Lower Limb Anatomy

• The anatomy of the lower limbs is outlined in the following notes.

Pelvic Girdle

• The coxal bone (hip bone) consists of the pubis, ischium, and ilium.
• The coxal bone is flat and irregularly shaped with two surfaces, four borders, and four angles.
• The two coxal bones are connected anteriorly by the pubic symphysis and posteriorly by the sacroiliac joint.
• The sacrum articulates superiorly with vertebra L5 at the lumbosacral joint.
• The pelvic bones articulate posteriorly with the sacrum at the sacro-iliac joints and anteriorly with each other at the pubic symphysis.

Coxal Bone Borders

• Anterior border: ASIS (anterior superior iliac spine) is the origin for the sartorius and tensor latae muscles, AIIS (anterior inferior iliac spine) is the origin for the rectus femoris, pectineal surface for pectineus muscle, pectineal crest, and pubic spine for rectus abdominis and pyramidalis muscle.
• Superior border: iliac crest serve as the origin for the external and internal obliques, as well as the transversus abdominis muscle.
• Posterior border: includes the greater sciatic notch, sciatic spine, and ischial tuberosity.
• Inferior border: medially, it is the origin of the levator ani and transversus perinei muscles; laterally, it is the origin of the adductor longus, brevis, and magnus muscles.

Ilium

• Anteriorely, the arcuate line separates the upper and lower parts of the ilium.
• The superior margin forms the iliac crest, which is a site for muscle attachment and terminates as the anterior or posterior iliac spine.
• The anterior inferior iliac spine (AIIS) is the attachment site for the rectus femoris muscle and iliofemoral ligament.
• The iliac tubercle is prominent and posterior.
• The posterior inferior iliac spine (PIIS) forms the superior margin of the greater sciatic notch.
• The hip joint is formed by the articular socket of the pelvic bone (acetabulum) and the head of the femur.

Thigh Bone (Femur)

• The femur is a long bone with two extremities and a diaphysis (shaft).
• It exhibits anterior convexity and posterior concavity.
• The diaphysis is prismatic, having three faces and three borders.
• The gluteal tuberosity serves as the attachment for the gluteus maximus.
• The posterior border, known as the linea aspera, has three parts: middle, upper, and lower.

Proximal End of Femur

• Features include the femur head with fovea capitis and the femur neck.
• The intertrochanteric line separates the trochanters.
• The greater (lateral) trochanter serves as an attachment site for the gluteus medius, gluteus minimus, and piriformis muscles.
• The lesser (medial) trochanter serves as the attachment for the iliopsoas muscle.

Distal End of Femur

• Features include the lateral and medial condyles, femoral trochlea, intercondylar notch, and popliteal fossa (posterior knee joint).

Patella

• The patella is a sesamoid bone, or kneecap, with an inverted triangular shape, featuring a superior base and an inferior apex.
• It has two surfaces: anterior and posterior.
• The anterior surface is convex and rough.
• The posterior surface is divided into a superior smooth surface and an inferior non-articular surface.
• The base serves as the attachment site for the quadriceps tendon.
• The apex is for the patellar ligament.

Leg Skeleton

• Composed of the tibia and fibula.

Tibia

• The Tibia is the medial and larger bone of the leg.
• It has a diaphysis and 2 extremities
• The diaphysis is triangular with 3 surfaces (medial, lateral, posterior) and 3 borders.

Proximal End of Tibia

• The proximal end is large and quadrangular
• It features two articular surfaces: the medial and lateral glenoid cavities which articulate with the lateral and medial femoral condyles.
• The intercondylar eminence is present.
• There are three tuberosities: medial tibial, lateral tibial, and anterior tibial.

Distal End of Tibia

• The distal end is cuboid with 6 faces.
• The superior face attaches to the diaphysis.
• The inferior face articulates with the superior surface of the talus.
• Grooves for tendons are present on the anterior and posterior faces.
• The lateral face articulates with the distal fibula.
• The medial face extends downward to form the medial malleolus, which articulates with the medial surface of the talus.

Fibula

• The fibula is the lateral and thinner bone of the leg.
• Has a diaphysis and 2 extremities
• The diaphysis is triangular with 3 faces (medial, lateral, posterior) and 3 borders.
• Proximal end includes the fibular head and styloid process.
• The medial face has an articular surface.
• The fibular neck connects to the distal end: the lateral malleolus articulates with the lateral side of the talus and provides attachment for the collateral ligament of the ankle.

Skeleton of Foot

• The skeleton of the foot has 26 bones, divided into the tarsus, metatarsus, and phalanges.

Tarsus

• The Tarsus has 7 bones divided into 2 parts

Proximal Part of Tarsus

• Talus (astragalus): cube-shaped with three segments: head, neck, body; articulates superiorly with the distal end of the tibia, inferiorly with the calcaneus, anteriorly with the navicular, laterally with the fibula, and medially with the lateral surface of the talus.
• Calcaneus: the largest bone of the tarsus, cube-shaped with 6 surfaces.

Distal Part of Tarsus

• Cuboid: cube-shaped, located in front of the calcaneus; articulates anteriorly with the 4th and 5th metatarsals and medially with the 3rd cuneiform.
• Navicular: boat-shaped, medial, articulates posteriorly with the head of the talus and anteriorly with the 3 cuneiform bones.
• Cuneiform bones: named 1-3 from medial to lateral; articulate anteriorly with the first four metatarsals, posteriorly with the navicular, and laterally with the cuboid.

Metatarsus

• The Metatarsus has 5 bones named 1-5 from medial to lateral, each having a shaft, proximal end, and distal end.

Phalanges

• The first toe (hallux) has two phalanges (proximal, distal).
• The other four toes each have three phalanges: proximal, middle, and distal.
• Each phalanx has a shaft, proximal end (base), and distal end (head).

Muscles

• Sciatic nerve supplies the muscles of the lower limb.
• Nerves of the medial compartment: obturator nerve
• Nerves of the anterior compartment: femoral nerve
• Nerves of the posterior compartment: sciatic nerve
• Medial thigh muscles are adductors of the hip joint.
• Anterior thigh muscles are flexors of the hip joint and extensors of the knee joint.
• Posterior thigh muscles are extensors of the hip joint and flexors of the knee joint.

Six Thigh Muscles of the Medial Compartment

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

Five Thigh Muscles of the Anterior Compartment

• Sartorius
• 4 quadriceps muscles;
• Rectus femoris
• Vastus medialis,
• Vastus lateralis
• Vastus intermedius

Three Thigh Muscles of the Posterior Compartment

• Biceps femoris
• Semimembranosus
• Semitendinous muscles

Four Gluteal Muscles (Posterior Side Hip Bone)

• Gluteus maximus
• Gluteus medius
• Gluteus minimus
• Tensor fasciae latae

Nine Inner Hip Muscles (Anterior Side of Pelvis)

• Iliacus
• Psoas major
• Psoas minor
• Obturator externus
• Obturator internus
• Superior gemelli
• Inferior gemelli
• Piriformis
• Quadratus femoris

Arteries of Lower Limb

• Thigh & Gluteal Region arteries consist of extrapelvic branches of the Internal iliac artery, Gluteal artery, Sciatic artery,Internal Pudendal artery

Femoral Artery

• Origin: Follows external iliac artery under inguinal ligament
• Scarpa Femoral Triangle Region
• Path: runs downward medial posteriorly joining crural arch and medial femoral condyle Artery has 5 Collateral branches
  • Superficial circumflex iliac artery
  • SuperficiaL epigastric artery
  • SUperficial external pudendal artery
  • Deep external pudendal artery
  • Profunda femoris artery

Profunda Femoris Artery

• The profunda femoris artery supplies main collateral artery to the hip & thigh its terminal branches

  • Anterior & Posterior Circumflex Arteries
  • Quadriceps artery
  • Perforating arteries

• Termination: femoral artery is continued by popliteal artery

Popliteal Artery

• Origin: follows femoral at third adductor ring
• Path: vertical, axis of popliteal fossa
• 7 Collateral branches
  • 5 articular arteries of knee
  • 2 gastrocnemius muscles
• Termination: end at ring of soleus muscle and gives rise to anterior tibial artery & tibioperoneal trunk
• Popliteal artery runs along popliteal fossa and connect with popliteal nerve and internal popliteal sciatic nerve located behind it

Leg Arteries

• Anterior Tibial artery:
  • Arises from popliteal artery
  • Passes over interosseous membrane to anterior compartments
  • Continues as pedal artery
  • It gives rise to:
    • Recurrent branches (tibial and peroneal)
    • Muscles branches for muscles anterior compartment

Tibio-Peroneal Trunk

• The Tibio-peroneal trunk:
  • Arises from bifurcation popliteal artery
  • Descends vertically into posterior compartment of leg
  • Terminates bifurcation into posterior tibial artery and peroneal artery
• Peroneal artery supplies fibula and peroneal muscles
• Posterior Tibial artery supplies posterior compartment of leg gives rise to internal and external plantar arteries
• Sciatic nerve branches into deep Fibular Nerve and Tibial nerves innervate the leg and foot

Foot Arteries

• Pedal artery innervates dorsum foot
• Runs on dorsal surface and terminates indorsal interosseous artery
• Internal and external plantar arteries innervate sole of foot
• Internal plantar artery is internal bifurcation branch of posterior tibial artery on medial border foot
• External plantar artery is external bifurcation branch of posterior tibial artery on lateralborder foot

Venous Drainage

• The superficial venous network has two main trunks:
  • Greater Saphenous vein: originates anterior to medial malleolus runs inside leg and knee and ascends to saphenofemoral junction
  • Lesser Saphenous vein: originates lateral border of foot runs upward to popliteal fossa joining popliteal vein
• The deep venous network consists of satellite veins of arteries, with 2 satellite veins per artery except for popliteal and femoral.
• Lymphatics: Lyphatic vessels lead to inguinal and retrocrural lymph does & inguinal nodes occupy femoral Scarpa triangle & receive from external genitalia and abdominal wall

Thigh Region

• The thigh region has 3 muscular compartments: anterior, medial, and posterior.

Anterior Region of Thigh

• Sartorius muscle
• Quadriceps muscles
  • Rectus Femoris
  • Vastus medialis
  • Vastus Lateralis
  • Vastus Intermedius

Gluteal Region

• The gluteal region has 2 layers: a superficial and a deep layer.
• Superficial Layer:
  • Gluteus maximus muscle
  • Tensor fascia latae muscle
  • Iliotibial tract
• Deep Layer:
  • Gluteus medius muscle
  • Gluteus minimus
  • Piriformis
  • Pelvic muscles

Pelvic Muscles

• Superior Gemellus Muscle
• Obturator internist
• Inferior Gemellus Muscle
• Obturator externus
• Quadratus Femoris

Limits of the Femoral Triangle

• The limits of the femoral triangle have;
  • Inguinal Ligament superiorly
  • Adductor Longus laterally
  • Sartorius Muscle medially

Contents of the Femoral Triangle

• Femoral nerve, artery, vein
• Iliac
• Superior circumflex artery
• Superficial epigastric artery
• Superficial external pudendal artery
• Deep External Pudendal artery

Foot Muscles

• Middle Compartment:
  • Middle plantar fascia
  • Digitorum brevis muscle
  • Flexor digitorum muscle accessories
  • Terminals tendons of flexor digitorum longus last four toes
  • Four lumbrical muscles
• Medial Compartment:
  • Muscles of big toe
    • Abductor hallucis
    • Halucis brevis
    • adductor hallucis
• Lateral Compartment:
  • Muscles of 5th toe
    • Abductor digiti minimi
    • Flexor digiti minimi