week 7 Flashcards
leg and foot – Retinacula
act to hold the tendons in place and to prevent bow-stringing
Superior extensor retinaculum
Binds the tendons of TA, EHL, EDL, PT Runs horizontally above ankle
Inferior extensor retinaculum
Binds down the TA, EHL, EDL, PT
Y shaped band anterior to the talocrural ligaments
Superior and inferior peroneal retinacula
bind down the PL and PB behind the lateral malleolus
Flexor retinaculum
- Converts the bony grooves into canals for the tendons of TP, FDL, FHL as they pass behind the medial malleolus
- Bridges over the posterior tibial vessels and nerves
leg and foot – synovial sheaths
- Double layer of synovial membrane surrounding each tendon as it passes under the retinacula
- Facilitate sliding of the tendons
Muscles of the foot
Intrinsic foot muscles: origin and insertion both within the foot as opposed to extrinsic muscles – origin in leg or thigh, insertion in
foot
Plantar layers described in FOUR layers Superficial to deep
what are Dorsal muscles of the foot
- Extensor digitorum brevis
- Extensor hallucis brevis
what are the Plantar muscles of the foot – Aponeurosis/Plantar Fascia
- Most superficial structure of plantar surface
- Triangular in shape: apex at the calcaneus, base at the heads of the metatarsals
what are the Plantar muscles of the foot – Aponeurosis/Plantar Fascia FUNCTIONS
- binds the skin of the foot
- provides an attachment site for foot muscles
- helps to maintain arches of the foot (more soon)
Plantar muscles of the foot – layer 1
One flexor and two abductors
* Flexor digitorum brevis * Abductor hallucis
* Abductor digit minimi
Plantar muscles of the foot – layer 2
Two tendons and two muscles:
* Flexor digitorum longus
* Flexor hallucis longus
* Flexor accessorius or Quadratus plantae
* Lumbricals
Plantar muscles of the foot – layer 3
One adductor and two flexors
* Adductor hallucis
* Flexor digiti minimi
(brevis)
* Flexor hallucis brevis
Plantar muscles of the foot – layer 4
Two tendons and two muscles:
* Peroneus longus
* Tibialis posterior
* Plantar interossei
* Dorsal interossei
leg and foot – Dorsal digital expansion
Expansion of the extensor tendons as they approach the digits (toes)
leg and foot – Dorsal digital expansion functions
- Allows all the joints of the toe to be extended simultaneously
- Provides attachment for some of the intrinsic muscles
Foot Functions
- Weight bearing (balance)
- Propulsion
- Shock absorption
when is the foot rigid
- Step-off
- Plantarflex ankle & extend MTP
joints - Tightens plantar aponeurosis (Windlass mechanism/effect)
- Raises medial longitudinal arch
- Head of talus moves superiorly
and subtalar joint supinates - Mid-tarsal joint is locked
when is the foot flexible
- Heel strike - vice versa
- Subtalar joint pronates
- Mid-tarsal joint unlocks
Foot longitude Arches
- Two Longitudinal – run from calcaneus to metatarsal heads
- Medial arch
- Lateral arch
- Transverse – runs in coronal plane
- Formed and supported by?
Fit of the bones
Joint integrity
Ligament tightness
Muscle tension
what makes up Medial Longitudinal Arches of the Foot
- Calcaneus
- Talus
- Navicular
- Cuneiforms (all 3)
- Metatarsals I, II, III
- Talus is highest point (keystone)
what are the Lateral Longitudinal Arches of the Foot
- Calcaneus
- Talus
- Cuboid
- Metatarsals IV, V
- Cuboid is highest point (keystone)
Transverse Arch
– At proximal end formed by
* Metatarsal bases
* Cuboid
* All 3 cuneiform bones at
proximal end
– At distal end formed by
* Head of the metatarsals
Functions of Foot Arches
- Absorb weight forces/shock
- Efficient weight bearing – weight bearing areas of foot (hindfoot & forefoot)
- Add to foot’s ability to adapt to changes in ground surface contour
- Efficient propulsion - elastic recoil of arch when weight lifted off (arches flatten slightly when weight-bearing)
Static Support for Foot Arches
– Shape of the bones
– Ligaments
* Plantar aponeurosis – both arches
* Long plantar ligament – lateral arch
* Short plantar ligament (plantar calcaneocuboid ligament) – lateral arch
* Spring ligament (plantar calcaneonavicular ligament) – medial arch
* All other interosseous ligaments within the medial arch – medial arch
Ligamentous Support
- Plantar aponeurosis very important
- Thick, triangular shaped
- Longitudinal fibres except anteriorly
- Near metatarsal head it splits into superficial and deep
layers - Toe extension increases the tension in the aponeurosis (due to attachments)
- This raises the longitudinal arches
Muscular (Dynamic) Support
- provide dynamic support to the arch – walking, running
- Two main ways muscle can support the arches which increase concavity
- Bowstring or tie beam – pull the ends of the arch together
- Sling – lift the summit upwards
Eversion
Eversion (combination movement) is Dorsiflexion, Abduction, Pronation
inversion
Inversion (combination movement) is Plantarflexion, Adduction, Supination
* iPADs – inversion Plantarflexion, ADduction, supination
Dorsal Digital Expansion
- Allows all the joints of the toe to be extended simultaneously
- Important in digital sweep
what is digital sweep
- Longest possible sweep (pathway) of the tips of the digits
- Flexion occurs at the MTP first
- While the IP joints are maintained in extension
- Flexion of the IP joints comes late
what happens to allow digital sweep
- Intrinsic muscles act to extend IP joints – to avoid ‘scrunching’ up toes
- Lumbricals and interossei
how does digital sweep occur
- Interplay between extrinsic & intrinsic foot muscles
- Intrinsic muscles modulate the extrinsic muscles
what do lumbricals attach to and what are their actions
- Attaches to the dorsal digital expansion * Action of lumbrical
- Flex MTP joints & extend IP joints
- Prevents toes clawing
