The lower extremity

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The lower extremity

• Lecture 8
• Handout
• BryanLGH College of Health Sciences

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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

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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

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• popliteal fossa ? posterior to the knee joint
• major contents of the popliteal fossa
• popliteal artery
• popliteal vein
• tibial and common fibular nerves

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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

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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

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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

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• 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)

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• 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.

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• 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

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• 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

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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

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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

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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.

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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)

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• 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

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• 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

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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

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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

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• 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

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• 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

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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

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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

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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

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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

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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.

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• 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

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• 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

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• 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

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• 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

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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

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• 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

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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

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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

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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

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• 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

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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

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• 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

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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

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• 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

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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

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• 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

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Muscles of the gluteal region

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

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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)

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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

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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

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• 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

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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

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• 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

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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

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Muscles of the anterior compartment of thigh

• Psoas major
• Iliacus
• Vastus medialis
• Vastus intermedius
• Vastus lateralis
• Rectus femoris
• Sartorius

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Muscles of the medial compartment of thigh

• Gracilis
• Pectineus
• Adductor longus
• Adductor brevis
• Adductor magnus
• Obturator externus

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Muscles of the posterior compartment of thigh

• Biceps femoris
• Semitendinosus
• Semimembranosus

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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

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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

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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

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• 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

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• 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

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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)

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• 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

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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

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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

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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

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Superficial group of muscles in the posterior
compartment of leg

• Gastrocnemius
• Plantaris
• Soleus

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Deep group of muscles in the posterior
compartment of leg

• Popliteus
• Flexor hallucis longus
• Flexor digitorum longus
• Tibialis posterior

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Muscles of the lateral compartment of leg

• Fibularis longus
• Fibularis brevis

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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

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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)

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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

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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

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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

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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

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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

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Arteries

• branches of the
• posterior tibial
• dorsalis pedis (dorsal artery of the foot)

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Nerves

• foot is supplied by
• Tibial
• Deep fibular
• Superficial fibular
• Sural
• Saphenous