Muscles and common muscle disorders and diseases 五班一组

Human muscular system

Forms of muscles

Type of Muscles The human body has more than 600 major muscles.About 240 of them have specific names. In general,muscles are classified into three groups:(1)skeletal muscles,(2)smooth muscles, and(3)cardiac muscles.

Skeletal muscle Skeletal muscle, as its name implies, is the muscle attached to the skeleton. It is also called striated muscle. The contraction of skeletal muscle is under voluntary control.

Function Skeletal muscles help hold the bones of the skeleton together and give the body shape.They also make the body move .

The biceps,triceps or other kinds of skeletal muscles are also called voluntary muscles because they are under the contol of our willpower. 肱二头肌、肱三头肌和其它类的骨骼肌也被称为随意肌，这是因为它们接受入主观意愿的驱使。

Skeletal muscle is also termed voluntary striated muscle Skeletal muscle is also termed voluntary striated muscle.The name "striated" comes from the characteristic cross striations of the muscle fibers when viewed under a microscope.These striations are caused by the arrangement of the protein molecules within the fibers that produce shortening or contraction of the fiber. 骨骼肌亦被称为随意条纹肌。所谓条纹一词来源于显微镜下肌肉组织所呈现的横状条纹特色。这些条纹是因肌纤维中蛋白分子的排列而引起的，可使肌纤维变短或收缩。

Skeletal muscle

Voluntary striated muscle fibers are arrange in bundles within the muscle.A transverse section through a striated muscle shows a group of muscle fibers surrounded by fibrous connective tissue to form a bundle.The many bundles surrounded by the fibrous connective tissue fascia form the fleshy belly of the muscle. 随意条纹肌纤维在肌肉中成束排列。在横纹肌的横截面上可见一组肌纤维被肌纤维结缔组织包绕形成纤维束。许多纤维束又被纤维结缔组织筋膜所包绕，最后形成肌肉的肌腹部分

muscle fibers

One end of the muscle must be fixed,or immobile,in order for it to produce movement at a joint.The movement the muscle performs is called the functionof that muscle.The function of a muscle may be to contract,the non-moving or fixed end,is called the origin.The attached end,which moves during contraction,is called the insertion of the muscle. 为了使关节处运动，肌肉的一端必须固定，不可移动。肌肉所做的运动被称做肌肉的功能。某块肌肉的功能可能是收缩，使骨骼屈曲，而肌腱的长度不变。肌肉的附着点，即不动或固定的一端，被称为肌起端。而另一个在收缩过程中发生了移动的附着点被称为肌止端。

Cardiac muscles Heart muscle — also called cardiac muscle — makes up the wall of the heart. Throughout our life, it contracts some 70 times per minute pumping about 5 liters of 。blood each minute.

heart They have some characteristics of both skeletal and smooth muscles.Like skeletal muscle fibers,cardiac muscle cells have striation.Like smooth muscle fibers,each cardiac muscle cell has only one nucleus and its contraction and relaxation are not under the willful control of the willpover.Therfore,it is also called involuntary striated muscle.它具有骨骼肌和平滑肌的某些特点。和骨骼肌一样，心肌细胞呈现条纹；像平滑肌纤维，每一个心肌细胞只有一个细胞核，而它的收缩和放松并不受主观意志的驱使。据此原因，它又被称为不随意条纹肌。

Right atrium

Right ventricle

Left atrium

Left ventricle

Smooth muscles Smooth muscle is found in the walls of all the hollow organs of the body (except the heart). Its contraction reduces the size of these structures. 第二种类型的肌肉被称为平滑肌，它构成血管壁和消化道的内壁，经常表现为围绕管状结构的一层肌肉纤维鞘。在显微镜下，肌肉中不呈现条纹，再则，因为它不受主观意志的控制，又被称为不随意非条纹肌。

Stomach

横结肠transversecolon small intestine小肠

common muscle disorders Muscle soreness is often caused by hard muscular work.. in severe cases, the soreness may last up to four days. 肌酸痛常因过度的肌肉劳累所致。严重时，症状可能会持续上数日。

Destroyed muscle fibers are never replaced Destroyed muscle fibers are never replaced.They do not have the ability to divide,and anindividual has as many muscle fibers at birth as he will during his lifetime. 肌肉的损伤被破坏的肌纤维不能再生。由于没有分化能力，人出生时有多少肌纤维，终坐如此。

The increase in the size of muscles of an adult compared with that of an infat is due to the increase in the size of the muscle fibers,not to an increase in their number.The increase in size of muscle is called hypertrophy.Exercise causes hypertrophy of muscles. 成人和婴儿时相比，肌肉体积的增长是因为肌纤维体积的增长，而不是数量上的增多。肌肉体积的增大称为“肥大”。锻炼可促使肌肉肥大。

Cramp肌痉挛 A person may experience painful cramps of certain skeletal muscles if he or she exercises too hard or for a long time. 一个人可能会因为运动过量或运动时间过长而骨骼肌发生肌痉挛

Myositis肌炎

muscular atrophy diseases肌萎缩 Localized muscle atrophy results from interference with the innervation and may be caused by traumatic denervation or neuromuscular disorders, such as polio. 局部性肌萎缩是由神经支配障碍所致，也可能因创伤而失去神经支配或神经肌肉疾病引起如脊髓灰质炎

Polio脊髓灰质炎

Muscle dystrophy肌营养不良 Muscle dystrophy. This term refers to a group of genetically determined myopathies characterized by progressive atrophy or degeneration of increasing numbers of individual muscle cells. 肌营养不良本术语指以逐渐加重的肌萎缩或单个肌细胞增速退变为特点的一组遗传性肌肉病变。

Muscle dystrophy肌营养不良

Mysasthenia gravis,MG重症肌无力