Wet Lab 7 - Instrinsic Muscles Of The Foot

Question 1

How is the plantar foot best studied?

Answer 1

In layers, from superficial to deep

Question 2

What are the dorsal intrinsics muscles of the foot?

Answer 2

Extensor Digitorum Brevis and Extensor Hallucis Brevis

Question 3

Where does EDB and EHB insert onto ?

Answer 3

The extensor expansion (extensor mechanism) of the toes

Question 4

What is the superficial pre-msucle layer of the foot?

Answer 4

Plantar Aponeurosis (Plantar Fascia)

Question 5

Where is the plantar aponeurosis msucle located?

Answer 5

On the underside of the foot

Question 6

What does the attachment of the planatar aponeurosis muscle ensure ?

Answer 6

It ensures that it grows taut (tight/stretched/flexed) when we rise on our toes and extend the metatarsophalangeal joints

Question 7

What muscles make up the 1st layer of the plantar muscles ?

Answer 7

The short flexor of toes and abducts of the outside toes
- Flexor digitorum brevis
- abductor hallucis (greater toe abductor)
- abductor digits minimi

Question 8

Where is the axis for abduction-adduction of the toes at their metatarsophalangeal (MTP) joint along ?

Answer 8

The middle of the 2nd metatarsal

Question 9

What nerves/vessels make up the foot?

Answer 9

The medial and lateral plantar nerves and vessels (Arteries and veins)

Question 10

What are the medial and lateral plantar nerve and vessel branches of?

Answer 10

The tibial nerve and the posterior tibial artery and vein

Question 11

What muscles make up the 2nd layer of plantar muscles ?

Answer 11

2 tendons and 2 muscles attaching to one of them
- tendons of flexor digitorum longus
- lumbricals
- flexor accessorius (quadratus plantae)
- tendon of flexor hallucis longus

Question 12

Where does the quadratus plantae/flexor accessorius insert onto ?

Answer 12

The tendon of flexor digitorum longus

Question 13

Where do the lumbrical muscles arise from ?

Answer 13

The tendons of flexor digitorum longus

Question 14

Where are sesamoids located in the foot

Answer 14

• there are two tubercles at the base of the back of the calcaneus which press against the ground
• there are also 2 sesamoids at the great toe’s MTP joint

Question 15

What is the function of the sesamoids at the great toe’s MTP joint?

Answer 15

They increase the moment arm which therefore increased the torque movement ability of the bone. They also decrease friction between the 2 joints and experience high levels of compressive stress

Question 16

What tendon are the sesamoid bones within ?

Answer 16

Tendons of flexor hallucis brevis

Question 17

What is the function of quadratus plantae?

Answer 17

Because the tendon of FDL crosses the foot diagonally, QP helps to redirect its LOP so that it is closer to the longitudinal axis of the toes

Question 18

What muscles make up the 3rd layer of plantar muscles ?

Answer 18

Short flexors of outside toes and adductor of the greater toe
- flexor hallucis brevis (check for sesamoids bones)
- flexor digiti minimi
- adductor hallucis
- transverse head of adductor hallucis
- oblique head of adductor hallucis
- flexor digiti pedis

Question 19

What is the function of the sesamoids bones at the MTP joint ?

Answer 19

The FHB passes through the middle of the sesamoids to ensure that is does not get squished

Question 20

Which muscles are responsible from abduction adn adduction of the toes at the MTP joint ?

Answer 20

• plantar interossei muscles
• dorsal interosseous muscles

Question 21

What is the rule for the axis of abduction-adduction at the MTP joint ?

Answer 21

PAD and DAB

Question 22

What is the action of the plantar interossei muscle ?

Answer 22

Adduct the MTP joints

Question 23

What is the action of the dorsal interossei muscle ?

Answer 23

Abduct the MTP joints

Question 24

What other actions of plantar and dorsal interossei can be observed from a side-on view?

Answer 24

Flexion or extension of the joints they cross

Question 25

What muscles make up layer 4 of plantar foot?

Answer 25

Interossei
- plantar Interossei
- dorsal Interossei
- tendon of Fibularis longus
- tendon of Tibialis posterioir

Question 26

What is the origin of the plantar interossei ?

Answer 26

Bases and medial sides of bodies of 3rd, 4th and 5th metatarsal bones

Question 27

Where does both the plantar and dorsal Interossei go into ?

Answer 27

They go into the extensor mechanism and attach on the metatarsals

Question 28

What is the extensor mechanism ?

Answer 28

It is a complex structure that provides detailed function to the joints of the fingers and toes.
Mechanism = multiple parts to it

Question 29

What is present in the extensor mechanism ?

Answer 29

There is a hood/expansion that the lumbricals and interossei insert onto as well as loosely the extensor tendons (EDL, EDB). There is also a continuation of this that inserts into the base of the middle phalanx

Question 30

What is the function of the lateral bands ?

Answer 30

They run around the PIP joint, reunite and insert into the base of the top of the distal phalanx

Question 31

What ligaments make up the plantar foot?

Answer 31

• long plantar ligament
• short plantar ligament
• “spring” ligament (plantar calcaneonavicular ligament)

Question 32

What does dorsum of the foot mean ?

Answer 32

the upper surface of the foot

Question 33

What muscles make up the dorsum of the foot?

Answer 33

Tendons of the intrinsic extensor muscles
- extensor digitorum brevis
- extensor hallucis brevis