Muscular System PDF

THE MUSCULAR SYSTEM  INTRODUCTION Muscles make up the bulk of the body and account for 1/3 of its weight. Blood vessels and nerves run to every muscle, helping control and regulate each muscle’s function. ❖ The muscular system creates body heat and also moves the: Bones of the Skeletal s...

THE MUSCULAR SYSTEM  INTRODUCTION Muscles make up the bulk of the body and account for 1/3 of its weight. Blood vessels and nerves run to every muscle, helping control and regulate each muscle’s function. ❖ The muscular system creates body heat and also moves the: Bones of the Skeletal system Food through Digestive system Blood through the Circulatory system Fluids through the Excretory system FUNCTIONS OF MUSCULAR SYSTEM ❖ Body movement (locomotion) ❖ Maintanance of posture ❖ Respiration (diaphragm and intercostal contraction) ❖ Communication (verbal and facial) ❖ Constriction of organs and vessels ❖ Heart beat ❖ Production of body head (thermogenesis) Properties of Muscle ❖ Excitability ❖ Contractility ❖ Extensibility ❖ Elasticity MUSCLE TISSUE The body has 3 main types of muscle tissue 1) Skeletal 2) Smooth 3) Cardiac SKELETAL MUSCLES Skeletal Muscle It attach to bone to bone by tendons (connective tissue). ▪ Feel the back of your ankle to feel your Achilles tendon- the largest tendon in your body. It makes about 40% of the body weight Responsible for locomotion, facial expression, posture, respiratory movement. It composed of muscles cells (fibers), connective tissues, blood vessels and nerves. Fibers are long, cylindrical and multinucleated It is about 1mm to 4cm in length. It develop from myoblast It is striated in appearance Nuclei are peripherally located. Skeletal muscles are mostly voluntary. NOTES: The typical male body contains approximately 640 muscles, which compose around two-fifths of its weight. The same number in a female body make up a slightly smaller proportion. A typical muscle spans a joint and tapers at each end into a fibrous tendon anchored to a bone.  Nomenclature Most muscles have descriptive names. Some muscles are named according to their location, such as the pectoralis (chest) muscles. Other muscles are named according to their origin and insertion, such as the brachioradialis (brachio, arm) muscle, which extends from the arm to the radius. Some muscles are named according to the number of origins, such as the biceps (bi, two + ceps, head) brachii, which has two origins, and Some according to their function, such as the flexor digitorum, which flexes the digits (fingers). Other muscles are named according to their size (vastus, large) their shape (deltoid, triangular) or the orientation of their fasciculi (rectus, straight). Recognizing the descriptive nature of muscle names makes learning those names much easier. SMOOTH MUSCLE Location: is found in the walls of body parts such as the airways, iris of the eye, stomach, alimentary canal, and blood vessels. This is called involuntary muscle, because it works automatically rather than under conscious control. – moves food through digestive organs – empties liquid from the bladder – controls width of the blood vessels Contractions are slow and uniform. Cells are not striated Fibers are smaller than those in the skeletal muscle Single, centrally nucleus.  Smooth muscle lines organs and is involuntary. – moves food through digestive organs – empties liquid from the bladder – controls width of the blood vessels CARDIAC MUSCLE It has characteristics of both skeletal and smooth muscles. The heart wall is composed of three layers. – The middle layer, the myocardium, is responsible for the heart’s pumping action. Cardiac muscle, found only in the myocardium, contracts in response to signals from the cardiac conduction system to make the heart beat. It is very fatigue resistant. Involuntary in action Found only in the heart Striated fibers that branche Each cell usually has one centrally located nucleus Fibers are joined by intercalated disks. It is under the control of the ANS (involuntary) and endocrine (hormones).