HUMAN ANATOMY – VOLUME 1

Fig. 77. Joints and ligaments of pelvic girdle.

A — anterior aspect: 1 — V lumbar vertebra; 2 — anterior longitudinal ligament; 3 — iliolumbar ligament; 4 — anterior sacro — iliac ligaments; 5 — inguinal ligament; 6 — obturator membrane; 7 — pubic symphysis; 8 — inferior (arcuate) pubic ligament; 9 — superior pubic ligament; 10 — greater trochanter; 11 — iliofemoral ligament; 12 — superior anteri-

or iliac spine.

B — posterior aspect: 1 — superior articular process of sacrum; 2 — iliolumbar ligament; 3 — posterior sacro-iliac ligaments; 4 — supraspinous ligament; 5 — posterior sacro-iliac ligament; 6 — superficial posterior sacro-coccygeal ligament; 7 — ischial tuber; 8 — sacrotuberous ligament; 9 — sacro-spinous ligament; 10 — greater sciatic foramen; 11 — superior

posterior iliac spine.

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Apart from joints and articular ligaments, bones of the pelvis connect with the sacrum by two strong ligaments. The s a c r o t u b e r a l l i g a - m e n t (l i g . s a c r o t u b e r á l e) stretches from the ischial tuberosity to the lateral edges of the sacrum and coccyx. The s a c r o s p i n o u s l i g a - m e n t (li g . s a c r o s p i n á l e) connects the ischial spine and the coccyx. The sacrum, which likes a wedge between the two hipbones, acts as the base of the pelvic ring. It does not get displaced forward and down in the sacroiliac joints by the weight of the trunk, because these articulations are strengthened by the interosseous sacroiliac, the sacrotuberal and the sacrospinous ligaments.

The pelvis (as a whole)

The pelvis is formed by the two hipbones and the sacrum (Fig. 78). It resembles a bone ring, which holds in itself a number of internal organs. The pelvic girdle is a connection between the trunk and the lower extremities. The pelvis can be divided into two compartments — the g r e a t e r and the l e s s e r p e l v e s. These two compartments are separated by a boundary line called the pelvic brim. The pelvic brim (línea terminális) passes through promontory of the sacrum, along the arched line of the iliac bone, over the crest of the pubic bones and the upper edge of the pubic symphysis.

The greater pelvis (pélvis major) is limited in the back by the body of the L5 vertebra, and at the sides by the upper flaring portion (wing) of the ilium. The greater pelvis does not have a bone wall in the front.

The lesser pelvis (pélvis minor) is limited in the back by the pelvic surfaces of the sacrum and the ventral surface of the coccyx. Its lateral walls are formed by the internal surfaces of the hipbones (below the pelvic brim) and the sacrospinous and sacrotuberal ligaments. The front wall of the lesser pelvis is formed by the superior and inferior rami of pubic bones and the pubic symphysis.

The lesser pelvis has an inlet and outlet apertures. The s u p e r i o r a p e r t u r e (inlet) corresponds to the pelvic brim. The outlet of the lesser pelvis (i n f e r i o r a p e r t u r e) is limited by the coccyx in the back, the sacrotuberal ligaments, rami of ischia and inferior rami of pubes from the sides, and in the front — by the pubic symphysis. The obturator foramen, located in the lateral wall of the lesser pelvis, is covered by a fibrous obturator membrane, which is a proper ligament of the pelvis. This membrane does not cover the obturator groove, thus forming the o b t u r a t o r c a n a l. This canal serves as a passage for vessels and a nerve from the lesser pelvis onto the femur. The lateral wall of the lesser pelvis also has

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Fig. 78. Female pelvis. Dimensions of greater and minor pelvis.

A — superior aspect. 1 — distance between the iliac crests (distantia cristarum); 2 — transverse dimension; 3 — distance between anterior superior iliac spines (distantia spinarum); 4 — oblique dimension (diameter obliqua); 5 — strait dimension (true conjugate); 6 — pubic symphysis; 7 — iliopubic eminence; 8 — superior anterior iliac spine; 9 — wing of ilium; 10 — sacro-iliac joint.

B — sagittal aspect. Inner view: 1 — external conjugate; 2 — straight dimension (of its cavity); 3 — axis of pelvis; 4 — true conjugate. Dot line reveals a pitch of a pelvis (60°).

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the greater and lesser sciatic foramina. The g r e a t e r s c i a t i c f o r a- m e n (fo r á m e n i s c h i á d i c u m m á j u s) is limited by the greater sciatic notch and the sacrospinous ligament. The l e s s e r s c i a t i c f o r a - m e n (f o r á m e n i s h i á d i c u m m í n u s) is formed between the lesser sciatic notch and the sacrotuberal and sacrospinous ligaments.

The structure of the pelvis is somewhat different in the male and female. In women, when the body is in a vertical position, the superior aperture of the pelvis is positioned at a 55–60 degree angle to the horizontal plane. The pelvis in women is wider and lower in height, and the sacrum is wider and shorter, compared to men. The promontory of the sacrum in women projects forwards much less, and the ischial tuberosities are more developed, while the distance between them is greater. The angle of junction of the inferior rami of pubes is approximately 90° in the female (forming the pubic arch) and 70–75° in the male (the infrapubic angle).

Knowing the sizes of the pelves in a woman is important for predicting possible complications in the process of child delivery. The sizes of both the greater and the lesser pelves have practical significance. The distance between the anterior superior iliac spines (d i s t á n t i a s p i n á r u m) in women is 25–27 cm. The measurement between the most distant parts of the upper flaring portion of the ilium (d i s t á n t i a c r i s t á r u m) is 28–30 cm.

The size of the inlet into the lesser pelvis, also called the true, or obstetric, conjugate, (conjugate vera seu. gynecologica), is measured between the promontory of the sacrum and the point of the pubic symphysis most prominent to the back. This size is approximately 11 cm. The transverse diameter of the inlet of the lesser pelvis (d i á m e t e r t r a n s v é r - s a) is the distance between the most remote points of the pelvic brim, which is approximately 13 cm. The oblique diameter (d i á m e t e r o b l i - q u a) of the inlet is 12 cm and is measured between sacroiliac articulation of one side and the iliopubic eminence of the other side.

Articulations of the free lower extremity

These junctions include connections of lower extremity bones with one another and with the hipbone (table 7).

The coxal, or hip, joint (art. cóxae) is formed between the semilunar surface of the acetabulum (cotyloid cavity) and the head of femur (Fig. 79). The articular surface of the hipbone is enlarged by the a c e t a b u l a r l a b r u m, which is a fibrocartilaginous formation, fixed onto the edge of the acetabulum. Over the acetabular notch stretches the t r a n s v e r s e a c - e t a b u l a r l i g a m e n t. The capsule of the hip joint attaches along the edges of the cotyloid cavity. On the femur it attaches nearly along the

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Fig. 79. Hip joint, right.

A — by frontal section articular cavity of hip joint is opened (acc. to R.D.Sinelnikov): 1 — epiphysial line; 2 — articular cartilage; 3 — pelvic bone; 4 — articular cavity; 5 — ligament of head of femur; 6 — transverse ligament of acetabulum; 7 — articular capsule; 8 — orbicular zone; 9 — acetabular labrum.

B — ligaments of the joint. Anterior aspect: 1 — iliofemoral ligament; 2 — pubofemoral ligament; 3 — intertrochanteric line; 4 — greater trochanter; 5 — inferior anterior iliac spine.

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intertrochanteric line in the front and above the intertrochanteric crest in the back. The joint cavity is very durable and is strengthened by five strong ligaments.

Within the fibrous membrane of the articular capsule there is a thick ligament called the o r b i c u l a r z o n e (z ó n a o r b i c u l á r i s), which loops around the neck of the femur. This ligament is attached to the iliac bone below the anterior inferior iliac spine.

The i l i o f e m o r a l l i g a m e n t (l i g . i l i o f e m o r á l e), which is approximately 1 cm thick, begins on the anterior inferior iliac spine and attaches to the intertrochanteric line. The p u b o f e m o r a l l i g a m e n t (l i g . p u b o f e m o r á l e) stretches from the superior ramus of pubis and the body of the iliac bone to the medial part of the intertrochanteric line. The i s c h i o f e m o r a l l i g a m e n t (l i g . i s c h i f e m o r á l e) is situated on the posterior surface of the joint. It begins on the body of the ischial bone, stretches laterally almost horizontally, and ends by the trochanteric fossa of greater trochanter. The articular cavity, covered by a synovial membrane, contains the l i g a m e n t o f h e a d o f f e m u r, which connects the fovea capitis of femur and the bottom of the cotyloid cavity. This ligament plays a key role in keeping the head of the femur by the acetabulum during the formation of the joint.

By structure the hip joint is spheroid. Movements in this joint include flexion and extension, abduction and adduction, circumduction and rotation. Flexion and extension take place about the frontal axis, their volume depending on the position of the leg in the knee joint. Maximal flexion (approximately 120°) is carried out when the leg is bent. With a straight leg the volume of flexion is reduced to 85° because of tension of the posterior group of muscles on the hip. Extension in the coxal joint has a volume of only 13–15° due to the strong pull of the iliofemoral ligament. Abduction and adduction are carried out about the sagittal axis at amplitude of 80–90°. The total volume of rotation about the vertical axis is up to 40–50°. The overall degree of movement in the hip joint is less compared to the shoulder joint. The hip joint, however, is more durable, strengthened by strong ligaments and muscles.

The knee joint (art. génus) is the largest and most complicated joint (Fig. 80 and 81). It is formed by the femur, tibia and patella. The articular surfaces of the medial and lateral condyles of the femur articulate with the superior articular surface of the tibia and with the patella.

The joint contains intra-articular semilunar cartilages called m e n i s - c i, which increase the congruence of articular surfaces, and also act as shock absorbers. The outer sides of the menisci are fused with the articular capsule. The inner edges are thin and are attached to the intercondylar

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On the posterior surface of this joint is the o b l i q u e p o p l i t e a l l i g a - m e n t (l i g . p o p l í t e u m o b l í q u u m), which begins on the medial condyle of the tibia and attaches on the posterior surface of the femur below the lateral epicondyle. The a r c u a t e p o p l i t e a l l i g a m e n t (l i g . p o p l í t e u m a r c u á t u m) begins on the posterior surface of the head of the fibula, curves medially and attaches to the posterior surface of the tibia. In the front the articular capsule is strengthened by the tendon of the quadriceps femoris muscle, which is also called the p a t e l l a r l i g a m e n t. The

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lateral and medial fascicles of this tendon pass from the patella onto the lateral and medial epicondyles of the femur, and are called the medial and lateral patellar ligaments (retinaculi patellae mediale et laterale).

The articular cavity of the knee joint contains two cruciate ligaments (Fig. 80, 81). The anterior cruciate ligament (lig. cruciátum antérius) begins on the medial surface of the lateral epicondyle of the femur and attaches to the anterior intercondylar field of the tibia. The posterior cruciate ligament (lig. cruciátum postérius) stretches between the lateral surface of the medial epicondyle of femur and the posterior intercondylar field of the tibia. The arcuate ligaments are covered by the synovial membrane. The knee joint has several synovial bursae (búrsae synoviáles). Their numbers and sizes may vary between individuals.

The knee joint is a complex (contains menisci) compound joint, condyloid according to the shape of its artic-

ular surfaces. It can undergo flexion and extension about the frontal axis with the total volume of 150°. Rotation about the vertical axis is possible when the leg is bent as a result of relaxation of the collateral ligaments. The volume of rotation is approximately 15°, and of passive rotation — 35°. The cruciate ligaments prevent pronation of the leg but become relaxed during supination. Supination is inhibited mainly by tension of the collateral ligaments, and pronation — by the cruciate ligaments and the tendon of quadriceps femoris muscle.

Articulations of the bones of the leg

Bones of the leg are connected by the tibiofibular joint and also by continuous fibrous connections, which include the tibiofibular syndesmosis and the interosseous membrane of the leg.

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The tibiofibular joint (art. tibiofibuláris) is formed between the fibular articular surface of the tibia and the articular surface on the head of the fibula. The articular surfaces are flat. The articular capsule is taut; it is strengthened by the a n t e r i o r and p o s t e r i o r l i g a m e n t s o f t h e f i b u l a r h e a d (ligg. cápitis fíbulae antérius et postérius).

The tibiofibular syndesmosis (syndesmósis tibiofibuláris) is a continuous fibrous connection between the fibular notch of the tibia and the corresponding articular surface on the lateral malleolus of the tibia. In the front and back the tibiofibular syndesmosis is strengthened by the a n t e - r i o r a n d p o s t e r i o r t i b i o f i b u l a r l i g a m e n t s (l i g g . t i b i o - f o b u l á r i a a n t é r i u s a t p o s t é r i u s). In some cases the capsule of the talocrural joint protrudes into this syndesmosis, in which case it could be considered a joint.

The i n t e r o s s e o u s m e m b r a n e o f t h e l e g (m e m b r á n a i n t e r ó s s e a c r ú r i s) is a continuos connection in the form of a strong connective membrane, stretched between interosseous margins of the tibia and fibula.

Articulations of the bones of the foot

The bones of the foot form articulations with the leg (the talocrural joint), articulations of the tarsus, metatarsus and phalanges. All these joints are fixated by the numerous ligaments (Fig. 82).

The ankle joint (art. talocrurális) is a compound hinge joint, formed between the inferior articular surface of the tibia and the articular surfaces of the trochlea of the talus and the medial and lateral malleoli. The fibula and tibia brace the trochlea of the talus like a fork. The articular capsule is attached from behind and the sides to the edges of articular surfaces and 0.5 cm away from them in the front. There are ligaments on the side surfaces of the joint. On the lateral part of the joint there are anterior and posterior talofibular and the calcaneofibular ligaments. They all begins on the lateral malleolus and spread out in a fan-like fashion. The a n t e - r i o r t a l o f i b u l a r l i g a m e n t (l i g . t a l o f i b u l á r e a n t é r i u s ) stretches to the neck of the talus, while the p o s t e r i o r t a l o f i b u l a r l i g a m e n t — to the posterior process of the talus. The c a l c a n e o f i b - u l a r l i g a m e n t (l i g . c a l c a n e o f i b u l á r e) stretches down and ends on the outer surface of the calcaneus. On the medial surface of the talocrural joint there is the m e d i a l (d e l t o i d) l i g a m e n t (l i g . c o l l a t e r a l e m e d i á l e, s e u d e l t o í d e u m). It begins on the medial malleolus, divides into four part and attaches to the navicular bone, talus and calcaneus.

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Fig. 82. Joints and ligaments of foot, right one. Superior and right aspects.

1 — tibia; 2 — interosseum membrane of leg; 3 — anterior tibiofibular ligament; 4 — anterior talofibular ligament; 5 — interosseum talocalcaneum ligament; 6 — calcaneonavicular ligament; 7 — calcaneocuboid ligament; 8 — dorsal tarsal ligaments; 9 — dorsal tarsometatarsal ligaments; 10 — dorsal metatarsal ligaments; 11 — collateral ligaments; 12 — lateral talocalcaneal ligament; 13 — calcaneofibalar ligament; 14 — lateral malleolus.

These are called the t i b i o n a v i c a l a r, t i b i o c a l c a n e a l and the a n t e - r i o r and p o s t e r i o r t i b i o t a l a r p a r t s of the medial ligaments.

Possible movements in the talocrural joint are plantar (flexion of the foot down) and extension (dorsal flexion) about the frontal axis with the total volume of approximately 70°. When the foot is flexed slight movements to the sides are also possible.

Articulations of the tarsus include the subtalar, talocalcaneonavicular, transverse tarsal, calcaneocuboid, cuneonavicular, and tarsometatarsal joints.

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