Anatomy of the foot and ankle Flashcards
What is in the tasral tunnel
Tarsal Tunnel – Posterior and inferior to medial malleolus, roofed by flexor retinaculum,
passage from leg to foot.
Contains (medial to lateral): tibialis posterior, flexor digitorum longus, posterior tibial
artery, posterior tibial vein, tibial nerve and flexor hallucis longus.
“Tom, Dick And Very Nervous Harry” or “Tiny Dogs Are Very Nervous Hunters”
What are the two retinicula at the front of the foot
Superior extensor retinaculum –
attached to tibia and fibula
* Inferior extensor retinaculum –
Y-shaped
Lateral to medial: fibularis
tertius, extensor digitorum
longus, dorsalis pedis,
extensor hallucis longus and
tibialis anterior.
How is integrity of the foot arches maintained
Integrity maintained by :
* Shape of bones
* Connective tissues
(passive)
* Plantar aponeurosis
* Ligaments
* Muscles (dynamic)
What is the plantar aponeurosis
Central thickening of deep
fascia composed of
longitudinal bands from
calcaneus to fibrous digital
sheaths of toes
Supports longitudinal (medial
and lateral) arches
What is the spring ligament of the foot
Spring ligament (plantar calcaneonavicular)
- Connects sustentaculum tali of calcaneus and navicular
- Supports head of talus and maintains medial arch of foot
What is the long plantar ligament of the foot
Long plantar ligament
* Connects calcaneus to cuboid and metatarsal bases
* Supports transverse tarsal joint and crucial to maintain lateral
arch of foot
What is the short plantar ligament of the foot
Short plantar ligament (plantar calcaneocuboid)
* Connects anterior calcaneus to cuboid
* Supports transverse tarsal joint and important to maintain
lateral arch of foot
Which muscles support which arches of the foot
Flexor hallucis longus – medial
arch
Tibialis posterior – transverse
and medial arches
Tibialis anterior – medial arch
Fibularis longus – transverse
and lateral arches
Intrinsic muscles – lateral,
medial and transverse arches
Describe pes planus (flat foot)
- Arch appears normal when unloaded (flexible flat feet)
- Typical in childhood
- Can occur due to looser ligaments with age (fallen arch) or
dysfunction of tibialis posterior - Foot flat when unloaded due to bone deformity (rigid flat feet)
What is extensor digitorum brevis
Innervation – deep
fibular nerve
* Action – extends toes I
- IV
What are the muscles in the first layer of the foot
ABDUCTOR HALLUCIS
* Innervation – medial plantar
nerve
* Action – abducts and flexes big
toe
FLEXOR DIGITORUM BREVIS
* Innervation – medial plantar
nerve
* Action – flexes digits II – V at
proximal IP joints
ABDUCTOR DIGITI MINIMI
* Innervation – lateral plantar
nerve
* Action – abducts digit V
What are the muscles in the second layer of the foot
QUADRATUS PLANTAE
* Innervation – lateral plantar
nerve
* Action – assists FDL in flexing
digits II - V
LUMBRICALS
* Innervation – medial plantar
nerve first lumbrical; lateral
plantar nerve second, third and
fourth lumbricals
* Action – flexion of MP and
extension of IP joints
What are the muscles in the 3rd layer of the foot
FLEXOR HALLUCIS BREVIS
* Innervation – medial plantar
nerve
* Action – flexes MP joint of big
toe
ADDUCTOR HALLUCIS
* Innervation – lateral plantar
nerve
* Action – adducts big toe at MP
joint
FLEXOR DIGITI MINIMI
* Innervation – lateral plantar
nerve
* Action – flexes little toe at MP
joint
What are the muscles in the 4th layer of the foot
DORSAL INTEROSSEI (4)
* Innervation – lateral plantar
nerve, also deep fibular (1st and
2
nd)
* Action – abduct digits II – IV, flex
MP joints, extend IP joints
PLANTAR INTEROSSEI (3)
* Innervation – lateral plantar
nerve
* Action – adducts toes III – V,
What is the blood supply to the posterior foot
Popliteal artery > divides to
anterior and posterior tibial
arteries > posterior tibial enters
foot
What is the blood supply to the sole of the foot
Posterior tibial artery branches into
* Medial plantar artery
* Lateral plantar artery
Lateral plantar becomes deep plantar
arch and anastomoses with deep
plantar artery
Medial plantar travels along medial
side of foot to supply big toe and joins
deep plantar arch
Describe dorsalis pedis
Anterior tibial artery becomes
dorsalis pedis as it crosses in front
of the ankle.
It passes between two heads of
first interosseous to join deep
plantar arch (deep plantar artery)
Branches include:
* Arcuate – passes laterally across
foot and gives off dorsal MT and
dorsal digital arteries
* 1
st dorsal metatarsal – supplies
digital branches to 1st and 2nd
toes
What is the venous drainage from the foot
Dorsal venous arch receives
blood from metatarsal veins and
drains into great (medial) and
small (lateral) saphenous veins
What is the nerve supply to the sole of the foot
Tibial nerve
* Enters though tarsal tunnel and
branches into:
- Medial plantar n. – MOTOR to
abductor hallucis, flexor
hallucis brevis, flexor
digitorum brevis, first
lumbrical; SENSORY to sole
including medial 3 ½ toes - Lateral plantar n.– MOTOR to
all other intrinsic muscles of
sole (remember 1st and 2nd
dorsal interossei get
additional from deep fibular);
SENSORY to lateral sole and
lateral 1 ½ toes. All via: - Deep branch
- Superficial branch
What is motor’s neuroma
In some cases the medial and lateral plantar nerves can fuse to form a
common plantar nerve – this sometimes occurs between the third and fourth
toes. This enlarged, superficial nerve can be squeezed during “toe off” leading
to inflammation and severe pain.
What is the nerve supply to the dorsum of the foot
Deep fibular nerve
* Descends with anterior tibial
artery
* Innervates extensor digitorum
brevis, first two dorsal
interossei and skin between
first and second toes
Superficial fibular nerve
* Sensory to dorsal aspect of skin
and toes except digits I – II, and
dorsolateral side
How does foot drop occur
Common fibular nerve
* Most frequently injured nerve in the body due to
superficial position around head and neck of fibula
* Impairs eversion, dorsiflexion of foot and
extension of toes
* Results in foot drop and a high-stepping gait as
well as loss of sensation on the dorsum of the foot
