Lower Limb Anatomy: Vessels, Nerves, Special Areas, Muscles, Bones, and Joints

Vocabulary flashcards covering anatomical terminology, pathways, compartments, muscles, innervation, blood supply, bones, and joints of the lower limb based on lecture content.

Abdominal Aorta Bifurcation

The point at spinal cord level $L4$ where the descending abdominal aorta divides into the right and left common iliac arteries.

Internal Iliac Artery

A branch of the common iliac artery that supplies pelvic structures and gives off the obturator artery, superior gluteal artery, and inferior gluteal artery.

External Iliac Artery Tree

The major arterial pathway for the lower limb, passing deep to the inguinal ligament as the femoral artery, transitioning to the popliteal artery at the adductor hiatus, and dividing into anterior and posterior tibial arteries.

Deep Femoral Artery

A non-terminal branch off the femoral artery that branches dorsilaterally to supply deep structures of the thigh.

Dorsalis Pedis Artery

The arterial vessel formed at the ankle joint as the direct continuation of the anterior tibial artery onto the dorsum of the foot.

Fibular Artery

A non-terminal branch originating from the posterior tibial artery that descends toward the lateral compartment in the posterior leg.

Greater Saphenous Vein

A major superficial vein of the lower limb arising from the dorsum of the foot that travels medially up the leg and thigh to drain into the femoral vein.

Lesser Saphenous Vein

A superficial vein located on the posterior aspect of the leg that drains directly into the popliteal vein.

Femoral Nerve ($L2-L4$)

A nerve of the lumbar plexus running superficial to the iliacus muscle and deep to the inguinal ligament that innervates all muscles of the anterior thigh, the iliacus muscle, and half of the pectineus muscle.

Obturator Nerve ($L2-L4$)

A nerve of the lumbar plexus passing medial to the psoas major muscle and entering the thigh through the obturator foramen to innervate all medial thigh muscles.

Superior Gluteal Nerve ($L4-S1$)

A nerve of the sacral plexus exiting the pelvis through the greater sciatic foramen superior to the piriformis muscle to innervate the gluteus medius, gluteus minimus, and tensor fasciae latae muscles.

Inferior Gluteal Nerve ($L5-S2$)

A nerve of the sacral plexus exiting inferior to the piriformis muscle that exclusively innervates the gluteus maximus muscle.

Sciatic Nerve ($L4-S3$)

The largest nerve of the sacral plexus, exiting the pelvis inferior to the piriformis muscle before bifurcating into the tibial and common fibular nerves.

Tibial Nerve ($L4-S3$)

The medial division of the sciatic nerve that innervates posterior thigh muscles (except biceps femoris short head) and all posterior leg muscles before bifurcating into medial and lateral plantar nerves.

Common Fibular Nerve ($L4-S2$)

The lateral division of the sciatic nerve wrapping around the neck of the fibula; innervates only the short head of the biceps femoris muscle before bifurcating into superficial and deep fibular nerves.

Superficial Fibular Nerve

The lateral branch of the common fibular nerve running between fibularis longus and brevis muscles, providing motor innervation to both lateral leg muscles and cutaneous innervation to the dorsum of the foot.

Deep Fibular Nerve

The medial branch of the common fibular nerve that innervates all anterior leg muscles and intrinsic dorsum foot muscles, providing sensory coverage specifically to the flip-flop web space.

Steppage Gait

A characteristic walking pattern caused by foot drop following damage to the common fibular nerve or its branches, resulting in an inability to dorsiflex the ankle and extend the digits.

Femoral Triangle

A region in the superoanterior third of the thigh bounded superiorly by the inguinal ligament, laterally by sartorius, and medially by adductor longus, containing (from medial to lateral) the femoral vein, femoral artery, and femoral nerve.

Adductor Canal

A compartment deep to the sartorius muscle located between the quadriceps femoris and medial femoral muscles that transmits the femoral artery, femoral vein, and saphenous nerve.

Popliteal Fossa

A diamond-shaped space located posterior to the knee joint containing, from deepest to most superficial, the popliteal artery, popliteal vein, tibial nerve, and common fibular nerve.

Tarsal Tunnel

An anatomical space posterior to the medial malleolus bound by the flexor retinaculum, containing from anterior to posterior: Tibialis posterior tendon, Flexor digitorum longus tendon, Posterior tibial artery, Tibial nerve, and Flexor hallucis longus tendon.

Leg Compartmentalization

The division of leg muscles into anterior, lateral, and posterior (superficial and deep) groups enclosed by crural fascia and intermuscular septa.

Tibialis Anterior Muscle

An anterior leg muscle originating from the anterior tibia and interosseous membrane that dorsiflexes and inverts the foot under deep fibular nerve innervation.

Fibularis Longus Muscle

A lateral leg muscle originating from the lateral fibula that inserts onto the base of metatarsal 1 and medial cuneiform to plantar flex and evert the foot via the superficial fibular nerve.

Gastrocnemius Muscle

A superficial posterior leg muscle originating from the medial and lateral femoral condyles that flexes the knee joint and plantar flexes the foot under tibial nerve innervation.

Soleus Muscle

A superficial posterior leg muscle originating from the soleal line of the tibia and fibula that inserts onto the calcaneal tuberosity to plantar flex the foot via the tibial nerve.

Popliteus Muscle

A deep posterior leg muscle originating from the lateral femoral condyle that flexes the knee and medially rotates the tibia to unlock the knee joint.

Extensor Hallucis Brevis Muscle

An intrinsic muscle on the dorsum of the foot originating from the superior surface of the calcaneus that extends the hallux under deep fibular nerve innervation.

Flexor Digitorum Brevis Muscle

A layer 1 plantar foot muscle originating from the calcaneus and plantar aponeurosis that flexes digits $2-5$, innervated by the medial plantar nerve.

Fascia Lata

The deep fascia investing the muscles of the thigh, reinforced laterally by the thickened iliotibial tract.

Gluteus Maximus Muscle

A superficial gluteal muscle originating from the posterior ilium, sacrum, and coccyx that extends and laterally rotates the hip joint, innervated by the inferior gluteal nerve.

Gluteus Medius Muscle

A superficial gluteal muscle originating from the outer ilium that inserts on the greater trochanter to abduct the hip and stabilize the pelvis during single-leg weight bearing.

Piriformis Muscle

A deep gluteal lateral rotator muscle originating from the anterior sacrum that inserts on the greater trochanter and acts as an anatomical landmark dividing superior and inferior gluteal structures.

Iliopsoas Muscle

The principal hip flexor formed by the psoas major (innervated by lumbar spinal nerves) and iliacus (innervated by the femoral nerve), inserting onto the lesser trochanter of the femur.

Sartorius Muscle

An anterior thigh muscle originating from the anterior superior iliac spine (ASIS) that acts to flex both the hip and knee joints under femoral nerve innervation.

Rectus Femoris Muscle

The two-joint muscle of the quadriceps femoris originating from the anterior inferior iliac spine (AIIS) that flexes the hip and extends the knee via the femoral nerve.

Pectineus Muscle

A medial thigh muscle originating from the pubic bone that adducts and flexes the hip, uniquely possessing dual innervation from the femoral nerve and obturator nerve.

Biceps Femoris Muscle (Short Head)

A posterior thigh muscle originating from the linea aspera of the femur that flexes the knee joint and is exclusively innervated by the common fibular nerve.

Pes Anserinus

The conjoined 'goose foot' insertion tendon on the anteromedial proximal tibia formed by the sartorius, gracilis, and semitendinosus muscles.

Pelvic Inlet

The bony boundary formed by the sacral promontory, arcuate line, and pubic crest that separates the false pelvis superiorly from the true pelvis inferiorly.

Acetabulum

The lateral socket of the os coxae formed by the fusion of the ilium, ischium, and pubis that articulates with the head of the femur.

Greater Sciatic Foramen

An opening created by the greater sciatic notch of the hip bone converted by the sacrospinous and sacrotuberous ligaments, transmitting the sciatic nerve and gluteal vessels.

Linea Aspera

A prominent longitudinal ridge on the posterior aspect of the femoral shaft serving as an attachment site for thigh adductors and muscle heads.

Sesamoid Bone

A bone that develops inside a tendon to protect the joint and improve mechanical leverage, exemplified by the patella.

Anterior Cruciate Ligament (ACL)

An intracapsular knee ligament running from the lateral femoral condyle to the anterior intercondylar area of the tibia that prevents anterior translation of the tibia relative to the femur.

Posterior Cruciate Ligament (PCL)

An intracapsular knee ligament connecting the medial femoral condyle to the posterior intercondylar area of the tibia that prevents posterior translation of the tibia relative to the femur.

Medial Collateral Ligament (MCL)

An extracapsular knee ligament extending from the medial femoral epicondyle to the medial tibial condyle that is directly adhered to the medial meniscus.

Unhappy Triad

A knee injury caused by a lateral impact to a fixed foot with rotation, involving simultaneous tearing of the anterior cruciate ligament (ACL), medial collateral ligament (MCL), and medial meniscus.