The lower extremity

Lecture 8

Handout

BryanLGH College of Health Sciences

The lower limb• directly anchored to the axial skeleton

sacroiliac joint + ligaments link the pelvic bone to the sacrum

• divided into:• Gluteal region posterolateral and between

the iliac crest and the fold of skin (gluteal fold; defines the lower limit of the buttocks)

• Thigh (anteriorly) between the inguinal ligament and the knee joint

• Leg between the knee and ankle joint • Foot distal to the ankle joint

The femoral triangle and popliteal fossa

• important areas of transition through which structures pass between regions

• femoral triangle pyramid-shaped depression formed by muscles in the proximal regions of the thigh and by the inguinal ligament

• blood supply and femoral nerve enter into the thigh from the abdomen passing under the inguinal ligament and into the femoral triangle

continued

• popliteal fossa posterior to the knee joint

• major contents of the popliteal fossa:

• popliteal artery

• popliteal vein

• tibial and common fibular nerves

FUNCTION -- Support the body weight

• standing erect center of gravity is anterior to the edge of the SII vertebra in the pelvis

• organization of ligaments at the hip and knee joints + the shape of the articular surfaces, (particularly at knee) facilitates 'locking' of these joints

Locomotion

• integration of movements at all joints in the lower limb

• at the hip joint flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction

• at knee flexion and extension• at ankle dorsiflexion (movement of the

dorsal side of foot towards the leg) and plantarflexion

RELATIONSHIP TO OTHER REGIONS

• four major entry and exit points between the lower limb and the abdomen, pelvis, and perineum:

• the gap between the inguinal ligament and pelvic bone

• the greater sciatic foramen• the obturator canal (at the top of the obturator

foramen)• the lesser sciatic foramen• Abdomen • lower limb + abdomen communicate directly

through a gap between the pelvic bone and the inguinal ligament

continued

• Structures:• muscles-psoas major, iliacus, and pectineus • femoral and femoral branch of the genitofemoral

nerves, lateral cutaneous nerve • femoral artery and vein • lymphatics• The gap between the pelvic bone and the

inguinal ligament weak area in the abdominal wall, often associated femoral hernia(usually occurs where the lymphatic vessels pass through the gap = the femoral canal)

continued

• Pelvis • Structures within the pelvis communicate with

the lower limb through two major apertures:• Posteriorly through the greater sciatic

foramen and include: • a muscle-piriformis • nerves-sciatic, superior and inferior gluteal, and

pudendal nerves• vessels-superior and inferior gluteal arteries and

veins, and the internal pudendal artery.

• sciatic nerve largest peripheral nerve of the body and major nerve of the lower limb

• Anteriorly, through the obturator canal the obturator nerve and vessels pass between the pelvis and thigh

continued

• Perineum • Structures pass through the lesser sciatic

foramen between the perineum and gluteal region:

• most important with respect to the lower limb tendon of the obturator internus muscle

• the internal pudendal artery and pudendal nerve pass out of the pelvis through the greater sciatic foramen into the gluteal region, then immediately pass around the ischial spine and sacrospinous ligament, through the lesser sciatic foramen to enter the perineum

Innervation

• lumbar and sacral plexuses• plexuses formed by the anterior rami of L1 to L3 and

most of L4 (lumbar plexus) and L4 to S5 (sacral plexus)• Terminal nerves exit the abdomen and pelvis through

a number of apertures and foramina and enter the limb• consequence of this innervation lumbar and upper

sacral nerves are tested clinically by examining the lower limb

• clinical signs (as pain, 'pins and needles', paresthesia, and fascicular muscle twitching) resulting from any disorder affecting these spinal nerves (e.g. herniated intervertebral disc in the lumbar region) appear in the lower limb

Dermatomes in the lower limb

• over the inguinal ligament-L1; • lateral side of the thigh-L2; • lower medial side of the thigh-L3; • meidal side of the great toe (digit 1)-L4; • meidal side of digit 2-L5; • little toe (digit 5)-S1; • back of the thigh-S2; • skin over the gluteal fold-S3. • The dermatomes of S4 and S5 are tested in the

perineum

Selected joint movements are used to test myotomes

• flexion of the hip is controlled primarily by L1 and L2;

• extension of the knee is controlled mainly by L3 and L4;

• knee flexion is controlled mainly by L5 to S2; • plantarflexion of the foot is controlled

predominantly by S1 and S2; • adduction of the digits is controlled by S2 and

S3.

Innervation of muscle groups

• large muscles in the gluteal region innervated by the superior and inferior gluteal nerves

• most muscles in the anterior compartment of the thigh innervated by the femoral nerve (except the tensor fasciae latae, which is innervated by the superior gluteal nerve)

• most muscles in the medial compartment innervated mainly by the obturator nerve (except the pectineus, which is innervated by the femoral nerve, and part of the adductor magnus, which are innervated by the tibial division of the sciatic nerve)

continued

• most muscles in the posterior compartment of the thigh and the leg and in the sole of the foot innervated by the tibial part of the sciatic nerve (except the short head of the biceps femoris in the posterior thigh, which are innervated by the common fibular division of the sciatic nerve;

• the anterior and lateral compartments of the leg and muscles associated with the dorsal surface of the foot innervated by the common fibular part of the sciatic nerve

continued

• Sensation from the following areas can be used to test for peripheral nerve lesions:

• the femoral nerve innervates skin on the anterior thigh, medial side of the leg, and medial side of the ankle

• the obturator nerve innervates the medial side of the thigh

• the tibial part of the sciatic nerve innervates the lateral side of the ankle and foot

• the common fibular nerve innervates the lateral side of the leg and the dorsum of the foot

Nerves related to bone

• The common fibular branch of the sciatic nerve curves laterally around the neck of the fibula when passing from the popliteal fossa into the leg

• the nerve can be rolled against bone just distal to the attachment of biceps femoris to the head of the fibula

• In this location the nerve can be damaged by impact injuries, fractures to the bone, or leg casts that are placed too high

Pelvis,lower limb and fractures

• Soft tissue and visceral organ damage must be suspected when the pelvis is fractured

• Pelvic fractures can be associated with:• appreciable blood loss (concealed

exsanguination) • this bleeding tends to form a significant pelvic

hematoma can compress nerves, press on organs, and inhibit pelvic visceral function

continued

• Pelvic fractures are generally of four types: • Type 1 injuries occur without disruption of the

bony pelvic ring (e.g. a fracture of the iliac crest)• unlikely to represent significant trauma• Type 2 injuries occur with a single break in

the bony pelvic ring (e.g. single fracture with diastasis, separation, of the symphysis pubis). relatively benign in nature

continued

• Type 3 injuries occur with double breaks in the bony pelvic ring

• bilateral fractures of the pubic rami may produce urethral damage

• fractures of the pubic rami and disruption of the sacro-iliac joint with or without dislocation significant visceral pelvic trauma and hemorrhage

continued

• Type 4 injuries occur at and around the acetabulum

• also stress fractures and insufficiency fractures, as seen in athletes and elderly patients with osteoporosis

The femur

• bone of the thigh, the longest bone in the body

• proximal end:

• characterized by a head, neck, and two large projections the greater and lesser trochanters

In the clinic-- Blood supply to the femoral head and neck

• extracapsular arterial ring formed around the base of the femoral neck

• medial femoral circumflex artery, branches of the lateral femoral circumflex artery

In the clinic -- Femoral neck fractures

• Most femoral neck fractures intracapsular and disrupt the cervical vessels femoral head may necrose

• typical fracture at and around the hip joint intertrochanteric fracture

• preserve the femoral neck blood supply and do not render the femoral head ischemic

• Femoral shaft fracture• accompanied by damage to the surrounding soft

tissues

Nerves that enter the lower limb from the abdomen and pelvis

• Femoral nerve • contributions from the anterior rami of L2 to L4 • innervates all muscles in the anterior

compartment of the thigh • gives rise to branches that innervate the iliacus

and pectineus muscles • innervates skin over the anterior aspect of the

thigh, anteromedial side of the knee, the medial side of the leg, and the medial side of the foot.

continued

• Obturator nerve • originates from L2 to L4• innervates: • all muscles in the medial compartment of the

thigh, except the part of adductor magnus muscle that originates from the ischium and the pectineus muscle innervated by the sciatic and the femoral nerves

• the obturator externus muscle• skin on the medial side of the upper thigh

continued

• Sciatic nerve • contributions from L4 to S3• in the posterior compartment of the thigh it divides into

its two major branches: • the common fibular nerve• the tibial nerve• innervates: • all muscles in the posterior compartment of the thigh• the part of adductor magnus originating from the ischium• all muscles in the leg and foot• skin on the lateral side of the leg and the lateral side and

sole of the foot

continued

• Gluteal nerves • superior gluteal nerve • contributions from L4 to S1• innervates: • the gluteus medius and minimus muscles • the tensor fasciae latae muscle • inferior gluteal nerve• contributions from L5 to S2• supply the gluteus maximus

continued

• ilio-inguinal nerve

• genitofemoral nerve

• lateral cutaneous nerve of the thigh

• nerve to quadratus femoris

• nerve to obturator internus

• posterior cutaneous nerve of the thigh

• perforating cutaneous nerve

Arteries

• Femoral artery• continuation of the external iliac artery in

the abdomen• Branches supply most of the thigh and all

of the leg and foot• superior and inferior gluteal arteries

originate in the pelvic cavity as branches of the internal iliac artery

• supply the gluteal region

continued

• obturator artery a branch of the internal iliac artery in the pelvic cavity

• supply the medial compartment of the thigh • Branches of the femoral, inferior gluteal, superior

gluteal and obturator arteries, together with branches from the internal pudendal artery of the perineum interconnect to form an anastomotic network in the upper thigh and gluteal region

• anastomotic channels provide collateral circulation when one of the vessels is interrupted

Veins

• draining the lower limb form superficial and deep groups

• The deep veins generally follow the arteries (femoral, superior gluteal, inferior gluteal, and obturator)

• major deep vein femoral vein becomes the external iliac vein when it passes under the inguinal ligament to enter the abdomen

• The superficial veins in the subcutaneous connective tissue

contined

• the great saphenous vein originates from the medial side of the dorsal venous arch, and then ascends up the medial side of the leg, knee, and thigh to connect with the femoral vein

• the small saphenous vein originates from the lateral side of the dorsal venous arch, ascends up the posterior surface of the leg, penetrates deep fascia to join the popliteal vein posterior to the knee

• proximal to the knee popliteal vein becomes the femoral vein

In the clinic -- Varicose veins• normal flow of blood in the venous system

depends upon the presence of competent valves, which prevent reflux

• Venous return supplemented with contraction of the muscles in the lower limb, which pump the blood towards the heart

• venous valves become incompetent tend to place extra pressure on more distal valves may also become incompetent

continued

• this condition produces dilated tortuous superficial veins = varicose veins in the long and short saphenous venous systems

• Typical sites for valvular incompetence include:

• junction between the long saphenous vein and the femoral vein, perforating veins in the mid-thigh, and the junction between the short saphenous vein and the popliteal vein

Lymphatics

• drain into superficial and deep inguinal nodes in fascia just inferior to the inguinal ligament

• The superficial inguinal nodes in the superficial fascia and parallel the course of the inguinal ligament in the upper thigh

• receive lymph from the gluteal region, lower abdominal wall, perineum, and superficial regions of the lower limb

• The deep inguinal nodes receive lymph from deep lymphatics associated with the femoral vessels and from the glans penis (or clitoris) in the perineum

• The popliteal nodes receive lymph from superficial vessels, drain into the deep and superficial inguinal nodes

continued

• Deep fascia and the saphenous opening

• Fascia lata • The outer layer of deep fascia in the lower

limb forms a thick 'stocking-like' membrane covers the limb and lies beneath the superficial fascia

• particularly thick in the thigh and gluteal region termed the fascia lata

In the clinic -- Vascular access to the lower limb

• Deep and inferior to the inguinal ligament the femoral artery and femoral vein

• femoral artery palpable as it passes over the femoral head, may be easily demonstrated using ultrasound

• arterial or venous access is needed rapidly a physician can use the femoral approach to these vessels

• radiological procedures involve catheterization of the femoral artery or the femoral vein to obtain access to:

continued

• contralateral lower limb, ipsilateral lower limb, vessels of the thorax and abdomen, cerebral vessels

• femoral artery place catheters in vessels around the arch of the aorta and into the coronary arteries to perform coronary angiography and angioplasty

• femoral vein catheters into the renal veins, the gonadal veins, the right atrium, and right side of the heart including the pulmonary artery and distal vessels of the pulmonary tree

GLUTEAL REGION

• lies posterolateral to the bony pelvis and proximal end of the femur

• Muscles in the region mainly abduct, extend, and laterally rotate the femur relative to the pelvic bone

• communicates anteromedially with the pelvic cavity and perineum through the greater and lesser sciatic foramina

• sciatic nerve enters the lower limb from the pelvic cavity by passing through the greater sciatic foramen and descending through the gluteal region into the posterior thigh and then into the leg and foot

continued

• pudendal nerve and internal pudendal vessels pass between the pelvic cavity and perineum by passing through the greater sciatic foramen to enter the gluteal region then immediately pass through the lesser sciatic foramen to enter the perineum

• other nerves and vessels passing through the greater sciatic foramen from the pelvic cavity supply structures in the gluteal region itself

Muscles of the gluteal region

• Piriformis• Obturator internus• Gemellus superior• Gemellus inferior• Quadratus femoris• Gluteus minimus• Gluteus medius• Gluteus maximus• Tensor fasciae latae

Nerves in gluteal region

• Seven nerves enter the gluteal region from the pelvis through the greater sciatic foramen:

• the superior gluteal nerve• sciatic nerve• nerve to the quadratus femoris• nerve to the obturator internus• posterior cutaneous nerve of the thigh• pudendal nerve• inferior gluteal nerve• (perforating cutaneous nerve, enters the gluteal region

by passing directly through the sacrotuberous ligament)

In the clinic -- Intramuscular injections

• to administer drugs intramuscularly direct injection into muscles

• without injuring neurovascular structures• typical site gluteal region• safest place to inject is the upper outer quadrant of either

gluteal region• gluteal region divided into quadrants by two imaginary

lines • anterior corner of the upper lateral quadrant normally

used for injections to avoid injuring any part of the sciatic nerve or other nerves and vessels in the gluteal region

• needle placed in this region enters the gluteus medius anterosuperior to the margin of the gluteus maximus

Arteries

• Inferior gluteal artery • originates from the anterior trunk of the

internal iliac artery in the pelvic cavity• leaves the pelvic cavity with the inferior

gluteal nerve through the greater sciatic foramen

• supplies adjacent muscles and descends through the gluteal region and into the posterior thigh

continued

• Superior gluteal artery • originates from the posterior trunk of the internal

iliac artery in the pelvic cavity• leaves the pelvic cavity with the superior gluteal

nerve through the greater sciatic foramen • divides into a superficial branch and a deep

branch: • the superficial branch passes onto the deep

surface of the gluteus maximus muscle• the deep branch passes between the gluteus

medius and minimus muscles

THIGH • the region of the lower limb, approximately

between the hip and knee joints • Structures enter and leave the top of the thigh by

three routes: • Posteriorly the thigh is continuous with the

gluteal region• major structure passing between the two regions

is the sciatic nerve• Anteriorly thigh communicates with the

abdominal cavity through the aperture between the inguinal ligament and pelvic bone

continued

• major structures passing through this aperture are the iliopsoas and pectineus muscles, the femoral nerve, artery and vein, and lymphatic vessels

• Medially structures (including the obturator nerve and associated vessels) pass between the thigh and pelvic cavity through the obturator canal

Thigh is divided into three compartments

• by intermuscular septa • the anterior compartment of thigh contains

muscles that mainly extend the leg at the knee joint

• the posterior compartment of thigh contains muscles that mainly extend the thigh at the hip joint and flex the leg at the knee joint

• the medial compartment of thigh consists of muscles that mainly adduct the thigh at the hip joint

Muscles of the anterior compartment of thigh

• Psoas major

• Iliacus

• Vastus medialis

• Vastus intermedius

• Vastus lateralis

• Rectus femoris

• Sartorius

Muscles of the medial compartment of thigh

• Gracilis

• Pectineus

• Adductor longus

• Adductor brevis

• Adductor magnus

• Obturator externus

Muscles of the posterior compartment of thigh

• Biceps femoris

• Semitendinosus

• Semimembranosus

In the clinic -- Muscle injuries to the lower limb

• Muscle injuries a result of direct trauma or as part of an overuse syndrome

• minor muscle tear demonstrated as a focal area of fluid within the muscle

• increasingly severe injuries more muscle fibers are torn may result in a complete muscle tear

• usual muscles in the thigh that tear hamstring muscles

• tears in the muscles below the knee typically within the soleus muscle

Arteries

• Three arteries enter the thigh: • the femoral artery• the obturator artery• the inferior gluteal artery• femoral artery largest and supplies

most of the lower limb• all three arteries contribute to an

anastomotic network of vessels around the hip joint

In the clinic -- Peripheral vascular disease

• characterized by reduced blood flow to the legs• may be due to stenoses (narrowings) and/or occlusions

(blockages) in the lower aorta, iliac, femoral, tibial, and fibular vessels

• Patients typically present with chronic leg ischemia and 'acute on chronic' leg ischemia

• Chronic leg ischemia• vessels have undergone atheromatous change and often

there is significant luminal narrowing (usually over 50%)• Some patients develop such severe ischemia that the

viability of the limb is threatened = critical limb ischemia

continued

• commonest symptom of chronic leg ischemia intermittent claudication

• history of pain that develops in the calf muscles (usually associated with occlusions or narrowing in the femoral artery) or the buttocks (usually associated with occlusion or narrowing in the aortoiliac segments)

• pain experienced in these muscles cramp-like and occurs with walking

continued

• Acute on chronic ischemia• acute event blocks the vessels or reduces

the blood supply to such a degree that the viability of the limb is threatened

• Critical limb ischemia• blood supply to the limb is so poor that the

viability of the limb is severely threatened• many patients present with gangrene,

ulceration, and severe rest pain in the foot

Knee joint

• the largest synovial joint in the body• consists of: • the articulation between the femur and tibia

(weightbearing)• the articulation between the patella and the femur

(allows the pull of the quadriceps femoris muscle to be directed anteriorly over the knee to the tibia without tendon wear)

• Two fibrocartilaginous menisci (one on each side, between the femoral condyles and tibia accommodate changes in the shape of the articular surfaces during joint movements)

continued

• knee joint reinforced by collateral ligaments, one on each side of the joint

• two very strong ligaments (the cruciate ligaments) interconnect the adjacent ends of the femur and tibia and maintain their opposed positions during movement

In the clinic -- Soft tissue injuries to the knee

• common at and around the knee joint• typical injuries include:• tears of the anterior and posterior cruciate

ligaments, meniscal tears, and trauma to the collateral ligaments

• Any soft tissue injury at and around the knee joint may involve the neurovascular bundle and assessment of neurovascular structures is critical in the management of patients with injury to the soft tissues

Degenerative joint disease/Osteoarthritis

• occurs throughout many joints within the body• Typically degenerative joint disease occurs in

synovial joints = osteoarthritis• typical findings include: reduction in the joint

space, eburnation (joint sclerosis), osteophytosis (small bony outgrowths), and bony cyst formation

• in the lower limb the hip and knee are typically affected

LEG

• part of the lower limb between the knee joint and ankle joint

• bony framework of the leg:• tibia • fibula• leg is divided into anterior (extensor), posterior (flexor),

and lateral (fibular) compartments by: • an interosseous membrane • two intermuscular septa• direct attachment of the deep fascia to the periosteum of

the anterior and medial borders of the tibia

Superficial group of muscles in the posterior compartment of leg

• Gastrocnemius

• Plantaris

• Soleus

Deep group of muscles in the posterior compartment of leg

• Popliteus

• Flexor hallucis longus

• Flexor digitorum longus

• Tibialis posterior

Muscles of the lateral compartment of leg

• Fibularis longus

• Fibularis brevis

FOOT

• the region of the lower limb distal to the ankle joint

• subdivided into the:• Ankle• Metatarsus• Digits• foot has a superior surface = dorsum of foot• inferior surface = sole

Bones

• There are three groups of bones:

• the seven tarsal bones form the skeletal framework for the ankle

• metatarsals (I to V) the bones of the metatarsus

• phalanges the bones of the toes -each toe has three phalanges, except for the great toe (two)

In the clinic -- Fracture of the talus

• problems with fractures of the talus blood supply to the bone is vulnerable to damage

• main blood supply to the bone enters the talus through the tarsal canal from a branch of the posterior tibial artery

• Fractures of the neck of the talus often interrupt the blood supply to the talus making the body and posterior aspect of the talus susceptible to osteonecrosis may in turn lead to premature osteoarthritis

Flexor retinaculum

• is a strap-like layer of connective tissue that spans across the bony depression formed by the malleolus, talus, calcaneus, sustentaculum tali

• retinaculum continuous above with the deep fascia of the leg and below with deep fascia (plantar aponeurosis) of the foot

• Septa from the flexor retinaculum convert grooves on the bones into tubular connective tissue channels for the tendons of the flexor muscles as they pass into the sole of the foot from the posterior compartment of leg free movement of the tendons in the channels

Arches of the foot

• The bones of the foot form longitudinal and transverse arches relative to the ground

• Longitudinal arch • formed between the posterior end of the

calcaneus and the heads of the metatarsals • Transverse arch • highest in a coronal plane that cuts through the

head of the talus and disappears near the heads of the metatarsals

Intrinsic muscles of the foot

• originate and insert in the foot• there is one intrinsic muscle extensor

digitorum brevis on the dorsal aspect of the foot

• other intrinsic muscles:• dorsal and plantar interossei• flexor digiti minimi brevis• flexor hallucis brevis• flexor digitorum brevis

continued

• quadratus plantae (flexor accessorius)

• abductor digiti minimi

• abductor hallucis

• lumbricals

• all are on the plantar side of the foot

• are organized into four layers

Arteries

• branches of the:

• posterior tibial

• dorsalis pedis (dorsal artery of the foot)

Nerves

• foot is supplied by:

• Tibial

• Deep fibular

• Superficial fibular

• Sural

• Saphenous