Bones of The Lower Limb

Main Anatomy Index

The Femur

• The femur is the longest, strongest, and heaviest bone in the body.
• It extends from the hip joint where its rounded head articulates with the acetabulum, to the knee joint, where its condyles articulate with the tibia.
• The proximal end consists of a head, neck, and greater and lesser trochanters.
• The distal end is broadened by medial and lateral condyles where it articulates with the tibia and patella to form the knee joint.
• The femur is so covered by muscles that it is palpable only near its ends.

Head of the Femur

• It is smooth and forms about two-thirds of a sphere.
• It is directed medially, superiorly, and slightly anteriorly to fit into the acetabulum of the hipbone.
• A little inferior and posterior to its centre is a fovea (L. pit) where the ligament of the head is attached. The head can sometimes be palpated, particularly in thin males, where the thigh is rotated laterally.

The Neck of the Femur

• It connects the head to body. It runs obliquely in an inferolateral direction to meet the body (shaft) at an angle of about 125 degrees.
• The neck is limited laterally by the greater trochanter and is narrowest in diameter at its middle.

The Intertrochanteric Line

• This broad, rough line runs inferomedially from the greater trochanter.
• This line passes inferior to the lesser trochanter and becomes continuous with the spiral line on the posterior aspect of the femur.
• The intertrochanteric line is produced by the attachment of the massive iliofemoral ligament.
• The intertrochanteric line separates the anterior surface of the neck from the body of the femur.

The Intertrochanteric Crest

• This unites the two trochanters with a prominent ridge.

The Greater Trochanter of the Femur

• This is a large, somewhat rectangular projection from the junction of the neck and body.
• It provides an attachment for several muscles of the gluteal region.
• The greater trochanter lies laterally, close to the skin, and can be easily palpated on the lateral side of the thigh. Because it is the most lateral point of the hip region, the greater trochanter cause you discomfort when you lie on your side on a hard surface.
• In the anatomical position, a line joining the tips of the greater trochanters normally passes though the centre of the femoral heads and the pubic tubercles.

The Lesser Trochanter of the Femur

• This projects from the posteromedial surface of the femur at the inferior end of the intertrochanteric crest.
• It is located in the angle between the neck and body of the femur.

The Body (shaft) of the Femur

• It is slightly bowed anteriorly and is narrowest at its midpoint.
• Its middle two-quarters are approximately circular in transverse section.
• Inferior to the neck, the body is smooth and featureless except for a rough ridge of bone, called the linea aspera (L. rough line), in the middle of its posterior surface.

The Linea Aspera

• The linea aspera (L. rough line), in the middle of its posterior surface.
• The linea aspera has medial and lateral lips, which diverge inferiorly to form medial and lateral supracondylar lines.
• The pectineal line runs from the lesser trochanter to the medial lip of the linea aspera.

The Condyles of the Femur

• The distal end of the femur is broadened for articulation with the tibia.
• Two, large, oblong condyles (G. knuckles) project posteriorly and are separated by a deep U-shaped intercondylar notch. The medial and lateral condyles blend with each other anteriorly; each condyle is separated from the patellar surface by a slight groove.
• The patellar surface is where the patella slides during flexion and extension of the leg at the knee joint.
• The lateral and medial margins of the patellar surface can be palpated when the leg is flexed.
• The adductor tubercle, a small prominence of bone, may be felt at the superior part of the medial femoral condyle.
• The medial and lateral condyles of the femur are subcutaneous and easily palpable when the knee is flexed and extended.
• Superior to each condyle is a prominent epicondyle to which the tibial and fibular collateral ligaments of the knee joint are attached.

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The Tibia

• The tibia is the second largest bone in the skeleton. It is located on the anteromedial side of the leg.
• The proximal end of the tibia is large because its medial and lateral condyles articulate with the large condyles of the femur.
• The superior surface of the tibia is flat and consists of medial and lateral tibial plateaux.
• The body (shaft) of the tibia is approximately triangular in transverse section and has medial, lateral and posterior surfaces. The muscles attach to its lateral surface.
• The distal end of the tibia is small and has facets inferiorly for the head of the fibula.

The Intercondylar Eminence of the Tibia

• This fits into the intercondylar notch between the condyles of the femur.

The Tibial Tuberosity

• This is prominent anteriorly, into which the patella ligament inserts.

The Medial Malleolus

• The distal projection is called the medial malleolus. It has a facet on its lateral surface for articulation with the talus.

The Lateral Border of the Tibia

• This border is sharp where it gives attachment to the interosseous membrane, uniting the two leg bones. This border is referred to as the interosseous border.

The Soleal Line of the Tibia

• On the posterior surface of the proximal part of the body of the tibia, there is a rough diagonal ridge known as the soleal line.
• It runs inferomedially to the medial border, about a third of the way down the body to the tibia.

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The Fibula

• This long pin-like bone (L. pin) lies posterolateral to the tibia.
• The fibula is the lateral bone of the leg. Its slender body (shaft) has little or no function in weight bearing, but its malleolus helps to hold the talus in its socket.
• The fibula's main function is to provide sites for muscles to attach. It also acts as a brace and provides support for the tibia.
• The fibula enables the tibia to withstand some bending and twisting. Without fibular support, tibial fractures would occur more frequently.
• The slightly constricted part of the body near the head is called the neck of the fibula.
• The sharp interosseous border of the fibula provides the surface for attachment of the interosseous membrane.

The Head of the Fibula

• It is the proximal end of the fibula. It is irregular in shape and knob-like.
• The head has a facet on its superior surface for articulation with the inferior surface of the lateral tibial condyle.

The Lateral Malleolus

• The distal end of the fibula or lateral malleolus forms a knob-like subcutaneous prominence on the lateral surface of the ankle.
• The medial surface of the fibula articulates with the lateral side of the tibia and talus.

The Malleolar Fossa

• Posteroinferior to the facet for the talus is a depression, called the malleolar fossa, for the attachment of the posterior talofibular ligament.
• The lateral malleolus lies more inferior and posterior than does the medial malleolus.

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Bones of the Foot (p. 437)

These bones comprise the tarsus, metatarsus, and phalanges. The medial border of the foot is almost straight and the line joining the midpoints of the medial and lateral borders of the foot is oblique and that the metatarsal bones and phalanges are located anterior to this line and the tarsal bones are posterior to it. The tarsus (G. tarsos, flat) consists of seven tarsal bones: talus, calcaneus, cuboid, navicular, and three cuneiforms. Only one of them, the talus, articulates with the leg bones.

The Talus (pp. 437, 440)

• The talus (L. ankle bone) has a body, neck and head.
• It looks somewhat like a saddle when viewed from its dorsal aspect or like a snail overall.
• The talus rests on the anterior two thirds of the calcaneus. It also articulates with the tibia, fibula, and navicular bones.
• The saddle-shaped superior surface of the talus bears the weight of the body transmitted via the tibia.

• The body of the talus is cuboid in shape. Its pulley-shaped superior surface, often called the trochlea (L. pulley), articulates with the inferior surface of the tibia as part of the ankle joint.
• The body of talus has three continuous facets for articulation: one for the facet on the inferior surface of the tibia; one for the facet on the lateral surface of the medial malleolus; and one for the facet on the medial surface of the lateral malleolus.
• The inferior surface of the body of the talus has an oval, deeply concave area for articulation with the calcaneus.
• The body also has a posterior process that has medial and lateral tubercles. There is a groove between these two tubercles for the tendon of the flexor hallucis longus muscle.

• The neck of the talus is the slightly constricted part between the head and the body. Inferiorly there is a deep groove called the sulcus tali for the ligaments connecting the talus and calcaneus.

• The head of the talus is its rounded anterior end; it is directed anteromedially. It has a large facet for articulation with the navicular bone and one for articulation with the shelf-like projection of the calcaneus, known as the sustentaculum tali, as well as a small articulation with the plantar calcaneonavicular ligament (spring ligament).

The Calcaneus (p. 440-1)

• The calcaneus (L. heel) is a rectangular block of bone. It is the largest and strongest bone of the foot. It is also the first one to ossify.
• It articulates with the talus superiorly and the cuboid anteriorly.
• The calcaneus lies inferior to the talus; thus its superior surface has articular facets for this bone.
• The posterior facet is demarcated anteriorly by a groove, the sulcus calcanei. Anterior to this sulcus is the sustentaculum tali, a shelf that projects from the superior border of the medial surface of the calcaneus. It helps to support the talus.
• The lateral surface has an oblique ridge called the fibular (peroneal) trochlea. The tendon of the peroneus longus muscle passes inferior to this ridge.

• The calcaneus is shaped somewhat like a pistol grip, the thumb gliding naturally into the hollow under the sustentaculum tali.
• The calcaneus projects posteriorly and forms the prominence of the heel. At the posterior end of its inferior surface, a tuber calcanei projects inferiorly. It is deep to the fibrous tissue and fat of the heel pad and it transmits the weight of the body to the floor or ground.
• The tuber calcanei or calcaneal tuberosity forms the projection of the heel; it has medial and lateral processes for the attachment of muscles.
• On the medial surface of the calcaneus is a groove on the inferior surface of the sustentaculum tali for the attachment of the flexor hallucis longus tendon.
• On the lateral surface is a tubercle, the fibular (peroneal) trochlea.

The Navicular (p. 441)

The navicular (L. little ship) is a flattened, oval, boat-shaped bone. Located between the head of the talus and the three cuneiform bones, it has facets for articulation with each of them. The navicular also has an occasional facet for articulation with the cuboid bone. Medially and inferiorly, there is a rough navicular tuberosity to which the tendon of the tibialis posterior muscle attaches.

The Cuboid (p. 441)

• This rather wedge-shaped bone, approximately cubical in shape, is the most lateral bone in the distal row of the tarsus.
• Posteriorly it presents an articular surface for the calcaneus and anterior two facets for the fourth and fifth metatarsal bones.
• On its medial surface are facets for the lateral cuneiform and navicular bones.
• Anterior to the tuberosity of the cuboid, on the lateral and inferior surfaces of the bone, there is a groove for the tendon of the peroneus longus muscle.

The Cuneiform Bones (p. 441)

The name of these three bones is derived from a Latin word meaning "wedge-shaped". They are referred to as the medial (first), intermediate (second), and lateral (third) cuneiforms. The medial cuneiform is the largest bone and the intermediate cuneiform the smallest. Each cuneiform articulates with the navicular bone posteriorly, and with the base of its appropriate metatarsal, anteriorly. In addition, the lateral cuneiform articulates with the cuboid bone.

The Metatarsus (p. 441)

• The metatarsus consists of five metatarsal bones. These miniature long bones are numbered from the medial side of the foot and each bone consists of a base, a body or shaft, and a head.
• The bases of the metatarsals articulate with the cuneiform and cuboid bones, and their heads articulate with the bases of the proximal phalanges.
• The second metatarsal bone is wedged between the medial and lateral cuneiforms and between the first and third metatarsals. This bone is the longest metatarsal.
• On the plantar surface of the head of the first metatarsal bone, there are prominent medial and lateral sesamoid bones. The heads of the metatarsals bear some of the weight of the body. The base of the fifth metatarsal has a large tuberosity that projects over the lateral margin of the cuboid bone. The tuberosity of the fifth metatarsal bone provides attachment on its dorsal surface for the peroneus brevis tendon.

The Phalanges (p. 441)

There are 14 phalanges: the first digit or great toe (L. hallux) has two strong phalanges (proximal and distal); the other four digits have three each (proximal, middle, and distal). Each phalanx consists of a base (proximally), a body or shaft, and a head (distally).

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