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Head musculature.
The extrinsic and intrinsic muscles of the tongue are thought to be derived from occipital myotomes that migrate forward.
The extrinsic muscles of the eye may derive from preop—tic myotomes that originally surround the prochordal plate.
The muscles of mastication, facial expression, the pharynx, and the larynx are derived from different pharyngeal arches and maintain their i
Limb musculature originates in the seventh week from soma mesoderm that migrates into the limb bud. With time, the limb musculature splits into ventral flexor and dorsal extern groups.
The limb is i
The cutaneous i
Smooth muscle: the smooth muscle coats of the gut, trachtea, bronchi, and blood vessels of the associated mesenteries are derived from splanchnic mesoderm surrounding the gastrointestinal tract. Vessels elsewhere in the body obtain their coat from local mesenchyme.
Cardiac muscle, like smooth muscle, is derived from splanchnic mesoderm.
New words
ventral – брюшной
somatic – соматический
cytoplasm – цитоплазма
cross—striations – поперечные бороздчатости
extensor – разгибающая мышца
dorsal – спинной
ivertebral – позвоночный
arche – дуга
abdomen – живот
facial – лицевой
branch – ветвь
10. Skeleton
The bones of our body make up a skeleton. The skeleton forms about 18 % of the weight of the human body.
The skeleton of the trunk mainly consists of spinal column made of a number of bony segments called vertebrae to which the head, the thoracic cavity and the pelvic bones are co
The human vertebrae are divided into differentiated groups. The seven most superior of them are the vertebrae called the cervical vertebrae. The first cervical vertebra is the atlas. The second vertebra is called the axis.
Inferior to the cervical vertebrae are twelve thoracic vertebrae. There is one rib co
The first pairs or ribs are short. All seven pairs join the sternum directly and are sometimes called the «true ribs». Pairs 8, 9, 10 are «false ribs». The eleventh and twelfth pairs of ribs are the «floating ribs».
Inferior to the thoracic vertebrae are five lumbar vertebrae. The lumbar vertebrae are the largest and the heaviest of the spinal column. Inferior to the lumbar vertebrae are five sacral vertebrae forming a strong bone in adults. The most inferior group of vertebrae are four small vertebrae forming together the соссуж.
The vertebral column is not made up of bone alone. It also has cartilages.
New words
skeleton – скелет
make up – составлять
weight – вес
trunk – туловище
vertebrae – позвоночник
thoracic cavity – грудная клетка
pelvic – тазовый
cervical – шейный
atlas – 1 шейный позвонок
sternum – грудина
mainly – главным образом
axis – ось
spinal column – позвоночник
inferior – нижний
rib – ребро
pair – пара
sacral – сакральный
соссу«– копчик
floating – плавающий
forming – формирующий
cartilage – хрящ
lumbar – поясничный
adult – взрослый
11. Muscles
Muscles are the active part of the motor apparatus; their contraction produces various movements.
The muscles may be divided from a physiological standpoint into two classes: the voluntary muscles, which are under the control of the will, and the involuntary muscles, which are not.
All muscular tissues are controlled by the nervous system.
When muscular tissue is examined under the microscope, it is seen to be made up of small, elongated threadlike cells, which arc called muscle fibres, and which are bound into bundles by co
There are three varieties of muscle fibres:
1) striated muscle fibres, which occur in voluntary muscles;
2) unstriated muscles which bring about movements in the internal organs;
3) cardiac or heart fibres, which are striated like (1), but are otherwise different.
Muscle consists of threads, or muscle fibers, supported by co
According to the form all the muscles are traditionally divided into three basic groups: long, short and wide muscles. Long muscles compose the free parts of the extremities. The wide muscles form the walls of the body cavities. Some short muscles, of which stapedus is the smallest muscle in the human body, form facial musculature.
Some muscles are called according to the structure of their fibres, for example radiated muscles; others according to their uses, for example extensors or according to their directions, for example, – oblique.
Great research work was carried out by many scientists to determine the functions of the muscles. Their work helped to establish that the muscles were the active agents of motion and contraction.
New words
muscles – мышцы active – активный
motor apparatus – двигательный аппарат
various – различный
movement – движение
elongated – удлиненный
threadlike – нитевидный
be bound – быть связанным
ability – возможность
capable – способность
scientist – ученый
basic – основной
12. Bones
Bone is the type of co
The bones of women are generally lighter than those of men, while children's bones are more resilient than those of adults. Bones also respond to certain physical physiological changes: atrophy, or waste away.
Bones are generally classified in two ways. When classified on the basis of their shape, they fall into four categories: flat bones, such as the ribs; long bones, such as the thigh bone; short bones, such as the wrist bones; and irregular bones, such as the vertebrae. When classified on the basis of how they develop, bones are divided into two groups: en—dochondral bones and intramembraneous bones. En—dochondral bones, such as the long bones and the bones at the base of the skull, develop from cartilage tissue. Intra—membraneous bones, such as the flat bones of the roof of the skull, are not formed from cartilage but develop under or within a co
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