Muscular System PDF

MUSCLES, BONES & JOINT DR. TARI AGBALALAH  Muscular system Muscles of the body make up the muscular system. They are vital for movement. Over 650 skeletal muscles attach to bones directly or via connective tissue called tendons. Muscle tissue consist of cells special...

MUSCLES, BONES & JOINT DR. TARI AGBALALAH  Muscular system Muscles of the body make up the muscular system. They are vital for movement. Over 650 skeletal muscles attach to bones directly or via connective tissue called tendons. Muscle tissue consist of cells specialized for contraction that allows for movement. Tendons- connect muscles to bones Aponeurosis- elastic tendon that cover a portion of the muscle belly and act as insertion sites for muscle fibers ***Aponeurosis connects muscles to other muscles  Muscles are made of highly specialized thin and elongated cells called muscle fibres. Muscle fibres contains specialized cytoplasm called sarcoplasm that contain sarcoplasmic reticulum. Muscle fibres may be bounded by a cell membrane called sarcolemma. Each muscle fibre may contain numerous longitudinal fibrils called myofibrils. Basic physiological property of muscle tissue Contractibility Excitability Extensibility Elasticity  Muscle types There are three types of muscle tissue. 1. Skeletal- 2. Smooth/visceral-stomach, intestines 3. Cardiac- heart muscle Cardiac muscle Also contract to push blood out of the heart to body tissues supplying oxygen and nutrients. Between each cardiomyocyte is an intercalated disc containing gap junctions which allow electrical stimulus required for contraction to rapidly spread across the cardiac tissue. Short branched, cylindrical muscle fibers with one nucleus and striations. Involuntary muscle.  MUSCLE TYPE Skeletal muscle Cover the skeleton and give our body its shape Have cylindrical multinucleated and striated muscle fibers. Responsible for voluntary movements and maintain posture. Forms sphincters in the digestive and urinary tract to allow for swallowing and urination.  MUSCLE TYPE Smooth/visceral muscle Lines walls of internal organs e.g stomach, bladder, intestines, and lungs. are uni-nucleated and have spindle –shaped muscle fibres. Are not striated. The weakest of all muscle tissues. It is an involuntary muscle  Muscle group Muscles according to their functions. The primary function of a muscle is to contract. Four functions of muscles 1. Prime movers/agonist 2. Antagonist 3. Synergist 4. fixators  Muscle groups Prime movers/agonist These muscles produce a particular motion. Antagonist Oppose a particular motion Synergist They stabilize the movement of prime movers during contraction. Fixators These muscles maintain our posture *It is important to note that a particular muscle can exhibit more than one of these roles depending on the motion it is producing.  MUSCULAR SYSTEM Composed of specialized cells called Muscle fibers. Each muscle fiber contains many myofibrils — the parts of the muscle fiber that contract. Myofibrils, give muscles a striated appearance. Myofibrils contract due to the sliding action of two filamentous cytoskeletal proteins, called actin and myosin:  Naming skeletal muscles Skeletal muscles are named according to seven criteria. Muscle location- temporalis muscle is located adjacent to the temporal bone. Muscle shape- the left trapezuis muscle is trapezoidal in shape. Muscle size – Maximus-large, gluteus max. Minimus- small, gluteus min. Longus- long, adductor longus Brevis- short,  Naming skeletal muscles Muscle direction- direction of muscle fibres in reference to some line such as the axis of a bone and the midline. Rectus- parallel transversus=horizontal Oblique - at some angle, diagonal Muscle origins Biceps- two origins Triceps- three origins Quadriceps- four origins  Types of muscle shapes Bundles of muscle fibers called fascicles arrange themselves to produce a variety of shapes. If arranged in concentric rings they are called circular muscles e.g orbicularis oculi. If they are spread out over a region but converge towards a tendon of insertion, they are called convergent muscles e.g. the pectorals.  Naming skeletal muscles Muscle location of attachment- according to points of origin and insertion. Sternocleidomastoid muscle has origin on sternum and clavicle and inserts on mastoid process. Muscle type of motion- according to the type of motion they produce like a flexor, extensor, adductor.  Type of muscle shapes If fascicles taper down to a tendon at two ends they are called fusiform. fascicles run in a straight line Parallel to the long axis of a muscle and are called parallel (non-fusiform) e.g. sartorious  Type of muscle shapes In a pennate muscle, fascicles are short and run at oblique angles, they can be uni-pennate, where muscles sit on one side of tendon, bipennate, with muscle on both sides resembling a feather and multipennate which look like several feathers inserted on same tendon. These different muscle shape determine the range of motion that the muscle can produce. Muscles contraction is 30% and contraction begins at neuromuscular junction(is a synaptic connection between the terminal end of a motor nerve and a muscle). THE HUMAN JOINT  WHAT ARE JOINTS? ► Joints are areas in our bodies where two or more bones meet. ► They are essential for all kinds of movements, from walking and running to writing and jumping. ► Joints allow our bodies to be flexible and mobile, making everyday activities possible.