Muscular System - Types and Functions PDF

# Muscular system: Types and Function ## Present by: Dr. Nadeeka ## Learning objectives At the end of the lecture, the students should be: 1. Identify the main characteristic of skeletal muscle. 2. Explain the function of muscle. 3. List the three types of muscle tissue. 4. Differentiate betwe...

# Muscular system: Types and Function ## Present by: Dr. Nadeeka ## Learning objectives At the end of the lecture, the students should be: 1. Identify the main characteristic of skeletal muscle. 2. Explain the function of muscle. 3. List the three types of muscle tissue. 4. Differentiate between smooth, cardiac and skeletal muscle. 5. Explain the term used to name the skeletal muscle. 6. Explain the function of the smooth, cardiac and skeletal muscle. ## Muscle tissue - Bone cannot move on its own all the movement are due to the contraction and relaxation of special cell called muscle. - Muscle made up about 40%-50% of total body weight and composed of highly specialized cells. ## The Muscular System An image of a human muscular system: - **Muscles that flex fingers:** Platysma, Sternocleidomastoid, Biceps brachil, Brachialis, Wrist and finger flexors, Muscles that flex fingers - **Neck:** Sternocleidomastoid, Trapezius, Clavicle, Deltoid - **Chest:** Deltoid, Pectoralis major, Biceps brachii, Brachialis, Brachio-radialis, Latissimus dorsi, External oblique - **Abdomen:** Latissimus dorsi, Rectus abdominis, Linea alba, External oblique, Gluteus medius, Gracilis, Sartorius, Quadriceps femoris, Patella - **Back:** Trapezius, Deltoid, Pectoralis major, Linea alba (band of connective tissue), External oblique, Aponeurosis of external oblique - **Legs:** Triceps brachii, Gluteus maximus, Hamstring muscles, Gracilis, Semitendinosus, Biceps femoris, Semi-membranosus, Gastrocnemius, Soleus, Achilles tendon, Calcaneus - **Arms:** Bicipital aponeurosis, Anconeus, Flexor carpi ulnaris, Extensor carpi radialis longus, Extensor carpi radialis brevis, Abductor pollicis longus, Extensor pollicis brevis, Extensor pollicis longus, Flexor retinaculum, Extensor retinaculum, Palmar aponeurosis, Tendons of flexor digitorum superficialis, Tendons of flexor digitorum profundus ## Facial Muscles An image of the facial muscles: - **Head:** Procerus, Occipitofrontalis (frontal portion), Orbicularis oculi, Orbicularis oculi (palpebral portion), Levator labii superioris, Zygomaticus minor, Zygomaticus major, Risorius, Levator anguli oris, Depressor anguli oris, Depressor labii inferioris, Mentalis - **Forehead:** Levator labii superioris alaeque nasi, Corrugator supercilii, Temporalis, Nasalis, Levator labii superioris, Zygomaticus minor and major (cut) - **Cheeks:** Masseter, Levator anguli oris (cut), Buccinator, Orbicularis oris - **Neck:** Platysma ## Muscles of Back An image of the muscles of the back: - **Neck:** Sternocleidomastoid - **Chest:** Pectoralis minor - **Abdomen:** Internal intercostal, Serratus anterior, Rectus abdominis, Internal oblique, Transversus abdominis - **Back:** Trapezius, Deltoid, Pectoralis major, Linea alba (band of connective tissue), External oblique, Aponeurosis of external oblique ## Abdomen Muscles Two images of abdomen muscles: - **Left:** External abdominal oblique, Internal abdominal oblique, Transversus abdominus - **Right:** Pectoralis major, Serratus anterior, Linea alba, Tendinous Intersection Rectus abdominis, Rectus abdominis, Internal oblique, External oblique, Tendinous Inscriptions, Aponeurosis of the external oblique, Inguinal ligament (formed by free inferior border of the external oblique aponeurosis) ## Abdomen Muscles Table | Muscle | Origin | Insertion | Action | |---|---|---|---| | Rectus Abdominis | Pubic crest and symphysis | Ribs 5-7, Xiphoid process | - Trunk flexion, - Hip Flexion | | External Obliques | Anterolateral borders of lower 8 ribs | - Anterior half of ilium, - Pubic crest and tubercle, - Linea alba via anterior fascia | - Trunk rotation, - Lateral flexion of trunk | | Internal Obliques | Iliac crest | - Cartilage of last 3 or 4 ribs, - Linea alba, - Pubic crest | - Trunk rotation, - Lateral flexion of trunk | | Transverse Abdominis | - Inguinal ligament, - Lumbar fascia, - Cartilage of last 6 ribs, - Iliac crest | - Linea alba, - Pubic crest | - Trunk stabilization, -Compression of abdominal contents | ## Muscles of Leg An image of anterior view of the leg muscles: - **Thigh:** iliopsoas muscle, tensor fasciae latae muscle, sartorius muscle, vastus lateralis muscle, iliotibial tract, lateral patellar retinaculum, patella, patellar ligament, head of fibula, tibial tuberosity, peroneus longus muscle, tibialis anterior muscle, extensor digitorum longus muscle, peroneus brevis muscle, extensor hallucis longus muscle - **Leg:** inguinal ligament, pectineus muscle, adductor longus muscle, gracillis muscle, adductor longus muscle, rectus femoris muscle, vastus medialis muscle, rectus femoris tendon, medial patellar retinaculum, sartorius tendon, gracilis tendon, semitendinosus tendon, pes anserinus, gastrocnemius muscle, soleus muscle, superior extensor retinaculum, inferior extensor retinaculum An image of posterior view of the leg muscles: - **Thigh:** gluteus medius, gluteus maximus, biceps femoris, adductor magnus, semitendinosus, gracilis, semimembranosus, sartorius, plantaris - **Leg:** gastrocnemius, Achilles' tendon, medial gastrocnemius, lateral gastrocnemius, calcaneus ## Muscles of the Forearm An image of the muscles of the forearm, right arm: - **Anterior:** Biceps brachii: Long head, Short head, Brachialis, Brachioradialis, Pronator teres, Bicipital aponeurosis, Flexor carpi radialis, Palmaris longus, Flexor carpi ulnaris, Flexor retinaculum, Palmar aponeurosis, Tendons of flexor digitorum superficialis, Tendons of flexor digitorum profundus - **Posterior:** Triceps brachii, Brachioradialis, Extensor carpi radialis longus, Extensor carpi radialis brevis, Abductor pollicis longus, Extensor pollicis brevis, Extensor pollicis longus, Extensor retinaculum, Anconeus, Flexor carpi ulnaris, Extensor carpi ulnaris, Extensor digiti minimi, Extensor digitorum ## Muscles of the Hand An image of the muscles of the hand: - **Wrist:** First dorsal interroseus muscle, Tendon of extensor indices, Trapezoid bone, Tendon of extensor pollicus longus, Tendon of extensor pollicus brevis - **Fingers:** Tendon of extensor digiti minimi, Tendons of extensor digitorum ## Muscles of Foot An image of the muscles of the foot: - **Ankle:** Gastrocnemius muscle, Tibialis anterior muscle, Extensor digitorum longus, Peroneus brevis muscle, Peroneus longus muscle, Superior extensor retinaculum, Achilles tendon, Superior peroneal retinaculum, Inferior extensor retinaculum, Extensor digitorum brevis, Inferior peroneal retinaculum - **Foot:** Flexor hallucis brevis, Abductor hallucis, Quadratus plantae, Lumbricals, Abductor digiti minimi, Flexor digitorum brevis ## Function of muscular tissue 1. **Produce body movement:** Include all types of movement which is visible or not. E.g Lifting, peristalsis, heart beating, bladder contraction. 2. **Maintain body posture:** Body posture maintain by contraction continuously 3. **Storing and moving substance within body:** Storage is accomplished by sustaining contraction and relaxation of smooth. 4. **Produce heat:** Need power/energy during contraction. Heat production necessary to maintain body temperature. 80% of body heat produce by muscle contraction. ## Type of muscle tissues - Muscle cell also known as fiber. - There are 3 types muscle tissues: - **Cardiac muscle** - **Smooth muscle** - **Skeletal muscle** - Each cell have different structure, location and function. ## 1. Cardiac muscle - Involuntary. - Exclusively found only in the heart. - Cylindrically in shape and striated. - Cell branch and interconnected to form complex network. - Point where cell attach to another called intercalated disc. - Has only one nucleus per cell. ## 2. Smooth muscle - Involuntary. - Non striated. - Small cell with one nucleus. - Lining wall of hollow organ. - Tubular structure, proper substance through tract. - Move in wave like contraction. ## 3. Skeletal muscle - Also called as voluntary muscle. - Striped/striated muscle. - Attached to bone by tendon, to move skeleton. - Forms the muscles that move the bone. - Fibre are cylindrically shape. - Movement can be controlled. ## Comparison of Muscle Types | Muscle Type | Skeletal | Cardiac | Smooth | |---|---|---|---| | Location | Attached to bone | Heart | Walls of internal organs + in skin | | Function | Movement of bone | Beating of heart | Movement of internal organs | | Control Mode | Voluntary | Involuntary | Involuntary | | Shape | Long + slender | Branching | Spindle shape | | Characteristics | Striated- light and dark bands, Many nuclei | Striated, One or two nuclei | Non-striated, One nucleus (visceral) | ## Skeletal Muscle Structure An image of a skeletal muscle structure: - **Epimysium:** Surrounds the entire muscle, blood vessels and nerve fibers - **Fascicle:** Discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath; Surrounded by perimysium - **Muscle fiber (cell):** Elongated multinucleate cell; has a banded (striated) appearance; Surrounded by endomysium ## Skeletal Muscle fiber Structure - **Myofibril or fibril:** Rodlike contractile element; myofibrils occupy most of the muscle cell volume; composed of sarcomeres arranged end to end; appear banded, and bands of adjacent myofibrils are aligned - **Sarcomere:** The contractile unit, composed of myofilaments made up of contractile proteins - **Myofilament or filament:** Contractile myofilaments are of two types-thick and thin: the thick filaments contain bundled myosin molecules, the thin filaments contain actin molecules (plus other proteins); the sliding of the thin filaments past the thick filaments produces muscle shortening. Elastic filaments (not shown here) maintain the organization of the A band and provide for elastic recoil when muscle contraction ends ## Site of muscle attachment An image of site of muscle attachment: - **Bones:** Scapula, Humerus, Radius, Ulna, Clavicle - **Cartilage:** Tendon, Biceps muscle, Triceps muscle, Serratus anterior muscle, Subscapularis muscle - **Connective tissue cartilage:** Muscles of the Rotator Cuff: Subscapularis, Supraspinatus, Infraspinatus ## Structure of skeletal muscle - Each skeletal muscle fibre is a single cylindrical muscle cell. - The cell membrane is called sacrolemma. The cytoplasma is the sarcoplasm. - The smooth endoplasmic reticulum (ER) that store calcium ion is the sarcoplasmic reticulum. - Cell is surrounded by connective tissue. ## Structure of skeletal muscle - **Endomysium**: encloses a single muscle fibre. - **Perimysium**: wrap around a fassicle (bundle) of muscle fibre. - **Epimysium**: covers the entire skeletal muscle. ## Structure of skeletal muscle fibre An image of the skeletal muscle fibre: - **Sarcolemma**: specialized plasma membrane - **Myofibrils**: long organelles muscle cell - **Sarcopalsmic reticulum**: specialized smooth endoplasmic reticulum - **Muscle contraction**: need energy, from numerous mitochondria ## Structure of skeletal muscle fibre - **Sarcolemma**: has multiple inward extension called transverse tubules - **Sarcolemma**: packed with myofibril - **Protein thread**: in the myofibril called myofilaments ## Muscle Fiber Anatomy - **Sarcolemma**: cell membrane - Surrounds the **sarcoplasm** (cytoplasm of fiber) - Contains many of the same organelles seen in other cells - An abundance of the oxygen-binding protein **myoglobin** - Punctuated by openings called the **transverse tubules** (T-tubules) - Narrow tubes that extend into the sarcoplasm at right angles to the surface - Filled with extracellular fluid - **Myofibrils**: cylindrical structures within muscle fiber - Are bundles of protein filaments (= **myofilaments**) - Two types of myofilaments - **Actin filaments** (thin filaments) - **Myosin filaments** (thick filaments) - At each end of the fiber, myofibrils are anchored to the inner surface of the sarcolemma - When myofibril shortens, muscle shortens (contracts) ## Sarcomere - **Smallest functional unit**: of muscle fiber - **Each myofibril**: contains 10,000 sarcomeres end to end - **Interaction**: between thick and thin filaments cause contraction - **Banded appearance** ## Sarcoplasmic Reticulum (SR) - **Smooth ER**: that surrounds each myofibril - **Stores calcium** ## Sarcolemma, T Tubules, and Sarcoplasm - **Skeletal muscle**:consists of fibers (cells) covered by a sarcolemma - **Transverse tube**: - The fibers contain **T tubules** and **sarcoplasm** - **Conduct impulses**: to the deepest part of the muscle - These impulses cause the release of **Ca2+** - **Sarcoplasm**: is the muscle cell cytoplasm and contains a large amount of glycogen for energy production and myoglobin for oxygen storage. ## Microanatomy - Sarcolemma and T-Tubules An image of the microanatomy of a skeletal muscle fiber showing the sarcolemma and T-tubules. - Very large cells - 100's of nuclei - Cell membrane - pores open to T-tubules - Network of narrow tubules - filled with extracellular fluid - form passageway through muscle fiber ## Myofibrils & Myofilaments An image of details of a muscle fiber, showing myofibrils and Myofilaments: - **Each fiber**: contains myofibrils that consist of thin and thick filaments (myofilaments) - **Muscle fibers**: are filled with threads called myofibrils separated by **SR** (sarcoplasmic reticulum) - **The sarcoplasmic reticulum**: encircles each myofibril. It is similar to smooth endoplasmic reticulum in nonmuscle cells and in the relaxed muscle stores calcium ions. - **Myofilaments**: (thick & thin filaments) are the contractile proteins of muscle ## Structure of Actin and Myosin Structure of a sarcomere showing how thin myofilaments and thick myofilaments interact with each other: - **Actin myofilament**: Thin myofilament, Actin myofilament, Factin strands, Tropomyosin, Troponin, Attachment sites, Gactin molecules - **Myosin myofilament**: Myosin myofilament, Myosin molecule, Rod, Coiled portion of the two alpha helices, Light chains, Two heavy chains, Hinge region of myosin, Heads ## Myosin (Thick) Myofilament - **Many elongated myosin molecules**: shaped like golf clubs - **Single filament**: contains roughly 300 myosin molecules - **Molecule consists**: of two heavy myosin molecules wound together to form a rod portion lying parallel to the myosin myofilament and two heads that extend laterally - **Myosin heads**: - **Can bind to active sites**: on the actin molecules to form cross-bridges. (Actin binding site) - **Attached to the rod portion**: by a hinge region that can bend and straighten during contraction. - **Have ATPase activity**: activity that breaks down adenosine triphosphate (ATP), releasing energy. Part of the energy is used to bend the hinge region of the myosin molecule during contraction ## Thick Filaments An image of a myosin molecule: - **Thick filaments**: are composed of the protein myosin - **Each myosin molecule**: has a rod-like tail and two globular heads - **Tails**: heavy polypeptide chains - **Heads**: two smaller, light polypeptide chains called cross bridges ## Thin Filaments An image of a thin filament, showing myofilaments: - **Thin filaments**: are made of actin - **Each actin molecule**: is a helical polymer of globular subunits called G actin - **The subunits**: contain the active sites to which myosin heads attach during contraction - **Tropomyosin and troponin**: are regulatory subunits bound to actin - **Actin filaments**: = thin filaments - **Myocine filaments**: = thick filaments ## Arrangement of the Filaments in a Sarcomere An image of a longitudinal section of filaments within one sarcomere of a myofibril showing thick filaments and thin filaments - **Thick filament** - **Thin filament** ## Filaments and the Sarcomere - **Thick and thin filaments**: overlap each other in a pattern that creates striations (light I bands and dark A bands) - **The I band region**: contains only thin filaments. - **They are arranged**: in compartments cal