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#14
Anatomy
Muscles and joints
of lower limb
Ahmad Abulhuda
8/10/2015
Nabil Khoury
Font : times new romans\ 16
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Hello AWN …
Today we will continue talking about the muscles of the lower limb and start
with the joints, so let’s start…
Muscles of the leg:
They are less complex than the muscles of the gluteal and thigh regions,
they are straight forward, also, they are classified into three groups; lateral,
posterior and anterior. The posterior group has two layers; superficial and
deep, the posterior muscles mainly have one insertion. You have to know that
all the anterior group do extension and all the posterior group do flexion at the
level of the foot; planter extension and flexion. The lateral group is important
because we have two muscles (fibularis longus and brevis) that go to the
planter of the foot and do two unique movements of the foot; eversion (lateral
rotation) and inversion (medial rotation), these two muscles participate in
forming the arches of the foot.
We said that the anterior group do dorsiflexion (or planter extension they
are the same) of the foot. In this group we have three muscles (extensor
digitorum longus, extensor hallicus longus, and fibularis (peroneus))
found in the lateral aspect of the leg (anterior-lateral).
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We have the tibialis anterior muscle which moves the foot and toes, then we
have the extensor digitorum longus and medial to it we have the extensor
hallicus longus.
* Tibialis anterior:
- The biggest muscle of the anterior aspect of the leg.
- The origin: tuberosity of tibia
- The insertion: tarsals (the medial aspect of the foot)
- The action: it helps the muscles of the lateral group (fibularis longus and
brevis) to do the eversion and the inversion of the foot
* Extensor digitorum longus:
- A long muscle which has a long wide fibers.
- The origin: the anterior aspect of tibia and fibula
- The insertion: phalanges 2-3-4-5
- The action: extension of toes
Note: the extensor hallicus longus is the same but it inserts to the base of the
first phalange (the big toe).
Any muscle that doesn’t have capturing aspect (for fixation), its action will be
lost, that is why we have something called the lever system which consist of
the base (fulcrum), weight and the action (force), it resembles the seesaw
system; it has the fixation aspect in the middle (the fulcrum), and on each side
we have the weight and the force which both will be equilibrated (the weight
gets you down and the force pushes you upward), the same in the muscle; if
there is no fulcrum, then the weight and the force are not equilibrated, so that
is why we have the extensor and flexor retinacula (the flexor is wider and
thicker) which serve as fulcrums for the muscles. If we look at the wrist joint,
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these retinacula are deep, thicker and composed of two layers, whereas at the
ankle joint we have only two bands but we still call them extensor and flexor
retinacula, also at lateral and medial aspect we have two retinacula; fibular
and flexor retinacula. So, each muscle that passes through these retinacula in
the ankle has to be fixed.
We said that we have the lateral group of muscles which is composed of
fibularis (peroneus) longus and brevis.
The fibularis longus muscle originates from the lateral fibula and will be
attached to tarsal bones at the lateral aspect, and then its tendon will go deeper
and passes the planter muscles to be inserted to the medial aspect of the foot
(fifth metatarsal), the fibularis brevis is a small muscle which originates
from the distal fibula (inferior to the longus) and will be inserted into the
lateral aspect of the foot (first metatarsal), both muscles wind around each
other at the ankle, by that we will have the two actions of eversion and
inversion of the foot.
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Fibularis retinaculum
Inferior Extensor
retinaculum
We can see the extensor and fibularis retinacula of the foot (the fibularis is
superior to the lateral part off the lower extensor retinaculum), and in order for
the fibularis muscle to make their action well, they lie behind a protrusion of
the callus and are captured by the fibularis tendon (retinaculum).
Now the posterior compartment of the leg has two layers, superficial and
deep, the superficial one is made of three muscles; gastrocnemius,soleus and
plantaris muscle which has the longest tendon in the human body; the
plantaris tendon is thin and it goes along the posterior aspect of tibia to the
planter surface of the foot, the gastrocnemius and soleus muscles form the
triceps surae with three heads (two for gastrocnemius and one for soleus)
which all will be held into one common tendon which will go to the posterior
calcaneus; the calcaneal (Achilles) tendon, the gastrocnemius has two heads,
one in the medial aspect and the other in the lateral one, they are bifurcated
and separated from each other but they fuse in the lower half of the muscle
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(calcaneal tendon), both heads will form the inferio-lateral and inferio-medial
border of the popliteal fossa posteriorly to the knee joint where they originate
from the condyles of the femur, (the upper lateral and the upper medial
borders of the fossa are made by bicips femoris ,semimembranousus and
semitendonosus muscles of femur), the soleus muscle is big and similar to
the semitendonosus muscle of the thigh, we call these two big muscles
(gastrocnemius and soleus) the duck of the leg :p.
Talking about the posterior deep muscles of the leg we have popliteus muscle
which originates from the lateral condyle of the femur and insert into the
proximal tibia medially so its small muscle that help in the medial rotation of
the knee joint and lasting the knee joint by preventing the departure of the
femoral condyle from the superior aspect of tibia by locking the medial and
lateral rotation (control the rotation) so it flex and medially rotate the leg,
some tendons of muscles goes in a groove behind the medial malleolus or a
groove on inferior surface of sustintaculum tali projection of calcaneus bone,
so these muscles are fixed in a very strong flexion retinaculum which is
composed of one or two bands, the flexor digitorum longus muscle comes
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from the tibia and go to the distal phalanges 2-5, flexor hallicus longus
muscle comes from fibula _so the digitorum is medial and the hallicus is
lateral, in the middle we have tibialis posterior which come from tibia, fibula
and the interosseus membrane, one of its tendons will go behind the groove of
the medial malleolus underneath the sustintaculum tali to their destination and
insert into the medial cuniform, both flexor digitorum and hallicus longus are
found in the same muscle layer of the foot but they cross-over each other
which helps in the eversion of foot. So these three muscles tibialis posterior,
flexor digitorum and hallicus longus form the deep posterior muscles of the
leg and will go through the deep sulcus of the medial malleolus of foot.
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These are the compartments of the lower limb, in the thigh part we have
three compartments; the anterior which is the biggest one, the posterior and
the lateral one which is the smallest, in the leg part also we have three
compartments; anterior, posterior and lateral, but the posterior one is the
biggest one, and the smallest one is lateral, in this region the interosseus
membrane plays a great role in separating the anterior muscles from the
posterior, whereas the fascia will send only two septa toward the fibula, so
that the lateral compartment is separated by the continuation of this fascia to
the fibula except for perforating sites in the upper leg where the arteries and
nerves pass to the lateral compartment.
Note: slides from 58 to 60, the muscles of lower limb organized in tables for
you to read.
IM injection in buttock:
The line that passes through the middle of the iliac crest vertically downward
is the dividing line because the gluteus maximus is more laterally, so we do
the injection laterally in that area because in the medial aspect you will be able
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to hit the sciatic nerve, superior gluteal artery and veins, and this is one of the
most common causes of litigation against medical personnel, if you don’t
divide this region with another horizontal line that passes through the anterior
superior iliac spine to the posterior superior iliac spine you will be ending
giving the injection in the capsule of the hip joint, so you choose the lateral
upper quadrant to inject through as deep as you go it doesn’t matter because
you have three muscles to go through; gluteus maximus; minimus and
medius. The gap is the canal of the needle through which the material pass to
the body, the longer the needle, the bigger the gap and the more pain person
feels, so when inject the patient you better inject him with intermediate or
small needle so he won’t get pain especially when you are dealing with
babies.
Now let’s move to the joints of the lower limb…
* Hip joint:
- It is ball and socket type of joints similar to the shoulder joint.
- The articular participants are the head of the femur and the acetabulum
of the hip bone to form the hip joint so we have two articular parts.
Note: The doctor said he will bring a question about the head of the femur
in the exam.
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- The articular surface of the acetabulum is not completely rounded; it has
lunate shape (horseshoe) and covered by articular cartilage anteriorly,
posteriorly and superiorly, the thin triangular fibrocartilaginous ring is called
the acetabular labrum which deepens the acetabulum and is similar to the
glenoid labrum of shoulder joint. Inferior surface is deficit due to the presence
of transverse acetabular ligament, and the absence of the acetabular labrum
and the articular cartilage in this area, so inferiorly we only have this ligament
which complete the lunate acetabulum and prevent the inferior dislocation of
the head of the femur
- The hip joint is unique by having degree of stability similar to the shoulder
joint but with 30 degree of motion compared with 70 degree in the shoulder
joint; because the head of the humerus is smaller and the glenoid cavity is
shallower, whereas the femur head is bigger and the acetabulum cavity is
deeper, but why??
Because all the weight of the human is carried on this joint (on the axis that
pass through the acetabulum and the head of the femur in this joint).
- we can also see the fovea capitis which is small non-articular surface of the
head of the femur that will go superior to the transverse acetabular ligament
and adhere to the non-articular surface of acetabulum which is filled with fat
pad to absorb the compression or the shock when you move or jump and
prevent the cut of the ligament of femur head by the articular cartilage which
causes the femur head displacement.
- How the femur head and the acetabulum adhere??
The head of the femur is sucked inside the acetabulum, with the support of
ligament of the femur head. (sucking and fixation)
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The joint capsule:
The capsule will adhere to most anterior
and posterior aspect of the acetabulum
covering the lower aspect of the Ilium, the
superior ramus of the pubic and the body
of the ischium, and it will cover only small
distance into the neck.
This capsule is enforced by strong
ligaments anteriorly. It has two directional
fibers; longitudinal and circular
- The circular fibers are found all
over the capsule but they form two
strong collars at the edges around
the femoral neck and around the
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Longitudinal
fibers
acetabulum called the zona
orbicularis.
- The longitudinal fibers travel along the neck and fuse with the
bone anteriorly (the neck of the femur) and posteriorly but not
inferiorly because it is loosed.
The ligaments of this joint are:
- The ischiofemoral and the iliofemoral ligament are located in the
posterior aspect of the capsule and they will enforce it posteriorly.
- Anteriorly we will have the iliofemoral ligament which is the
strongest ligament in human body, and it has two bands; superior and
inferior, if you cut the superior aspect of the inferior one you will be
able to see the synovial membrane, cotyloid ligament (which is located
within the capsule in the anterior aspect as it initiates from the anterior
border of the acetabulum) and the head of the femur. Practically, if the
surgeon wants to repair this area, he will never touch this area because
he will hit very crucial ligament; iliofemoral ligament.
Posterior view
anterior view
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The synovial membrane:
The capsule of this joint is similar to
the capsule of the shoulder joint; it is
loosed inferiorly, but here it is less
loosed than the one of the shoulder
joint.
The capsule has two separated layers,
the synovial membrane will cover the
inner aspect of the capsule excluding
the ligament of the femur head which
is very important because it allows the
artery of the femur head to go inside it
to irrigate the capsule, the ligaments
and the synovial membrane.
You have to that this structure is very
vascularized, in addition to the
obturator artery which goes into the
fovea capitis and it is called the artery of
the ligament of the femur head, we also
have another two arteries that go
inferior to the tuberosity of the femur;
lateral and medial femoral circumflex
arteries that irrigate the neck and head
of femur.
The fracture of the femur head is dangerous because it is much
vascularized, the surgeon should repair the head and the neck and make
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sure that the vascularization is fine, otherwise there will be necrosis, in
this situation we have to replace it.
These are the ranges and degrees of motions:
- Flexion is limited anteriorly by the anterior
abdominal wall so no flexion more than 120
degrees.
- Extension is limited posteriorly by the gluteus
maximus muscle, so no extension more than 20
degrees.
- The abduction is limited by 60 degrees of
movement.
- The adduction is made by the adductor group that
is located in the medial aspect, it is limited by 30
degrees of range of movement by the presence of
the other leg.
- Lateral (external) hip rotation is
limited by 45 degrees of movement
around the axis of the joint and it is made
by gluteus maximux, quadratis femoris,
piriformis, obturator internus and
externus, gemelli.
- Medial (internal) hip rotation is also
limited by 40-45 degrees of movement
and it is made by gluteus maximus,
minimus and tensor fascia latae muscles.
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- Coxa vara is the decreased angle of
inclination of hip joint (walk like a
duck), normally it ranges between (110
and 130) degrees, but here it reaches 90
degree
- Coxa valga is the increased angle of
inclination of hip joint
These are the fracture types of the
femur neck; subcapital neck fracture,
transcervical fracture and the
intertrochanteric fracture (occurs at
the level of the crest in the line
between the two trochanters), at the
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upper aspect of the femur we have
the subtrochanteric fracture, the
greater and the lesser trochanteric
fractures.
The doctor wanted us to read the two following slides, so i copied
them here:
Osteoarthritis:
• It is a disease of old age, characterized by growth of osteophytes
at the articular ends, which makes the movements limited &
painful.
• In arthritis of hip joint, the position of the joint is partially flexed,
abducted& laterally rotated.
• FRACTURE OF THE NECK OF THE FEMUR may be
subcapital, cervical, or near the trochanter.
SHENTONS LINE in an x-ray:
It is a curve line that occurs between the upper border of obturator
foramen and the lower border of the neck of the femur, the greater
and lesser trochanter are at the same line and the obturator foramen is
in the middle, the number of neck femur lines becomes abnormal in
the dislocated hip, so this line should be continuous and smooth.
THE END
Forgive me if the lecture was long
but the record was almost an hour
and it took 2 days (ella shahta) to
write it
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