Anatomy & Physiology B Muscular System 1

Remember from last Trimester? What are the three types of muscle tissue? Where are each located? Which are voluntary and which are involuntary? Which are striated which are unstriated? Which are multinucleated?

3 Types of Muscle Tissue Skeletal muscle multinucleated attaches to bone, skin or fascia striated with light & dark bands visible with scope voluntary control of contraction & relaxation

3 Types of Muscle Tissue Cardiac muscle striated in appearance involuntary control Uninucleated autorhythmic because of built in pacemaker

3 Types of Muscle Tissue Smooth muscle Uninucleated attached to hair follicles in skin in walls of hollow organs -- blood vessels & GI nonstriated in appearance involuntary

Structure and Organization 600 Human skeletal muscles Regional descriptions functions of muscle general anatomy of skeletal muscles muscle shape and function coordinated actions of muscle groups

Muscle Tissue Alternating contraction and relaxation of cells Chemical energy changed into mechanical energy

What are the functions of Muscles? Producing body movements Stabilizing body positions Regulating organ volumes bands of smooth muscle called sphincters Movement of substances within the body blood, lymph, urine, air, food and fluids, sperm Producing heat involuntary contractions of skeletal muscle (shivering)

Connective Tissue Components

Connective Tissues of a Muscle Epimysium covers whole muscle belly blends into connective tissue that separates muscles Perimysium slightly thicker layer of connective tissue surrounds a bundle of cells called a fascicle Endomysium thin layer of areolar tissue surrounding each cell allows room for capillaries and nerve fibers

Myofibrils & Myofilaments Muscle fibers are filled with threads called myofibrils Myofilaments (thick & thin filaments) are the contractile proteins of muscle

Filaments and the Sarcomere A bands Thick and thin filaments overlap each other in a pattern that creates dark band, six thin filaments surround each thick filament I bands – light bands, contains only thin filaments Sarcomeres - compartments separated by Z discs. I A I

Overlap of Thick & Thin Myofilaments within a Myofibril Dark(A) & light(I) bands visible with an electron microscope

Thick & Thin Myofilaments Supporting proteins (M line, titin and Z disc help anchor the thick and thin filaments in place)

Thick Filaments : Myosin Made of 200 to 500 myosin molecules Arranged in a bundle with heads (cross bridges) directed outward in a spiral array around the bundled tails central area is a bare zone with no heads

Thin Filaments : Actin Two intertwined strands of fibrous (F) actin

A Band Overlap of Thick & Thin Filaments

Striations and Sarcomeres

Relaxed versus Contracted Sarcomere Muscle cells shorten because their individual sarcomeres shorten pulling Z discs closer together pulls on sarcolemma Notice neither thick nor thick filaments change length during shortening Their overlap changes as sarcomeres shorten

Muscle Tissue Components

Now work with it …… Textbook : Read pp. 154 - 162 Packet Fill in p. 2-4 in packet Color p. 5

MYOFILAMENTS MYOSIN ACTIN SARCOMERE MYOFIBRILS MUSCLE FIBERS (CELLS) __________________ Threadlike Protein that consist of: MYOFILAMENTS MYOSIN ACTIN ____________: Dark Bands provide energy for movement _________: Light Bands __________________ Contractile Units made of Actin and Myosin that make up: SARCOMERE __________________ Which are Organelles found in MYOFIBRILS __________________ Which have a plasma membrane called a MUSCLE FIBERS (CELLS) __________________ “Muscle Husk” which is wrapped in SARCOLEMMA __________________ Which is connective tissue that covers the muscle cell ENDOMYSIUM

ENDOMYSIUM PERIMYSIUM FASCICLE EPIMYSIUM TENDON APONEUROSIS __________________ Which is connective tissue that covers the muscle cell ENDOMYSIUM __________________ Connective tissue that bundles the muscle fibers together to form a: PERIMYSIUM __________________ Structure of bundled muscle fibers; many fascicles are bound together by a tough connective tissue called FASCICLE __________________ Which cover the entire muscle and blends into EPIMYSIUM TENDON __________________ Cord of Connective tissue to connect muscle to bone APONEUROSIS __________________ “Sheet of connective tissue

Aponeurosis Bicipital Aponeurosis Epicranial Aponeurosis Palmar Aponeurosis

Origin and Insertion Origin: The place where the fixed end attaches to a bone, cartilage, or connective tissue. Insertion: The site where the movable end attaches to another structure.

Origin and Insertion The tendon at the non-moving (or fixed) end is known as the origin. The tendon at the moving end is known as the insertion. Muscles pull by contracting – they cannot push to produce the opposite movement.

MOTION TERMS FLEXION: reduces the angle of the joint from the anatomical position. Flex elbow EXTENSION: movement that returns you to anatomical position. Extend elbow.

MOTION TERMS ABDUCTION: move body part away from midline; arm, fingers, thumb ADDUCTION: bring back to midline; arms, fingers, thumb

MOTION TERMS ROTATION: pivot on an axis; shake head “no”; can rotate head and shoulder CIRCUMDUCTION: to draw a circle with body part; shoulder, head

MOTION TERMS PRONATION (to lie prone is on stomach). Turn hands downward. SUPINATION: refers to arms; want a bowl of soup, supinate

ANKLE MOTION TERMS Some terms relate only to certain areas, such as the ankle: INVERSION: when sole of foot points inward EVERSION: sole of foot points outward. DORSIFLEXION: lift up toes PLANTARFLEXION: move toes down

Coordinated Muscle Actions Prime Mover : agonist, produces most of force Synergist : aids the prime mover stabilizes the nearby joint modifies the direction of movement that occurs Antagonist opposes the prime mover preventing excessive movement and injury Fixator prevents movement of bone that prime mover is attached to Prime mover or agonist produces most of force Synergist aids the prime mover stabilizes the nearby joint modifies the direction of movement that occurs Antagonist opposes the prime mover preventing excessive movement and injury Fixator prevents movement of bone that prime mover is attached to

Muscle Actions for Elbow Flexion Prime mover (agonist) = biceps brachii m. Synergist = brachialis m. Antagonist = triceps brachii m. Fixator = muscle that holds scapula firmly in place such as rhomboideus m. Definitions

How Muscles are Named? Nomina Anatomica system of Latin names developed in 1895 updated since then English names for muscles are slight modifications of the Latin names.

Naming Skeletal Muscles Location of muscle – bone or body region associated with the muscle Shape of muscle – e.g., the deltoid muscle (deltoid = triangle) Relative size – e.g., maximus (largest), minimus (smallest), longus (long) Direction of fibers – e.g., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis)

Naming Skeletal Muscles Number of origins – e.g., biceps (two origins) and triceps (three origins) Location of attachments – named according to point of origin or insertion (sternocleidomastoid) Action – e.g., flexor or extensor, as in the names of muscles that flex or extend, respectively (extensor digitorum)

Skeletal Muscle Shapes Arrangement of Fascicles Fusiform muscles thick in middle & tapered at ends biceps brachii m. Convergent muscle broad at origin and tapering to a narrower insertion Parallel muscles parallel fascicles rectus abdominis m. Fusiform muscles thick in middle & tapered at ends biceps brachii m. Convergent muscle broad at origin and tapering to a narrower insertion Parallel muscles parallel fascicles rectus abdominis m.

Skeletal Muscle Shapes (2) Circular muscles act as sphincters ring around body opening orbicularis oris m. Pennate muscles fascicles insert obliquely on a tendon unipennate, bipennate or multipennate palmar interosseus m., rectus femoris m. & deltoid m. Circular muscles act as sphincters ring around body opening orbicularis oris Pennate muscles fascicles insert obliquely on a tendon unipennate, bipennate or multipennate palmar interosseus, rectus femoris & deltoid

Muscles are Not Boring Figure 10.4b