Human Anatomy - G. I. Koliadenko 2009

Musculoskeletal System
Skeleton of the Lower Limb
Structure and Joints of the Bones of the Free Lower Limb

The free lower limb consists of the thigh, leg, and FOOT (Fig. 39, 40).

The Femur is the longest and strongest tubular bone in the human Skeleton. Its shaft is nearly cylindrical in shape and slightly curved anteriorly. The proximal epiphysis features a HEAD, with a depression in its center known as the fovea of the head of the femur. Below the head lies the femoral neck, at the transition of which into the shaft are two tubercles — the greater and lesser trochanters. Anteriorly, they are connected by the intertrochanteric line, and posteriorly by the intertrochanteric crest. The posterior surface of the femur presents the linea aspera, which bifurcates into medial and lateral Lips.

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Fig. 39. Skeleton of the Lower Limb (anterior view):

1 — sacrum; 2 — coccyx; 3 — pubic tubercle; 4 — obturator foramen; 5 — ischial tuberosity; 6 — medial epicondyle of the femur; 7 — medial condyle of the femur; 8 — medial condyle of the Tibia; 9 — medial malleolus; 10 — head of the talus; 11 — navicular bone; 12 — medial cuneiform bone; 13 — first metatarsal bone; 14 — proximal phalanx; 15 — distal phalanx; 16 — cuboid bone; 17 — calcaneus; 18 — lateral malleolus; 19 — anterior border of the tibia; 20 — shaft of the Fibula; 21 — tibial tuberosity; 22 — head of the fibula; 23 — lateral condyle of the tibia; 24 — lateral condyle of the femur; 25 — Patella; 26 — lateral epicondyle of the femur; 27 — shaft of the femur; 28 — intertrochanteric line; 29 — greater trochanter; 30 — neck of the femur; 31 — head of the femur; 32 — anterior inferior iliac spine; 33 — anterior superior iliac spine; 34 — iliac crest; 35 — ischial spine

The distal epiphysis bears two condyles: medial and lateral, which carry articular surfaces. Above them on the lateral surfaces are epicondyles, where Muscles and ligaments attach. The anterior surface of the distal epiphysis features an articular surface for articulation with the patella. On the posterior surface of the epiphysis between the condyles lies the intercondylar fossa.

The patella is the largest sesamoid bone in the human skeleton. It is located between the tendon of the quadriceps femoris Muscle and participates in The formation of the knee joint. The upper surface of the patella is called the base, the lower is the apex; the posterior surface is covered with Cartilage, while the anterior surface is rough.

Fig. 40. Skeleton of the lower limb (posterior view):

1 — posterior superior iliac spine; 2, 3 — iliac crest; 4 — neck of the femur; 5 — greater trochanter; 6 — intertrochanteric crest; 7 — lesser trochanter; 8 — linea aspera; 9 — patellar surface; 10 — lateral epicondyle of the femur; 11 — lateral condyle of the femur; 12 — lateral condyle of the tibia; 13 — head of the fibula; 14 — lateral malleolus; 15 — trochlea of the talus; 16 — tuberosity of the fifth metatarsal bone; 17 — calcaneal tuberosity; 18 — medial cuneiform bone; 19 — tuberosity of the navicular bone; 20 — medial malleolus; 21 — posterior surface of the tibial shaft; 22 — soleus line; 23 — medial condyle of the tibia; 24 — medial condyle of the femur; 25 — medial epicondyle of the femur; 26 — ischial tuberosity; 27 — coccyx; 28 — sacrum

The hip joint (articulatio coxae; Fig. 41) is formed by the femoral head and the acetabulum of the hip bone, surrounded by a thick cartilaginous acetabular labrum, which makes the socket even deeper, allowing the femoral head to fit deeply into it. This joint is nut-shaped, which is a variety of ball-and-socket joint. Movements in this joint occur around three axes: transverse — flexion and extension, sagittal — abduction and adduction, and vertical — medial and lateral rotation. In addition, circular movements (circumduction) are possible in the joint. Because the femoral head enters more than halfway into the acetabulum, movements in this joint are somewhat restricted compared to the shoulder joint.

The hip joint is reinforced by well-developed ligaments. The largest of these is the iliofemoral ligament, which originates from the anterior inferior iliac spine of the hip bone and attaches to the intertrochanteric line of the femur. The round ligament of the femur extends from the fovea of the femoral head, connecting it to the central surface of the acetabulum. Blood Vessels and nerves to the femoral head pass through this ligament.

Fig. 41. Hip joint (anterior view):

1 — sacrospinous ligament; 2 — sacrotuberous ligament; 3 — obturator membrane; 4 — pubofemoral ligament; 5 — acetabular labrum; 6 — iliofemoral ligament

The leg (crus) consists of two bones — the tibia and the fibula. The tibia lies medially, and the fibula laterally.

The tibia (tibia; Fig. 42). The shaft of this bone is triangular in shape, providing it with three surfaces: medial, lateral, and posterior. The medial and lateral surfaces form the anterior border, which in its upper part transitions into the tuberosity where the tendon of the quadriceps femoris muscle attaches. The posterior and lateral surfaces of this bone meet to form the interosseous border, located laterally. The proximal epiphysis of the bone is thickened and features two condyles with articular surfaces — medial and lateral. Between the condyles lies the intercondylar eminence, to which ligaments attach. On the lateral side of the lateral condyle is an articular surface for articulation with the head of the fibula. The distal epiphysis has two articular surfaces: the inferior surface connects the bone with the talus of the tarsus, and the lateral surface connects with the fibula. On the medial side of the distal epiphysis is a robust prominence — the malleolus, which also bears an articular surface for articulation with the talus.

The fibula (fibula; see Fig. 42) has a long and slender triangular shaft with the same surfaces as the tibia. The surfaces are separated from each other by anterior, posterior, and interosseous borders. The proximal epiphysis features a head with an articular surface through which the fibula articulates with the tibia. The distal epiphysis is more massive than the proximal one and features a thickened lateral malleolus, on the Medial surface of which is an articular surface for articulation with the talus.

Fig. 42. BONES OF THE right leg (anterior view):

1 — intercondylar eminence of the tibia; 2 — medial condyle; 3 — tibial tuberosity; 4 — medial surface; 5 — lateral surface; 6 — anterior border; 7 — interosseous border; 8 — medial malleolus; 9 — lateral malleolus of the fibula; 10 — lateral condyle of the medial bone

Fig. 43. Right knee joint (anterior view):

1 — patellar surface; 2 — posterior cruciate ligament; 3 — anterior cruciate ligament; 4 — medial meniscus; 5 — tibial collateral ligament; 6 — patellar ligament; 7 — patella; 8 — tendon of the quadriceps femoris muscle; 9 — interosseous membrane of the leg; 10 — head of the fibula; 11 — articular capsule; 12 — lateral meniscus; 13 — fibular collateral ligament

The knee joint (articulatio genus) is formed by the distal epiphysis of the femur, the articular condyles of the proximal epiphysis of the tibia, and the patella (Fig. 43). In shape, the joint is classified as modified hinge (bicondylar/trochoginglymus). It permits the following movements: flexion and extension as in a hinge joint, and when the knee is flexed, the joint also becomes ball-and-socket-like, allowing rotation around a vertical axis, as well as abduction and adduction. The articular surfaces of the bones forming the knee joint are not entirely congruent; therefore, two menisci are interposed between them, shaped like incomplete rings and resting on the articular surface of the proximal epiphysis of the tibia. The ends of the menisci are attached by ligaments to the intercondylar eminence of the tibia. Their outer thickened margin connects with the articular capsule, while the inner, sharpened, and free margin surrounds the ring opening. The opening of the meniscus connects the two compartments of the joint lying above and below it. Inside the joint are two cruciate ligaments that originate from the intercondylar fossa and attach to the intercondylar eminence of the tibia. On the lateral surfaces of the joint are strong collateral and medial ligaments, posteriorly is the oblique popliteal ligament, and extending from the patella to the tibial tuberosity is the patellar ligament proper.

Inside the joint, the synovial membrane forms numerous folds and synovial bursae. The largest of these is located above the patella, beneath the tendon of the quadriceps femoris muscle.

The tibia and fibula are connected by a dense fibrous plate—the interosseous membrane of the leg—which attaches to the interosseous borders of these bones. The articular surface of the lateral condyle of the tibia articulates with the head of the fibula via a plane joint reinforced by accessory ligaments. Distally, the articular surfaces of the tibia and the medial surface of the lateral malleolus form a syndesmosis bound by the tibiofibular ligaments, rendering this joint virtually immovable.

The Bones of the foot (ossa pedis; Fig. 44) comprise three segments: the tarsus, metatarsus, and Phalanges of the digits.

The tarsus consists of seven bones: the calcaneus, talus, navicular, three cuneiforms, and cuboid.

The calcaneus (calcaneus) is the largest of the Tarsal Bones, featuring a body with articular surfaces and a calcaneal tuberosity for muscle tendon attachments. The superior articular surface articulates with the talus, while the anterior cuboid articular surface articulates with the cuboid bone.

Fig. 44. Bones of the foot:

1 — calcaneal tuberosity; 2 — calcaneus; 3 — body of the talus; 4 — neck of the talus; 5 — head of the talus; 6 — cuboid bone; 7 — navicular bone; 8 — lateral cuneiform bone; 9 — intermediate cuneiform bone; 10 — medial cuneiform bone; 11 — Base of the metatarsal bone; 12 — body of the first metatarsal bone; 13 — head of the first metatarsal bone; 14 — base of the phalanx; 15 — body of the phalanx; 16 — trochlea of the phalanx; 17 — distal phalanx; 18 — middle phalanx; 19 — proximal phalanx; 20 — trochlea of the talus

The talus (talus) features a body and a head, with the trochlea of the talus located on its superior surface. Together with the bones of the leg, it forms the talocrural joint. The head of the talus presents a convex articular surface for articulation with the navicular bone.

The navicular bone (os naviculare) features a deep socket posteriorly that articulates with the head of the talus. Anteriorly, it articulates with the three cuneiform bones.

The cuboid bone (os cuboideum) occupies the lateral part of the distal tarsal row, has a cube-like shape, and articulates with the calcaneus and the IV–V Metatarsal Bones.

The cuneiform bones (ossa cuneiformia)—medial, lateral, and intermediate—occupy the medial portion of the tarsus and articulate with the navicular and I, II, and III metatarsal bones.

The ankle joint (articulatio talocruralis) is formed by the bones of the leg and the talus. The articular surfaces of the distal epiphysis of the tibia and both malleoli articulate with the trochlea of the talus. The joint is ginglymus (hinge) in shape. Flexion and extension are possible around a frontal axis. Additionally, plantar flexion allows for pronation and supination movements. Plantar flexion refers to the movement that lowers the foot, whereas dorsal flexion raises it toward the leg. The Joint Capsule of the ankle is thin and highly distensible. The ankle joint is reinforced by strong ligaments extending from the leg to the calcaneus, talus, and navicular bones (Fig. 45).

The metatarsus (ossa metatarsae) consists of five small tubular bones, each comprising a base, body, and head. Their bases articulate with the cuneiform and cuboid bones of the tarsus, while their heads articulate with the proximal phalanges of the digits. The first metatarsal bone is shorter but significantly thicker than the others.

Fig. 45. Frontal section of the right ankle joint:

1 — epiphyseal synchondrosis (between the diaphysis and epiphysis of the tibia); 2 — medial malleolus; 3 — talus; 4 — tendon of the tibialis posterior muscle; 5, 7 — talar joint; 6 — talocalcaneal interosseous ligament; 8 — calcaneal tuberosity; 9 — long plantar ligament; 10 — calcaneus; 11 — tendon of the fibularis (peroneus) longus muscle; 12 — tendon of the fibularis (peroneus) brevis muscle; 13 — articular capsule; 14 — calcaneofibular ligament; 15, 18 — ankle joint; 16 — lateral malleolus; 17 — epiphyseal synchondrosis between the diaphysis and epiphysis of the fibula; 19 — interosseous membrane; 20 — diaphysis of the fibula; 21 — diaphysis of the tibia

The digits of the foot share the same Structure as those of the hand. The first digit consists of two phalanges—proximal and distal—whereas the II, III, IV, and V digits consist of three phalanges—proximal, middle, and distal. The digits of the foot are considerably shorter, especially the IV and V, while the first digit is long and broad.

Joints and ligaments of the foot. Several joints are distinguished. Between the talus and calcaneus lies the talocalcaneal joint, which approaches a cylindrical shape in form. The talocalcaneonavicular joint involves three bones: the calcaneus, talus, and navicular. In shape, this joint is close to a ball-and-socket joint. The talocalcaneal and talocalcaneonavicular joints form a single combined subtalar joint (articulatio subtalaris) and function together. These joints enable abduction, pronation, and supination of the foot. The joints formed between the remaining tarsal bones are complex, have limited mobility, and may be classified as amphiarthroses.

Fig. 46. Bones and joints of the foot (section of the foot):

1 — fibula; 2 — tibia; 3 — ankle joint; 4 — medial deltoid ligament; 5 — transverse tarsal joint; 6 — talocalcaneonavicular joint; 7 — navicular bone; 8 — cuneiform bones I, II, III; 9 — tarsometatarsal joints; 10 — interphalangeal joints; 11 — metatarsophalangeal joint; 12 — cuboid bone; 13 — calcaneocuboid joint; 14 — talar joint

The tarsometatarsal joints (articulationes tarsometatarseae) are formed by the articular surfaces of the bases of the metatarsal bones and the articular surfaces of the three cuneiform bones and the cuboid bone. The joint capsule is stabilized by dorsal and plantar tarsometatarsal ligaments.

The heads of the metatarsal bones articulate with the proximal phalanges of the digits, forming ball-and-socket joints that allow flexion and extension, while other movements are restricted by a well-developed ligamentous apparatus. The interphalangeal JOINTS OF THE foot, much like those of the hand, are ginglymus (hinge) in shape.

The Foot as a whole. The foot performs two primary Functions: support and Shock absorption. During standing, the weight-bearing points are the calcaneal tuberosity and the heads of the metatarsal bones. Changes in body posture alter the pressure exerted by body weight on these points (Fig. 46).

The cushioning function of the foot is primarily determined by its arched structure. There are two arches: the longitudinal and the transverse, which together form the arch of the foot. The longitudinal arch runs along both the lateral and medial margins of the foot; in fact, there are two longitudinal arches (vaults). The highest point (5–7 cm above the floor) is located on the inner arch—on the Inferior surface of the head of the talus—while on the outer arch, the highest point (2–3 cm above the floor) corresponds to the lower level of the calcaneocuboid joint space. The Formation of the transverse arch of the foot is related to The structure of the cuneiform bones. The highest point of this arch coincides with the level of the tarsometatarsal joints.

Both foot arches are reinforced by the plantar metatarsal and interosseous ligaments, the plantar aponeurosis, and the Muscles of the foot. These structures not only stabilize the bones but also maintain tension in the ligaments to which they partially attach.

The arches of the foot develop throughout a person's life under METABOLISM/18.html">The Influence of standing, walking, running, and jumping. They grow gradually until the onset of Puberty. In individuals—particularly children—with weak foot Ligaments and Muscles, flat feet may develop, sometimes as an occupational condition. Proper footwear and regular Physical Exercise also play a significant role in shaping the foot arches.