Lecture 3.5 The Extrinsic Leg (Ankel, Foot & Toes) PDF

Lecture Objectives Overview Introduction to the osteology of the leg and foot Tibia, Fibula & the Bones of the Foot Detail the Ankle Joint Arthrological features & Movements Detail the Tarsal Joints Arthrological features & Movements Detail the Toe Joints...

Lecture Objectives Overview Introduction to the osteology of the leg and foot Tibia, Fibula & the Bones of the Foot Detail the Ankle Joint Arthrological features & Movements Detail the Tarsal Joints Arthrological features & Movements Detail the Toe Joints Arthrological features & Movements Describe the Muscles of the Leg by Compartment Anterior, Lateral & Posterior Compartments The Leg to Foot Basic Overview The Leg Bony components include: Tibia & Fibula Boundaries: Distal to Knee & Proximal to Ankle Common terms: Shin = Anteromedial surface of Tibia Calf = Posterior leg musculature Anatomical terms: Crurae/Crus = leg Surae/Sural = calf The Leg to Foot Basic Overview The Ankle Bony Components include: Tibia, Fibula, Talus (tarsal) Boundaries: Articular surfaces of Tibia, Fibula & Talus The Foot Bony Components include: Tarsals, Metatarsal, Phalanges Boundaries: Ankle to phalanges Other joints: Tarsal, tarsometarsal, metatarsaophalangeal, interphalangeal  Patellar Surface The Leg Osteology Plateau The Proximal Tibia Condyle Gerdy’s Head containing Plateaus, Condyles, Gerdy’s tubercle Tubercle Neck containing Tibial Tuberosity (anterior) and Soleal line Tibial Tuberosity (posterior) The Proximal Fibula Head and neck with no specialised landmarks as it serves to ‘increase surface area of tibia for muscle attachment’ The Leg Osteology The Distal Tibia Shaft contains an Anterior Border / Crest Can be palpated (the shin) Anterior Border Distal head contains the Medial Malleolus FIBULA TIBIA The Distal Fibula Distal head contains the Lateral Malleolus Lateral Malleolus Medial Malleolus The “Internal” surface of Distal Head and Malleoli is the site of Talus articulation with the talus bone (i.e. the ankle)  What is The Foot your pe rspectiv e? Bony Contents The Foot Will a Pneum on ic He IL lp? C N ee d M Tiger Cubs Bony Contents The Tarsals Bones Superior View Inferior View The Foot Osteology The foot contains tarsal, metatarsals & phalangeas The Tarsus (i.e. the section containing the tarsal bones) The Hindfoot: Talus & Calcaneus The Midfoot: Navicular, Cuneiforms (x3) & Cuboid Forefoot The Forefoot: Metatarsals & Phalanges Midfoot Talus Calcaneus Hindfoot The Tarsus Talus Calcaneal Tuberosity Osteology The Hindfoot: Calcaneus Talus – Contains the Trochlear Surface Superior surface for articulation with the Tibia and Fibula and their respective malleoli Inferior surface for articulation with Calcaneus Distal surface for articulation with Navicular Navicular Cuboid Calcaneus – Forms the Heel of the Foot Superior surface articulates with inferior talus Posterior surface contains the calcaneal tuberosity for Talus calcaneal (‘Achilles’) tendon Distal surface for articulation with Cuboid Calcaneus The Tarsus Osteology The Midfoot: Navicular – Medial side of foot Proximal surface for articulation with Talus Distal surface articulates with medial, intermediate & lateral Cuneiform Lateral surface articulates with Cuboid Cuneiforms – Medial & Distal midfoot Contain a medial, intermediate & lateral cuneiform bone that articulates with digit I, II, and III respectively Lateral cuneiform articulates with Cuboid The Tarsus Osteology The Midfoot: Cuboid – Lateral side of foot Proximal surface for articulation with Calcaneus Distal surface articulates digits IV & V The Forefoot: Metatarsals & Phalanges Big toe (digit I) is called the Hallux Contains only a proximal & a distal phalanx Digits II-V contain a proximal, intermediate & distal phalanges Clinical Appreciation SHOCK FACTOR WARNING!! c a ti o n? thi s dislo i th volved w i s i n What Clinical Appreciation SHOCK FACTOR WARNING!! Wha ti s i nv olve d wit h thi s di s loca tion? Lecture Objectives Overview Introduction to the osteology of the leg and foot Tibia, Fibula & the Bones of the Foot Detail the Ankle Joint Arthrological features & Movements Detail the Tarsal Joints Arthrological features & Movements Detail the Toe Joints Arthrological features & Movements Describe the Muscles of the Leg by Compartment Anterior, Lateral & Posterior Compartments The Ankle Key Structures The Ankle - AKA The Talocrural Joint Talo = Talus Crural = refers to Crurae or Crus (i.e. Leg) Specialised hinge joint - Considered a type of Mortise & Tenon Joint Articular Surfaces: Mortise: Tibia & Fibula Tenon: Talus The Inferior Tibiofibular Syndesmosis FIBROUS BOND BETWEEN TWO PARALLEL BONES As this is an ”open mortise and tenon” The “mortise” needs to be incredibly stable to support the “tenon” Isolates sagittal plane movements of the talus within the distal tibiofibular joint The Distal Tibiofibular Joint is fixed A syndesmosis joint – Two parallel bones held together firmly by a fibrous band Interosseus membrane AITFL – Anterior Inferior Tibiofibular Ligament PITFL – Posterior Inferior Tibiofibular Ligament The Talocrural (ankle) Movements Sagittal plane movements at the talocrural joint include flexion & extension Muscles on the anterior leg will pull the foot “up” Dorsiflexion = True Extension Muscles on the posterior leg will pull th e our shins? e d to s so big c ompar r c a l v e the foot “down” Why a re ou Plantarflexion = True Flexion The Talocrural (ankle) Movements Medio-lateral axis of rotation does not sit perfectly on the coronal plane Due to external Tibial torsion during Anterior development Enables foot/toe position to face slightly lateral to the midline Increases surface area of support balance and weight distribution Talocrural Joint Axis Mediolateral Posterior compartment muscles (PF) are farther from the axis to increase the mechanical advantage/power Posterior  Anterior Retinaculum Extensor Retinaculum Enhancing Precision Of Muscle Function A Retinaculum is a thickened band of fascia that is attached to bone Flexor Retinaculum Muscle tendons that pass under it are supported and contained beneath it Posterior Function: To prevent ”bowstringing” of tendon Note: there will be increased friction in this area With Extensor Without Extensor Retinaculum Retinaculum Resolution: tendons surrounded by a synovial tendon sheath Retinaculum Enhancing Precision Of Muscle Function A Retinaculum is a thickened band of fascia that is attached to bone Muscle tendons that pass under it are supported and contained beneath it Function: To prevent ”bowstringing” of tendon Note: there will be increased friction in this area Resolution: tendons surrounded by a synovial tendon sheath  superior extensor ret. inferior extensor ret. Retinaculum Enhancing Precision Of Muscle Function Synovial Tendon Sheath Extensor Retinacula superior Superior & Inferior peroneal ret. Covers anterior compartment muscles inferior peroneal Fibular/Peroneal Retinacula ret. Superior & Inferior Covers the lateral compartment muscles Superior peroneal ret. Flexor Retinacula Covers posterior compartment Flexor ret. muscles Moore et al: chap 7 Ligaments of the Talocrural Joint Providing Strength & Support Where would the ligaments be located that Ligaments do NOT want to stretch prevent this movement… Thus be damaged when excessively stretched i.e. when they are taught, they are doing their job by preventing excessive movements The Talocrural joint is a hinge joint Allows Flexion & Extension on the sagittal plane We do not want movements on the coronal plane! ”rolling your ankle” Ligaments of the Talocrural Joint Providing Strength & Support Lateral Collateral Ligament 3 individual bands named after their PTL ATL bony attachments from the lateral CFL malleolus to a tarsal bone Calcaneofibular Ligament (CFL) Anterior Talofibular Ligament (ATL) Posterior Talofibular Ligament (PTL) Limits Inversion at the talocrural joint PTL The most common ankle sprain occurs here (hyper-inversion) partly due to weaker, smaller CFL and fewer co-lateral ligaments on the lateral side Ligaments of the Talocrural Joint Providing Strength & Support Medial Collateral Ligament = The Deltoid Ligament Triangular shaped 4 connected bands named after their bony attachment from the medial malleolus to a tarsal Deltoid Ligament bone Anterior Tibiotalar Ligament Posterior Tibiotalar Ligament Tibiocalcaneal Ligament Tibionavicular Ligament Limits Eversion at the talocrural joint The Talocrural Joint IT IS A HINGE JOINT!!! If the Talocrural Joint is structurally & functionally a Hinge Joint and we have additional ligaments that limit movements on the coronal plane... Then why can I invert and evert my “ankle”? Deltoid Ligament Lecture Objectives Overview Introduction to the osteology of the leg and foot Tibia, Fibula & the Bones of the Foot Detail the Ankle Joint Arthrological features & Movements Detail the Tarsal Joints Arthrological features & Movements Detail the Toe Joints Arthrological features & Movements Describe the Muscles of the Leg by Compartment Anterior, Lateral & Posterior Compartments Tarsal Joints Short bones of the foot A complex (but simple) arrangement of articulations between the tarsal joints Essential for: Weight Distribution Balance Foot Arches Gait (walking) Tarsal Joints Short bones of the foot 3 Key Joints (separated by synovial joint capsules) Subtalar Talocalcaneonavicular Midtarsal Joint Complex Tarsal Joints Short bones of the foot Subtalar Joint The Talus articulates with the posterior articular facet of the calcaneus = Posterior Talocalcaneal Joint Talus Subtalar Joint Calcaneus Tarsal Joints Short bones of the foot Talocalcaneonavicular Joint The Talus articulates with Medial & Anterior Calcaneal Facets = Anterior Talocalcaneal Joint Posterior Navicular = Talonavicular Joint Rests on the “spring” ligament Talocalcaneonavicular Joint Talus Navicular Calcaneus Tarsal Joints Short bones of the foot Midtarsal Joint The Talus articulates with Posterior Navicular = Part of Talocalcaneonavicular Joint The Calcaneus articulates with the Posterior Cuboid = Calcaneocuboid Joint Mid Tarsal Joint Complex Talus Navicular Calcaneus Cuboid Ligaments of the Talocrural Joint Providing Strength & Support Medial Collateral Ligament = The Deltoid Ligament Triangular shaped 4 connected bands named after their bony attachment from the medial malleolus to a tarsal Deltoid Ligament bone Anterior Tibiotalar Ligament * Posterior Tibiotalar Ligament * * Tibiocalcaneal Ligament * * Tibionavicular Ligament * Limits Eversion at the talocrural joint These ligaments* also act at the talar joints Ligaments of the Talocrural Joint Providing Strength & Support Lateral Collateral Ligament 3 individual bands named after their PTL ATL bony attachments from the lateral CFL* malleolus to a tarsal bone Calcaneofibular Ligament (CFL) * Anterior Talofibular Ligament (ATL) Posterior Talofibular Ligament (PTL) Limits Inversion at the talocrural joint This ligament* also PTL acts at a talar joint The most common ankle sprain occurs here (hyper-inversion) partly due to weaker, smaller CFL * and fewer co-lateral ligaments on the lateral side Plantar Ligaments Providing Strength & Support Long Plantar ligaments support Talar Joints Plantar + provide tension & spring for the arches of the foot and gait Most superficial is the Long Plantar Ligament Deep is the Short Plantar & the Plantar Calcaneonavicular Ligament (i.e. the Spring) Short Plantar Plantar Calcaneonavicular Tarsal Joints REVIEW Joint Cavity #1 Posterior = Subtalar Joint Talocalcaneal Anterior Joint Cavity #2 Talocalcaneal = Talocalcaneonavicular Joint + Talonavicular Midtarsal Joint Complex Joint Cavity #3 Calcaneocuboid = (includes talonavicular joint)  Mediolateral Axis Movements of the Foot MAINLY SUBTALAR Mobility of the foot can be simplified as standard Vertical Axis uniplanar movements However, note that foot extends at 90 anteriorly so movements differ from other body segments Mediolateral Axis = Flexion & Extension Anteroposterior Axis Vertical Axis = Abduction & Adduction Anteroposterior Axis = Inversion & Eversion Movements of the Foot MAINLY SUBTALAR In reality, there is only 1 axis of rotation for the foot The Oblique Axis Antero-supero-medial to Postero-infero-lateral This allows for a “Triplanar” movement that uses all three ‘simplified’ axes and planes of movement Supination & Pronation OBLIQUE AXIS Movements of the Ankle & Foot Can you identify where a muscle would act in order to complete the following Muscle Location movements? Dorsiflexion, Plantar flexion, Inversion, Eversion, Adduction, Abduction, Supination, Pronation Mediolateral Axis (Talocrural) Oblique Axis (Subtalar) Lecture Objectives Overview Introduction to the osteology of the leg and foot Tibia, Fibula & the Bones of the Foot Detail the Ankle Joint Arthrological features & Movements Detail the Tarsal Joints Arthrological features & Movements Detail the Toe Joints Arthrological features & Movements Describe the Muscles of the Leg by Compartment Anterior, Lateral & Posterior Compartments Joints of the “Toes” Long bones of the Foot Metatarsophalangeal (MTP) Joint Head of metatarsal articulates with base of proximal phalanx Proximal Interphalangeal (PIP) Joint Head of proximal phalanx articulates with base of intermediate phalanx Distal Interphalangeal (DIP) Joint Head of intermediate phalanx articulates with base of distal phalanx PIP MTP DIP Is this true for Digit I The Hallux? Intermediate Proximal Distal Phalanx Phalanx Metatarsal Phalanx Digit II (#2) Joints of the “Toes” ABduction ABduction Long bones of the Foot ADduction ADduction Metatarsophalangeal (MTP) Joint Condyloid/Ellipsoid Synovial Flexion, Extension, Abduction, Adduction Interphalangeal Joints Hinge Synovial Splayed toes Flexion & Extension Anteroposterior Axis  Planter Aspect Arthrology of ”toes” Unique/Supportive Features Collateral Ligaments Limits movements of phalanges on horizontal plane Deep Transverse Metatarsal Ligament Limits metatarsal movements on horizontal plane at the tarsometatarsal joint Prevents toes splaying apart  Planter Aspect Arthrology of ”toes” Unique/Supportive Features Plantar Plates (i.e. ligaments) Increase articular surface for the MTP joint on dorsal side Support weight/load on plantar side Provide passageway for flexor tendons on Sesamoids plantar side Sesamoid Bones (Hallux only) Support weight/load & increase protection for flexor tendons Arthrology of ”toes” Unique/Supportive Features Plantar Plates (i.e. ligaments) Increase articular surface for the MTP joint MTP on dorsal side Support weight/load on plantar side Proximal tatar sal Phalanx Me Plantar Plate Provide passageway for flexor tendons on Flexor Tendon plantar side Sesamoid Bones (Hallux only) Digit II (#2) Support weight/load & increase protection for flexor tendons Lecture Objectives Overview Introduction to the osteology of the leg and foot Tibia, Fibula & the Bones of the Foot Detail the Ankle Joint Arthrological features & Movements Detail the Tarsal Joints Arthrological features & Movements Detail the Toe Joints Arthrological features & Movements Describe the Muscles of the Leg by Compartment Anterior, Lateral & Posterior Compartments Review Osteology of the Leg Tibia Large, Medial, Weight bearing bone of the leg Fibula Smaller, lateral, increase surface area for muscle attachment Interosseous Membrane A tough, dense, fibrous membrane between two parallel bones Increase surface area for muscle attachments Separates muscle compartments Contains openings for neurovascular pathways Muscles of the Leg Muscle Compartments - Transverse Section Anterior - Dorsiflexion Extensor Tibialis Digitorum Fibularis Longus Anterior Longus Extensor Hallucis Lateral Fibularis Brevis Longus ous Mem b. Tibia - Eversion Inte r Os se Fibula Tibialis Posterior ongus L Flexo r Hal itorum lucis ig Long us exor D Fl.) Soleus s (med Gastro cnemu emu s (lat.) strocn Ga Posterior - Plantarflexion Muscles of the Leg Muscle Compartments - Transverse Section Anterior Lateral Deep Posterior Superficial Posterior  ANTERIOR Compartment Muscles of the Leg Tibialis Anterior Note the inferior perspective Origin: Upper 2/3rd of lateral tibia + IoM Insertion: Inner surface of medial cuneiform Function: Dorsiflexion (True Extension) & Inversion* Extensor Digitorum Longus Origin: Lateral tibial condyle/head of fibula & shaft + IoM Insertion: Dorsal surface of phalanges (digit II-V) Function: Dorsiflexion (True Extension) & Toe Extension Extensor Hallucis Longus Origin: Middle 2/3 of anterior fibula + IoM Insertion: Dorsal surface of hallux (digit I) Function: Dorsiflexion (True Extension) & Toe Extension *NOTE: Requires Posterior muscle antagonism of dorsiflexion to support inversion  ANTERIOR Compartment Muscles of the Leg Tibialis Anterior Origin: Upper 2/3rd of lateral tibia + IoM Insertion: Inner surface of medial cuneiform Function: Dorsiflexion (True Extension) & Inversion* Extensor Digitorum Longus Origin: Lateral tibial condyle/head of fibula & shaft + IoM Insertion: Dorsal surface of phalanges (digit II-V) Function: Dorsiflexion (True Extension) & Toe Extension Extensor Hallucis Longus Origin: Middle 2/3 of anterior fibula + IoM Insertion: Dorsal surface of hallux (digit I) Function: Dorsiflexion (True Extension) & Toe Extension *NOTE: Requires Posterior muscle antagonism of dorsiflexion to support inversion  ANTERIOR Compartment Muscles of the Leg Tibialis Anterior Origin: Upper 2/3rd of lateral tibia + IoM Insertion: Inner surface of medial cuneiform Function: Dorsiflexion (True Extension) & Inversion* Extensor Digitorum Longus Origin: Lateral tibial condyle/head of fibula & shaft + IoM Insertion: Dorsal surface of phalanges (digit II-V) Function: Dorsiflexion (True Extension) & Toe Extension Extensor Hallucis Longus Origin: Middle 2/3 of anterior fibula + IoM Insertion: Dorsal surface of hallux (digit I) Function: Dorsiflexion (True Extension) & Toe Extension *NOTE: Requires Posterior muscle antagonism of dorsiflexion to support inversion  ANTERIOR Compartment Muscles of the Leg Tibialis Anterior Origin: Upper 2/3rd of lateral tibia + IoM Insertion: Inner surface of medial cuneiform Function: Dorsiflexion (True Extension) & Inversion* Extensor Digitorum Longus Origin: Lateral tibial condyle/head of fibula & shaft + IoM Insertion: Dorsal surface of phalanges (digit II-V) Function: Dorsiflexion (True Extension) & Toe Extension Extensor Hallucis Longus Origin: Middle 2/3 of anterior fibula + IoM Insertion: Dorsal surface of hallux (digit I) Function: Dorsiflexion (True Extension) & Toe Extension *NOTE: Requires Posterior muscle antagonism of dorsiflexion to support inversion  ANTERIOR Compartment Muscles of the Leg Tibia Tibialis Anterior Note the inferior perspective Origin: Upper 2/3rd of lateral tibia + IoM Tibialis Anterior Insertion: Inner surface of medial cuneiform Extensor Digitorum Function: Dorsiflexion (True Extension) & Inversion* Longus Extensor Extensor Digitorum Longus Hallucis Longus Origin: Lateral tibial condyle/head of fibula & shaft + IoM Insertion: Dorsal surface of phalanges (digit II-V) Function: Dorsiflexion (True Extension) & Toe Extension Extensor Hallucis Longus Origin: Middle 2/3 of anterior fibula + IoM Insertion: Dorsal surface of hallux (digit I) Function: Dorsiflexion (True Extension) & Toe Extension *NOTE: Requires Posterior muscle antagonism of dorsiflexion to support inversion LATERAL Compartment Muscles of the Leg Tibia Fibularis (aka Peroneus) Longus Note the inferior perspective Origin: Fibular Head & Upper lateral shaft Fibularis Longus Insertion: Plantar surface of medial cuneiform & 1st metatarsal Function: Eversion & Essential for lateral longitudinal arch support Fibularis (aka Peroneus) Brevis Origin: Lower fibular shaft Fibularis Insertion: lateral surface of 5th metatarsal Brevis Function: Eversion Fibularis Brevis LATERAL Compartment Muscles of the Leg Fibularis (aka Peroneus) Longus Origin: Fibular Head & Upper lateral shaft Insertion: Plantar surface of medial cuneiform & 1st metatarsal Function: Eversion & Essential for lateral longitudinal arch support Fibularis (aka Peroneus) Brevis Origin: Lower fibular shaft Insertion: lateral surface of 5th metatarsal Function: Eversion LATERAL Compartment Muscles of the Leg Fibularis (aka Peroneus) Longus Origin: Fibular Head & Upper lateral shaft Insertion: Plantar surface of medial cuneiform & 1st metatarsal Function: Eversion & Essential for lateral longitudinal arch support Fibularis (aka Peroneus) Brevis Origin: Lower fibular shaft Insertion: lateral surface of 5th metatarsal Function: Eversion POSTERIOR Compartment Muscles of the Leg Superficial Posterior Group = The Triceps Surae Note the inferior perspective Gastrocnemius (two heads) Origins: Medial: Posterior Medial Femoral Condyle Lateral: Posterior Lateral Femoral Condyle Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) Soleus Origin: Posterior Tibia, IoM & Fibula Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) Plantaris (Absent in about 10-15% of the population) Origin: Lateral Femoral Supracondylar Ridge Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) POSTERIOR Compartment Muscles of the Leg Superficial Posterior Group = The Triceps Surae Gastrocnemius (two heads) Origins: Medial: Posterior Medial Femoral Condyle Lateral: Posterior Lateral Femoral Condyle Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) Soleus Origin: Posterior Tibia, IoM & Fibula Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) Plantaris (Absent in about 10-15% of the population) Origin: Lateral Femoral Supracondylar Ridge Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) POSTERIOR Compartment Muscles of the Leg Superficial Posterior Group = The Triceps Surae Gastrocnemius (two heads) Origins: Medial: Posterior Medial Femoral Condyle Lateral: Posterior Lateral Femoral Condyle Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) Soleus Origin: Posterior Tibia, IoM & Fibula Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) Plantaris (Absent in about 10-15% of the population) Origin: Lateral Femoral Supracondylar Ridge Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) POSTERIOR Compartment Muscles of the Leg Superficial Posterior Group = The Triceps Surae Plantaris Gastrocnemius (two heads) Gastrocnemius Medial Origins: Lateral Soleus Medial: Posterior Medial Femoral Condyle Lateral: Posterior Lateral Femoral Condyle Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Gastroc. (cut) Function: Plantarflexion (True Flexion) Soleus Origin: Posterior Tibia, IoM & Fibula Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion) Plantaris (Absent in about 10-15% of the population) Origin: Lateral Femoral Supracondylar Ridge Insertion: Calcaneal Tuberosity - through Calcaneal ’Achilles’ tendon Function: Plantarflexion (True Flexion)  POSTERIOR Compartment Muscles of the Leg Deep Posterior Group Note the inferior perspective Tibialis Posterior Origin: Posterior Tibia/Fibula & IoM Insertion: Plantar surface of tarsals and metatarsals Function: Plantarflexion (True Flexion), Inversion* & Essential for medial longitudinal arch support Flexor Digitorum Longus Origin: Lower Posterior Tibia Insertion: Base of distal phalanges (digits II-IV) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* Peroneal Flexor Hallucis Longus Retinacula Origin: Lower Posterior Fibula Flexor Retinacula (The Tarsal Tunnel) Insertion: Base of distal phalanx of Hallux (digit I) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* *NOTE: Requires Anterior muscle antagonism of plantarflexion to support inversion  POSTERIOR Compartment Muscles of the Leg Deep Posterior Group Tibialis Posterior Origin: Posterior Tibia/Fibula & IoM Insertion: Plantar surface of tarsals and metatarsals Function: Plantarflexion (True Flexion), Inversion* & Essential for medial longitudinal arch support Flexor Digitorum Longus Origin: Lower Posterior Tibia Insertion: Base of distal phalanges (digits II-IV) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* Flexor Hallucis Longus Origin: Lower Posterior Fibula Insertion: Base of distal phalanx of Hallux (digit I) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* *NOTE: Requires Anterior muscle antagonism of plantarflexion to support inversion  POSTERIOR Compartment Muscles of the Leg Deep Posterior Group Tibialis Posterior Origin: Posterior Tibia/Fibula & IoM Insertion: Plantar surface of tarsals and metatarsals Function: Plantarflexion (True Flexion), Inversion* & Essential for medial longitudinal arch support Flexor Digitorum Longus Origin: Lower Posterior Tibia Insertion: Base of distal phalanges (digits II-IV) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* Flexor Hallucis Longus Origin: Lower Posterior Fibula Insertion: Base of distal phalanx of Hallux (digit I) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* *NOTE: Requires Anterior muscle antagonism of plantarflexion to support inversion  POSTERIOR Compartment Muscles of the Leg Deep Posterior Group Tibialis Posterior Origin: Posterior Tibia/Fibula & IoM Insertion: Plantar surface of tarsals and metatarsals Function: Plantarflexion (True Flexion), Inversion* & Essential for medial longitudinal arch support Flexor Digitorum Longus Origin: Lower Posterior Tibia Insertion: Base of distal phalanges (digits II-IV) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* Flexor Hallucis Longus Origin: Lower Posterior Fibula Insertion: Base of distal phalanx of Hallux (digit I) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* *NOTE: Requires Anterior muscle antagonism of plantarflexion to support inversion  POSTERIOR Compartment Muscles of the Leg Deep Posterior Group Tibialis Posterior Origin: Posterior Tibia/Fibula & IoM Insertion: Plantar surface of tarsals and metatarsals Function: Plantarflexion (True Flexion), Inversion* & Essential for medial Tibialis Posterior longitudinal arch support Fibularis Flexor Digitorum Longus Flexor Longus Digitorum Origin: Lower Posterior Tibia Longus Insertion: Base of distal phalanges (digits II-IV) Flexor Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* Hallucis Fibularis Longus Brevis Flexor Hallucis Longus Origin: Lower Posterior Fibula Insertion: Base of distal phalanx of Hallux (digit I) Function: Plantarflexion (True Flexion), Toe Flexion & Inversion* *NOTE: Requires Anterior muscle antagonism of plantarflexion to support inversion