(in conjunction with the subtalar joint)
Page !10 of ! 12
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
(25) Tarsometatarsal Joints
♦
There are five tarsometatarsal (TMT) joints, which are located
between the distal row of tarsals and the base of the metatarsals
o The 1st thru 3rd TMT joints are located between the cuneiforms
and the base of the 1st thru 3rd metatarsals
o The 4th and 5th TMT joints are located between the cuboid and
the base of the 4th and 5th metatarsals
♦
They are all classified as freely movable synovial, gliding joints
♦
The base of the 2nd metatarsal is set back more posteriorly than
the other metatarsals, causing it to be wedged between the 1st and
3rd cuneiforms and making it the most stable of the five TMT joints
(an imaginary line through its corresponding ray is known as the
central stable pillar of the foot)
(26) Intermetatarsal Joints
♦
All five metatarsal bones articulate with each other proximally (at
their bases) and distally (at their heads) via the intermetatarsal
joints
♦
All are freely movable, gliding synovial joints that allow non-axial
gliding motion of one metatarsal relative to the adjacent metatarsal
(27) Metatarsophalangeal Joints
♦
The metatarsophalangeal (MTP) joints are located between the
heads of the metatarsals and the bases of the proximal phalanges
of the toes
Page 11
! of 12
!
© Anatomy Studies for Yoga Teachers 2017
ASFYT Part I: The Skeletal System
Module S4 (Leg Ankle and Foot)
♦
They are classified as freely movable, synovial condyloid joints
(biaxial)
(28) Motions Available At The M-T-P Joints
♦
Flexion and extension within the sagittal plane around a
mediolateral axis
♦
Abduction and adduction within the transverse plane around a
vertical axis (the reference for abduction/adduction is an imaginary
line drawn through the 2nd toe when it is in anatomic position)
♦
Ideal range of motion of the MTP joints is:
o Toes #2-5: Extension (60O) / Flexion (40O)
o Big Toe: Extension (80O) / Flexion (40O)
(29) Interphalangeal Joints
♦
♦
The interphalangeal (IP) joints of the foot are located between the
head of the more proximal phalanx and the base of the more distal
phalanx
♦
The big toe has one IP joint between the proximal and distal
phalanges of the big toe
♦
Toes #2-5 have two IP joints – a proximal IP joint (PIP) between
the proximal and middle phalanges, and a distal IP joint (DIP)
between the middle and distal phalanges
These joints are freely movable, synovial hinge joints (uniaxial),
allowing flexion and extension within the sagittal plane around a
mediolateral axis
Page !12 of ! 12
© Anatomy Studies for Yoga Teachers 2017