Other Components of Lower Limb

8/7/2019 Other Components of Lower Limb

1/8

The Lower Limb

Blood and Nerve Supply of Lower Limb and Other Notable Components

Fascia of Lower Limb

The fascia of the lower limb consists of deep and superficial layers.

Thesubcutaneoussuperficial fascia , lies deep to the skin and consists of looseconnective tissue containing variable amounts offat, cutaneous nerves, superficialveins, lymphatics and lymph nodes. At the knee the subcutaneous tissue loses its fatand blends with the deep fascia but fat ispresent in the subcutaneous tissue of leg.

The deep fascia is a dense layer of connective tissue between the subcutaneous tissue

and the muscles. It forms septa that separate muscles from one another and invest

them. The deep fascia prevents muscles from bulging during contraction. The deep

fascia of the thigh is called the fascia lata. The deep fascia of the leg is called the

crural fascia.

The fascia lata is continuous with the crural fascia.

The fascia lata is thickened laterally by additional longitudinal fibres to form theiliotibial tract. This broad band of fibres is the conjoint aponeurosis of the tensor of

fascia lata and the gluteus maximus muscles. The iliotibial tract extends from the

iliac tubercle to the lateral condyle of the tibia.

Thesaphenous openingin the fascia lata is a deficiency inferior to the medial part of

the inguinal ligament. Its medial margin is smooth but its lateral, superior and inferior

margins form a crescenteric edge, the falciform margin.

This sickle-shaped margin of the saphenous opening is joined at its medial margin by

fibrofatty tissue the cribriform fascia. This fascia is sievelike as it is pierced by

numerous openings for the passage of lymphatics and the great saphenous vein and its

tributaries.

The crural fascia is thick in the proximal part of the leg and thin in the distal part.

The crural fascia thickens where it forms the extensor retinacula.

Venous Drainage of the Lower Limb

The lower limb has superficial and deep veins; the superficial veins are in the

subcutaneous tissue; the deep veins accompany all major arteries. Both sets of veins

have valves although the deep veins have more.

Superficial Veins of the Lower LimbThe two major superficial veins of the lower limb are the great and small saphenous

veins.

Thegreat saphenous vein is formed by the union of the dorsal vein of the great toeand the dorsal venous arch of the foot. It ascends anterior to the medial malleolus,

passes posterior to the medial condyle of the femur, traverses the saphenous opening

in the fascia lata and empties into the femoral vein.

Thesmall saphenous vein arises from the union of the dorsal vein of the little toe andthe dorsal venous arch. It ascends posterior to the lateral malleolus, ascends between

the heads of the gastrocnemius muscle and empties into the popliteal vein in thepopliteal fossa.


2/8

The Lower Limb

Perforating veins penetrate the deep fascia close to their origin from the superficial

veins and contain valves that, when functioning normally, only allow blood to flow

from the superficial veins to the deep veins.

Deep Veins of the Lower Limb

The deep veins accompany all the major arteries. The deep veins usually occur aspaired, inter-connecting veins that flank the artery they accompany. They are

contained within the vascular sheath containing the artery, whose pulsations help

compress and move blood in the veins.

Lymphatic Drainage of the Lower Limb

The lower limb has superficial and deep lymphatic vessels. The superficial vessels

accompany the saphenous veins and their tributaries. The vessels following the great

saphenous vein end in the superficial inguinal lymph nodes. Most lymph from here

passes to the external iliac nodes. The lymphatic vessels accompanying the small

saphenous vein enter the popliteal lymph nodes. The deep vessels accompany thedeep veins and enter the popliteal lymph nodes. Most6 lymph from the popliteal

nodes ascends to the deep inguinal lymph nodes and then the external iliac nodes.

Cutaneous Innervation of the Lower Limb

Cutaneous nerves in the subcuatenous tissue supply the skin of the lower limb. These

nerves are branches of the lumbar and sacral plexuses. The are supplied by branches

from a single spinal nerve is called a deramtome. The cutaneous nerves are:

- subcostal nerve (T12)

-iliohypogastrci nerve (L1)

- ilioinguinal nerve (L1)

- genitofemoral nerve (L2-L3)

- lateral femoral cutaneous nerve (L2-L3)

- femoral nerve (L2,3,4)

- anterior femoral cutaneous nerves (from femoral nerve)

- obturator nerve (L2,3,4)

- posterior femroal cutaneous nerve (S2-S3)

- sciatic nerve (L4-S3)

The Adductor Canal

The adductor canal (subsartorial canal; Hunters Canal) is a narrow fascial tunnel in

the thigh running from the apex of the femoral triangle to the adductor hiatus in the

tendon of adductor magnus. It provides an intermuscular passage through which the

femoral vessels pass to reach the popliteal fossa and become the popliteal vessels.

The contents of the canal are the:

- femoral artery and vein

- saphenous nerve

- nerve to vastus medialis

The boundaries of the canal are:

- anteriorly and laterally: vastus medialis- posteriorly: adductor magnus and longus


3/8

The Lower Limb

- medially: sartorius

The Femoral Triangle

The femoral triangle is a triangular fascial space in the superoanterior third of the

thigh. Its boundaries are:

- superiorly; the inguinal ligament

- medially; adductor longus

- laterally; sartorius

The base of the femoral triangle is formed by the inguinal ligament and its apex is

where the lateral border of sartorius crosses the medial border of adductor longus.

The muscular floor of the triangle is formed by the iliopsoas and pectineus.

The roof is formed by fascia lata and the cribriform fascia, subcutaneous tissue and

skin.

The contents of the triangle are (from lateral to medial):

-femoral nerve and branches

- femoral sheath and its contents

- femoral artery and branches

- femoral vein and tributaries

The Femoral Nerve

The femoral nerve (L2-L4) is the largest branch of the lumbar plexus; it forms within

psoas major in the abdomen and descends posterolaterally to the midpoint of the

inguinal ligament. It passes deep to the ligament and enters the femoral triangle lateral

to the femoral vessels. It supplies:

- the anterior thigh muscles

- the hip joint

- the knee joint

- skin on the anteromedial thigh

the terminal cutaneous branch of the femoral nerve is thesaphenous nerve which

descends through the femoral triangle and accompanies the femoral artery and vein

through the adductor canal, lateral to the femoral sheath. It then becomes superficial

and runs to supply the skin and fascia on the anteromedial side of the knee, leg and

foot.

The Femoral Sheath

The femoral sheath is a funnel-shaped fascial tube enclosing the proximal parts of thefemoral vessels and the femoral canal. The sheath does not enclose the femoral nerve

and ends by becoming continuous with the adventitia of the vessels.

The compartments of the femoral sheath are:

- lateral compartment for the femoral artery

- intermediate compartment for the femoral vein

- medial compartment which is the femoral canal

The femoral canalis the smallest compartment and is short and conical. The base of

the femoral canal (its abdominal end) is called the femoral ring. The femoral canal

contains loose connective tissue, fat, lymphatic vessels and sometimes a deep inguinal

lymph node (Cloquets node). The femoral ring is closed by extraperitoneal fatty


4/8

The Lower Limb

tissue forming the femoral septum which is pierced by lymphatic vessels connecting

the inguinal and external iliac lymph nodes.

The Femoral Artery

The femoral artery is the continuation of the external iliac artery.

It begins at the inguinal ligament and enters the femoral triangle deep to the ligamentand lateral to the femoral vein. It lies posterior to the fascia lata, and passes through

the femoral triangle to enter the adductor canal. It exits the adductor canal by passing

through the adductor hiatus and becoming the popliteal artery.

The deep artery of the thigh (profunda femoris) arises in the femoral triangle from the

lateral side of the femoral artery. It passes posterior to the femoral artery and vein and

medial to the femur. It leaves the femoral triangle between pectineus and adductor

magnus and gives off perforating arteries to supply adductor magnus and hamstrings.

The circumflex femoral arteries are ussually branches of the deep artery of the thigh.

They anastamose with one another and supply the thigh muscles and the proximal endof the femur.

The obturator artery helps supply the adductor muscles of the thigh. It usually arises

from the internal iliac artery, passes through the obturator foramen and enters the

thigh, dividing into an anterior and posterior branch which anastamose. The posterior

branch gives the artery to the head of the femur.

The Femoral Vein

The femoral vein is the continuation of the popliteal vein, proximal to the adductor

hiatus. The femoral vein enters the femoral sheath lateral to the femoral canal and

ends posterior to the inguinal ligament where it becomes the external iliac vein.

The femoral vein receives the deep vein of the thigh, the great saphenous vein and

other tributaries.

Gluteal Region Gluteal Nerves

Several important nerves arise from the sacral plexus and either supply the gluteal

region or pass through to supply the perineum or thigh.

Superficial Gluteal Nerves

The skin of the gluteal region is richly innervated by superior, middle and inferior

clunial nerves.

Deep Clunial Nerves

The deep gluteal nerves are:

- sciatic nerve

- posterior cutaneous nerve of thigh

- superior gluteal nerve

- inferior gluteal nerve

- nerve to quadratus femoris


5/8

The Lower Limb

- pudendal nerve

- nerve to obturator internus

The Sciatic Nerve

The largest nerve in the body is formed from the ventral rami of L4-S3. It passes

through the inferior part of the greater sciatic foramen and emerges inferior topiriformis. It runs inferolaterally under gluteus maximus, midway between the ischial

tuberosity and the greater trochanter. It receives its own blood supply from the

inferior gluteal artery.

The sciatic nerve supplies no structures in the gluteal region. It supplies the skin of the

foot, most of the leg, the posterior thigh muscles and all leg and foot muscles. It also

supplies branches to alljoints of the lower limb.The sciatic nerve branches into:

- common peroneal nerve

-tibial nerve

Summary of Other Nerves

Nerve Origin Course Distribution

Posterior cutaneous

nerve of thigh

Sacral plexus

(S1-S3)

Leaves pelvis through

greater sciatic foramen

inferior to piriformis

Gives off inferior clunial

nerve; Supplies skin of

buttock, posterior thigh

and calf, lateral perineum

and upper medial thigh

Superior gluteal L4-S1 Leaves pelvis through

greater sciatic forameninferior to piriformis

Innervates gluteus

medius, gluteus minimisand tensor fasciae latae

Inferior gluteal L5-S2 Leaves pelvis through


inferior to piriformis

Supplies gluteus maximus

Nerve to quadratus

femoris

L4, L5, S1 Leaves pelvis through


deep to sciatic nerve

Innervates hip joint,

inferior gemellus and

quadratus femoris

Pudendal nerve S2-S4

Enters gluteal region

through greater sciaticforamen, enters

perineum through lesser

sciatic foramen

Supplies perineum;supplies no structures in

gluteal region

Nerve to obturator

internus

L5, S1, S2

Enters gluteal region

through greater sciatic

foramen, descends

posterior to ischial

spine and enters lesser

sciatic foramen

Supplies superior

gemellus and obturator

internus

Gluteal Arteries


6/8

The Lower Limb

The gluteal arteries arise, directly of indirectly, from the internal iliac artery:

- superior gluteal artery

- inferior gluteal artery

- internal pudendal artery

The Popliteal Fossa

The popliteal fossa is the diamond-shaped depression of the posterior aspect of theknee. The fossa is bounded superiorly by the hamstrings and inferiorly by the two

heads of gastrocnemius and plantaris. All important vessels and nerves from the thigh

to the leg pass through this fossa.

The fossa is formed:

- superolaterally by biceps femoris

- superomedially bysemimebranosus, lateral to which issemitendinosus

- inferolaterally and inferomedially bygastrocnemius

- posteriorly (roof) byskin and fascia

- anteriorly (floor) bypopliteal surface of femur and popliteal fascia over popliteus

The contents of the fossa are:

- small saphenous vein

- popliteal arteries and veins

- tibial and common peroneal nerves

- posterior cutaneous nerve of thigh

- popliteal lymph nodes and lymphatic vessels

The popliteal artery is the continuation of the femoral artery and begins when this

artery passes through the adductor hiatus. It passes through the popliteal fossa andends at the inferior border of popliteus by dividing into anterior and posterior tibialarteries. Fivegenicular branches supply the knee joint They participate in the

foramtion of the genicular anastamosis, a network of vessels around the knee.

The popliteal vein is formed at the distal border of the popliteus. The popliteal vein

has several valves and ends at the adductor hiatus by becoming continuous with the

femoral vein. Thesmall saphenous veinpierces the deep popliteal fascia and empties

into the popliteal vein.

The sciatic nerve ususally ends at the superior angle of the popliteal fossa by

dividing into the tibial and common peroneal nerves.

The tibial nerve is the medial and larger terminal branch of the sciatic nerve. While in

the fosssa it gives branches to:

- soleus

- gastrocnemius

- plantaris

- popliteus

A medial sural nerve derives from the tibial nerve and joins with the lateral sural

nerve to form the sural nerve which supplies the lateral leg and ankle cutaneously.

The common peroneal nerve is more lateral and leaves the fossa by passing

superficial to the lateral head of gastrocnemius and over the posterior aspect of the

head of the fibula. It winds around the fibular neck and divided into terminal branches deep and superficial peroneal nerves.


7/8

The Lower Limb

Lymph Nodes in the Popliteal Fossa

Superficial Popliteal Lymph nodes lymph from small saphenous vein

Deep Popliteal Lymph nodes lymph from knee joint and arteries of leg.

This lymph follows the femoral vessels to the deep inguinal lymph nodes.

Anterior Compartment of LegThe nerve in the anterior compartment of the leg is the deep peroneal nerve.

It accompanies the anterior tibial artery which ends at the ankle joint midway

between the malleoli, becoming the dorsalis pedis artery, or dorsal artery of the foot.

Lateral Compartment of the Leg

The superficial peroneal nerve is the nerve of the lateral compartment. It supplies

skin on the dital part of the leg and most of the dorsum of the foot.

The lateral compartment does not have an artery; the muscles are supplied by

branches of the anterior tibial artery and perforating branches of the fibular artery.

Posterior Compartment of the LegThe tibial nerve leaves the popliteal fossa between the two heads of gastrocnemius

and supplies all the muscles in the posterior compartment of the leg, both superficial

and deep. At the ankle the nerve lies between the flexor hallucis longus and the flexor

digitorum longus. The tibial nerve divides into the medial and lateral plantar nerves.A branch of the tiobial nerve, the medial sural nerve joins the lateral sural nerve to

form the sural nerve which supplies skin on the lateral and posterior leg and the

lateral foot.

The posterior tibial arteryprovides the main blood supply to this compartment and

to the foot

Summary of the Nerves of the Leg

Nerve Origin Course Distribution

Saphenous nerve Femoral nerve

Descends through

femoral triangle and

adductor canal then

follows great saphenous

vein

Skin on medial side of

foot

Sural nerve Tibial nerve

and common

peroneal nerve

Descends between heads

of gastrocnemius, then

with small saphenous

vein to lateral foot

Skin on posterior and

lateral leg

Skin on lateral foot

Tibial nerve Sciatic nerve

Descends through

popliteal fossa, runs with

posterior tibial vessels,

divides into medial and

lateral planter nerves at

flexor retinaculum

Posterior muscles of leg

Knee joint

Commonperoneal nerve

Sciatic nerve

Through popliteal fossa,

around neck of fibula,

divides into deep and

superficial nerves

Skin on lateral posterior

leg via lateral sural

cutaneous nerve

Superficial CommonDescends in lateralcompartment of leg, Peroneus longus and


8/8

The Lower Limb

peroneal nerve peroneal nerve pierces fascia to becomesubcutaneous

brevis; skin on anterior

leg and dorsum of foot

Deep peroneal

nerve

Common

peroneal nerve

Descends on interosseus

membrane, crosses tibia

to enter dorsum of foot

Anterior muscles of leg

Dorsum of foot

The Foot

Other Components of Lower Limb

Documents

Transcript of Other Components of Lower Limb