Notes on Lower Extremity Bones
Lower Extremity Bones
Pelvis
Composed of the following bones:
Innominate Bones: Also known as os coxae or hip bones.
Ilium: The largest and most superior part of the innominate bone.
Iliac Crest: The superior border of the ilium.
Iliac Fossa: The large, smooth, concave surface on the inner side of the ilium, forming the entire body of the ilium.
Anterior Superior Iliac Spine (ASIS): A prominent projection at the anterior end of the iliac crest.
Anterior Inferior Iliac Spine (AIIS): Located inferior to the ASIS.
Posterior Superior Iliac Spine (PSIS): A prominent projection at the posterior end of the iliac crest.
Posterior Inferior Iliac Spine (PIIS): Located inferior to the PSIS.
Greater Sciatic Notch: A large indentation inferior to the PSIS, through which blood vessels and nerves pass.
Lesser Sciatic Notch: A smaller indentation located below the ischial spine.
Ischial Spine: A sharp projection dividing the greater and lesser sciatic notches.
Ischium: The inferoposterior part of the innominate bone.
Ischial Tuberosities: The rough, bony prominences, often referred to as the "sit bones."
Obturator Foramen: A large hole in the middle of the innominate bone, largely covered by a membrane.
Ramus of Ischium: A part of the ischium that extends medially.
Pubis: The anteroinferior part of the innominate bone.
Superior Pubic Ramus: Part of the pubis extending superiorly.
Inferior Pubic Ramus: Part of the pubis extending inferiorly.
Pubic Tubercle: A small projection that divides the superior and inferior rami of the pubis.
Pectineal Line: A ridge on the superior ramus of the pubis.
Sacrum: A large, triangular bone at the base of the spine, formed by the fusion of five sacral vertebrae.
Coccyx: The tailbone, a small triangular bone at the end of the sacrum.
Femoral Acetabular Joint: The hip joint, formed by the articulation of the head of the femur with the acetabulum of the innominate bone.
Femur
Head of Femur: The spherical proximal end that articulates with the acetabulum.
Neck of Femur: The constricted region connecting the head to the shaft.
Anterior Intertrochanteric Line: A ridge on the anterior aspect of the femur, connecting the greater and lesser trochanters.
Posterior Intertrochanteric Crest: A prominent ridge on the posterior aspect of the femur, connecting the greater and lesser trochanters.
Greater Trochanter: A large, irregular quadrilateral eminence at the upper part of the femur, serving as an attachment for various muscles.
Lesser Trochanter: A conical eminence projecting from the posteromedial part of the base of the femoral neck, serving as an attachment for the iliopsoas muscle.
Gluteal Tuberosity: A roughened ridge on the posterior surface of the femoral shaft, where the gluteus maximus muscle inserts.
Pectineal Line: A ridge on the posterior aspect of the femoral shaft, medial to the gluteal tuberosity.
Shaft: The long, central part of the femur.
Abductor Tubercle: A small indent on the medial side of the distal femur, specifically on the medial epicondyle.
Epicondyles: More pointy projections located medially and laterally above the condyles, serving as attachment points for ligaments and muscles.
Condyles: The entire smooth, rounded bottom portion of the distal femur (medial and lateral condyles) that articulate with the tibia.
Patella
Base: The top, wider portion of the patella.
Apex: The bottom, pointy portion of the patella.
Articulation: The patella articulates with the femur.
Function: It is important to note that the patella does not directly make the knee flex and extend; rather, it increases the leverage of the quadriceps femoris muscle.
Patellofemoral Joint: The articulation between the posterior surface of the patella and the patellar surface of the femur.
Medial and Lateral Borders: The edges of the patella.
Posterior Surface: Features two articular facets:
Medial Articular Facet: Articulates with the medial condyle of the femur.
Lateral Articular Facet: Articulates with the lateral condyle of the femur.
Tibia
Tibiofemoral Joint: The articulation between the tibia and the femur, considered the largest joint in the body.
Position: Sits more medially than the fibula.
Tibial Plateaus: The flat surfaces on the superior aspect of the tibia that articulate with the femoral condyles.
Medial Condyle: The larger, medial articular surface of the proximal tibia.
Lateral Condyle: The smaller, lateral articular surface of the proximal tibia.
Intercondylar Eminence: A raised area between the medial and lateral condyles of the tibia.
Medial Intercondylar Tubercle: Part of the intercondylar eminence.
Lateral Intercondylar Tubercle: Part of the intercondylar eminence.
Tibial Tuberosity: A large, roughened projection on the anterior aspect of the proximal tibia, serving as the attachment site for the patellar ligament.
Gerdy's Tubercle: A lateral tubercle on the proximal tibia, serving as the attachment for the iliotibial (IT) band.
Tibial Shaft: The long, central part of the tibia.
Medial Malleolus: A prominent projection on the medial side of the distal tibia, forming the medial ankle bone.
Fibular Notch: An indentation on the lateral side of the distal tibia, where the fibula articulates.
Fibula
Position: Sits more laterally than the tibia.
Apex: The very top, pointy tip of the fibula (stylus).
Head of Fibula: The enlarged proximal end of the fibula, articulating with the lateral condyle of the tibia.
Neck: The constricted region inferior to the head.
Shaft of Fibula: The long, slender central part of the fibula.
Lateral Malleolus: A prominent projection on the lateral side of the distal fibula, forming the lateral ankle bone.
Foot Bones
Divisions of the Foot:
Hindfoot: Comprises the talus and calcaneus.
Midfoot: Comprises the cuboid, navicular, and the three cuneiforms.
Forefoot: Comprises all metatarsals and all phalanges.
Specific Bones:
Talus: The uppermost tarsal bone, articulating with the tibia and fibula to form the ankle joint. It is superficial to the calcaneus.
Calcaneus: The heel bone, the largest tarsal bone.
Calcaneal Tuberosity: The posterior prominence of the calcaneus, where the Achilles tendon attaches.
Sustentaculum Tali: A shelf-like projection on the medial side of the calcaneus, supporting the talus.
Peroneal/Fibular Trochlea: A small projection on the lateral aspect of the calcaneus, located between the tendons of the fibularis (peroneus) longus and brevis muscles.
Sinus Tarsi: A tunnel or canal located between the calcaneus and the talus, containing ligaments and blood vessels.
Navicular: A boat-shaped tarsal bone located on the medial side of the foot, anterior to the talus.
Navicular Tuberosity: A prominent projection on the medial aspect of the navicular.
Cuneiforms: Three wedge-shaped tarsal bones (medial, intermediate, and lateral cuneiforms), articulating with the navicular posteriorly and the metatarsals anteriorly.
Metatarsals: Five long bones in the mid-foot, each consisting of:
Base: The proximal end, articulating with the tarsals.
Shaft: The body of the metatarsal.
Head: The distal end, articulating with the phalanges.
First Metatarsal: The shortest and thickest metatarsal.
Sesamoid Bones: Two small, pea-shaped bones embedded in the plantar surface (bottom) of the first metatarsal head, near the big toe joint. They aid in movement and protect tendons.
Phalanges: The bones of the toes. There are phalanges in each foot (two in the great toe, three in each of the other toes).