Foot/Ankle/Lower leg Flashcards
What do you call the common accessory bone of the talus?
why does it form?
Os trigonum.
It sits posterior to the talus on the lateral foot radiograph and represents a failure of fusion of the lateral tubercle of the posterior process.
It is estimated to be present in ~7% of adults.
The ossicle usually forms between 7-13 years of age and fuses with the talus in a majority of patients, otherwise persisting as an os trigonum.
What attaches to the posterior process of the talus?
Posterior talofibular ligament. It attaches to the lateral tubercle of the posterior process
What runs under the posterior process of the talus?
Tendon of FHL - between lateral and medical tubercles
What structure wraps directly under the sustentaculum?
FHL tendon
What runs in the sinus tarsi? Name all structures.
- Interosseous talocalcaneal ligament
- cervical ligament
- medial, intermediate and lateral roots of the inferior extensor retinaculum
- artery of tarsal sinus
(artery of tarsal canal runs in the canal, which is the continuation of the sinus)
What parts of the talus articulate with the calcaneus?
Anterior, middle and posterior articular facets
Describe the blood supply to the talus. What is the main supply?
- Main blood supply is from the posterior tibial artery through the deltoid branches
- Peroneal artery has the least contribution
All 3 terminal arteries have a contribution though:
- posterior tibial a. (MAIN SUPPLY) - deltoid branch to BODY, artery of tarsal CANAL
- Anterior tibial/dorsalis pedis aa.–branch to dorsal head/neck, contributes to artery of tarsal SINUS
- perforating peroneal aa. - contributes to artery of tarsal SINUS - supply head/neck, lateral body
What is the Lisfranc ligament?
Interosseous portion of the oblique ligament from medial cuneiform to 2nd MT base
3 components of the lisfranc ligament complex:
Dorsal - IO - Plantar
IO is the strongest.
Fails - dorsal, plantar, then IO
What are the components of the Lisfranc ligament? which is the strongest one? weakest?
Dorsal (weakest), plantar and interosseous (strongest)
What is the Chopart joint?
The midtarsal joint, comprising the talonavicular & Calcaneocuboid joints
What are the ligamentous components of the ankle syndesmosis?
AITFL
PITFL
Interosseous membrane (IoM)
Interosseous ligament (IoL)
Inferior transverse ligament (ITL) (really just the distal fibrocartilagenous component of the PITFL)
What are the components of the deltoid ligaments of the ankle?
Superficial: - Tibionavicular & Tibiocalcaneal
Deep: - Anterior & posterior tibiotalar
What is an Os Navicular? What are the 3 types?
Accessory navicular.
Type 1: Sesamoid within the distal part of the tendon
Type 2: Attachment to the posterior tibialis tendon, separated by synchondrosis
type 3: enlargement of navicular
What benign structure can often be confused with a Lisfranc Injury?
Os intermetatarseum
What are the plantar layers of the foot?
4 layers:
1st:
- Abductor hallucis brevis
- Abductor digiti minimi
- Flexor digitorum brevis
- plantar fascia
2nd:
- Quadratus plantae
- Lumbricals
- FHL tendon
- FDL tendon
3rd:
- Flexor hallucis brevis
- Flexor digiti minimi brevis
- Adductor hallucis
4th:
- Dorsal interossei
- Plantar interossei
- (also tendons of peroneus longus and tib post)
1st layer (from medial to lateral):
Abductor Hallucis (medial)
Flexor Digitorum Brevis (Middle)
Abductor digiti minimi (lateral)
Plantar fascia
Specifics:
flexor digitorum brevis (=FDS) - medial plantar nerve. Flexes toes in any ankle position
Arises from the medial calcaneus and inserts into the sides of each middle phalanx excluding the great toe.
ABductor Hallucis - medial plantar nerve, great toe abduction
Arises from the medial calcaneus and flexor retinaculum and inserts into the medial base of the proximal first phalanx
ABductor digiti minimi - lateral plantar nerve. Abducts 5th toe.
Arises from the medial and lateral processes of the calcaneus deep to Flexor Dig Brevis. Inserts into the lateral side of the proximal phalanx of 5th toe.
2nd layer:
- consists of the long flexors
Tendon of Flexor digitorum longus (medial)
Tendon of Flexor hallucis longus (adjacent but crosses underneath to run most medial)
Quadratus planae AKA Flexor accessorius (Two heads coming off either side of the calcaneus)
Lumbricals (arises from FDL similar to the hand)
Specifics
Tendon of FDL (tibial nerve) enters the foot medial to FHL but then passes over it. It then splits into 4 and receives insertion from Flexor Accesorius. The tendons pass deep to FDB and give off the lumbricals (medially). Each tendon then enters the fibrous sheath of the lateral 4 toes each perforating the FDB to insert into the base of the distal phalanx (also medially)
Tendon of Flexor Hallucis Longus - Tibial nerve. Passes forward medial like a bowstring beneath the medial longitudinal arch. It is passed over by FDL and it gives off two strong slips to the medial two digits. It lies in a groove between two small sesamoid bones beneath the head of the first metatarsal and inserts into the distal phalanx of the large tow. It is invested by a synovial sheath throughout its whole course in the foot.
- Quadratus plantae (Flexor Accessorius) - lateral plantar nerve. Arises from the medial and lateral aspects of the calcaneus. The posterior part of the long plantar ligament is visible through the two heads. It converges and then inserts into the tendon FDL before it splits. Allows for flexion of the toes with the foot plantar flexed.
Lumbricals - arise from the tendon of FDL (like the lumbricals in the hand arise from FDS). Unlike their counterpart in the hand, they pass medially to the digit into which they insert. The tendons lie on the plantar aspect of the deep transverse metatarsal ligaments (similar to the hand lumbricals which lie volarly). They insert into the extensor expansions.
The medial (1st) lumbrical is unipennate with origin from the first tendon of FDL and attaches to the second digit medially. It is innervated by the medial plantar nerve
The lateral 3 lumbricals are all bipennate arising from both adjacent tendons and inserting medially into their respective extensor expansions
They all function to extend the interphalangeal joints while FDL are flexing the toes
*** Lumbricals innervated by the medial plantar and median nerve are Unipennate
*** Lumbricals innervated by the lateral plantar and ulnar nerve are multipennate.
3rd layer: Consists of 3 muscles. 2 act on big toe, one on small toe. Confined to the metatarsal area.
Flexor Hallucis Brevis (medial)
Adductor Hallucis brevis (middle)
Flexor Digiti Minimi Brevis (lateral)
Specifics
- Flexor hallucis brevis - medial plantar nerve. Has common origin but splits into two heads. Arises from the cuboid and the lateral cuneiform. It splits into two muscle bellies which are inserted BY WAY OF SESAMOID BONE into the medial and lateral sides of the base of the plantar, proximal great toe.
Adductor Hallucis brevis - Lateral plantar nerve. ADDucts and functions to maintain the transverse arch. Has two heads, Oblique and Transverse. The oblique head is large and wide, it arises from the long plantar ligament and the bases of the 2nd thru fourth metatarsals. The Transverse head is slender and has no bony origin. It arises from the deep transverse ligament and the plantar ligaments of the lateral MTP joints. The two heads unite before insertion into the proximal phalanx of the big toe.
Flexor digiti minimi Brevis - lateral plantar nerve. Arises from the base of the 5th MT and the adjoining fibrous peroneus longus. Lies along the 5th MT bone and inserts into the base of the proximal phalanx medially to the insertion of Abductor digiti minimi
4th layer: Consists of the Interossei
Interossei - Also follow the DAB and PAD rule, all are innervated by the lateral plantar nerve (similar to the ulnar in the hand). The important thing to remember is that the longitudinal axis of the foot is shifted medially as compared to the hand such that the axis lies thru the 2nd digit (not the third like the hand).
Like the hand the 3! plantar interossei are smaller and arise from the bone on the toe on which they act. The bulkier 4! dorsal interossei arise from 2 heads from the 2 MTs between which it lies.
The 3 plantar interossei adduct towards the second toe. Digits 3,4 and 5 each have a plantar interossei which pass dorsal to the deep transverse metatarsal ligament. The insert into the dorsal expansion as well as the proximal phalanges.
The 4 dorsal interossei abduct away from the second toe. As such, the 2nd dorsal interossei attaches to the medial second toe. The second to the lateral second toe. The third to the lateral third toe and the fourth to the lateral fourth toe. The also attach to the dorsal expansion as well as the proximal phalanges.
ACTION - their AD/ABduction function is not really important, more so is their ability to assist the lumbricals in extending the IP joints and flexing the MTP joints.
What are the muscles in the dorsal intrinsic compartment of the foot?
Extensor hallucis brevis (deep peroneal nn)
Extensor digitorum brevis (deep peroneal nn)
What is the Master Knot of Henry? Why is it important?
which of the two structures is dorsal/plantar?
Crossing between the FHL and FDL in the foot
Important as dividing it allows access to the deeper layers of the foot and because it can be a site of graft harvest (either FHL or FDL tendon transfers)
FHL is dorsal to FDL which is plantar
What are the compartments of the foot and their key structures?
Compartments:
- Calcaneal - QP, PostTib nn and aa, Med/Lat plantar nn
- Adductor - AD Hallucis
- Interossei - 4 interossei
- Medial - FHB, Abd Hallucis
- Lateral - ADM, FDM
- Superficial - FDL, lumbricals, FDB
HINDFOOT
1) Calcaneal
Quadratus plantae
Posterior tibial nerve, aa, vv
Lateral plantar nerve, aa, vv
medial plantar nn, aa,vv (sometimes in the superficial)
FOREFOOT
2) Interosseous x 4
interossei
3) Adductor
adductor hallucis
4,5,and 6 are FULL LENGTH
4) Medial
FHB
Abductor hallucis
5) Lateral
Abductor Digiti Minimi
Flexor Digiti Minimi
6) Superficial
flexor digitorum brevis
FDL
lumbricals
possibly the medial plantar nerve
What are the borders and contents of the tarsal tunnel?
Floor: talus, Calcaneus (sustentaculum tali, medial wall)
Roof: Lacinate ligament (flexor retinaculum)
Contents: TP, FDL, PT artery, vein, Tibial nerve, FHL “Tom Dick And Very Nervous Harry”
What is Baxter’s Nerve? What is it’s clinical significance?
What layer does it run in?
What mm does it innervate?
1st branch of the lateral plantar nerve It runs obliquely plantarly on quadratus plantae It’s a cause of medial heel pain if impinged (dDx of plantar fascitis)
Runs between layer 1 and 2 FDB (1) and QP (2)
Innervates ADM
Where does the Plantaris tendon insert? be specific.
Medial to the achilles tendon. It may be a part of the achilles tendon but it will still be on the medial side
Origin: posterolateral lateral femoral condyle.
What structures combine to form the Sural Nerve?
Medial and lateral sural cutaneous nerves
Lateral: branch of common peroneal nerve
Medial: branch of tibial nerve
What does the Sural nerve run with? On which side is the nerve?
Runs with short saphenous vein and it is lateral to it
Where does the superficial peroneal nerve pierce the fascia and become subcutaneous?
10-12cm proximal to the tip of the lateral malleolus
Describe the posterolateral approach to the Ankle:
Position: Prone or supine w/ large bump Incision: posterior border of fibula, centered around fracture
Plane: FHL (tibial) & peroneal muscles (sup. peroneal)
can also go anterior to peroneals depending on target anatomy
Dangers: Do not take off PITFL (devitalizes segments),
Sural nerve
Short saphenous
Describe the posteromedial approach to the ankle:
Position: supine
Incision: 10cm vertical incision, can curve towards foot. Midway between the medial mall and the achilles.
Plane: pick optimal interval:
Tibialis posterior & flexor digitorum longus (both tibial) OR
FHL and NV bundle OR
FDL and NV bundle
Dangers: posterior tibial artery and vein, tibial nerve
Describe the anterior approach to the ankle:
Position: supine Incision: 15cm incision over ankle joint, between the 2 malleoli, beginning 10cm proximal to ankle joint
Plane:
Workhorse is the interval between EHL and EDL
The tendons from med to lateral are:
- Above retinaculum:
- TA—-NVB—-EHL—-EDL
- Below retinaculum:
- TA—-EHL––NVB––EDL
Can use any of these intervals
Dangers: Superficial peroneal nerve, Neurovascular bundle
Where does the neurovascular bundle of the anterior compartment of the leg run a) above and b) below the ankle joint level?
Bundle includes deep peroneal nerve and anterior tibial artery
Above joint, runs between EHL and tib-ant. At the joint, crosses behind extensor hallucis longus then below, it runs between EHL and EDB (EDB is bit more medial than EDL)
What is the innervation of peroneus tertius?
Deep peroneal nerve
- *Origin:** Arises with the extensor digitorum longus from the medial fibular shaft surface and the anterior intermuscular septum (between the extensor digitorum longus and the tibialis anterior)
- *Insertion:** Dorsal surface of the base of the fifth metatarsal
- *Action:** Works with the extensor digitorum longus to dorsiflex, evert and abduct the foot
- *Innervation:** Deep peroneal nerve
- *Arterial Supply:** Anterior tibial artery
what are normal ankle syndesmosis measurements on XRay? what views?
MEAURED ON AP
Tibiofibular overlap
- normal >6 mm on AP view
- normal >1 mm on mortise view
Tibiofibular clearspace (1cm proximal to the plafond, from anterior incisura to the medial fibula)
- normal <5 mm on both AP and mortise views
Medial clear space
-normal less than or equal to 4 mm
How much of the talus is covered with articular cartilage?
60%
What are parts of the posterior process of the talus? What attaches here?
What are the eponymous names associated with fractures here?
- Medial and lateral tubercles
- Posterior talofibular ligament attaches to lateral tubercle.
- Posterior 1/3 of deep deltoid attaches to the medial tubercle
Fractures of the posterior process:
- injury to lateral tubercle (also called a Shepherd fracture) is caused by inversion or extreme equinus - snowboarder’s fracture
- injury to medial tubercle (also called a Cedell fracture) is uncommon and is caused by forced dorsiflexion and pronation (avulsion type injury)
What are the different facets of the body of the talus?
Anterior
Medial
Posterior
Articulates with the Anterior, medial, and posterior facets of the calcaneus respectively
What bony structure supports the middle articular facet of the talus?
What attaches to it and runs underneath it?
Sustentaculum tali
Attachments:
Anteriorly: plantar calcaneonavicular ligament
Medially: deltoid ligament
Flexor hallucis longus runs in a groove under it - FHL runs between the medial and lateral tubercles of the posterior process of the calcaneus and then runs under sustentaculum tali of the medial calcaneus
From medial to lateral, what are the order of the extrinsic extensor tendons to the ankle distal to ankle joint?
Tibialis anterior, EHL, EDL, Per Tertius (EDB is intrinsic)
What bones does the talus articulate with?
4 bones: - Tibia: via trochlea and medial articular process - Fibula: via the lateral aticular facet - Calcaneus - Navicular
What are the talar and calcaneal bony components of the sinus tarsi?
Talar: sulcus tali (talar sulcus)
Calcaneus: calcaneal sulcus These 2 halves form the sinus tarsi
What is the sinus tarsi? What are its boundaries?
Anatomical space that is medially continuous with the much narrower tarsal canal
Boundaries:
Superior: talus
Inferior: calcaneus
Anterior: Anterior facet of subtalar joint
Posterior: posterior facet of the subtalar joint
Contents:
- lateral cervical ligament
- medial talocalcaneal interosseous ligament (ligament of the sinus tarsi)
- Sinus tarsi artery
What inserts into the navicular tuberosity?
Tibialis posterior
What 2 muscles attaches to the medial cuneiform and first metatarsal of the foot?
Tibialis anterior, peroneus longus
What constitutes the lateral fibular ligaments of the ankle? which is weakest? strongest?
Anterior talofibular ligament (ATFL) - weakest - an intracapsular thickening
Posterior talofibular ligament (PTFL) - deepest, strongest
Calcaneofibular ligament (CFL) - longest - narrow cord covered by peroneus longus and brevis
What is the origin and insertion of the spring ligament?
AKA plantar calcaneonavicular ligament
Origin: sustantaculum tali
Insertion: navicular
Describe the compartment release of the foot
midfoot dorsal incision over MT 2 (open interosseous compartments between 1,2 and 2,3) and MT4 (open interosseous compartment between 3,4 and 4,5)
medial calcaneus incision to access calcaneal compartment and all full length compartments (medial, lateral, superficial
What is the OI of the Bifurcate ligament?
AKA internal Calcaneocuboid, interosseous ligament or bifurcate ligament
O: Calaneus
I: cuboid and navicular
he bifurcate ligament is a strong Y-shaped band. It is attached by its stern proximally to the anterior part of the upper calcaneal surface, and distally it divides into calcaneocuboid and calcaneonavicular parts. The (medial) calcaneocuboid ligament extends to the dorsomedial aspect of the cuboid, forming a main bond between the two rows of tarsal bones; the (lateral) calcaneonavicular ligament is attached to the dorsolateral aspect of the navicular.
What is the OI of the long plantar ligament?
Calcaneocuboid-metatarsal ligament
O: calcaneus
O: Cuboid & 2nd, 3rd and 4th MT
What is the OI of the short plantar ligament?
Plantar calcaneocuboid ligament
O: calcaneus
I: Cuboid
What is the OI of the spring ligament?
Plantar calcaneonavicular ligament
O: Calcaneus
I: Navicular
Peroneus longus runs anterior/posterior to brevis through the fibroosseous tunnel?
Posterior
What is the OI of the Plantar Aponeurosis?
O: Medial Calcaneal tubercle
I: thick fibrous structure sending slips to prox phalanx of each toe
What is the primary restraint to lateral instability of the peroneal tendons?
What structures form the fibroosseus tunnel at the level of the distal fibula?
Superior peroneal retinaculum, 3.5mm proximal to the tip of the distal fibula
Fibroosseous tunnel:
- Groove in fibula
- Fibrocartilaginous ridge
- Superior Peroneal Retinacular ligament
What is the OINA of Flexor digitorum brevis?
O: Calcaneal tuberosity
I: middle phalanges of 2-5th toes
N: Medial plantar
A: Flex toes at PIPJ
analagous to FDS of the hand - it splits to allow FDL tendon passing thru to distal phalanx
OINA abductor digiti minimi
O: Calcaneal tuberosity
I: Base of 5th toe (prox phal)
N: Lateral plantar
A: Abducts 5th toe
OINA adductor hallucis
O:
- Oblique head: 2-4th proximal MT
- Transverse head: plantar Metatarsal ligaments of D3-5
I: Lateral proximal phalanx great toe
N: Lateral plantar nerve
A: adduct great toe
OINA dorsal interossei?
x4
O: Metatarsals
I: Dorsal extensors
N: Lateral plantar nerve
A: abduct toes. Also, together with the plantar interossei, the dorsal interossei also produce flexion at the metatarsophalangeal joints.
OINA plantar interossei
x3
O: 3-5th MT
I: Proximal phalanges medially
N: Lateral plantar nerve
A: Adduct toes
Describe the course of the dorsalis pedis artery?
Continuation of Anterior tibial artery
Travels down foot lateral to EHL
Gives off branches:
- Medial and lateral Tarsal branhces
- Arcuate artery: passes over dorsal TMT joint, deep to tendons
- Deep Plantar artery - large branch that dives deep through 1st/2nd webspace at MT bases
- This forms the deep plantar arch
- DP ends as digital arteries
Describe the arthroscopic portals for ankle arthroscopy and their main dangers
Anterolateral portal:
Medial to lateral malleolus, lateral to peroneus tertius
Danger: intermediate dorsal cutaneous branch of superficial peroneal nerve (Other branch is the medial dorsal branch)
Anteromedial portal:
Medial to tibialis anterior and lateral to medial malleolus
Danger: Saphenous nerve & vein
Posterolateral portal:
Medial to peroneal tendons, lateral to achilles
Danger: sural nerve, small saphenous vein
Posteromedial portal:
Can injure posterior tibial artery
cuboid has a groove along its plantar aspect - what runs in it?
Peroneus longus
What neurovascular bundle(s) are in the deep posterior compartment of the leg? Name each component
- Tibial nerve
- Posterior tibial artery and veins
- peroneal artery and veins
Describe the path of the tibial nerve from start to finish
starts as bundle of the sciatic nerve which splits into tibial nerve and common peroneal nerve at top of popliteal fossa
tibial nerve gives off medial sural cutaneous nerve in popliteal fossa, then goes between heads of gastroc
lies superficial to plantaris and popliteus
dives deep to soleus through fibrous arch
enters deep posterior compartment, travels just deep to transverse IM septum
runs with posterior tibial a and v, between FHL and FDL
stays between them and wraps behind medial malle in tarsal tunnel
gives off medial calcaneal branch (lateral calcaneal branch comes form sural nerve). These branches often perforate the lacinate ligament
enters tarsal tunnel, bifurcates into medial and lateral plantar nerves
exits tunnel (both) and runs between 1st and 2nd plantar layer
MPN is deep to abductor hallucis
LPN is obliquely superficial to quad plantae
LPN gives off baxter’s nerve
Describe the sensory distribution of the plantar foot–be specific
central and medial heel: medial calcaneal branch of tibial nerve
lateral foot and heel: sural nerve
medla foot: saphenous nerve
D1-half of D4: medial plantar nerve
D5 to half of D4: lateral plantar nerve
describe the path of the sural nerve from start to finish (all branches and how they relate)
common peroneal n gives off lateral sural cutaneous n in popliteal fossa and then travels subcutaneously along lateral gastroc
tibial n gives off medial sural cutaneous n in popliteal fossa which travels between heads of gastroc along with short saphenous v DEEP to deep fascia (no sensory fxn yet)
pierces fascia in middle of calf to become subcutaneous
joins up with a branch from lateral sural cutaneous - becomes the sural nerve itself
sural n travels with short saphenous v (lateral to v) and runs between lateral mall and achilles - more proximal=closer to achilles, more distal=closer to lateral mall
gives off lateral calcaneal branches
terminates as lateral dorsal cutaneous n on lateral side of foot/5th toe
