Ch. 24: Plantar Foot

Question 1

Plantar Aponeurosis: what do the transverse fibers make up?

Answer 1

• thickened central portion of plantar fascia
• superficial layer: longitudinally oriented fibers attaching proximally to the tuberosity of the calcaneous; distally provides digital slips which fuse with and reinforce the fibrous digital sheaths of the long flexor tendons
• deep layer: transversly oriented fibers attached to the heads of the metacarpals forming the superficial transverse metatarsal ligament.

Question 2

transverse fasiculi

Answer 2

transversely oriented bundles of deep fascia which reinforce the webs of toes

Question 3

fibrous digital sheaths: what is their purpose?

Answer 3

specializations of deep fascia, anchored to the phalanges, which form a fibro-osseous canal that prevents “bowstringing” of the flexor tendons which pass through them.

NOTE: as in the hand, these sheaths are lined by a synovial digital sheath which provides a means of lubricating the flexor tendons through excursion

Question 4

Intermuscular septae (lateral and medial): what is the purpose?

Answer 4

extends from lateral and medial edges of plantar aponeurosis to attch to the 1st and 5th metatarsal, thereby delineating the following compartments.

1. medial compartment (great toe): contains the flexor and abductor for the great toe, tendon of flexor hallucis longus and medial plantar vessles and nerves
2. lateral compartment (5th toe): contains abductor and flexor of digiti minimi
   3.

Question 5

what is contained in the central compartment of the plantar foot?

Answer 5

lies deep to plantar aponeurosis and contains flexor dibigorum brevis, lumbricals, quadratus plantae and adductor hallucis muscles and tendons of the flexor digitorum longus and lateral plantar vessels and nerve.

Question 6

what does the interosseous compartment contain?

Answer 6

exists between layers of plantar and dorsal interosseous fascia and contains interosseous muscles

Question 7

Abductor Hallucis

Answer 7

O: Calcaneus

I: medial side of base ofproximal phlanx of great toe

A: abducts great toe

N: medial plantar n.

Question 8

Abductor Digiti minimi

Answer 8

O: Calcaneus

I: Lateral side of base of proximal phlanx of fifth digit

A: Abducts fifth digit

N: Lateral plantar n.

Question 9

Flexor digitorum brevis

Answer 9

“powerful for toe grip” - like flexor digitorum superficialis in hand

O: calcaneus

I: middle phlanges of four small toes

A: flexes middle and proximal phlanges of four small toes

N: medial plantar n.

NOTE; the tendons of the flexor digitorum brevis bifurcate to allow passage of the tendons of flexor digitorum longus to reach distal phlanges

Also, the posterior tibial a. and tibial n. divide into lateral and medial plantar branches deep to the proximal portion of abductor hallucis and pass forward between the muscles of 1st and second layer.

Question 10

What does the posterior tibial a. and tibial n. divide into in the foot?

Answer 10

the posterior tibial a. and tibial n. divide into lateral and medial plantar branches deep to the proximal portion of abductor hallucis and pass forward between the muscles of 1st and second layer.

Question 11

What two tendons of the posterior leg muscles pass through the second layer of the plantar foot?

Answer 11

flexor hallucis longus and flexor digitorum longus (the latter msucle is what the second layer has an intimate relationship with)

Question 12

Quadratus plantae

Answer 12

O: calcaneus

I: tendon of flexor digitorum longus

A: pulls on tendon of flexor digitorum longus muscle so that its action on the four small digits is directed exactly posteriorly

N: lateral plantar n.

Question 13

Lumbricals

Answer 13

O: Tendons of flexor digitorum longus

I: medial side of metatarsophalangeal joints via extensor tendons

A: flexes M-P joints, extends distal phalanges

N: first lumbrical = medial plantar n.

2nd-4th lumbrical = lateral plantar n.

Question 14

Flexor Hallucis Brevis

Answer 14

“toe off” in walking

O: plantar surface of cuboid and lateral cuneiform

I : lateral and medial sides of base of proximal phlanx of great toe

A: flexes great toe

N: medial plantar n.

NOTE: this muscle has two heads, a lateral heach which attaches with the adductor hallucis muscle and medial head which attaches to the to the abductor hallucis muscle. the tendon of the flexor hallucis longus passes between the two heads.

Question 15

Flexor digiti minimi

Answer 15

A: flexes and abducts small toe

N: lateral plantar n.

Question 16

Adductor Hallucis

Answer 16

• looks like a 7

O: oblique head: base of 2,3,4 metatarsal: transverse head: lateral four plantar ligaments of MP joints

I: lateral side of base of proximal phlanx of great toe

A: adducts and flexes great toe

N: lateral plantar n.

Question 17

Plantar interossei

Answer 17

p-ad (3 - single pennate)

located at bases of digits 3,4,5

A: adducts digits 3,4,5. flexes MP and extends PIPs and DIPs

N: Lateral plantar n.

Question 18

Dorsal Interossei

Answer 18

d-ab (4 bippenate)

O: adjacent sides of all metatarsals

A: abducts 2,3,4 flexes MP joints and extends PIPs and DIPs

N: lateral plantar n.

Question 19

Where do plantar nerves and vessels emerge in the foot?

Answer 19

from beneath the flexor retinaculum, they travel b/w the muscles of the 1st and 2nd layer, branch and appear distally coursing parallel to the lateral and medial sides of the flexor digitorum brevis

Question 20

what supplies the plantar aa?

Answer 20

• posterior tibial a.
• passes from beneath the flexor retinaculum, continues deeply beneath the abductor hallucis muscle and bifurcates in lateral and medial plantar aa.

Question 21

lateral plantar a. : what does it give off? what does it anastamose with?

Answer 21

• larger of two terminal aa. of posterior tibial a.
• accompanied by lateral plantar n. and vein - passes from under cover of abductor hallucis muscle to course between the 1st and 2nd muscular layers (flexor digitorum brevis and quadratus plantae)
• forms the plantar arterial arch
• provides three plantar metatarsal aa. and terminates int eh 1st metatarsal space by anastomosing with the deep plantar branch of the dorsalis pedis a.

Question 22

what are the branches of the lateral plantar a?

Answer 22

• provides calcaneal, muscular, cutaneous and articular branches
• also provides the plantar metatarsal aa. which spring from the plantar arterial arch and provide proper plantar digital aa. to the 2nd-5th digits.
• 5th digit is supplied directly by lateral plantar a. prior to formation of arch

Question 23

Medial plantar a.

Answer 23

• smaller of two terminal branches of posterior tibial a.
• accompanied by medial plantar veins anerve, along the medial plantar surface of foot betwen abductor hallucis and flexor digitorum brevis muscle
• terminates by formint the 1st proper plantar digital a.
• anastamoses with plantar metatarsal aa. and plantar proper digital aa.

Question 24

what are the two plantar nerves and where do they come from?

Answer 24

• the tibial n. after exiting from beneath the flexor retinaculum, passes deep to the abductor hallucis muscle and bifurcates into medial and lateral plantar nerves

Question 25

Medial plantar n. : what does it innervate? what does it terminate in?

Answer 25

• homolog of median n. in hand
• larger of two terminal branches of tibial n.

1. 1st lumbrical
2. abductor hallucis
3. flexor hallucis brevis
4. flexor digitorum brevis

Question 26

Lateral plantar n. : what are 6 things it innervates?

Answer 26

• homologue of ulnar n. in the hand
• abductor digiti minimi,
• quadratus plantae,
• 2nd-4th lumbricals,
• flexor digiti minimi,
• adductor hallucis,
• all interossei