1 Learn the key words and phrases:

muscles, contract, contraction, attach, resist, fascia, connective tissue, tendon, fibrous, fascicle, network, subcutaneous fascia, subserous fascia, cavity

2 Memorize the explanation to the terms:

fascia (pl. fasciae) a sheet of connective tissue covering or binding

together body structures

fascicle a small bundle

subcutaneous being under the skin

fibrous containing or consisting of fibers

Muscular System

Muscles, the organs of the muscular system, consist largely of cells that are specialized to undergo contractions. During these contractions, chemical energy from nutrients is converted into mechanical energy, or movement.

When muscle cells contract, they pull on the body parts to which they are attached. This action usually causes movement, as when joints of the legs are flex and extended during walking. But at other times, muscular contractions resist motion, as when they help hold body parts in postural positions. Muscles are also responsible for the movement of body fluids such as blood and urine. In addition, they function in heat production, which helps maintain body temperature.

Structure of a Skeletal Muscle

A skeletal muscle is an organ of the muscular system composed of several kinds of tissue, including skeletal muscle tissue, nerve tissue, blood, and various connective tissues.

An individual skeletal muscle is separated from adjacent muscles and held in position by layers of fibrous connective tissue called fascia. This connective tissue surrounds each muscle and may project beyond the end of its muscle fibers to form a cordlike tendon. Fibers in a tendon intertwine with those in the periosteum of a bone, thus attaching the muscle to the bone. In other cases, the connective tissues associated with a muscle form broad fibrous sheets called aponeuroses, which may be attached to the coverings of adjacent muscles.

The layer of connective tissue that closely surrounds a skeletal muscle is called the epimysium. Other layers of connective tissue, called the perimysium, extend inward from the epimysium and separate the muscle tissue into small sections. These sections contain bundles of skeletal muscle fibers called fascicles (fasciculi). Each muscle fiber within a fascicle is surrounded by a layer of connective tissue in the form of a thin, delicate covering called endomysium.

Thus, all parts of a skeletal muscle are enclosed in layers of connective tissue. This arrangement allows the parts to move independently. Also, numerous blood vessels and nerves pass through these layers.

The fascia associated with the individual organs of the muscular system is part of a complex network of fasciae that extends throughout the body. The portion of the network that surrounds and penetrates the muscles is called deep fascia. It is continuous with the subcutaneous fascia that lies just beneath the skin, forming the subcutaneous layer. The network is also continuous with the subserous fascia that forms the connective tissue layer of the serous membranes covering organs in various body cavities and lining those cavities.

Post-text assignments

1 Respond to the following tasks:

1 List the three types of muscle tissue.

2 Describe the connective tissue coverings of a skeletal muscle.

3 Describe how connective tissue is associated with a skelelal muscle.

4 Distinguish between deep fascia, subcutaneous fascia, and subserous fascia.

5 Describe the major events that occur when a muscle fiber contracts.

2 Fill in the blanks with the words given below:

1 There are many ..in the spine. 2 We use the ... and the tongue when we speak 3 There are a great number of ... ... ... in the muscles. 4 The cells are connected by connective ... . 5 ... ... ... move our internal organs such as the digestive tract, blood vessels and secretory ducts. 6 The teeth and a tongue are located in ... ... . 7 The skull encloses ... ... . 8 We chew our food with the ... . 9 The joints allow the bones ... ... . 10 The bones are of various sizes and .... .

(a – the smooth muscles; b – shapes; c – vertebrae; d – lips; e – teeth; f – nerves and blood vessels; g – to move; h – the brain; i – tissue; j – the mouth)

3 Read and retell the article:

Experience floating muscles. Stand in a doorway with your hands pressing on the door frame as hard as you possibly can. Hold it for a full minute. Walk away from the door. Your muscles memory will keep pushing your arms out, and they will float up without any effort on your part.

4 Translate in writing:

There are two main varieties of muscle: voluntary and involuntary. Voluntary muscle is striated in appearance and may be contracted at will. It is usually attached at each end to different bones, which it brings closer together (e. g. in bending the arm) when it contrasts. Involuntary muscle is smooth in appearance and may not be contracted at will. It is found chiefly in internal organs, such as the intestine wall and the heart, whose function is automatic.

Unit 6

Pre-text assignments