Arthrology of the Lower Limb Flashcards

Vocabulary practice flashcards covering anatomy, classification, structure, ligaments, movements, and clinical concepts of lower limb joints.

Arthrology

The scientific study of joints (articulations), which are functional junctions where two or more bones meet.

Synarthrosis

A functional joint classification referring to immovable joints, such as the sutures of the skull.

Amphiarthrosis

A functional joint classification referring to slightly movable joints, such as the pubic symphysis.

Diarthrosis

A functional joint classification referring to freely movable joints, such as the hip, knee, and ankle.

Fibrous Joint

A structural joint type bound by dense connective tissue without a joint cavity; mostly immovable.

Cartilaginous Joint

A structural joint type bound by cartilage without a joint cavity; slightly movable.

Synovial Joint

A structural joint type characterized by a fluid-filled capsule and a joint cavity; freely movable.

C.A.S.L.

A memory trick for remembering key components of a synovial joint: Cartilage, Articular capsule, Synovial fluid, and Ligaments.

Articular Cartilage

Smooth hyaline cartilage covering the ends of articulating bones to reduce friction and absorb shock inside a synovial joint.

Synovial Fluid

A lubricating fluid in the joint cavity that nourishes cartilage and absorbs shock, normally present in amounts under $3\,m L$.

Acetabulum

The cup-shaped socket of the hip joint formed by the ilium (superior 2/5), ischium (posterior 2/5), and pubis (anterior 1/5).

Acetabular Labrum

A ring of fibrocartilage that deepens the acetabular socket and grips the femoral head, acting like a seal to maintain negative intra-articular pressure.

Coxa Vara

A decreased angle of inclination ($< 125^\circ$) between the femoral neck and shaft, causing the leg to bend inward.

Coxa Valga

An increased angle of inclination ($> 125^\circ$) between the femoral neck and shaft, causing the leg to straighten outward.

Femoral Anteversion

An increased anterior angle of torsion ($> 20^\circ$) of the femur, leading to an 'in-toeing' (pigeon-toed) gait.

Femoral Retroversion

A decreased anterior angle of torsion ($< 10^\circ$) of the femur, leading to an 'out-toeing' gait.

Iliofemoral Ligament

Also known as the Y-Ligament of Bigelow, it is located anteriorly and is the strongest ligament in the body, preventing hyperextension and stopping backward falls when standing.

Pubofemoral Ligament

An anterior/inferior hip ligament that resists hip extension and abduction to prevent over-stretching.

Ischiofemoral Ligament

A posterior hip ligament that acts to resist internal rotation and extension of the hip.

Ligamentum Teres

An intra-articular but extrasynovial ligament that attaches to the fovea capitis and carries a small blood supply to the femoral head.

Medial Meniscus

A C-shaped fibrocartilaginous disc firmly anchored to the MCL, making it less mobile and more prone to tearing.

Lateral Meniscus

A circular fibrocartilaginous disc forming about four-fifths of a circle that does not attach to the LCL, making it highly mobile.

Unhappy Triad

A severe knee injury involving combined tears of the Anterior Cruciate Ligament (ACL), Medial Collateral Ligament (MCL), and Medial Meniscus.

Medial Collateral Ligament (MCL)

A knee ligament located on the medial side that functions to resist valgus (abduction) force.

Lateral Collateral Ligament (LCL)

A knee ligament located on the lateral side that functions to resist varus (adduction) force.

Anterior Cruciate Ligament (ACL)

An intra-articular knee ligament that resists anterior translation of the tibia, preventing it from sliding forward.

Posterior Cruciate Ligament (PCL)

An intra-articular knee ligament that resists posterior translation of the tibia, preventing it from sliding backward.

Oblique Popliteal Ligament

A ligament located on the posterior aspect of the knee joint that prevents hyperextension.

Talocrural Joint

The formal name for the ankle joint, which is a synovial hinge joint formed between the mortise (tibia/fibula) and the tenon (talus).

Trochlear Surface

The convex superior surface of the talus body that is wedge-shaped (wider anteriorly than posteriorly), contributing to greater joint stability in dorsiflexion.

Deltoid Ligament

A strong, triangular medial ankle ligament that resists eversion, consisting of four parts: tibionavicular, tibiocalcaneal, anterior tibiotalar, and posterior tibiotalar ligaments.

Anterior Talofibular Ligament (ATFL)

A lateral ankle ligament that resists inversion and is the most commonly injured ligament in ankle sprains.

Posterior Talofibular Ligament (PTFL)

The strongest of the three lateral ankle ligaments, which is rarely injured.

Subtalar Joint

Also known as the talocalcaneal joint; a synovial plane joint between the talus and calcaneus that serves as the primary joint for inversion and eversion.

Inversion

A movement in the frontal plane ($0^\circ\text{ to }25^\circ$ ROM) that turns the sole of the foot inward toward the midline.

Eversion

A movement in the frontal plane ($0^\circ\text{ to }12^\circ$ ROM) that turns the sole of the foot outward.

Pronation (Foot)

A composite movement combining eversion, abduction, and dorsiflexion occurring during the loading phase of walking to absorb shock.

Supination (Foot)

A composite movement combining inversion, adduction, and plantarflexion occurring during the push-off phase of walking to create a rigid lever.