Module 23: The Appendicular Skeleton

Lesson 5: Embryonic Development of the Appendicular Skeleton

Phát Triển Của Bộ Xương Chi Trong Giai Đoạn Phôi Thai

Nội dung bài học:
Mỗi bài học (lesson) bao gồm 4 phần chính: Thuật ngữ, Luyện Đọc, Luyện Nghe, và Bàn Luận.
Sử dụng tính năng:
Bôi hoặc nhấp đôi vào từ, sau đó ấn vào biểu tượng để tra nghĩa từ đó. Khi bạn đưa chuột đến câu (hoặc khi nhấp vào câu trên màn hình điện thoại), gợi ý về cách hiểu câu đó sẽ hiện lên. Cuối cùng, bạn có thể đánh dấu hoàn thành toàn bộ bài học bằng cách ấn vào nút “Hoàn Thành” ở cuối trang.
Đăng ký và đăng nhập
Bạn cần đăng ký và đăng nhập vào tài khoản để lưu quá trình học.
Xem hướng dẫn đầy đủ
Dưới đây là danh sách những thuật ngữ Y khoa của module The Appendicular Skeleton.
Khái quát được số lượng thuật ngữ sẽ xuất hiện trong bài đọc và nghe sẽ giúp bạn thoải mái tiêu thụ nội dung hơn. Sau khi hoàn thành nội dung đọc và nghe, bạn hãy quay lại đây và luyện tập (practice) để quen dần các thuật ngữ này. Đừng ép bản thân phải nhớ các thuật ngữ này vội vì bạn sẽ gặp và ôn lại danh sách này trong những bài học (lesson) khác của cùng một module.

Medical Terminology: The Appendicular Skeleton

acetabulum
large, cup-shaped cavity located on the lateral side of the hip bone; formed by the junction of the ilium, pubis, and ischium portions of the hip bone
acromial end of the clavicle
lateral end of the clavicle that articulates with the acromion of the scapula
acromial process
acromion of the scapula
acromioclavicular joint
articulation between the acromion of the scapula and the acromial end of the clavicle
acromion
flattened bony process that extends laterally from the scapular spine to form the bony tip of the shoulder
adductor tubercle
small, bony bump located on the superior aspect of the medial epicondyle of the femur
anatomical neck
line on the humerus located around the outside margin of the humeral head
ankle joint
joint that separates the leg and foot portions of the lower limb; formed by the articulations between the talus bone of the foot inferiorly, and the distal end of the tibia, medial malleolus of the tibia, and lateral malleolus of the fibula superiorly
anterior border of the tibia
narrow, anterior margin of the tibia that extends inferiorly from the tibial tuberosity
anterior inferior iliac spine
small, bony projection located on the anterior margin of the ilium, below the anterior superior iliac spine
anterior sacroiliac ligament
strong ligament between the sacrum and the ilium portions of the hip bone that supports the anterior side of the sacroiliac joint
anterior superior iliac spine
rounded, anterior end of the iliac crest
apical ectodermal ridge
enlarged ridge of ectoderm at the distal end of a limb bud that stimulates growth and elongation of the limb
arcuate line of the ilium
smooth ridge located at the inferior margin of the iliac fossa; forms the lateral portion of the pelvic brim
arm
region of the upper limb located between the shoulder and elbow joints; contains the humerus bone
auricular surface of the ilium
roughened area located on the posterior, medial side of the ilium of the hip bone; articulates with the auricular surface of the sacrum to form the sacroiliac joint
base of the metatarsal bone
expanded, proximal end of each metatarsal bone
bicipital groove
intertubercular groove; narrow groove located between the greater and lesser tubercles of the humerus
calcaneus
heel bone; posterior, inferior tarsal bone that forms the heel of the foot
capitate
from the lateral side, the third of the four distal carpal bones; articulates with the scaphoid and lunate proximally, the trapezoid laterally, the hamate medially, and primarily with the third metacarpal distally
capitulum
knob-like bony structure located anteriorly on the lateral, distal end of the humerus
carpal bone
one of the eight small bones that form the wrist and base of the hand; these are grouped as a proximal row consisting of (from lateral to medial) the scaphoid, lunate, triquetrum, and pisiform bones, and a distal row containing (from lateral to medial) the trapezium, trapezoid, capitate, and hamate bones
carpal tunnel
passageway between the anterior forearm and hand formed by the carpal bones and flexor retinaculum
carpometacarpal joint
articulation between one of the carpal bones in the distal row and a metacarpal bone of the hand
clavicle
collarbone; elongated bone that articulates with the manubrium of the sternum medially and the acromion of the scapula laterally
coracoclavicular ligament
strong band of connective tissue that anchors the coracoid process of the scapula to the lateral clavicle; provides important indirect support for the acromioclavicular joint
coracoid process
short, hook-like process that projects anteriorly and laterally from the superior margin of the scapula
coronoid fossa
depression on the anterior surface of the humerus above the trochlea; this space receives the coronoid process of the ulna when the elbow is maximally flexed
coronoid process of the ulna
projecting bony lip located on the anterior, proximal ulna; forms the inferior margin of the trochlear notch
costoclavicular ligament
band of connective tissue that unites the medial clavicle with the first rib
coxal bone
hip bone
cuboid
tarsal bone that articulates posteriorly with the calcaneus bone, medially with the lateral cuneiform bone, and anteriorly with the fourth and fifth metatarsal bones
deltoid tuberosity
roughened, V-shaped region located laterally on the mid-shaft of the humerus
distal radioulnar joint
articulation between the head of the ulna and the ulnar notch of the radius
distal tibiofibular joint
articulation between the distal fibula and the fibular notch of the tibia
elbow joint
joint located between the upper arm and forearm regions of the upper limb; formed by the articulations between the trochlea of the humerus and the trochlear notch of the ulna, and the capitulum of the humerus and the head of the radius
femur
thigh bone; the single bone of the thigh
fibula
thin, non-weight-bearing bone found on the lateral side of the leg
fibular notch
wide groove on the lateral side of the distal tibia for articulation with the fibula at the distal tibiofibular joint
flexor retinaculum
strong band of connective tissue at the anterior wrist that spans the top of the U-shaped grouping of the carpal bones to form the roof of the carpal tunnel
foot
portion of the lower limb located distal to the ankle joint
forearm
region of the upper limb located between the elbow and wrist joints; contains the radius and ulna bones
fossa
(plural = fossae) shallow depression on the surface of a bone
fovea capitis
minor indentation on the head of the femur that serves as the site of attachment for the ligament to the head of the femur
glenohumeral joint
shoulder joint; formed by the articulation between the glenoid cavity of the scapula and the head of the humerus
glenoid cavity
(also, glenoid fossa) shallow depression located on the lateral scapula, between the superior and lateral borders
gluteal tuberosity
roughened area on the posterior side of the proximal femur, extending inferiorly from the base of the greater trochanter
greater pelvis
(also, greater pelvic cavity or false pelvis) broad space above the pelvic brim defined laterally by the fan-like portion of the upper ilium
greater sciatic foramen
pelvic opening formed by the greater sciatic notch of the hip bone, the sacrum, and the sacrospinous ligament
greater sciatic notch
large, U-shaped indentation located on the posterior margin of the ilium, superior to the ischial spine
greater trochanter
large, bony expansion of the femur that projects superiorly from the base of the femoral neck
greater tubercle
enlarged prominence located on the lateral side of the proximal humerus
hallux
big toe; digit 1 of the foot
hamate
from the lateral side, the fourth of the four distal carpal bones; articulates with the lunate and triquetrum proximally, the fourth and fifth metacarpals distally, and the capitate laterally
hand
region of the upper limb distal to the wrist joint
head of the femur
rounded, proximal end of the femur that articulates with the acetabulum of the hip bone to form the hip joint
head of the fibula
small, knob-like, proximal end of the fibula; articulates with the inferior aspect of the lateral condyle of the tibia
head of the humerus
smooth, rounded region on the medial side of the proximal humerus; articulates with the glenoid fossa of the scapula to form the glenohumeral (shoulder) joint
head of the metatarsal bone
expanded, distal end of each metatarsal bone
head of the radius
disc-shaped structure that forms the proximal end of the radius; articulates with the capitulum of the humerus as part of the elbow joint, and with the radial notch of the ulna as part of the proximal radioulnar joint
head of the ulna
small, rounded distal end of the ulna; articulates with the ulnar notch of the distal radius, forming the distal radioulnar joint
hip bone
coxal bone; single bone that forms the pelvic girdle; consists of three areas, the ilium, ischium, and pubis
hip joint
joint located at the proximal end of the lower limb; formed by the articulation between the acetabulum of the hip bone and the head of the femur
hook of the hamate bone
bony extension located on the anterior side of the hamate carpal bone
humerus
single bone of the upper arm
iliac crest
curved, superior margin of the ilium
iliac fossa
shallow depression found on the anterior and medial surfaces of the upper ilium
ilium
superior portion of the hip bone
inferior angle of the scapula
inferior corner of the scapula located where the medial and lateral borders meet
inferior pubic ramus
narrow segment of bone that passes inferiorly and laterally from the pubic body; joins with the ischial ramus to form the ischiopubic ramus
infraglenoid tubercle
small bump or roughened area located on the lateral border of the scapula, near the inferior margin of the glenoid cavity
infraspinous fossa
broad depression located on the posterior scapula, inferior to the spine
intercondylar eminence
irregular elevation on the superior end of the tibia, between the articulating surfaces of the medial and lateral condyles
intercondylar fossa
deep depression on the posterior side of the distal femur that separates the medial and lateral condyles
intermediate cuneiform
middle of the three cuneiform tarsal bones; articulates posteriorly with the navicular bone, medially with the medial cuneiform bone, laterally with the lateral cuneiform bone, and anteriorly with the second metatarsal bone
interosseous border of the fibula
small ridge running down the medial side of the fibular shaft; for attachment of the interosseous membrane between the fibula and tibia
interosseous border of the radius
narrow ridge located on the medial side of the radial shaft; for attachment of the interosseous membrane between the ulna and radius bones
interosseous border of the tibia
small ridge running down the lateral side of the tibial shaft; for attachment of the interosseous membrane between the tibia and fibula
interosseous border of the ulna
narrow ridge located on the lateral side of the ulnar shaft; for attachment of the interosseous membrane between the ulna and radius
interosseous membrane of the forearm
sheet of dense connective tissue that unites the radius and ulna bones
interosseous membrane of the leg
sheet of dense connective tissue that unites the shafts of the tibia and fibula bones
interphalangeal joint
articulation between adjacent phalanx bones of the hand or foot digits
intertrochanteric crest
short, prominent ridge running between the greater and lesser trochanters on the posterior side of the proximal femur
intertrochanteric line
small ridge running between the greater and lesser trochanters on the anterior side of the proximal femur
intertubercular groove (sulcus)
bicipital groove; narrow groove located between the greater and lesser tubercles of the humerus
ischial ramus
bony extension projecting anteriorly and superiorly from the ischial tuberosity; joins with the inferior pubic ramus to form the ischiopubic ramus
ischial spine
pointed, bony projection from the posterior margin of the ischium that separates the greater sciatic notch and lesser sciatic notch
ischial tuberosity
large, roughened protuberance that forms the posteroinferior portion of the hip bone; weight-bearing region of the pelvis when sitting
ischiopubic ramus
narrow extension of bone that connects the ischial tuberosity to the pubic body; formed by the junction of the ischial ramus and inferior pubic ramus
ischium
posteroinferior portion of the hip bone
knee joint
joint that separates the thigh and leg portions of the lower limb; formed by the articulations between the medial and lateral condyles of the femur, and the medial and lateral condyles of the tibia
lateral border of the scapula
diagonally oriented lateral margin of the scapula
lateral condyle of the femur
smooth, articulating surface that forms the distal and posterior sides of the lateral expansion of the distal femur
lateral condyle of the tibia
lateral, expanded region of the proximal tibia that includes the smooth surface that articulates with the lateral condyle of the femur as part of the knee joint
lateral cuneiform
most lateral of the three cuneiform tarsal bones; articulates posteriorly with the navicular bone, medially with the intermediate cuneiform bone, laterally with the cuboid bone, and anteriorly with the third metatarsal bone
lateral epicondyle of the femur
roughened area of the femur located on the lateral side of the lateral condyle
lateral epicondyle of the humerus
small projection located on the lateral side of the distal humerus
lateral malleolus
expanded distal end of the fibula
lateral supracondylar ridge
narrow, bony ridge located along the lateral side of the distal humerus, superior to the lateral epicondyle
leg
portion of the lower limb located between the knee and ankle joints
lesser pelvis
(also, lesser pelvic cavity or true pelvis) narrow space located within the pelvis, defined superiorly by the pelvic brim (pelvic inlet) and inferiorly by the pelvic outlet
lesser sciatic foramen
pelvic opening formed by the lesser sciatic notch of the hip bone, the sacrospinous ligament, and the sacrotuberous ligament
lesser sciatic notch
shallow indentation along the posterior margin of the ischium, inferior to the ischial spine
lesser trochanter
small, bony projection on the medial side of the proximal femur, at the base of the femoral neck
lesser tubercle
small, bony prominence located on anterior side of the proximal humerus
ligament of the head of the femur
ligament that spans the acetabulum of the hip bone and the fovea capitis of the femoral head
limb bud
small elevation that appears on the lateral side of the embryo during the fourth or fifth week of development, which gives rise to an upper or lower limb
linea aspera
longitudinally running bony ridge located in the middle third of the posterior femur
lunate
from the lateral side, the second of the four proximal carpal bones; articulates with the radius proximally, the capitate and hamate distally, the scaphoid laterally, and the triquetrum medially
medial border of the scapula
elongated, medial margin of the scapula
medial condyle of the femur
smooth, articulating surface that forms the distal and posterior sides of the medial expansion of the distal femur
medial condyle of the tibia
medial, expanded region of the proximal tibia that includes the smooth surface that articulates with the medial condyle of the femur as part of the knee joint
medial cuneiform
most medial of the three cuneiform tarsal bones; articulates posteriorly with the navicular bone, laterally with the intermediate cuneiform bone, and anteriorly with the first and second metatarsal bones
medial epicondyle of the femur
roughened area of the distal femur located on the medial side of the medial condyle
medial epicondyle of the humerus
enlarged projection located on the medial side of the distal humerus
medial malleolus
bony expansion located on the medial side of the distal tibia
metacarpal bone
one of the five long bones that form the palm of the hand; numbered 1–5, starting on the lateral (thumb) side of the hand
metacarpophalangeal joint
articulation between the distal end of a metacarpal bone of the hand and a proximal phalanx bone of the thumb or a finger
metatarsal bone
one of the five elongated bones that forms the anterior half of the foot; numbered 1–5, starting on the medial side of the foot
metatarsophalangeal joint
articulation between a metatarsal bone of the foot and the proximal phalanx bone of a toe
midcarpal joint
articulation between the proximal and distal rows of the carpal bones; contributes to movements of the hand at the wrist
navicular
tarsal bone that articulates posteriorly with the talus bone, laterally with the cuboid bone, and anteriorly with the medial, intermediate, and lateral cuneiform bones
neck of the femur
narrowed region located inferior to the head of the femur
neck of the radius
narrowed region immediately distal to the head of the radius
obturator foramen
large opening located in the anterior hip bone, between the pubis and ischium regions
olecranon fossa
large depression located on the posterior side of the distal humerus; this space receives the olecranon process of the ulna when the elbow is fully extended
olecranon process
expanded posterior and superior portions of the proximal ulna; forms the bony tip of the elbow
patella
kneecap; the largest sesamoid bone of the body; articulates with the distal femur
patellar surface
smooth groove located on the anterior side of the distal femur, between the medial and lateral condyles; site of articulation for the patella
pectineal line
narrow ridge located on the superior surface of the superior pubic ramus
pectoral girdle
shoulder girdle; the set of bones, consisting of the scapula and clavicle, which attaches each upper limb to the axial skeleton
pelvic brim
pelvic inlet; the dividing line between the greater and lesser pelvic regions; formed by the superior margin of the pubic symphysis, the pectineal lines of each pubis, the arcuate lines of each ilium, and the sacral promontory
pelvic girdle
hip girdle; consists of a single hip bone, which attaches a lower limb to the sacrum of the axial skeleton
pelvic inlet
pelvic brim
pelvic outlet
inferior opening of the lesser pelvis; formed by the inferior margin of the pubic symphysis, right and left ischiopubic rami and sacrotuberous ligaments, and the tip of the coccyx
pelvis
ring of bone consisting of the right and left hip bones, the sacrum, and the coccyx
phalanx bone of the foot
(plural = phalanges) one of the 14 bones that form the toes; these include the proximal and distal phalanges of the big toe, and the proximal, middle, and distal phalanx bones of toes two through five
phalanx bone of the hand
(plural = phalanges) one of the 14 bones that form the thumb and fingers; these include the proximal and distal phalanges of the thumb, and the proximal, middle, and distal phalanx bones of the fingers two through five
pisiform
from the lateral side, the fourth of the four proximal carpal bones; articulates with the anterior surface of the triquetrum
pollex
(also, thumb) digit 1 of the hand
posterior inferior iliac spine
small, bony projection located at the inferior margin of the auricular surface on the posterior ilium
posterior sacroiliac ligament
strong ligament spanning the sacrum and ilium of the hip bone that supports the posterior side of the sacroiliac joint
posterior superior iliac spine
rounded, posterior end of the iliac crest
proximal radioulnar joint
articulation formed by the radial notch of the ulna and the head of the radius
proximal tibiofibular joint
articulation between the head of the fibula and the inferior aspect of the lateral condyle of the tibia
pubic arch
bony structure formed by the pubic symphysis, and the bodies and inferior pubic rami of the right and left pubic bones
pubic body
enlarged, medial portion of the pubis region of the hip bone
pubic symphysis
joint formed by the articulation between the pubic bodies of the right and left hip bones
pubic tubercle
small bump located on the superior aspect of the pubic body
pubis
anterior portion of the hip bone
radial fossa
small depression located on the anterior humerus above the capitulum; this space receives the head of the radius when the elbow is maximally flexed
radial notch of the ulna
small, smooth area on the lateral side of the proximal ulna; articulates with the head of the radius as part of the proximal radioulnar joint
radial tuberosity
oval-shaped, roughened protuberance located on the medial side of the proximal radius
radiocarpal joint
wrist joint, located between the forearm and hand regions of the upper limb; articulation formed proximally by the distal end of the radius and the fibrocartilaginous pad that unites the distal radius and ulna bone, and distally by the scaphoid, lunate, and triquetrum carpal bones
radius
bone located on the lateral side of the forearm
sacroiliac joint
joint formed by the articulation between the auricular surfaces of the sacrum and ilium
sacrospinous ligament
ligament that spans the sacrum to the ischial spine of the hip bone
sacrotuberous ligament
ligament that spans the sacrum to the ischial tuberosity of the hip bone
scaphoid
from the lateral side, the first of the four proximal carpal bones; articulates with the radius proximally, the trapezoid, trapezium, and capitate distally, and the lunate medially
scapula
shoulder blade bone located on the posterior side of the shoulder
shaft of the femur
cylindrically shaped region that forms the central portion of the femur
shaft of the fibula
elongated, slender portion located between the expanded ends of the fibula
shaft of the humerus
narrow, elongated, central region of the humerus
shaft of the radius
narrow, elongated, central region of the radius
shaft of the tibia
triangular-shaped, central portion of the tibia
shaft of the ulna
narrow, elongated, central region of the ulna
soleal line
small, diagonally running ridge located on the posterior side of the proximal tibia
spine of the scapula
prominent ridge passing mediolaterally across the upper portion of the posterior scapular surface
sternal end of the clavicle
medial end of the clavicle that articulates with the manubrium of the sternum
sternoclavicular joint
articulation between the manubrium of the sternum and the sternal end of the clavicle; forms the only bony attachment between the pectoral girdle of the upper limb and the axial skeleton
styloid process of the radius
pointed projection located on the lateral end of the distal radius
styloid process of the ulna
short, bony projection located on the medial end of the distal ulna
subpubic angle
inverted V-shape formed by the convergence of the right and left ischiopubic rami; this angle is greater than 80 degrees in females and less than 70 degrees in males
subscapular fossa
broad depression located on the anterior (deep) surface of the scapula
superior angle of the scapula
corner of the scapula between the superior and medial borders of the scapula
superior border of the scapula
superior margin of the scapula
superior pubic ramus
narrow segment of bone that passes laterally from the pubic body to join the ilium
supraglenoid tubercle
small bump located at the superior margin of the glenoid cavity
suprascapular notch
small notch located along the superior border of the scapula, medial to the coracoid process
supraspinous fossa
narrow depression located on the posterior scapula, superior to the spine
surgical neck
region of the humerus where the expanded, proximal end joins with the narrower shaft
sustentaculum tali
bony ledge extending from the medial side of the calcaneus bone
talus
tarsal bone that articulates superiorly with the tibia and fibula at the ankle joint; also articulates inferiorly with the calcaneus bone and anteriorly with the navicular bone
tarsal bone
one of the seven bones that make up the posterior foot; includes the calcaneus, talus, navicular, cuboid, medial cuneiform, intermediate cuneiform, and lateral cuneiform bones
thigh
portion of the lower limb located between the hip and knee joints
tibia
shin bone; the large, weight-bearing bone located on the medial side of the leg
tibial tuberosity
elevated area on the anterior surface of the proximal tibia
trapezium
from the lateral side, the first of the four distal carpal bones; articulates with the scaphoid proximally, the first and second metacarpals distally, and the trapezoid medially
trapezoid
from the lateral side, the second of the four distal carpal bones; articulates with the scaphoid proximally, the second metacarpal distally, the trapezium laterally, and the capitate medially
triquetrum
from the lateral side, the third of the four proximal carpal bones; articulates with the lunate laterally, the hamate distally, and has a facet for the pisiform
trochlea
pulley-shaped region located medially at the distal end of the humerus; articulates at the elbow with the trochlear notch of the ulna
trochlear notch
large, C-shaped depression located on the anterior side of the proximal ulna; articulates at the elbow with the trochlea of the humerus
ulna
bone located on the medial side of the forearm
ulnar notch of the radius
shallow, smooth area located on the medial side of the distal radius; articulates with the head of the ulna at the distal radioulnar joint
ulnar tuberosity
roughened area located on the anterior, proximal ulna inferior to the coronoid process
Nội dung này đang được cập nhật.
Dưới đây là các bài văn nằm ở bên trái. Ở bên phải là các bài luyện tập (practice) để đánh giá khả năng đọc hiểu của bạn. Sẽ khó khăn trong thời gian đầu nếu vốn từ vựng của bạn còn hạn chế, đặc biệt là từ vựng Y khoa. Hãy kiên nhẫn và đọc nhiều nhất có kể, lượng kiến thức tích tụ dần sẽ giúp bạn đọc thoải mái hơn.
Embryologically, the appendicular skeleton arises from mesenchyme, a type of embryonic tissue that can differentiate into many types of tissues, including bone or muscle tissue. Mesenchyme gives rise to the bones of the upper and lower limbs, as well as to the pectoral and pelvic girdles. Development of the limbs begins near the end of the fourth embryonic week, with the upper limbs appearing first. Thereafter, the development of the upper and lower limbs follows similar patterns, with the lower limbs lagging behind the upper limbs by a few days.
Each upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after (Figure 1).

Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying mesenchyme to rapidly proliferate, producing the outgrowth of the developing limb. As the limb bud elongates, cells located farther from the apical ectodermal ridge slow their rates of cell division and begin to differentiate. In this way, the limb develops along a proximal-to-distal axis.

During the sixth week of development, the distal ends of the upper and lower limb buds expand and flatten into a paddle shape. This region will become the hand or foot. The wrist or ankle areas then appear as a constriction that develops at the base of the paddle. Shortly after this, a second constriction on the limb bud appears at the future site of the elbow or knee. Within the paddle, areas of tissue undergo cell death, producing separations between the growing fingers and toes. Also during the sixth week of development, mesenchyme within the limb buds begins to differentiate into hyaline cartilage that will form models of the future limb bones.

The early outgrowth of the upper and lower limb buds initially has the limbs positioned so that the regions that will become the palm of the hand or the bottom of the foot are facing medially toward the body, with the future thumb or big toe both oriented toward the head. During the seventh week of development, the upper limb rotates laterally by 90 degrees, so that the palm of the hand faces anteriorly and the thumb points laterally. In contrast, the lower limb undergoes a 90-degree medial rotation, thus bringing the big toe to the medial side of the foot.
All of the girdle and limb bones, except for the clavicle, develop by the process of endochondral ossification. This process begins as the mesenchyme within the limb bud differentiates into hyaline cartilage to form cartilage models for future bones. By the twelfth week, a primary ossification center will have appeared in the diaphysis (shaft) region of the long bones, initiating the process that converts the cartilage model into bone. A secondary ossification center will appear in each epiphysis (expanded end) of these bones at a later time, usually after birth. The primary and secondary ossification centers are separated by the epiphyseal plate, a layer of growing hyaline cartilage. This plate is located between the diaphysis and each epiphysis. It continues to grow and is responsible for the lengthening of the bone. The epiphyseal plate is retained for many years, until the bone reaches its final, adult size, at which time the epiphyseal plate disappears and the epiphysis fuses to the diaphysis.

Small bones, such as the phalanges, will develop only one secondary ossification center and will thus have only a single epiphyseal plate. Large bones, such as the femur, will develop several secondary ossification centers, with an epiphyseal plate associated with each secondary center. Thus, ossification of the femur begins at the end of the seventh week with the appearance of the primary ossification center in the diaphysis, which rapidly expands to ossify the shaft of the bone prior to birth. Secondary ossification centers develop at later times. Ossification of the distal end of the femur, to form the condyles and epicondyles, begins shortly before birth. Secondary ossification centers also appear in the femoral head late in the first year after birth, in the greater trochanter during the fourth year, and in the lesser trochanter between the ages of 9 and 10 years. Once these areas have ossified, their fusion to the diaphysis and the disappearance of each epiphyseal plate follow a reversed sequence. Thus, the lesser trochanter is the first to fuse, doing so at the onset of puberty (around 11 years of age), followed by the greater trochanter approximately 1 year later. The femoral head fuses between the ages of 14–17 years, whereas the distal condyles of the femur are the last to fuse, between the ages of 16–19 years. Knowledge of the age at which different epiphyseal plates disappear is important when interpreting radiographs taken of children. Since the cartilage of an epiphyseal plate is less dense than bone, the plate will appear dark in a radiograph image. Thus, a normal epiphyseal plate may be mistaken for a bone fracture.

The clavicle is the one appendicular skeleton bone that does not develop via endochondral ossification. Instead, the clavicle develops through the process of intramembranous ossification. During this process, mesenchymal cells differentiate directly into bone-producing cells, which produce the clavicle directly, without first making a cartilage model. Because of this early production of bone, the clavicle is the first bone of the body to begin ossification, with ossification centers appearing during the fifth week of development. However, ossification of the clavicle is not complete until age 25.

OpenStax. (2022). Anatomy and Physiology 2e. Rice University. Retrieved June 15, 2023. ISBN-13: 978-1-711494-06-7 (Hardcover) ISBN-13: 978-1-711494-05-0 (Paperback) ISBN-13: 978-1-951693-42-8 (Digital). License: Attribution 4.0 International (CC BY 4.0). Access for free at openstax.org.

Limb buds are visible in an embryo at the end of the seventh week of development (embryo derived from an ectopic pregnancy). (credit: Ed Uthman/flickr)

Nội dung này đang được cập nhật.
Dưới đây là video và các luyện tập (practice) của bài này. Nghe là một kĩ năng khó, đặc biệt là khi chúng ta chưa quen nội dung và chưa có nhạy cảm ngôn ngữ. Nhưng cứ đi thật chậm và đừng bỏ cuộc.
Xem video và cảm nhận nội dung bài. Bạn có thể thả trôi, cảm nhận dòng chảy ngôn ngữ và không nhất thiết phải hiểu toàn bộ bài. Bên dưới là script để bạn khái quát nội dụng và tra từ mới.
Script:
  1. The bones of the appendicular skeleton arise from embryonic mesenchyme.
  2. Limb buds appear at the end of the fourth week.
  3. The apical ectodermal ridge, located at the end of the limb bud, stimulates growth and elongation of the limb.
  4. During the sixth week, the distal end of the limb bud becomes paddle-shaped, and selective cell death separates the developing fingers and toes.
  5. At the same time, mesenchyme within the limb bud begins to differentiate into hyaline cartilage, forming models for future bones.
  6. During the seventh week, the upper limbs rotate laterally and the lower limbs rotate medially, bringing the limbs into their final positions.
  7. Endochondral ossification, the process that converts the hyaline cartilage model into bone, begins in most appendicular bones by the twelfth fetal week.
  8. This begins as a primary ossification center in the diaphysis, followed by the later appearance of one or more secondary ossifications centers in the regions of the epiphyses.
  9. Each secondary ossification center is separated from the primary ossification center by an epiphyseal plate.
  10. Continued growth of the epiphyseal plate cartilage provides for bone lengthening.
  11. Disappearance of the epiphyseal plate is followed by fusion of the bony components to form a single, adult bone.
  12. The clavicle develops via intramembranous ossification, in which mesenchyme is converted directly into bone tissue.
  13. Ossification within the clavicle begins during the fifth week of development and continues until 25 years of age.
Bật video, nghe và điền từ vào chỗ trống.
Dưới đây là phần bàn luận. Bạn có thể tự do đặt câu hỏi, bổ sung kiến thức, và chia sẻ trải nghiệm của mình.
Subscribe
Notify of

0 Comments
Inline Feedbacks
View all comments

Ấn vào ô bên dưới để đánh dấu bạn đã hoàn thành bài học này

Hoàn Thành

Quá dữ! Tiếp tục duy trì phong độ nhé!

Đã Hoàn Thành