 Movement  Posture  Stabilize joints  Generate heat

 Compare all three muscle types.  Look at: Location/number of nuclei Associated structures What controls the muscle contraction?  You should be able to answer the “Practice” questions on page 301when finished.

Muscle (wrapped in fascia, epimysium)  Fascicles (bundles of muscle fibers, wrapped in perimysium)  Muscle Fibers (cells, wrapped in endomysium)  Myofibrils  Filaments

 Skeletal muscle fiber = single muscle cell Multinucleated Striated  Myofibrils: myosin (thick filaments) and actin (thin filaments)  Myosin and actin alternate forming striations (light and dark areas)

 Sarcomeres – pattern of actin/myosin alternating throughout muscle fiber Contractile unit of muscle  Sarcolemma – cell membrane of muscle cells  Sarcoplasm – cytoplasm of muscle cells

 KYDxrKc KYDxrKc

Muscle Epimysium Endomysium Perimysium Fascicle Muscle fiber/cell Myofibrils Sarcolemma Sarcoplasm

Actin Myosin Z line I band A band H zone Sarcomere Sarcoplasmic Reticulum

 Myosin: composed of many myosin fibers Heads and tails Forms cross-bridge with actin Heads of myosin come in contact with actin during muscle contraction  Actin: double strands twisted into a helix Troponin – wraps around actin Tropomyosin – contact point for myosin

Troponin Tropomyosin Thin filament

Heads Tails Thick filament

 Corresponds with the endoplasmic reticulum in other cells  Cisternae Enlarged portions of SR on either side of the T tubule  Transverse tubules (T tubules) Extends into sarcoplasm, contains extracellular fluid

T tubule Sarcoplasmic reticulum Sarcomere Myosin Actin Sarcolemma Mitochondria Myofibril

 Occurs when thin and thick filaments slide past one another  Shortens sarcomeres/whole muscle cell  Stimulated by neurons

 Motor neurons control skeletal muscle  Neuromuscular junction: where nerve cell synapses with the muscle Motor end plate: specialized part of muscle to receive neural signals (higher amount of mitochondria, nuclei/SR)

 One motor neuron can innervate many muscle cells Motor unit: neuron AND the muscle(s) it controls

 Separation between the neuron and the muscle  Nerve fiber releases synaptic vesicles containing neurotransmitters into the synaptic cleft

 Acetylcholine (ACh) Increases membrane permeability to sodium Sodium influx causes muscle impulse which transmits the contraction along the muscle  Through the sarcoplasmic reticulum, cisternae, T tubules

 Sarcomeres shorten through movement of actin and myosin sliding past one another, not shortening themselves H zone, A bands narrow Z lines come closer together  Needs ATP (energy), Ca 2+

 4omFDM 4omFDM

 Summarize the contraction cycle in your textbooks (pg. 292)  Summarize relaxation What enzyme is needed? What does this enzyme do? When ACh breaks down, what happens?

 Cellular respiration is critical in muscle contraction  Myoglobin stores oxygen in muscle cells Gives muscle the reddish/brown color Similar to what other molecule?

 Lactic acid threshold  Muscle forms lactic acid in absence of oxygen Anaerobic respiration

 Loss of ability to contract  Caused by: decrease in blood flow, ion imbalances, accumulation of lactic acid in muscle tissue  Cramps: sustained contraction of muscle Changes in extracellular matrix of muscle causes extended contraction

 Muscle is a major source of body heat  Blood transfers heat throughout body

 Use your textbook to compare and contrast fast twitch and slow twitch muscles  Give some examples for the ideal muscle types for different activities  Use human and animals in your answer.

 kZGkvM kZGkvM

 201/head/head1b.htm 201/head/head1b.htm  Muscles of facial expression  Muscles of mastication

 Epicranius Frontalis Temporalis  Orbicularis occuli  Orbicularis oris  Buccinator

 Masseter – elevates mandible  Temporalis – elevates mandible

 Sternocleidomastoid – pulls head to one side, flexes neck, elevates sternum

 Trapezius – rotates scapula, pull scapula (raise, medial, downward)  Rhomboid major – connects scapula with vertebrae  Rhomboid minor – smaller than rhomboid major, connects scapula with vertebrae  Levator scapulae – elevates scapula

Levator scapulae Trapezius Rhomboid major and minor (external oblique) (Latissimus dorsi) (Deltoid)

 We need to get into the muscle actions: Flexor – flexion – bend at joint so angle between two parts gets closer together Extensor – extension – straightening joint so angle between two parts increases Abductors – abduction – movement away from the midline Adductors – adduction – movement toward the midline Rotators – movement around an axis

 Posterior: 201/muscle/musc14.htm 201/muscle/musc14.htm  Anterior: 201/muscle/musc13.htm 201/muscle/musc13.htm

 Posterior Shoulder:  201/muscle/arm/shldrp.htm 201/muscle/arm/shldrp.htm  Anterior Shoulder:  201/muscle/arm/shldra.htm 201/muscle/arm/shldra.htm

 Coracobrachialis Scapula to middle of humerus Flexes and adducts arm  Pectoralis major Thick muscle of upper chest Flexes, adducts, rotates arm medially

 Teres major Scapula to the humerus Adduct and rotate arm medially  Latissiums dorsi From middle of the back, around the side of your body and into the armpit Extend, adduct, rotate arm medially Pull shoulder downward

 Deltoid Thick, triangular muscle that covers the shoulder joint Connects clavicle and scapula to the lateral side of the humerus Abducts arm

 Subscapularis Anterior surface of scapula Connects scapula and humerus Rotate arm medially  Teres minor Scapula to humerus Rotates arm laterally

 Biceps brachii  Triceps brachii

 Extensor carpi radialis longus  Extensor carpi radialis brevis  Both extend wrist, abduct hand

 Extensor carpi ulnaris Extends wrist, adducts hand  Extensor digitorum Extends fingers  Flexor carpi radialis – flexes wrist, abducts hand  Flexor carpi ulnaris – flexes wrist, adducts hand

 Rectus abdominus – creates “6-pack”  External oblique – outermost layer, wraps around to the back of the body  Transversus abdominus – between external and internal oblique  Internal oblique – within external oblique  Linea alba: band of tough connective tissue down medial line of abdomen

Deltoid Pectoralis major Biceps brachii Rectus abdominus Transversus abdominus Internal oblique External oblique

 Gluteus maximus  Gluteus medius  Gluteus minimus

 Tensor fasciae latae Connects ilium to lateral portion of thigh

 201/muscle/leg1.htm 201/muscle/leg1.htm

 Hamstring muscles: Biceps femoris (most lateral) Semitendonosis (middle) Semimembranosus (most medial)

 Sartorius – hip to most distal, medial portion of the femur (medial portion of knee)

 Quadriceps femoris group: Rectus femoris Vastus lateralis Vastus medialis  Patellar tendon

 Tibialis anterior  Gastrocnemius  Soleus