Flashcards in Manual 34-42: Dorsum of Foot Deck (77):
dorsalis pedis fascia is the continuation of _______
the deep fascia (dosalis pedis fascia) is the continuation of the deep fascia (crural fascia) of the leg
The deep fascia divides the dorsum of the foot into three layers. what does each layer contain?
superficial: tendons and accompanying synovial sheaths of the tibialis anterior, extensor hallucis longus, extensor digitorum longus and peroneus tertius muscles
intermediate: extensor digitorum brevis m.
deep: dorsalis pedis a. and branches, deep peroneal n. and branches, veins accompanying the dorsalis pedis, and termination of the perforating branch of peroneal a.
the deep fascia of the dorsum is continuous with
where does the deep fascia of the dorsum attach?
tuerosity of 5th metatarsal laterally
first metatarsal laterally
where does the superior extensor retinaculum attach?
laterally -- to the distal end of the fibula on its anterior border AND on the lateral surface of the lateral malleolus
medially -- anterior crest of the tibia and to the medial malleolus
it blends with superior peroneal retinaculum laterally, and with the proximal border of the inferior extensor retinaculum and the flexor retinaculum medially
what tendons are bound in the sheath of the superior extensor retinaculum?
extensor digitorum longus
extensor hallucis longus
tendon of tibialis anterior
where does the frondiform portion of the inferior extensor retinaculum attach?
dorsal and anterior aspect of the calcaneus just anterior to the sulcus calcanei
what is the usual shape of the inferior extensor retinaculum?
if it is x-shaped, it has an extra oblique superolateral band
where do the intermediate and medial roots of the inferior extensor retinaculum attach?
intermediate - deeper portions of sulcus calcanei
medial/deep - sulcus tali posterior to attachment of interosseous talocalcaneal ligament
fibers of the ________ root of the inferior extensor retinaculum continue medially to form the superomedial and inferomedial obique bands.
what m. takes partial origin from the deep surface of the frondiform ligament?
extensor digitorum brevis m.
describe the deep and superficial layers of the superomedial oblique band of inferior extensor retinaculum. When the two layers fuse after passing the extensor hallucis longus tneson, it forms a tunnel for what?
tendon of the tibialis anterior
superficial layer passes superficial to the tendon of the extensor hallucis longus, the anteiro tibial artery and ven and deep fibular n.
where does the superomedial oblique band of the inferior extensor retinaculum attach?
medially on the anterior surface of the medial malleolus
where does the inferomedial oblique band of the inferior extensor retinaculum attach?
plantar fascia; navicular tuberosity; medial cuneiform
the inferomedial oblique band of the inferior extensor retinaculum passes _________ to the dorsalis pedis a, deep peoneal n and tendons of the EHL and TA.
the superolateral oblique band of the inferior extensor retinaculum is present in about...
25% of persons
it extends from the superomedial oblique band and frondiform ligament laterally to attach on the lateral surface of the lateral malleolus
will merge with superior extensor retinaculum and the superior peroneal retinaculum
the extensor expansions are formed by...
tendons of the extensor digitorum longus and brevis muscles
The extensor digitorum longus tendon divides into 3 slips. Describe where each slip goes.
central slip passes distally along the dorsum of the proximal phalanx and inserts on teh base of the middle phalanx
the two lateral slips run along each side of the proximal and middle phalanges and converge over the distal end of the middle phalanx
these rejoined tendinous slips pass distally as the terminal slip to insert on the base of the distal phalanx
tendons of the EDB join the EDL at the level ...
of the metatarsophalangeal joints on the fibular side just proximal to their division into three slips
what do the extensor expansions look like on fifth digit?
for the fifth digit, tendons of the abductor digiti minimi and flexor digiti minimi contribute to the lateral aspect of the expansion
what is an extensor hood?
long and short extensor tendons are held in place by two fibrous sheaths. these sheaths are continuous with each other and form a strong fibrous structure called the extensor hoods
the more proximal part, called the extensor sling, is formed from fibers which encircle the digit to attach to a thickening in the plantar metatarsophalangeal ligament called the plantar plate
the distal part of the extensor hood, called teh extenosr wing, is formed mostly from expansions of the tendons of the lumbrical muscles
how many plantar plates are there?
interosseous muscles contribute to the formation of the _______ but not of the ____
what is the function of the EDL?
- acting alone, it tightens the sling and loosens the wing
- when the muscle contracts the plantar plate is pulled against the metatarsal head resulting in extension (or hyperextension) of the metatarsophalangeal joints
- it CANNOT extend the interphalangeal joints
- wing portion of the extensor hood is loose and the interphalangeal joints cannot be extended
what is the function of the lumbrical muscles?
- on contraction, they tighten the wing and loosen the sling allowing the more proximal parts of the extensor expansion to permit flexion at the metatarsophalangeal jt while holding more distal joints in extension
- it should be noted that the FDL, because of its relationship with the lumbricals, does contribute to the function of the extensor hood
what is the function of the interosseous muscles?
on the first digit, what is attached to the extensor expansion?
only the tendon of the EHL
-- the plantar plate is attached to the deep transverse ligament on the lateral side only
-- a wing and sling are present, but lumbricals and interosei do not contribute to them
-- on medial side they are formed by the abductor hallucis, while on the lateral side, they are formed by the adductor hallucis and flexor hallucis brevis
what is the only intrinsic muscle of the dorsum of the foot?
extensor digitorum brevis
origin of the extensor digitorum brevis
- tubercle on the superolateral surface of the calcaneus just anterior to the sinus tarsi, from the interosseous talocalcaneal ligament and from the frondiform ligament
most medial tendon of the extensor digitorum brevis which crosses over the dorsalis pedis a.
sometimes a separate m. called the extensor hallucis brevis
insertion of extensor digitorum brevis
- extensor hallucis brevis inserts on dorsal surface of the base of the proximal phalanx of the first digit
- other 3 tendons insert into the lateral surface of the tendons of the extensor digitorum longus muscles of the 2nd, 3rd, and 4th digits, just distal to the metatarsophalangeal joints
function of extensor digitorum brevis
- aid to extensor digitorum longus in extension of the phalanges of the 2nd, 3rd and 4th digits
- if contraction continues, it also extends the metatarsophalangeal joints
- when acting without the lumbricals, the extensors extend the MP joints by tightening the extensor sling and pulling the plantar pad against the proximal phalanx
innervation to extensor digitorum brevis
- lateral terminal branch of the deep peroneal n. most commonly
*** however, when an accessory peroneal branch of the superficial peroneal n. is present (20% of cases) it usually aids in innervating the muscle
describe the course of the saphenous n. ( sensory branch of femoral n.)
- follows great saphenous v. in the leg along its lateral side and enters the dorsum of the foot anterior to the medial malleolus.
- courses along the medial border of the foot as far as the first metatarsal bone
what skin is innervated by the saphenous n. ?
the medial side of the foot as far as the base of the 1st metatarsal bone
describe the course of the sural n.
- enters foot inferior to lateral malleolus
- follows small saphenous vein in leg
- courses into lateral side of the foot where it becomes the lateral dorsal cutaneous n. of the foot
describe the course fo the lateral dorsal cutaneous n. of the foot
- terminal part of n courses distally along the lateral side of the 5th toe where it is known as the 10th dorsal digital n.
- on occassion will give rise to or anastomose with intermediate dorsal cutaneous n. of foot
where does the superficial peroneal n. come from?
- one of two terminal branches of common peroneal
- arises deep to peroneus longus m. and passes inferiorly
- penetrates through crural fascia and divides into two terminal branches
what n. does the medial dorsal cutaneous n. of the foot communicate with?
- saphenous n.
- and on occasion with medial terminal branch of the deep peroneal
what does the medial dorsal cutaneous n. give rise to? ***
- one dorsal digital branch (1st dorsal digital n)
- one common dorsal digital branch (1st common dorsal digital n)
where is the 1st common dorsal digital branch located and what does it give rise to?
- space between toes two and three
- divides into 4th and 5th dorsal digital n.
the intermediate dorsal cutaneous n. divides into ...
- 2nd and 3rd common dorsal digital n.
- for intermetatarsal spaces 3 and 4
- each common dorsal digital branch divides to give rise to two dorsal digital n.
where does the 10th dorsal digital n. originate from?
lateral dorsal cutaneous n.
describe the course of the deep peroneal n.
- passes from its origin deep to the peroneus longus to the anterior surface of the interosseous membrane
- accompanies the anterior tibial a. from the proximal 1/2 of the leg and passes with it deep to the extensor retinaculum
- immediately distal to the retinaculum, it divides into medial and lateral terminal branches
what muscles are innervated by branches of the deep peroneal n. ?
- tibialis anterior
- extensor digitorum longus
- peroneus tertius
- extensor hallucis longus
also provides articular branch to ankle joint
what branch of deep peroneal n. innervates the extensor digitorum brevis?
- lateral terminal branch passes deep to extensor digitorum brevis and innervates it
how many interosseous branches does the lateral terminal branch have?
three interoseous branches which serve the tarsal joints and the metatarsophalangeal joint of digits 2, 3 and 4
a muscular branch from the 1st interosseous branch off of what nerve ________ serves the second dorsal interosseous m?
lateral terminal branch
which n. is found accompanying the dorsalis pedis a. on the dorsum of the foot?
medial terminal branch
what skin is supplied by the medial terminal branch ?
- in the first intermetatarsal space, it divides into 2 dorsal digital n. which supply the skin of adjacent sides of the 1st and 2nd digits
supplies the metatarsophalangeal joint of the first digit and provides a sensory branch to first dorsal inteosseous m.
interosseous branch of medial terminal branch (off of deep peroneal n. )
when does the anterior tibial a. become the dorsalis pedis a. ?
after crossing the transmalleolar line
how often can teh dorsalis pedis be traced distally across the talus, navicular, intermediate cuneiform and base of the 2nd metatarsal bone to the first intermetatarsal space
- in about 10% of the cases the artery is deviated the medial or lateral side
what are the two terminal branches of the dorsalis pedis?
- deep plantar
- 1st dorsal metatarsal
what percentage of people have a small and difficult to locate dorsalis pedis?
in cases where the artery is deficient or absent, the plantar arteries or teh perforating branch of the peroneal a. take over
how often is teh anterior tibial a. absent?
if absent, the dorsalis pedis originates from the perforating branch of the peroneal a.
where can a dorsalis pedis pulse be taken?
- while the a is passing anterior to the tarsal bones, between the tendons of the extesnor hallucis longus medially and extensor digitorum longus laterally
- if pulse can't be detected, it is because the anterior tibial a. after giving off its malleolar branches terminates as a small twig at ankle joint and the perforating branch of the peroneal a. vascularizes the area of the dorsum of the foot normally suppplied by dorsalis pedis
how many significant branches are there off the dorsalis pedis a.?
1st dorsal metatarsal a.
what is often the largest branch off the dorsalis pedis?
lateral tarsal a.
where does the lateral tarsal a. branch off the dorsalis pedis?
- arises at the neck of the talus
- if second lateral tarsal a is present, often smaller and will originate while dorsalis pedis is crossing over the intermediate cuneiform bone
- if two lateral tarsal present, then they are known as the proximal and distal lateral tarsal aa
Describe the path of the lateral tarsal a.
- courses distally and laterally across the calcaneonavicular junction and the dorsum of cuboid
- passes below the tendon the peroneus brevis m.
- anastomose with lateral plantar a.
- passes below extesnor digitorum brevis m. which is supplies
- brnaches anastomose with perforating branch of peroneal a. , arcuate a. and anterior lateral malleolar rete
provide vascular supply of head and neck of talus
branches from proximal part of lateral tarsal a.
smaller branches upply other tarsal bones and intertarsal joints
how often does the artery to the sinus tarsi originate from the lateral tarsal a.. ?
describe the medial tarsal a.
- small and variable
- usually 2
- originate from dorsalis pedis opposite the origin of the proximal lateral tarsal a.
- supply medial aspect of tarsal bones and terminate by contributing to medial malleolar rete
In _____ % of cases, this artery originates from the dorsalis pedis a at the level of the first tarsometatarsal jt
65% - arcuate a.
in other cases, its origin can be slightly more proximal and therefore can be confused with distal lateral tarsal a.
describe the course of the arcuate a.
- runs laterally across the bases of the second, thrid and fourth metatarsal bones
- tendons of extensor digitorum brevis cross its supeficial surface
- ansastomoses laterally with lateral tarsal and lateral plantar a.
- gives rise to 2nd, 3rd, and 4th dorsal metatarsal a.
how many dorsal metatarsal a. are there?
- 1st: direct brnach of dorsalis pedis
- 2-4: branches of arcuate a.
terminal branches of dorsalis pedis
- deep plantar
- first dorsal metatarsal a.
The first dorsal metatarsal a. divides into ...
medial and lateral branch
- medial branch courses medially over the head of first metatarsal bone and deep to the tendons of the extensor hallucis longus and brevis to vascualrize the medial side of great toe as first dorsal digital a.
- lateral branch continues distally and a the webbin gof the toes divides into two branches to supply the adjoining sides of first and second toes as the second and third dorsal digital a.
what is the vascular supply to medial side of great toe?
fist dorsal digital a. -- a continuation of the medial branch of the first dorsal metatarsal a.
to what does the first dorsal metatarsal a. provide vascular supply?
- first dorsal interosseous m
- articular branches to first metatarsophalangeal jt
- soft tissues around medial side of first toe
- adjacent side of 1st and 2nd toes
at the proximal end of the itnerosseous space, dorsal metatarsal arteries 2-4 receive ___________ peforating branches of the plantar arch.
- at the distal end of the interosseous space, the dorsal metatarsal a. receive the anterior perforating branches from the plantar metatarsal a.
what gives rise to the dorsal metatarsal arteries 2-4 in the absence of the arcuate a?
posterior perforating arteries
after receiving the distal perforating arteries, the dorsal metatarsal arteries are known as ...
common dorsal digital arteries
what a. do the dorsal digita a. of each toe communicate with?
each other at the distal end of the toes
where does the 10th dorsal digital a. come from?
- direct branch from lateral part of acruate a. OR from the 4th dorsal metatarsal ar.