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THE FOOT JOINTS

28 BONES / 25 ARTICULATIONS

THERE ARE A NUMBER OF INDIVIDUAL JOINTS IN THE FOOT AND FUNCTIONAL COMPOSITE JOINTS. THREE MAIN REGIONS: REARFOOT or hindfoot, MIDFOOT, FOREFOOT.

1. SUBTALAR JOINT - TALOCALCANEAL JOINT 2. TALO-CALCANEO-NAVICULAR JOINT ] 3. CALCANEO-CUBOID JOINT ] 4. COMPOSITE JOINT: CUNEO-NAVICULAR JOINT CUBOIDEO-NAVICULAR JOINT ] INTERCUNEIFORM JOINTS ] CUNEO-CUBOID JOINT ] 5. TARSOMETATARSAL JOINTS 6. METATARSOPHALANGEAL JOINTS 7. INTERPHALANGEAL JOINTS

TRANSVERSE TARSAL J. or MIDTARSAL JOINTS. ] INTER-TARSAL JOINTS

ASSOCIATED WITH THESE INDIVIDUAL JOINTS, AND INTERACTING BETWEEN AND ACROSS THEM, A SERIES OF LIGAMENTS AND MUSCLE TENDONS WHICH SERVE AND SUPPORT THE JOINTS TO CREATE A FUNCTION UNIT - THE FOOT. THIS COMPOSITE IS DESIGNED TO COPE WITH WEIGHT BEARING, FORCE TRANSMISSION - IN VARIED POSITIONS, AND POSITIONAL ADAPTABILITY.

1. SUBTALAR TALOCALCANEAL JOINT COMPOSITE JOINT FORMED BY T  HREE ARTICULATIONS: ARTICULATION OF THE POSTERIOR, MIDDLE AND ANTERIOR FACETS OF THE CALCANEUS AND TALUS ARE ALL I NDIVIDUAL MULTIAXIAL PLANE JOINTS. THE POSTERIOR FACET COMPRISES 70% OF THE JOINT SURFACE AREA. IT WORKS IN UNISON WITH TALOCALCANEONAVICULAR JOINT. ★ VERY SMALL AMOUNT OF MOVEMENT FOR A RELATIVELY LARGE JOINT.

ARTICULAR SURFACES POSTERIORLY A CONCAVE TALAR SURFACE AND A MATCHING CONVEX CALCANEUS SURFACE.

ANTERIORLY see below THE TALO-CALCANEO-NAVICULAR MULTIAXIAL B&S JOINT. FIBROUS CAPSULE LOOSE AND THIN, STRENGTHEN BY MEDIAL AND LATERAL TALOCALCANEL LIGs. ATTACHES AROUND THE ARTICULAR MARGINS IT IS SUPPORTED BY ACCESSORY LIGAMENTS. IT IS LINED BY SYNOVIUM. SIZE AND SHAPE OF ARTICULAR SURFACE VARY BETWEEN INDIVIDUALS. THE ANTERIOR ARTICULATION IS DIVIDED INTO TWO SEPARATE ARTICULATIONS. FIBROUS CAPSULE AROUND ARTICULAR MARGINS SEPARATES ANTERIOR AND POSTERIOR SPACES. LIGAMENTS 1. LATERAL TALOCALCANEAL LIGAMENT SHORT, FLAT, RUNNING FROM THE LATERAL PROCESS OF THE TALUS TO THE LATERAL CALCANEAL SURFACE. 2. MEDIAL TALOCALCANEAL LIGAMENT LIES DEEP TO THE DELTOID LIGAMENT, WITH WHICH IT BLENDS CONNECTS THE MEDIAL TUBERCLE OF THE TALUS W” POSTERIOR ASPECT OF SUSTENTACULUM TALI AND THE ADJACENT MEDIAL SURFACE OF THE CALCANEUS. 3. INTEROSSEOUS TALOCALCANEAL LIGAMENT WIDE, FLATTENED AND LYING TRANSVERSELY ACROSS THE SINUS TARSI FROM SULCUS TALI TO THE SULCUS CALCANEI PREVENTS SEPARATION OF THE BONES DURING EVERSION OF THE FOOT. 4. CERVICAL LIGAMENT FROM LATERAL ASPECT OF THE SULCUS TALI ON THE SUPERIOR SURFACE OF THE CALCANEUS, TOWARDS THE LATERAL SURFACE AND TO THE LATERAL ASPECT OF THE NECK OF TALUS. IT PREVENTS EXCESSIVE INVERSION OF THE FOOT. ❖ THE TARSAL CANAL, WITH THE CERVICAL AND INTEROSSEOUS LIGAMENTS SEPARATES THE TALOCALCANEAL FACETS INTO TWO SEPARATE NON-COMMUNICATING JOINT CAVITIES. THE POSTERIOR HAS ITS OWN

CAPSULE AND THE MIDDLE AND ANTERIOR ARTICULATIONS SHARE A CAPSULE WITH THE TALONAVICULAR JOINT.

NERVE SUPPLY DORSALLY: SUPERFICIAL PERONEAL NERVE (See exceptions below) PLANTAR : TIBIAL NERVE ANTERO-MEDIAL: MEDIAL PLANTAR NERVE (TIBIAL) ANTERO-LATERAL: LATERAL PLANTAR NERVE (TIBIAL) TARSAL TUNNEL-TIBIAL NERVE SPLITS INTO 3 CACANEAL N MEDIAL PLANTAR N LATERAL PLANTAR N

TRANSVERSE TARSAL JOINTS or MIDTARSAL JOINTS. COMPOUND ARTICULATION CONSISTING OF THE TALONAVICULAR AND CALCANEOCUBOID JOINTS. S-SHAPED JOINT LINE SEPARATING THE HINDFOOT FROM THE MID AND FOREFOOT.

FUNCTIONALLY RELATED TO THE SUBTALAR JOINT, PARTICULARLY IN CONTROL OF SUPINATION AND PRONATION OF THE FOOT.

2. TALO-CALCANEO-NAVICULAR JOINT TYPE SYNOVIAL, MULTIAXIAL, B&S JOINT THREE BONES AND THREE LIGAMENTS BONES: TALUS (BALL), CALCANEUS (SOCKET), NAVICULAR (SOCKET) ARTICULAR SURFACES HEAD OF THE TALUS (THE BALL), POSTERIOR SURFACE OF THE NAVICULAR (THE SOCKET), POSTERIOR FACET OF CALCANEUS (SOCKET) SUPERIOR SURFACE OF PLANTAR CALCANEONAVICULAR LIGAMENT. lined with fibrocartilage THE JOINT IS REINFORCED BY THE CAPSULE AND BY LIGAMENTS. FIBROUS CAPSULE THIN AND POORLY DEFINED

EXCEPT THE MOST P/I SEGMENT WHERE IT FILLS THE SINUS TARSI AND BLENDS W THE INTEROSSEOUS LIGAMENT OF THE TALO CALCANEUM. ASSOCIATED LIGAMENTS 1. DORSAL TALONAVICULAR LIGAMENT THIN, BROAD BAND FROM NECK OF TALUS TO DORSUM OF NAVICULAR FORMS THE ROOF OF THE SOCKET LIES IMMEDIATELY DEEP TO THE EXTENSOR TENDONS. 2. PLANTAR CALCANEO-NAVICULAR THICK, BROAD BAND

SPRING LIGAMENT

FROM THE ANTERIOR MARGIN OF SUSTENTACULUM TALI OF CALCANEUS TO THE TUBEROSITY ON THE PLANTAR SURFACE OF THE NAVICULAR. IMMEDIATELY BELOW THE JOINT UNDER THE HEAD OF TALUS, GIVING A STRONG SUPPORT. UPPER SURFACE OF THE LIGAMENT IS LINED W FIBROCARTILAGE AND SYNOVIAL FLUID. FORMS A FACET SUPPORTING THE TALUS HEAD BENEATH THE LIGAMENT, ARE TENDONS: TIBIALIS POSTERIOR - MEDIALLY, FLEXOR HALLUCIS LONGUS AND FLEXOR DIGITORUM LONGUS - LATERALLY. THE MEDIAL BORDER OF THE LIGAMENT BLENDS WITH THE DELTOID LIGAMENT OF THE TALOCRURAL JOINT. THE MAINTENANCE OF THE TRANSVERSE ARCH OF THE FOOT, AND ITS SECURITY, IS IN LARGE PART DUE TO THIS LIGAMENT. IF THE SPRING LIGAMENT FAILS, THE MEDIAL ARCH DROPS GIVING FLAT FLOOT 3. BIFURCATE LIGAMENT COMPOSED OF TWO PARTS: A CALCANEO-NAVICULAR LIGAMENT A CALCANEO CUBOID LIGAMENT THEY ARISE FROM A COMMON POINT ON THE UPPER SURFACE OF A/M ASPECT OF THE CALCANEUS AS A STRONG FIBROUS BAND. THIS DIVIDES, ONE TO THE DORSOLATERAL ASPECT OF THE NAVICULAR

THE SECOND TO THE DORSOMEDIAL SIDE OF THE CUBOID.

3. CALCANEO-CUBOID JOINT TYPE SHALLOW, MULTI AXIAL, SADDLE JOINT. AMPHIARTHROSIS.  ALTHOUGH MULTIAXIAL, THE MAJORITY OF MOVEMENT IS ROTATIONAL THROUGH THE COMPOUND MIDTARSAL JOINT. MOVEMENT DURING WALKING, THE MOVEMENTS OF FLEX/EXT AND SLIGHT ABD/ADD ALSO OCCUR. ROTATION ON INV/EVE IS ALSO PART OF THE NORMAL WALKING/WEIGHT BEARING MOVEMENT. FIBROUS CAPSULE ATTACHES ALONG THE MARGINS OF THE ARTICULAR SURFACES RELATIVELY TAUGHT. LINED BY SYNOVIUM. INDEPENDENT OF THE OTHER TARSAL JOINTS. REINFORCED ON THE DORSAL SURFACE BY BLENDING WITH THE DORSAL CALCANEOCUBOID LIGAMENT - PART OF BIFURCATE. ASSOCIATED LIGAMENTS A. LONG PLANTAR LIGAMENT LONGEST TARSAL LIGAMENT BROAD AND STRONG RUNS FROM THE PLANTAR SURFACE OF CALCANEUS ANTERIOR TO MEDIAL AND LATERAL PROCESSES, AND VIA THE DEEP FIBRES FROM THE ANTERIOR TUBERCLE OF THE CALCANEUS AND PLANTAR SURFACE OF THE CUBOID, TO THE PLANTAR SURFACES OF THE BASES OF THE 2ND, 3RD, 4TH AND VARIABLY 5TH METATARSALS. WITH THE GROOVE IN THE CUBOID ABODE, THIS LIGAMENT FORMS A TUNNEL FOR PERONEUS LONGUS TENDON, WHICH AIDS THE LIGAMENT IN SUPPORTING THE LATERAL ARCH OF THE FOOT. B. SHORT PLANTAR LIGAMENT PLANTAR CALCANEOCUBOID LIGAMENT. SHORT, WIDE BAND, GREAT STRENGTH. RUNS FROM THE ANTERIOR TUBERCLE OF THE CALCANEUS TO THE ADJACENT PLANTAR SURFACE OF THE CUBOID. IT FUNCTIONS WITH THE LONG PLANTAR LIGAMENT, SUPPORTING THE LONGITUDINAL FOOT ARCH.

C. BIFURCATE LIGAMENT - see above.

4. "COMPOSITE" JOINT INTERTARSAL JOINTS COMPLEX OF JOINTS SHARING A CAPSULE AND JOINT SPACE. INDIVIDUAL JOINT IS A PLANE JOINT, EXCEPT CUBOIDEONAVICULAR JOINT. IT ALLOWS FLEXIBILITY OF THE MIDFOOT. THEY ACT IN CONCERT. CUNEO-NAVICULAR JOINT CUBOIDEO-NAVICULAR JOINT INTERCUNEIFORM JOINTS CUNEO-CUBOID JOINT

] ] ]

] INTER-TARSAL JOINTS

I. CUNEONAVICULAR JOINT AMPHIARTHROSIS THE NAVICULAR ARTICULATES ANTERIORLY WITH THREE CUNEIFORMS. THE NAVICULAR ANTERIOR ARTICULAR SURFACE IS CONVEX AND DIVIDED INTO THREE FACETS BY SMALL RIDGES. EACH IS CONSIDERED AS A PLANE JOINT. X3 PLANE JOINTS THE CAPSULE ATTACHES AROUND THE ARTICULAR MARGINS AND CONTINUES TO THE OTHER COMPOSITE JOINTS. THE CAPSULE IS LINED BY SYNOVIUM IT IS THICKER ON THE PLANTAR SURFACE WITH THICKER AND NUMEROUS ASSOCIATED LIGAMENTS AND SUPPORTING MUSCLE TENDONS. EACH SET OF BONES IS CONNECTED BY INTEROSSEOUS LIGAMENTS DIVIDED INTO PLANTAR AND DORSAL GROUPS. THE PLANTAR ARE REINFORCED BY TENDON SLIPS FROM THE TIBIALIS POSTERIOR. II. CUBOIDEONAVICULAR JOINT MAINLY AN INTEROSSEOUS, FIBROUS JOINT SYNOVIAL EXTENSION POSTERIORLY THE CAPSULE AND SYNOVIUM ARE CONTINUOUS WITH THE COMPOSITE JOINT. DORSAL AND THICKER PLANTAR LIGAMENTS REINFORCE THE INTEROSSEOUS LIGAMENTS. III. INTER-CUNEIFORM JOINTS BETWEEN THE MEDIAL AND THE INTERMEDIATE AND BETWEEN THE INTERMEDIATE AND LATERAL CUNEIFORMS. SMALL PLANE JOINTS

CAPSULE AND SYNOVIUM COMMON TO THE COMPOSITE JOINTS. INTEROSSEOUS, DORSAL AND THICKER PLANTAR LIGAMENTS UNITE THE BONES. THE PLANTAR LIGAMENTS ARE REINFORCED BY TENDON SLIPS FROM TIBIALIS POSTERIOR MUSCLE. THE INTEROSSEOUS AND PLANTAR LIGAMENTS ARE VERY STRONG AND HELP TO SUPPORT THE TRANSVERSE ARCH. IV. CUNEOCUBOID JOINT SIMILARLY STRUCTURED TO THE INTERCUNEIFORM.

TARSOMETATARSAL JOINTS AND INTERMETATARSAL JOINTS AMPHI ARTHROSIS TYPE SMALL, SYNOVIAL, MULTI-AXIAL, PLANE JOINTS. ARTICULAR SURFACES BETWEEN THE DISTAL ROW OF TARSALS AND THE METATARSAL BASES. THE 1ST TARSOMETATARSALI JOINT: (MEDIAL)CUNEO-1ST METATARSAL. IT IS A SEPARATE AND INDIVIDUAL JOINT. IT HAS ITS OWN ARTICULAR CAPSULE AND IS NOT CONNECTED TO THE 2ND METATARSAL BONE BY LIGAMENT. SIMILAR TO THE THUMB. HOWEVER IT IS CONNECTED TO THE 2ND METATARSAL AT THEIR DISTAL ENDS. A SMALL BURSA OCCURS BETWEEN THE BASE OF THE 1ST AND PROXIMAL SHAFT OF 2ND METATARSAL. THE LIGAMENT OCCURS BETWEEN THE BASE OF THE SECOND METATARSAL AND THE DISTAL AND LATERAL MARGIN OF THE 1ST METATARSAL.

CUNEO-2ND METATARSAL JOINT. THE BASE OF THE 2ND METATARSAL FITS INTO A RECESS FORMED BY CUNEIFORMS AND 3RD METATARSAL. THE MEDIAL CUNEIFORM AND BASE OF THE 2ND METATARSAL HAVE THE STRONGEST AND LARGEST INTEROSSEOUS LIGAMENT - A FIBROUS JOINT. THE REMAINDER OF THE SPACE AROUND THE BASE OF THE 2ND METATARSAL IS A SHARED CAPSULE AND SYNOVIUM WITH THE COMPOSITE JOINT. THE ARTICULATION BETWEEN THE 2ND METATARSAL AND THE MIDDLE CUNEIFORM IS SET MORE POSTERIORLY THAN THE OTHER TARSOMETATARSAL JOINTS.

IT IS STRONGER AND MORE RESTRICTED, WITH A MORTISE TYPE CONFIGURATION. SHARES THE JOINT CAPSULE WITH THE ARTICULATION BETWEEN THE 3RD METATARSAL AND THE LATERAL CUNEIFORM. THE 4TH AND 5TH METATARSAL BASES BOTH ARTICULATE WITH THE CUBOID WITH AN INDEPENDENT JOINT CAPSULE. ●

CUNEO-3RD METATARSAL JOINT

BETWEEN THE BASE OF THE 3RD METATARSAL AND LATERAL CUNEIFORM. COMMON CAPSULE/SYNOVIUM WITH THE COMPOSITE JOINT. SMALL, COMMON JOINT SPACE ARTICULATION, BETWEEN THE 2ND AND 4TH METATARSAL BONES. ●

CUBOIDEO - 4TH & 5TH METATARSAL JOINT

CUBOID AND BASE OF THE 4TH AND 5TH METATARSAL AND BETWEEN THE BASES OF THE 4TH AND 5TH METATARSAL COMMON CAPSULE AND SYNOVIUM, WHICH IS SEPARATE FROM THE COMPOSITE JOINT SPACE. SMALL SYNOVIAL PLANE ARTICULATIONS EXIST BETWEEN THE ADJACENT METATARSAL BASES OF THE FOUR LATERAL METATARSAL - 1ST IS INDEPENDENT AS WE SHOW. ASSOCIATED LIGAMENTS A. PLANTAR LIGAMENTS BETWEEN THE TARSAL AND METATARSAL LONGITUDINAL AND OBLIQUE BANDS STRONG, ESPECIALLY THOSE ATTACHED TO THE 1ST AND 2ND METATARSALS. B. DORSAL LIGAMENTS FLAT, STRONG BANDS, SIMILAR TO PLANTAR EXCEPT THAT THE 1ST METATARSAL-MEDIAL CUNEIFORM IS ALSO ATTACHED BY A FIBROUS CAPSULE. C. INTEROSSEOUS CUNEOMETATARSAL LIGAMENTS. xTHREE. TRANSVERSELY BETWEEN THE BASES OF THE ADJACENT METATARSALS.

1. BETWEEN THE MEDIAL CUNEIFORM AND ADJACENT ANGLE OF THE 2ND METATARSAL - THE STRONGEST. 2. FROM THE LATERAL CUNEIFORM TO THE ADJACENT ANGLE OF THE 2ND VARIABLE AND INCONSISTENT. 3. FROM THE LATERAL ANGLE OF THE LATERAL CUNEIFORM TO THE ADJACENT BASE OF THE 4TH METATARSAL. D. DORSAL & PLANTAR INTERMETATARSAL LIGAMENTS TRANSVERSELY BETWEEN THE BASES OF THE ADJACENT METATARSALS. EXCEPT 1ST AND 2ND.

METATARSOPHALANGEAL JOINTS [x5] TYPE: SYNOVIAL, BIAXIAL, ELLIPSOID (CONDYLOID) JOINTS MOVEMENT: FLEXION, EXTENSION, ABDUCTION, ADDUCTION ARTICULAR SURFACE: PROXIMALLY THE BICONVEX METATARSAL HEAD, WITH LARGER SURFACE AREA. DISTALLY THE BICONCAVE PHALANGEAL BASE, WITH SMALLER SURFACE AREA. SIMILAR TO METACARPO-PHALANGEAL JOINTS WITH SOME MODIFICATION. E.G. NO OPPOSITION HAPPENING!

THE FIRST MTP HAS T  WO SESAMOID BONES ON THE PLANTAR ASPECT OF THE METATARSAL HEAD AND A SLIGHT MIDLINE RIDGE.

THESE LIE IN TWO GROOVES ON THE METATARSAL HEAD. THEY ACT AS PULLEYS TO INCREASE THE MECHANICAL ADVANTAGE OF THE FLEXOR HALLUCIS BREVIS, WHILE ALSO PROTECTING THE FLEXOR HALLUCIS LONGUS TENDON SITTING IN THE INTERSESAMOID RIDGE. THE FIBROUS CAPSULE THIN DORSALLY AND SEPARATED FROM THE LONG EXTENSOR MUSCLE TENDONS BY BURSAE. THE CAPSULES BLEND WITH THE PLANTAR AND COLLATERAL LIGAMENTS. LIGAMENTS - GIVE STABILITY TO THE JOINTS 1. PLANTAR LIGAMENTS 2. DEEP TRANSVERSE METATARSAL LIGAMENTS 3. COLLATERAL LIGAMENTS PLANTAR LIGAMENTS THICK, DENSE, FIBROUS PLATES BETWEEN, AND ATTACHED TO, THE COLLATERAL LIGAMENTS. AS IN THE HAND, THEY ARE FIRMLY ATTACHED TO THE PHALANGEAL BASES AND LOOSELY ATTACHED TO THE METATARSALS. RUNNING FROM THEIR COLLATERAL ASPECTS ARE DEEP TRANSVERSE LIGAMENTS AND THEIR PLANTAR SURFACE IS GROOVED FOR THE FLEXOR TENDONS. DEEP TRANSVERSE METATARSAL LIGAMENTS FOUR, SHORT, WIDE, FLAT BANDS BETWEEN ADJACENT PLANTAR PLATES. IN CONTRAST TO THE HAND, THE LIGAMENTS IN THE FOOT ALSO UNITE THE 1ST METATARSOPHALANGEAL JOINT, SO THAT THE GREAT TOE IS BOUND TO THE REMAINDER OF THE FOOT. COLLATERAL LIGAMENTS TWO STRONG, ROUND, CORDS ON EITHER SIDE OF THE INTERPHALANGEAL JOINTS. SAME RELATIVE POSITION AS THOSE IN HAND. THE PLANTAR PLATES ARE ATTACHED TO THE PROXIMAL PHALANGES AND JOINT CAPSULE. THEY ARE HELD IN PLACE BY THE DEEP TRANSVERSE LIGAMENT AND PLANTAR FASCIA. THE PLANTAR PLATES PROTECT THE WEIGHT BEARING SURFACE OF THE METATARSAL HEADS. THERE IS NO PLANTAR PLATE AT THE 1ST MTP, SESAMOIDS INSTEAD.

INTERPHALANGEAL JOINTS

TYPE: AS IN THE HAND, THEY ARE SYNOVIAL, UNIAXIAL, HINGE JOINTS MOVEMENT: FLEXION AND EXTENSION PALMAR PLATES AND COLLATERAL LIGAMENTS SIMILAR TO METACARPALS.

CLINICAL CONSIDERATIONS What is anatomically interesting in a bunion?

THE TARSAL CANAL WITH THE CERVICAL AND INTEROSSEOUS LIGAMENTS SEPARATE THE TALOCALCANEAL FACETS INTO TWO SEPARATE NON-COMMUNICATING JOINT CAVITIES....