Development of the bones of the upper and lower limbs

Scapula. In the area of the neck of the scapula, at the end of the 2nd month of intrauterine life, the primary ossification point is laid. From this point, the body and spine of the scapula ossify.

At the end of the first year of life, the ossification point is laid in the coracoid process, and at 15-18 years - in the acromion. Fusion of the coracoid process and acromion with the scapula occurs at 15-19 years. Additional ossification points that arise in the scapula near its medial edge at 15-19 years merge with the main ones at 20-21 years.

The clavicle ossifies early. The ossification point appears in it on the 6th-7th week of development in the middle of the connective tissue rudiment (endesmal ossification). From this point, the body and acromial end of the clavicle are formed, which in a newborn are almost completely built of bone tissue. In the sternal end of the clavicle, cartilage is formed, in which the ossification nucleus appears only on the 16th-18th year and fuses with the body of the bone by 20-25 years.

Humerus. Three secondary ossification centers are formed in the proximal epiphysis: in the head - most often in the 1st year of life; in the greater tubercle - in the 1st-5th years and in the lesser tubercle - in the 1st-5th years. These ossification centers grow together by the age of 3-7 years and are attached to the diaphysis at the age of 13-25 years. In the head of the humeral condyle (distal epiphysis), the ossification center is laid from the neonatal period to 5 years, in the lateral epicondyle - at 4-6 years, in the medial - at 4-11 years. All parts grow together with the diaphysis of the bone by the age of 13-21 years.

Ulna. The ossification point in the proximal epiphysis is laid at 7-14 years. The ulnar and coronoid processes arise from it. In the distal epiphysis, ossification points appear at 3-14 years. The bone tissue grows and forms the head and styloid process. The proximal epiphysis fuses with the diaphysis at 13-20 years, and the distal epiphysis at 15-25 years.

Radius bone. In the proximal epiphysis, the ossification point is laid at 2.5-10 years, and it grows to the diaphysis at 13-21 years. The ossification point formed in the distal epiphysis at 4-9 years of age merges with the diaphysis of the bone at 13-25 years.

Wrist bones. Ossification of the cartilages from which the wrist bones develop begins after birth. In the 1st-2nd year of a child’s life, the ossification point appears in the capitate and hamate bones, in the 3rd (6 months - 7.5 years) - in the triquetral, in the 4th (6 months - 9.5 years) - in the lunate, in the 5th (2.5-

9 years) - in the scaphoid, at 6-7 (1.5-10 years) - in the polygonal and trapezoid bones and at 8 (6.5-16.5 years) - in the pisiform bone.

Metacarpal bones. The metacarpal bones are laid down much earlier than the carpal bones. In the diaphyses of the metacarpal bones, the ossification points are laid down at the 9th-10th week of intrauterine life, except for the first metacarpal bone, in which the ossification point appears at the 10th-11th week. Epiphyseal ossification points appear in the metacarpal bones (in their heads) at the age of 10 months to 7 years. The epiphysis (head) fuses with the diaphysis of the metacarpal bone at the age of 15-25 years.

Phalanges of the fingers. The ossification point in the diaphyses of the distal phalanges appears in the middle of the 2nd month of intrauterine life, then in the proximal phalanges - at the beginning of the 3rd month and in the middle ones - at the end of the 3rd month. At the base of the phalanges, the ossification points are laid at the age from 5 months to 7 years, and grow to the body at 14-21 years. In the sesamoid bones of the first finger of the hand, the ossification points are determined at 12-15 years.

Pelvic bone. The cartilaginous rudiment of the pelvic bone ossifies from three primary ossification centers and several additional ones. In the 4th month of intrauterine life, an ossification center appears in the body of the ischium, in the 5th month - in the body of the pubic bone, and in the 6th month - in the body of the ilium. The cartilaginous layers between the bones in the acetabulum area are preserved until the age of 13-16. At the age of 13-15, secondary ossification centers appear in the crest, spines, in the cartilage near the auricular surface, in the ischial tuberosity and pubic tubercle. They fuse with the pelvic bone by the age of 20-25.

Femur. In the distal epiphysis, the ossification point is laid shortly before birth or soon after birth (up to 3 months). In the 1st year, the ossification point appears in the head of the femur (from the neonatal period to 2 years), at 1.5-9 years - in the greater trochanter, at 6-14 years - in the lesser trochanter. Fusion of the diaphysis with the epiphyses and apophyses of the femur occurs in the period from 14 to 22 years.

The patella. Ossifies from several points that appear 2-6 years after birth and merge into one bone by the age of 7.

Tibia. In the proximal epiphysis, the ossification point is formed shortly before or shortly after birth. In the distal epiphysis, the ossification point appears before the age of 2. It fuses with the diaphysis at 14-24 years, the proximal epiphysis - at the age of 16 to 25 years.

Fibula. The ossification point in the distal epiphysis is laid before the 3rd year of life of the child, in the proximal - in the 2nd-6th year. The distal epiphysis fuses with the diaphysis at 15-25 years, the proximal - at 17-25 years.

Tarsal bones. In a newborn, there are already 3 ossification centers in the tarsal bones: in the calcaneus, talus, and cuboid bones. The ossification centers appear in the following order: in the calcaneus - in the 6th month of intrauterine life, in the talus - in the 7th-8th, in the cuboid - in the 9th month. The remaining cartilaginous rudiments ossify after birth. In the lateral sphenoid bone, the ossification center is formed at 9 months - 3.5 years, in the medial sphenoid - at 9 months - 4 years, in the intermediate sphenoid - at 9 months - 5 years; the navicular bone ossifies in the period from 3 months of intrauterine life to 5 years. The additional ossification point in the calcaneal tubercle is laid at 5-12 years and fuses with the calcaneus at 12-22 years.

Metatarsal bones. Ossification points in the epiphyses occur at 1.5-7 years, the epiphyses fuse with the diaphyses at 13-22 years.

Phalanges of the fingers. Diaphyses begin to ossify in the 3rd month of intrauterine life, ossification points at the base of the phalanges appear at 1.5-7.5 years, epiphyses grow to diaphyses at 11-22 years.

Variants and anomalies of limb bone development

There are numerous variants and anomalies in the development of the skeletal limbs.

Scapula. The depth of the scapular notch varies, sometimes its edges grow together and instead of a notch, a hole is formed. In rare cases, the ossification point in the acromion does not grow to the spine of the scapula. As a result, a cartilaginous layer is preserved between the acromion and the spine throughout life.

Clavicle. Its curves may vary. The conical tubercle and trapezoid line on the clavicle are not always defined.

Humerus. Above the medial epicondyle there may be a process - processus supracondylaris. Sometimes it is very long and, bending, forms a hole.

Ulna and radius. The olecranon does not always fuse with the body of the radius. The radius may be absent (a rare anomaly).

Bones of the hand. In rare cases, additional bones of the wrist develop, in particular the central bone (os centrale). Additional fingers may develop (polydactyly). The additional finger is usually located on the side of the little finger, less often on the side of the thumb.

Pelvic bone. There may be a hole in the center of the iliac fossa. In some cases, the iliac bones are greatly elongated.

Femur. The gluteal tuberosity can be very pronounced, in its place a tubercle is formed - the third trochanter.

Bones of the lower leg. The shape of the body of the tibia may not be triangular, but flattened.

Bones of the foot. Additional tarsal bones may develop. Thus, the posterior process of the talus turns into an independent triangular bone (os trigonum); the medial sphenoid bone is divided into two independent bones, etc.

The foot, like the hand, can have additional toes.

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