The Lower Extremity
BIOL 1010
FEMUR
TIBIA
FIBULA
ERROR:
#7 is CUBOID
#4 is LATERAL
CUNEIFORM
• Very similar to the upper extremity
• Some definitions:
a. Thigh – part from the hips to knees
b. Leg – part from the knee to the ankle
• Note that the hip joint is a ball and socket joint.
It allows movement in all direction. The knee
only allows flexion and extension – not
circumduction. It is never normal for
hyperextension of knee (genu recurvatum)
CAT
In humans, the
abdominal aorta
terminates into
the common
iliac arteries.
The common
iliacs divide into
the external and
internal iliacs.
In humans, the
aorta terminates
as the middle
sacral artery.
• The nerves of the lower extremity are
simpler than the upper limb. There are
three nerves entering the thigh. Their
lateral branches serve the gluteal muscles.
femoral nerve
obturator nerve
sciatic nerve
L2,3,4
anterior compartment
L2,3,4
medial compartment
L4,5,S1,2,3 (sacral plexus) posterior compartment
• The only one of the three that travel below
the knee is the sciatic nerve.
• The sciatic nerve branches into two nerve:
1. tibial nerve
2. common peroneal nerve
a. Superficial peroneal nerve
b. Deep peroneal nerve
Anterior compartmentExtensors of the knee
Femoral Nerve
lateral
medial
femur
Medial compartmentAdductors of the knee
Obturator Nerve
Posterior
compartmentFlexors of the
knee
Sciatic Nerve
• The anterior compartment of the thigh is
homologous to the posterior compartment
of the arm.
• The posterior compartment of the thigh is
homologous to the anterior compartment
of the arm.
• The leg has three compartments
1. Anterior compartment
- dorsiflexors (flexors) of the foot
- deep peroneal nerve
2. Posterior compartment
- plantarflexors (extensors) of the foot
- tibial nerve
3. Lateral compartment
- extensors of the foot
- superficial peroneal nerve
Muscle
Origin
Insertion
Action
Psoas major
FEMORAL NERVE
Transverse
processes and
bodies of T12-L5
femur
Prime flexor of thigh
and trunk.
Iliacus
FEMORAL NERVE
Iliac fossa
femur
Same as psoas
major
Gluteus Maximus
GLUTEAL NERVES
for all gluteal
muscels
Outside of ilium,
sacrum, and coccyx
Iliotibial tract and
femur
Extends the thigh
Gluteus Medius
- Part exposed and
part covered by
maximus. Shots
given here.
Outside of ilium
Lateral surface of
femur
Abducts thigh.
Pelvic tilt to allow
opposite limb to
clear ground during
gait.
Muscle
Gluteus
Minimus
Tensor
Fascia
Latae
Origin
Outer
surface of
ilium
Iliac crest
Insertion
Action
Lateral side Abductor of
of femur
thigh
Iliotibial
tract
(lateral side
of femur)
Extends
knee,
abducts,
and
medially
rotates
• The FASCIA LATA (not to be confused with
the muscle of similar name) is connective
tissue on the lateral side of the femur.
This forms the ILIOTIBIAL BAND. This
band connects the ilium and tibia and is
the site of inflammation in runners –
iliotibial band syndrome.
Muscles of the Medial
Compartment of the Thigh
Obturator Nerve
Muscle
Adductor
Femoris
(magnus and
brevis)
Adductor
Longus
Gracilis
Origin
Insertion
Action
Os coxae
Posterior
Adduct thigh
medial femur at hip
Body of pubis
– medial side
Medial
surface of
pubis and
ischium
Posterior
medial femur
Medial
surface of
tibia
Adduct thigh
and hip
Adduct thigh,
flex leg
Muscles of the Posterior
Compartment of the Thigh
Tibial portion of Sciatic Nerve
Muscle
Origin Insertion
Action
Biceps Femoris
ischium fibula
Flex leg and
extend thigh
semitendinosis
ischium tibia
Flex leg and
extend thigh
semimembranosis ischium tibia
Flex leg and
extend thigh
Muscles of Anterior Thigh
*Femoral Nerve
Muscle
Origin
Insertion
Action
Pectineus
pubis
Linea aspera of
femur
Adduct, flex, and
laterally rotate
thigh
sartorius
ASIS
Medial side of
tibia shaft
Flex, abduct, and
laterally rotate hip.
Flex leg
Vastus lateralis
Femoral shaft
Patella/tibial
tuberosity
Extend leg
Vastus medialis
Femoral shaft
Patella/tibial
tuberosity
Extend leg
Vastus
intermedius
Femoral shaft
Patella/tibial
tuberosity
Extend leg
Rectus femoris
AIIS
Patella/tibial
tuberosity
Extend leg and
flex thigh
1.
Semitendinosus
2.
Biceps Femoris
3.
Caudofemoralis
4.
Gluteus Maximus
5.
Gluteus Medius
6.
Tensor Fascia Lata
7.
Sartorius
• The rectus femoris cross two joints, therefore it has
actions on the two joints involved.
• The patella is articulates with the FEMUR, not the tibia.
• The patella is attached to the femur and tibia by the
PATELLAR LIGAMENT. When this ligament is pulled,
the patella is lifted superiorly and brings the leg into an
extended position.
• In the posterior leg, the GASTROCNEMIUS muscle is
responsible for plantarflexion. It originates at the femur
and inserts on the posterior surface of the calcaneus. It
crosses two joints so it can flex the knee and plantarflex
(extend) the foot. It is innervated by the tibial nerve.
Motor Branches of the
L2
Femoral Nerve
L3
L4
Rectus
femoris
iliopsoas
pectineus
sartorius
Vastus
lateralis
Vastus
Vastus
intermedius medialis
Motor Branches of the
Obturator Nerve
Adductor
brevis
Adductor
longus
gracilis
Adductus magnus
Motor Branches of the
L4
L5
S1
Sciatic Nerve
S2
Hamstrings
S3
Semitendinosis
Biceps femoris
semimembranosus
Tibial
nerve
Gastrocnemius
and posterior
compartment of
the leg and foot
Common
peroneal
nerve
Superficial peroneal
nerve
Lateral
compartment of leg
Deep peroneal
nerve
Anterior
compartment of
leg
The Foot
navicular
Medial, intermediate, and
lateral cuneiforms
talus
calcaneus
cuboid
metatarsals
phalanges
Anterior Leg Structures - Superficial
Identify the Following:
Tibialis Anterior
Peroneus Longs
Peroneus Brevis
Extensor Digitorum Longus
Patellar Tendon
Patella
Tibia
Peroneus Tertius
Extensor Hallucis Longus
Popliteus Tendon
Sartorius Tendon
Posterior Leg Structures Superficial
Identify the Following:
Femur
Tibia
Fibula
Soleus
Achilles Tendon
Plantaris
Popliteus
Calcaneus
Posterior Leg Structures Deep
Identify the Following:
Achilles Tendon
Flexor Hallucis Longus
Flexor Digitorum Longus
Calcaneus
Talus
Tibia
Fibula
Femur
Intrinsic Muscles of the Foot
• These muscles all originate and insert on
foot bones.
• They help to flex, extend, abduct, or
adduct the toes.
• All the intrinsic muscles of the foot are
found on the plantar surface (except the
one on the dorsal aspect).
• The plantar muscles are arranged in 4
layers, from superficial to deep.
Intrinsic Muscles of the Foot
Muscle
Origin
Insertion
Action
Layer
Extensor
Digitorum Brevis
(deep fibular
nerve)
Anterior part of
calcaneus
Base of proximal
phalanx 1,
extensor
expansions of
toes 2-4
Extend the MPJ
Only one on
dorsum of foot
Flexor Digitorum
Brevis
(medial plantar
nerve)
Calcaneal tuber
Middle phalanx
of toes 2-4
Flex toes
1
Abductor
Hallucis
(medial plantar
nerve)
Tuber calcanei
and flexor
retinaculum
Proximal
phalanx of hallux
Abducts hallux
1
Abductor digiti
minimi
(lateral plantar
nerve)
Tuber calcanei
Lateral side base
of little toe
proximal phalanx
Abducts little toe
1
Muscle
Origin
Insertion
Action
Layer
Quadratus Plantae
(lateral plantar
nerve)
calcaneus
Tendon on FDL
Straightens the pull
of FDL
2
Lumbricales
(medial and lateral
plantar nerve)
Tendons of FDL
Extensor expansion
of proximal phalanx
of toes 2-5 on
medial side
Flex at MPJ and
extend at IPJ
2
Flexor Hallucis
Brevis
(medial plantar
nerve)
Lateral cuneiform
and cuboid bones
Base of proximal
phalanx of hallux.
Each tendon of this
muscle has an
associated
sesamoid bone
Flex hallux at MPJ
3
Adductor Hallucis
(lateral plantar
nerve)
Bases of
metatarsals 2-4,
Base of proximal
phalanx of great
toe
Weak adductor of
great toe
3
Flexor Digiti Minimi
Brevis
(lateral plantar
nerve)
Base of 5th
metatarsal
Base of 5th toe
proximal phalanx
Flexes little toe
3
Plantar and Dorsal
Interossei
(lateral plantar
nerve)
Same as interossei
of hand
Same as interossei
of hand
Same as interossei
of hand
4