Joints (Articulations)• Functional junctions between bones&nbsp;<div>• Bind parts of skeletal system together&nbsp;</div><div>• Make bone growth possible&nbsp;</div><div>• Permit parts of the skeleton to change shape during childbirth&nbsp;</div><div>• Enable body to move in response to skeletal muscle contractions</div>
Structural Classification of Joints• Fibrous&nbsp;<div>• Cartilaginous&nbsp;</div><div>• Synovial</div>
Functional Classification of Joints• Synarthrotic—immovable&nbsp;<div>• Amphiarthrotic—slightly movable&nbsp;</div><div>• Diarthrotic—freely movable</div>
Fibrous Joints"Held together with dense connective tissue containing many collagen fibers; found in bones in close contact&nbsp;<div>• There are 3 types of fibrous joints:&nbsp;<div>&nbsp; &nbsp;• Syndesmosis&nbsp;</div><div>&nbsp; &nbsp;• Suture&nbsp;</div><div>&nbsp; &nbsp;• Gomphosis</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.34.46 PM.png""><br></div></div>"
Syndesmosis• Bones bound by a sheet of dense connective tissue (interosseous membrane) or a bundle of dense connective tissue (interosseous ligament)&nbsp;<div>• Amphiarthrotic (flexible, may twist)&nbsp;</div><div>• Lies between tibia and fibula</div>
Suture"• Between flat bones of skull&nbsp;<div>• Thin layer of connective tissue (sutural ligament) connects bones&nbsp;</div><div>• Synarthrotic (immovable)</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.36.32 PM.png""><br></div>"
Gomphosis"• Cone-shaped bony process in a socket in jawbone&nbsp;<div>• Tooth in jawbone by periodontal ligament&nbsp;</div><div>• Synarthrotic (immovable)</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.38.12 PM.png""><br></div>"
Cartilaginous Joints"Connected by hyaline cartilage or fibrocartilage<br><div>• There are 2 types of cartilaginous joints:&nbsp;</div><div>&nbsp; &nbsp;• Synchondrosis&nbsp;</div><div>&nbsp; &nbsp;• Symphysis<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.39.15 PM.png""><br></div>"
Synchondrosis• Bands of hyaline cartilage unite bones&nbsp;<div>• Some are temporary, such as epiphyseal plate (ossification converts this to a synostosis)&nbsp;</div><div>• Between manubrium and the first rib (costal cartilages, permanent, synarthrotic)</div>
Symphysis"• Pad of fibrocartilage between bones&nbsp;<div>• Articular surfaces covered by hyaline cartilage&nbsp;</div><div>• Amphiarthrotic (limited movement)&nbsp;</div><div>• Pubic symphysis&nbsp;</div><div>• Joint between bodies of adjacent vertebrae (intervertebral discs)</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.40.21 PM.png""><br></div>"
Synovial Joints• Most joints are synovial joints&nbsp;<div>• All are diarthrotic joints</div><div>• Structure of a synovial joint:&nbsp;</div><div>&nbsp; &nbsp;• Articular cartilage covers articular ends of &nbsp; &nbsp; &nbsp;bones&nbsp;</div><div>&nbsp; &nbsp;• Joint capsule, consists of 2 layers:&nbsp;</div><div>&nbsp; &nbsp; &nbsp; - Outer fibrous layer, composed of &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ligaments&nbsp;</div><div>&nbsp; &nbsp; &nbsp; - Inner layer, synovial membrane, which &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; secretes synovial fluid<br></div>
General Structure of Synovial Joints"Synovial joints are more complex than other types of joints, and contain the following parts: • Articular cartilage&nbsp;<div>• Joint capsule&nbsp;</div><div>• Ligaments&nbsp;</div><div>• Synovial membrane&nbsp;</div><div>• Synovial cavity&nbsp;</div><div>• Synovial fluid&nbsp;</div><div>• Meniscus (-i) in some joints&nbsp;</div><div>• Bursa (-ae) in some joints</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.42.38 PM.png""><br></div>"
Knee Joint Diagram"Diagram of the knee joint, showing typical synovial joint structures, as well as less common structures, such as menisci and bursae<div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.43.23 PM.png""><br></div>"
Types of Synovial JointsThere are 6 types of synovial joints, classified by shape and movements they allow:<div>• Ball-and-Socket Joint<br></div><div>• Condylar Joint<br></div><div>• Plane Joint</div><div>• Hinge Joint</div><div>• Pivot Joint</div><div>• Saddle Joint</div>
Ball-and-Socket Joint"• Also called spheroidal joint&nbsp;<div>• Round head in cup-shaped cavity&nbsp;</div><div>• Widest range of motion&nbsp;</div><div>• Multiaxial, plus rotation&nbsp;</div><div>• Hip, shoulder</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.45.09 PM.png""><br></div>"
Condylar Joint"• Also called ellipsoidal joint&nbsp;<div>• Oval condyle fits into elliptical cavity&nbsp;</div><div>• Back-and-forth, side-to-side movement&nbsp;</div><div>• Biaxial movement, no rotation&nbsp;</div><div>• Joints between metacarpals and&nbsp; phalanges</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 2.45.58 PM.png""><br></div>"
Plane Joint"• Also called gliding joint&nbsp;<div>• Almost flat, or slightly curved&nbsp;</div><div>• Back-and-forth and twisting&nbsp;</div><div>• Nonaxial movement&nbsp;</div><div>• Wrist and ankle joints</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.35.27 PM.png""><br></div>"
Hinge Joint"• Convex surface fits into concave surface of other bone&nbsp;<div>• Uniaxial movement (in 1 plane)&nbsp;</div><div>• Elbow, joints between phalanges</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.35.57 PM.png""><br></div>"
Pivot Joint"• Also called trochoid joint&nbsp;<div>• Cylindrical surface rotates within ring of other bone&nbsp;</div><div>• Uniaxial movement&nbsp;</div><div>• Rotation only&nbsp;</div><div>• Atlas (C1) and dens of axis (C2)</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.36.35 PM.png""><br></div>"
Saddle Joint"• Also called sellar joint&nbsp;<div>• Both bones have concave and convex surfaces&nbsp;</div><div>• Biaxial movement (in 2 planes)&nbsp;</div><div>• Carpal and metacarpal of thumb</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.37.12 PM.png""><br></div>"
Joint Movements• Action of skeletal muscle produces movement at synovial joints&nbsp;<div>• Relatively fixed end of a skeletal muscle is called the origin&nbsp;</div><div>• More movable end of a skeletal muscle is called the insertion&nbsp;</div><div>• Movement at a joint occurs when a muscle contracts, and its fibers pull the insertion towards the origin</div>
Types of Joint Movements"• Abduction / adduction&nbsp;<div>• Flexion / extension / hyperextension&nbsp;</div><div>• Lateral flexion</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.38.24 PM.png""><br></div><div>• Dorsiflexion / plantar flexion&nbsp;</div><div>• Circumduction / rotation&nbsp;</div><div>• Medial rotation / lateral rotation&nbsp;</div><div>• Supination / pronation<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.39.01 PM.png""><br></div><div>• Inversion / eversion&nbsp;</div><div>• Protraction / retraction&nbsp;</div><div>• Elevation / depression<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.39.36 PM.png""><br></div>"
Examples of Synovial JointsExamples of large, complex synovial (also freely movable) joints:&nbsp;<div>• Shoulder&nbsp;</div><div>• Elbow&nbsp;</div><div>• Hip&nbsp;</div><div>• Knee</div>
Shoulder Joint"• Ball-and-socket&nbsp;<div>• Head of humerus and glenoid cavity of scapula&nbsp;</div><div>• Loose joint capsule&nbsp;</div><div>• Ligaments prevent displacement&nbsp;</div><div>• Glenoid labrum&nbsp;</div><div>• Several bursae&nbsp;</div><div>• Very wide range of movement, including rotation, circumduction</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 3.40.39 PM.png""><br></div><div><img src=""Screen Shot 2023-07-07 at 3.41.36 PM.png""><br></div><div>Major ligaments of the shoulder joint:&nbsp;</div><div>• Coracohumeral ligament&nbsp;</div><div>• Glenohumeral ligaments&nbsp;</div><div>• Transverse humeral ligament<br></div>"
Elbow Joint"Contains 2 articulations:&nbsp;<div>• Hinge joint:&nbsp; </div><div>&nbsp; &nbsp;- Between trochlea of humerus and trochlear &nbsp; &nbsp;notch of ulna&nbsp;</div><div>&nbsp; &nbsp;- Flexion / extension only&nbsp;</div><div>• Plane (gliding) joint:&nbsp;</div><div>&nbsp; &nbsp;- Between capitulum of humerus and fovea &nbsp; &nbsp; &nbsp;on head of radius&nbsp;</div><div>&nbsp; &nbsp;- Pronation / supination&nbsp;</div><div>• Several reinforcing ligaments</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 4.43.10 PM.png""><br></div><div><img src=""Screen Shot 2023-07-07 at 4.43.24 PM.png""><br></div><div>Major ligaments of elbow joint:&nbsp;</div><div>• Radial collateral ligament&nbsp;</div><div>• Ulnar collateral ligament&nbsp;</div><div>• Anular ligament<br></div>"
Hip Joint"• Ball-and-socket joint&nbsp;<div>• Head of femur and acetabulum of hip bone&nbsp;</div><div>• Acetabular labrum&nbsp;</div><div>• Heavy joint capsule&nbsp;</div><div>• Many reinforcing ligaments&nbsp;</div><div>• Variety of movement, yet less than at shoulder joint</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 4.44.25 PM.png""><br></div><div><img src=""Screen Shot 2023-07-07 at 4.44.37 PM.png""><br></div><div>Major ligaments of the hip joint:&nbsp;</div><div>• Iliofemoral ligament (strongest ligament in body)&nbsp;</div><div>• Pubofemoral ligament&nbsp;</div><div>• Ischiofemoral ligament<br></div>"
Replacing Joints• Synthetic materials are used to replace joints damaged by arthritis or injury&nbsp;<div>• Steel and titanium replace larger joints, silicone used for smaller joints, some are ceramic&nbsp;</div><div>• Hip replacements are the most common&nbsp;</div><div>• New technology for joint replacement:&nbsp;</div><div>&nbsp; &nbsp;- Use of materials that resemble natural &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;body chemicals, such as coating implant &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;with hydroxyapatite&nbsp;</div><div>&nbsp; &nbsp;- 3D printing technology used to create &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;custom replacement joints</div>
Knee Joint"• Largest and most complex joint&nbsp;<div>• 3 bones:&nbsp;</div><div>&nbsp; &nbsp;• Femur: Medial and lateral condyles of&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;distal end&nbsp;</div><div>&nbsp; &nbsp;• Tibia: Medial and lateral condyles of &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;proximal end&nbsp;</div><div>&nbsp; &nbsp;• Patella: Articulates with anterior surface of &nbsp; &nbsp;femur&nbsp;</div><div>• Strengthened by many ligaments and tendons&nbsp;</div><div>• Cushioned by bursae, fat pads&nbsp;</div><div>• Menisci separate femur and tibia</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 4.47.35 PM.png""><br></div><div><img src=""Screen Shot 2023-07-07 at 4.47.50 PM.png""><br></div><div>Major ligaments of the knee joint:&nbsp;</div><div>• Patellar ligament&nbsp;</div><div>• Oblique popliteal ligament&nbsp;</div><div>• Arcuate popliteal ligament&nbsp;</div><div>• Tibial (medial) collateral ligament&nbsp;</div><div>• Fibular (lateral) collateral ligament&nbsp;</div><div>• Anterior cruciate ligament&nbsp;</div><div>• Posterior cruciate ligament&nbsp;</div><div>Knee joint characteristics:&nbsp;</div><div>• Modified hinge joint between condyles&nbsp;</div><div>• Flexion / extension&nbsp;</div><div>• Some rotation when knee is flexed&nbsp;</div><div>• Plane joint between femur and patella<br></div>"
Joint Disorders• Sprains:&nbsp;<div>&nbsp;Tearing of connective tissue in joint, without bone dislocation&nbsp;</div><div>• Bursitis:&nbsp;</div><div>&nbsp;Inflammation of a bursa, from overuse or stress&nbsp;</div><div>• Arthritis:&nbsp;</div><div>&nbsp;Inflammation, swelling, and pain in a joint&nbsp;</div><div>&nbsp;- Rheumatoid arthritis: autoimmune disease&nbsp;</div><div>&nbsp;- Osteoarthritis: degenerative, most common type, occurs with aging&nbsp;</div><div>&nbsp;- Lyme arthritis: caused by Lyme disease, passed through tick bite</div>
Lifespan Changes• Joint stiffness is an early sign of aging&nbsp;<div>• Many people develop arthritis as they age&nbsp;</div><div>• Fibrous joints first to change; can strengthen, however, over a lifetime&nbsp;</div><div>• Cartilage in synchondroses stiffens&nbsp;</div><div>• Ligaments lose elasticity&nbsp;</div><div>• Changes in symphysis joints of vertebral column diminish flexibility and decrease height (due to water loss from the intervertebral discs)&nbsp;</div><div>• Synovial joints lose function, as capillary supply diminishes&nbsp;</div><div>• Disuse hampers the nutrient supply to joints; speeds up stiffening&nbsp;</div><div>• Activity and exercise can keep joints functional longer</div>
Origin and Insertion"One end of a skeletal muscle is more fixed, and the other end is more movable:&nbsp;<div>Origin: less movable end the attachment to stationary bone&nbsp;</div><div>Insertion: more movable end attachment to movable bone</div><div>When a muscle contracts, insertion is pulled toward origin</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 4.58.55 PM.png""><br></div>"
Structure of a Skeletal MuscleSkeletal Muscles:&nbsp;<div>• Attach to bones, and skin of face&nbsp;</div><div>• Under conscious control (voluntary)&nbsp;</div><div>• A skeletal muscle is an organ of the muscular system&nbsp;</div><div>• Skeletal muscles are composed of:&nbsp;</div><div>&nbsp; &nbsp;• Skeletal muscle tissue&nbsp;</div><div>&nbsp; &nbsp;• Nervous tissue&nbsp;</div><div>&nbsp; &nbsp;• Blood&nbsp;</div><div>&nbsp; &nbsp;• Connective tissues</div>
Interaction of Skeletal MusclesMost skeletal muscle function in groups.&nbsp;<div>Roles of muscles in performing certain actions:&nbsp;</div><div>• Agonist: muscle that causes an action&nbsp;</div><div>• Prime mover: agonist primarily responsible for movement&nbsp;</div><div>• Synergists: muscles that assist agonist / prime mover&nbsp;</div><div>• Antagonist: muscles whose contraction causes movement in the opposite direction of the prime mover</div>
TMJ SyndromeTemporomandibular Joint Syndrome:&nbsp;<div>• Articulation problem between mandibular condyle of mandible and mandibular fossa of temporal bone&nbsp;</div><div>• Affects nerves passing through neck and jaw region&nbsp;</div><div>• Caused by misaligned jaw, grinding/clenching of teeth&nbsp;</div><div>• Causes clicking jaw, facial pain, ringing in ears, insomnia, tooth sensitivity to heat/cold, backache, dizziness, ear pain&nbsp;</div><div>• Treatments: physical therapy, oral appliances, arthrocentesis, injections of botulism toxin or steroids</div>
Function&nbsp;Examples"<img src=""Screen Shot 2023-07-07 at 5.01.39 PM.png""><div><img src=""Screen Shot 2023-07-07 at 5.01.53 PM.png""><br></div>"
Naming of Muscles• Named according to any of the following criteria:&nbsp;<div>&nbsp; &nbsp;Size&nbsp;</div><div>&nbsp; &nbsp;Shape&nbsp;</div><div>&nbsp; &nbsp;Location&nbsp;</div><div>&nbsp; &nbsp;Action&nbsp;</div><div>&nbsp; &nbsp;Number of attachments&nbsp;</div><div>&nbsp; &nbsp;Direction of fibers&nbsp;</div><div>• Size: maximus, (larger, largest)- gluteus maximus</div><div>• Shape: trapezius (like a trapezoid) - trapezius, deltoid (triangular)</div><div>• Location: pectoralis (in the chest)- pectoralis major; brachia (arm) - brachialis<br></div><div>• Attachment: sternoclediomastoid (sternum, clavicle and mastoid process)&nbsp;</div><div>• Orientation of fibers: rectus (straight) - rectus abdominis&nbsp;</div><div>• Relative position: lateral, medial, internal, and external (vastus lateralis, vastus = great, large, extensive)</div><div>• Functions: flexor - flexor carpi ulnaris, pronator - pronator teres, levator (lifter) - levator scapulae</div>
Muscles of Facial Expression"Buccinator:&nbsp;<div>• Compresses cheek&nbsp;</div><div>• Trumpeter’s muscle&nbsp;</div><div>• Whistling muscle&nbsp;</div><div>• Helps with chewing&nbsp;</div><div>Platysma:&nbsp;</div><div>•&nbsp;Pulls corner of mouth downward&nbsp;</div><div>• Pouting muscle</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.11.32 PM.png""><br></div>"
Muscles of Mastication (Chewing)"Masseter:&nbsp;<br><div>• Raises mandible&nbsp;</div><div>• Closes the jaw</div><div>Temporalis:&nbsp;</div><div>• Synergist to masseter&nbsp;</div><div>• Closes jaw</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.11.32 PM.png""><br></div>"
Muscles That Move the Head and Vertebral Column"Sternocleidomastoid:<br><div>• Extends from sternum/clavicle to mastoid process&nbsp;</div><div>• Rotates head&nbsp;</div><div>• Flexes neck&nbsp;</div><div>• Praying muscle&nbsp;</div><div>Splenius capitis:</div><div>• Connects base of skull to lower cervical and &nbsp; &nbsp; upper thoracic vertebrae&nbsp;</div><div>• Bends head to one side</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.06.09 PM.png""><br></div><div><img src=""Screen Shot 2023-07-07 at 5.18.25 PM.png""><br></div>"
Muscle That Move the Trunk (Abdominal Wall)"Rectus abdominis:&nbsp;<div>• Compress contents of abdominal cavity&nbsp;</div><div>• Flexes vertebral column&nbsp;</div><div>External and Internal Oblique, Transverse Abdominis:</div><div>• Tense and support abdominal wall</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.14.52 PM.png""><br></div>"
Muscles Used in BreathingDiaphragm:&nbsp;<br><div>• A dome-shaped musculotendinous partition&nbsp;</div><div>• Separates thoracic and abdominal cavities<div>External intercostals:&nbsp;</div><div>• Pulls the ribs up and out&nbsp;</div><div>Internal intercostals:&nbsp;</div><div>• Pulls the ribs down and in</div></div>
Muscles that Move the Pectoral Girdle"Rhomboideus major:&nbsp;<br><div>• Raises and adducts scapula</div><div>Serratus anterior:&nbsp;</div><div>• Pulls scapula downward and forward</div><div>Trapezius:&nbsp;</div><div>• Extends neck&nbsp;</div><div>• Elevates shoulders/shrugs shoulders&nbsp;</div><div>• Pulls shoulders back</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.17.09 PM.png""><br></div>"
Muscles that Move the Arm"Pectoralis major:<br><div>• Large anterior muscle of chest flexes arm (raises anteriorly)&nbsp;</div><div>• Adducts the arm/pulling across chest Latissimus dorsi:&nbsp;</div><div>• A wide triangular muscle&nbsp;</div><div>• Lower back muscle&nbsp;</div><div>• Used in swimming/rowing and climbing Deltoid:</div><div>• Triangular shaped muscle&nbsp;</div><div>• Abducts the arm lateral side&nbsp;</div><div>• Common injection site</div><div>Rotator cuff muscles of the shoulder: &nbsp;</div><div>• Subscapulairs – Rotates arm medially&nbsp;</div><div>• Infraspinatus – Rotates arm laterally&nbsp;</div><div>• Teres minor – Rotates arm laterally<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.22.04 PM.png""><br></div>"
Muscles that Move the Forearm"Flexors<div>Biceps brachii:&nbsp;</div><div>• Flexes forearm&nbsp;</div><div>• Bulges when forearm is flexed</div><div>• Supinates the hand&nbsp;</div><div>Brachioradialis:&nbsp;</div><div>• Connects humerus to radius&nbsp;</div><div>• Aid in flexing the elbow</div><div>Brachialis:&nbsp;</div><div>• Flexes the forearm&nbsp;</div><div>• Strongest flexor of elbow&nbsp;</div><div>• Connects shaft of humerus to ulna<br></div><div>Extensor&nbsp;</div><div>Triceps brachii:&nbsp;</div><div>• Extend the forearm&nbsp;</div><div>• The boxers muscles<br></div><div>Rotators&nbsp;</div><div>Supinator:&nbsp;</div><div>• Assists biceps in rotating arm laterally&nbsp;</div><div>Pronator teres:</div><div>• Rotates arm medially&nbsp;</div><div>• Turns palms downward&nbsp;</div><div>Pronator quadratus:</div><div>• Aid pronator teres in rotating arm medially<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.24.36 PM.png""><br></div>"
Muscles That Move the Hand"Extensor carpi and flexor carpi:<br><div>• Moves wrist and hand</div><div>Extensor digitorum and flexor digitorum&nbsp;</div><div>• Move the fingers</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.26.41 PM.png""><br></div><div><br></div>"
Muscles That Move the Forearm and Hand"<img src=""Screen Shot 2023-07-07 at 5.27.06 PM.png"">"
Muscles That Move the Thigh"Posterior group:<div>• Gluteus maximus&nbsp;</div><div>• Gluteus medius&nbsp;</div><div>• Gluteus minimus&nbsp;</div><div>• Tensor fasciae latae<br></div><div>Anterior group:&nbsp;</div><div>• Psoas major&nbsp;</div><div>• Iliacus<br></div><div>Adductor group:</div><div>• Pectineus&nbsp;</div><div>• Adductor longus&nbsp;</div><div>• Adductor magnus&nbsp;</div><div>• Gracilis<br></div><div>Gluteus maximus:</div><div>• Extends thigh&nbsp;</div><div>• Raises body from a sitting position&nbsp;</div><div>Psoas major:&nbsp;</div><div>• Flexes thigh</div><div>• Connects lumbar to femur</div><div>Gluteus medius:&nbsp;</div><div>• Abducts thigh&nbsp;</div><div>• Injection site for 2-3 ml of medication<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.30.08 PM.png""><br></div><div><img src=""Screen Shot 2023-07-07 at 5.30.37 PM.png""><br></div>"
Muscles That Move the Lower Leg"Quadriceps femoris group:<div>• Extends lower leg<br></div><div>• Found in front and both sides of thigh</div><div>1. Rectus femoris - Intramuscular injection site&nbsp;</div><div>2. Vastus medialis (vastus = great, large, extensive)&nbsp;</div><div>3. Vastus lateralis - Intramuscular injection site&nbsp;</div><div>4. Vastus intermedius&nbsp;</div><div>Note: Rectus femoris and Vastus lateralis are used in infants who have poorly developed gluteus</div><div>Hamstring group:&nbsp;</div><div>• Flexes lower leg and extends hip</div><div>• Found on back of thigh<br></div><div>1. Semitendinosus&nbsp;</div><div>2. Biceps femoris&nbsp;</div><div>3. Semimembranosus<br></div><div>Sartorius:&nbsp;</div><div>• Longest muscle of body&nbsp;</div><div>• Flexes, abducts and rotates leg&nbsp;</div><div>• Tailors muscle</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.34.15 PM.png""><br></div>"
Muscles That Move the Ankle and Foot"Gastrocnemius:&nbsp;<div>• Located on the back of leg&nbsp;</div><div>• Forms a large part of calf&nbsp;</div><div>• Powerful plantar flexor of foot&nbsp;</div><div>• Pushes body forward when walking or running&nbsp;</div><div>• The toe dancer’s muscle&nbsp;</div><div>Soleus:&nbsp;</div><div>• A broad, flat muscle deep to gastronemius&nbsp;</div><div>• Named because of resemblance to flat fish (sole)&nbsp;</div><div>• Plantar flexes foot</div><div>Tibialis anterior:&nbsp;</div><div>• A long spindle-shaped muscle on front of lower leg&nbsp;</div><div>• Contraction causes dorsiflexion and inversion of foot&nbsp;</div><div>Peroneus longus:&nbsp;</div><div>• Connects tibia and fibula to foot</div><div>• Supports arch of foot<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.37.39 PM.png""><img src=""Screen Shot 2023-07-07 at 5.37.13 PM.png""><img src=""Screen Shot 2023-07-07 at 5.37.26 PM.png""><br></div>"
Connective Tissue Covering"• Fascia –&nbsp;covers entire muscle and separates them from each other&nbsp;<div>• Endomysium – surrounds individual muscle cells (muscle fibers)</div><div>• Epimysium – lies deep to the fascia of a muscle and surrounds the entire muscle</div><div>• Perimysium – divides a muscle into sections called fascicles</div><div>• Aponeurosis – sheet-like tissue that attaches muscle to muscle</div><div>• Tendon – cord-like tissue that connect muscle to bone</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.39.21 PM.png""><br></div>"
Types of Fascia• Deep fascia surrounds and penetrates skeletal muscles.&nbsp;<div>• Subcutaneous fascia lies beneath the skin.&nbsp;</div><div>• The subserous fascia forms the connective tissue layer of the body’s serous membranes.</div>
Skeletal Muscle Fibers"• Muscle fiber - a single, long, cylindrical muscle cell with many nuclei&nbsp;<div>• Cell membrane is the ""sarcolemma""&nbsp;</div><div>• Cytoplasm is the ""sarcoplasm""</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.40.50 PM.png""><br></div><div><img src=""Screen Shot 2023-07-07 at 5.41.29 PM.png""><br></div><div>Muscle fibers are protein myofibrils:&nbsp;</div><div>Thick myofibril filaments are myosin.&nbsp;</div><div>Thin myofibril filaments are actin.&nbsp;</div><div>The organization of actin and mysoin filaments produces striations<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.42.17 PM.png""><br></div><div>• A sarcomere extends from Z line to Z line.&nbsp;</div><div>• I bands (light bands) are actin filaments anchored to Z lines&nbsp;</div><div>• A bands (dark bands) are overlapping thick and thin filaments&nbsp;</div><div>• The center of A bands is an H zone, consisting of myosin filaments only<br></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.42.53 PM.png""><br></div>"
Sliding Filament Theory"• Two researcher Jean Hanson and&nbsp;Hugh Huxley proposed the sliding filament theory.&nbsp;<div>• This theory states that the thin filaments slide over the thick ones and causing the cell to shorten.</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.43.45 PM.png""><br></div>"
Neuromuscular Junction• Where a neuron and a muscle fiber meet.&nbsp;<div>• Where a neuron stimulates a muscle fiber to contract.&nbsp;</div><div>• Motor neuron&nbsp;</div><div>&nbsp; &nbsp;– Stimulates muscle fiber to contract&nbsp;</div><div>&nbsp; &nbsp;– Located in the brain and spinal cord&nbsp;</div><div>&nbsp; &nbsp;– Has fibers that contracts a muscle cell on a muscle cell’s motor end plate&nbsp;</div><div>• Motor end plate&nbsp;</div><div>&nbsp; &nbsp;– An area on the sarcolemma that receive messages from motor neuron fibers&nbsp;</div><div>• Motor neuron fibers</div><div>&nbsp; &nbsp;– Releases chemical onto the motor end plate to make a muscle fiber contract&nbsp;</div><div>&nbsp; &nbsp;– The chemicals are neurotransmitters</div>
Skeletal Muscle ContractionMuscle contraction involves several components that result in the shortening of sarcomeres and the pulling of the muscle against its attachments.
Stimulus for Contraction"• Acetylcholine (ACh) is the neurotransmitter&nbsp;<div>• Nerve impulse causes release of ACh from synaptic vesicles&nbsp;</div><div>• ACh binds to ACh receptors on motor end plate&nbsp;</div><div>• ACh causes changes in membrane permeability to Na+ and K+ ions, which generates a muscle impulse (action potential)&nbsp;</div><div>• Impulse causes release of Ca+2 from SR, which leads to muscle contraction</div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.45.34 PM.png""><br></div>"
Myasthenia Gravis (MG)• MG is an autoimmune disorder&nbsp;<div>• Antibodies attack Acetylcholine receptors on skeletal muscle fibers (motor end plates) in neuromuscular junctions&nbsp;</div><div>• Person may have only 1/3 normal number of ACh receptors&nbsp;</div><div>• Leads to widespread muscle weakness and muscle fatigue&nbsp;</div><div>• Treatments:&nbsp;</div><div>&nbsp; &nbsp;- Drugs that inhibit acetylcholinesterase</div><div>&nbsp; &nbsp;- Immunosuppressant drugs</div><div>&nbsp; &nbsp;- Administering antibodies that inactivate &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;harmful antibodies&nbsp;</div><div>&nbsp; &nbsp;- Plasma exchange</div>
Types of Contractions"Isotonic: muscle contracts and changes length; equal force (example: running, breathing, lifting and twisting movements)<br><div>• Concentric: shortening contraction</div><div>• Eccentric: lengthening contraction<br><div>Isometric: muscle contracts but does not change length; change in force (example: pushing against a wall or an immovable object)</div></div><div><br></div><div><img src=""Screen Shot 2023-07-07 at 5.48.47 PM.png""><br></div><div>• Most body actions involve a mix of isotonic and isometric</div><div>• Isokinetic: lengthening of a muscle during contraction (laying a book down on the table)<br></div>"
Oxygen Supply and Cellular Respiration• Hemoglobin in red blood cells carries oxygen to muscle.&nbsp;<div>• The pigment myoglobin stores oxygen in muscle tissue.</div><div>Oxygen deficiency may develop during strenuous exercise and lactic acid accumulates as an end product of anaerobic respiration.<br></div>
Use and Disuse of Skeletal MusclesHypertrophy: Enlargement of skeletal muscle that is exercised&nbsp;<div>Atrophy: Decrease in size and strength of skeletal muscle that is unused&nbsp;</div><div>Aerobic exercise stimulates slow-twitch fibers. In response, fibers increase their capillaries and mitochondria.&nbsp;</div><div>Forceful exercise stimulates mainly fast-twitch fibers. In response, fibers produce new actin and myosin filaments, and the muscle enlarges.</div>
Muscle Fatigue• When a muscle loses its ability to contract after strenuous exercise, it is referred to as fatigue.&nbsp;<div>• Muscle fatigue usually arises from the accumulation of lactic acid in the muscle.&nbsp;</div><div>• A lowered pH as a result of accumulated lactic acid prevents the muscle from contracting.</div>