topic 7

Question 1

what are the 4 muscles in the anterior compartment of the leg muscles

what actions do they do

Answer 1

tibialis anterior
extensor hallucis longus
extensor digitorum longus
peroneus/fibularis tertius

all do dorsiflexion & tibialis anterior does little bit of inversion as well.

Question 2

what are the 2 muscles in the lateral compartment of the leg

Answer 2

peroneus longus
peroneus brevis

both do plantarflexion and eversion

Question 3

what are the muscles in the posterior compartment of the leg

what are their actions

Answer 3

deep compartment

• tibialis posterior
• flexor digitorum longus
• flexor hallucis longus
• popliteus

superficial

• gastrocnemius
• soleus
• plantaris

all do platarflexion
flexor digitorum longus flexes digits 2-5
flexor hallucis longus flexes digit no. 1

Question 4

describe the location of and the mechanical function of the extensor retinaculum

Answer 4

superior extensor retinaculum

• binds to the tendons of the tib ant, EHL, EDL and tib post.
• runs horizontally above ankle.

inferior extensor retinaculum

• binds the tendons of tib ant, EHL, EDL and tib post.
• is a Y shaped band anterior to the talocrural ligaments.

retinaculum acts to hold the tendons in place and prevent bow-stringing.

Question 5

describe the location of and the mechanical function of the flexor retinaculum

Answer 5

located posterior-medially.

flexor retinaculum converts the bony grooves into canals for the tendons of tib post, FDL and FHL as they pass behind the medial malleolus.

it bridges over the posterior tibial vessels and nerves.

Question 6

describe the location of and the mechanical function of the peroneal retinaculum

Answer 6

superior and inferior peroneal retina bind down the peroneal longus and peroneal brevis behind the lateral malleolus.

Question 7

describe the location of and the mechanical function of the tendon synovial sheaths

Answer 7

double layer of synovial membrane surrounding each tendon as it passes under the retinacula. It facilitates sliding of the tendons.

Question 8

describe the location of and the mechanical function of the plantar aponeurosis

Answer 8

plantar aponeurosis is the most superficial structure of the plantar surface of the foot (except the skin). it is immediately deep to the skin.

• triangular shaped (apex @ calcaneous, base at metatarsal heads).

functions

1. binds to skin of foot and keeps it in place.
2. provides an attachment site.
3. helps maintain arch of foot.

Question 9

describe the location of dorsal digital expansion the role in facilitating efficient functioning of the foot

Answer 9

dorsal digital expansion refers to the expansion of the extensor tendons as they approach the digits. They appear as winged structures that wraps over and around the top digits to form an extensor hood).

functions:

1. allows all toe joints to be extended simultaneously.
2. provides an attachment site for some intrinsic muscles.

Question 10

what are the dorsal muscles of the foot

Answer 10

extensor digitorum longus

extensor hallucis longus

Question 11

define instrinsic and extrinsic muscles

Answer 11

intrinsic muscles - origin and insertion are both within the foot.

extrinsic muscles - origin in the leg and insertion in the foot.

Question 12

what comprises the 1st layer of the foot’s plantar surface

Answer 12

1 x flexor and 2 x ABductors

flexor digitorum brevis (in middle)
abductor hallucis (outside)
abductor digit minimi (outside)

Question 13

what comprises the 2nd layer of the foot’s plantar surface

Answer 13

2 x tendons and 2 x muscles

tendon of flexor digitorum longus
tendon of flexor hallucis longus

flexor accessorius (for quadratus plantae) 
lumbricals

Question 14

what comprises the 3rd layer of the foot’s plantar surface

Answer 14

1 x Adductor and 2 x flexors

adductor digit minimi brevis (more medial than AB)
flexor digit minimi brevis (lateral outside)
flexor hallucis brevis (medial outside)

Question 15

what comprises the 4th layer of the foot’s plantar surface

Answer 15

2 x tendons and 2 x muscles

tendon of peroneus longus (cross over to medial underneath foot).
tendon of tibialis posterior

plantar interossei (closer to bottom of foot) PAD
dorsal interossei (closer to top of foot). DAB. 

note - the tendons are not specifically in layer 4.

Question 16

what do the lumbricals do

Answer 16

the lumbricals flex the MTP joints and extend the IP simultaneously to prevent toe clawing.

assists with digital sweep

Question 17

what is digital sweep

Answer 17

digital sweep is the longest possible pathway of the tips of the digits.

flexion occurs at the MTP joints first while the IP joints are maintained in extension, IP joints are flexed layer.

interplay between the extrinsic muscles and intrinsic muscles (lumbricals), intrinsic muscles modulate the extrinsic muscles. instrinisic muscles act to extend the IP joints to avoid toe clawing.

Question 18

describe toe clawing

Answer 18

toe clawing is when the long extensor and long flexor work unopposed. multi-joint muscles tend to move their most distal joint first.

during toe clawing, the FDL pulls the IP joints into flexion and the EDL pulls the MTP joints into hyperextension creating an abnormal position of rest.

Question 19

what are the functions of the foot arches

Answer 19

absorb weight forces/shock
efficient weightbearing
adds to foot’s ability to adapt to ground surface changes.
efficient propulsion-elastic recoil of arch when lifted off.

Question 20

what are the static features that maintain foot arches

Answer 20

shape of bones

ligaments - plantar aponeurosis, long plantar lig, short plantar lig, spring lig.

Question 21

what are the dynamic features that maintain foot arches

Answer 21

intrinsic foot muscles
extrinsic muscles

medial longitudinal arch - FHL and FDL.
lateral longitudinal arch - FDL.

transverse arch - peroneus longus, tibialis posterior, active and tonic contraction.