Download Anatomy of the Lower limb Plate 486-491 The lower limb specializes

Anatomy of the Lower limb
Plate 486-491
The lower limb specializes in weight bearing, maintaining equilibrium and locomotion. Divded into 4
parts:
Pelvic Girdle
Thigh region- Femur + Patella
Leg- Tib + Fib
Foot- Tarsals + metatarsals, phalanges.
Pelvis
The composite hip bone spans the sacrum and femur. Each hip bone consists of three individual bones
that are fused in adulthood (ileum ,ischium and pubis). These bones are separated by cartilage usually
until puberty upon which ossification occurs. In adults the only place where you can see the remnants of
the three bones is within the acetablum. The ileum is the largest of the three and forms the superior
part of the hip. The ischium forms the posterior inferior part of the hipbone. The pubis forms the
anterior part of the hip bone, of the acetabulum, and the anterio-medial portion of the hipbone.
- I would urge you to take a look at the composite hip bone and be able to identify the various spines.
Femur
Superior end- Head, neck, greater and lesser trochanter. The head is in the acetablum. Trochanters are
below the neck. The head and the neck are an angle of between 115-140 degrees with the shaft. When
this angle is reduced- coxavara- weight of body stresses head and neck, easy fracture. When the angle is
increased- coxavalga- mobility reduced. The normal angle allows for greatest mobility while at the same
time least stress at the point where the neck meets the shaft.
Body(shaft of femur)- curved w/ anterior convexity, distal end of femur ends in two large condyles.
Tibea and Fibula
Tibea is the larger weight bearing bone, articulates w/ condyles of femur superiorly and the tallus
infeiorly. There is an opening (nutrient foramen) which is the largest foramen on any bone in the body
and its located on the posterior surface of the tibea, upper 1/3rd.
Fibula- posterior-lateral to Tibea, mostly for muscle attachment. Shaft of two bones are connected by
an interosseous membrane. The distal end of the Tibea on the medal side ends in to medial mallelous,
and the distal end of the fibula laterally ends in the lateral mallelous. Easy to palpate.
Tarsal Bones
7 Tarsal bones, Tallus, calcaneous (heel bone), cuboid, navicular and three cuniformes- unlike the
carpals. Tallus only one that articulates with tibea above. The tallus has body, head and neck distally
(order). The tallus sits on the anterior 2/3rds of the calcaneous. The tallus articulates with the tibea, and
on the lateral side, the fibea. The tallus also articulates with the tibea, fibula, navicular bone, it is critical
in weight distribution().
Calcaneous- largest and strongest bone in the foot, has on its superior medial border a shelf like
structure called the sustantaculum tali that supports the tallus. The lateral surface has an oblique ridge
that’s called the fibula (peronial) trochlea. The posterior surface of the calcaneous has a large
prominence called the tuberosity of the calcaneous. This tuberosity has a medial, lateral and anterior
tubercle. Only the medial rests on the ground when standing. The navicular located b/w the tallus and
the cuniformes. The cuboid is the most lateral bone in the distal bone.
- Three cuniformes, all of them articulate with navicular posteriorly and with metatarsals anteriorly. The
three cuniformes are lateral, intermediate and mediate. 5 Metatarsals, numbered 1-5 medial to lateral.
Each metatarsal has a base proximally which articulates with navicular, head, body- distally. The head of
each articulates with proximal phalange of a toe.
- On the plantar surface of the first metatarsal are 2 sesamoid bones. As far as phalanges are concerned
there are 14 or them, 2 in great toe (big toe- Hallux) and three in every other toe.
Surface anatomy
Know iliac crest is. Posteriorly iliac crest is at the level of L4-5. The crest ends anteriorly at the anterior
superior iliac spine. The pubic tubercle- anterior, about 2 and a half centimeters on either side of the
median plane. Important for inguinal hernias. The condyles of the femur, and patella are easily palpated.
The lateral and medial malleoli are ez to palpate. In some indivs, you can palpate the greater trochanter.
In the anatomical position a horizontal side through the greater trochanters pass through the head of
the femur and pubic tubercles.
Muscle
- Thicker= stronger.
Fascia of lower limb
- Superficial + deep layer- Starting at hip moving down.
- Superficial layer- lies just deep to skin, contains fat, nerves, lymphatic vessels and lymph nodes. 2
Important veins- great saffrones vein (longest vein in body) and small saffrones vein. Great saffrones is
usually used for bypass. At the knee, the superficial fascia loses its fat and blends w/ deep fascia. Below
knee, fascias merge. The deep fascia is dense connective tissue b/w superficial fascia and muscles. The
deep fascia sorrounds the leg like a elastic stocking around the leg (muscles?). Deep fascia is called a
fascia lata in the thigh. And below the knee where the two layers merge the fascia is called the crural.
The fascia lata is very strong laterally (bilaterally) where it runs from iliac to tibea. This part of the fascia
is called the ilieo-tibeal tract. This tract receives the tendon from the tensa fascia latae and tendons
from the gluteous muscle. Distally the ileo-tibeal tract is attached to the lateral condyle of the tibea. The
thigh muscles are separated into 3 groups. Seperated into anterior, medial and posterior group by 3
fascial intermuscular septum. These three septa arise from the fascia latae. They attach to the linear
aspera of the femur. The lateral septum is much stronger than the other 2. Moving distally, the crural
fascia is continous with the fascia latae- its attached to the tibea and it is thick proximally and anteriorly.
It is weak distally except at the inferior and superior extensor retinaculum.
- The leg is divided into compartments by the crural fascia. The compartments are first the anterior or
extensor compartment, second a lateral which is also known as the fibula or peronial compartment, and
a posterior flexor compartment- further divded into superficial and deep region. Movements around
ankle- dorsiflexion and plantar flexion.
Nerves and Vasculature
Nerves are branches of lumbar and sacral plexuses. Veins- major (long) saphenous and (lesser) short
saphenous veins. Veins from the dorsum, or dorsal surface of arch merge medially to form major
saphenous and laterally to form small saphenous. The great saphenous vein which is the longest in to
body runs from the foot to the groin, enters the femoral vein near the femoral triangle through the
saphenous openings. The small saphenous vein ends in the popliteal fossa (back of knee) where it
becomes the popliteal vein. Most lymph vessels parallel the saphenous vein. The lymph vessels end in
superficial inguinal lymph nodes. The lymph vessels associated with the small saphenous end in popliteal
lymph nodes.
Muscles
- Thigh muscles- Divided into 3 compartments by fascia latae, anterior medial and posterior. Anterior
compartment- include- ilioso- begins as two separate muscles spous? And (). Muscles arise in abdomen
and distally attach to lesser trochanter. They span the hipjoint anteriorly, hip flexors. Tensor fascia lataestrap like muscle b/w fascia latae, and anterior superior iliac spine. It runs down to the lateral condyle of
the tibea. It Abducts at the hip primarily. Small roll in hip flexion. Third- sartorious, very important as a
landmark. Longest muscle in body, most superficial muscle in anterior compartment. Sartorius- spans 2
joints, parallels much of the femoral artery. It runs across the iliac crest to the superior medial surface
of the tibea. This muscle flexes at the hip, laterally rotates at the hip, flexes at the knee. It also to a small
degree is a hip abductor. – Crossing legs motion.
Anterior group muscles- quadriceps femoris- 4 parts. All extensors of leg at knee joint. They all do that. 1
of them spans two joints and has an action on the hip as well. 1. Rectus femoris- (action on hip), spans
anterior inferior iliac spine and it runs to base of patella and then to the tibeal tuberosity which is right
below the patella. All 4 of these muscles have a common insertion on tibeal tuberosity through the
quadriceps tendon. Along w/ the tendon distally, will be the patella ligament. The patella ligament
merges w/ quadriceps tendon and the tibeal tuberosity. They are all extensors, but since the rectus
femoris begins at the anterior inferior iliac spine it also acts to rotate hips.
- Vastus lateralis- Originates @ greater trochanter
- Vastus Medialis- originates @ intertrochanteric line
- Vastus intermedius- originates on body of femur.
- All 3 muscles tendons distally attach to the tendon of rectus femoris to form the quadriceps tendon
which attaches to the tibeal tuberosity.
Be familiar with chondromalacia of the patella (runner’s knee)- presents w/ soreness and achy feeling
deep to patella. And it usually is due to erosion of underside of patella which is due to an imbalance in
the tension placed on the quadriceps tendon.
- When the patella is fractured, there is a dramatic decrease in the muscles acting at the knee joint. The
patella acts like a fulcrum in a lever system. Without the patella, would need 30% more force to do same
work.