Muscle are the machines converting chemical energy to mechanical energy!

Introduction to Muscles What are the functions of muscles? Muscle are the machines converting chemicalenergy to mechanicalenergy! Control openings Tone/posture Movements http://dennismitchell.wordpress.com/2007/04/26/beer-muscles/ Heat production Electricity production?!?

Introduction to Muscles What is the difference between muscle vs. muscles? Muscle is a tissue and there are three types… Skeletal Cardiac Smooth Muscles (organs) fall in 2 main categories and a third minor group… Somatic, visceral &branchiomeric(somatic subtype)

Introduction to Muscles What are the 4 common characteristics of muscle tissue? All muscle tissue has 4 common characteristics: Excitability Contractility Extensibility Elasticity Respond to stimuli with electric current Ability to shorten when stimulated Can be stretched up to 3 times contracted length Recoils to resting length after tension released

Introduction to Muscles What are the series elastic components? The connective tissue of the bone is continuous with the connective tissue of skeletal muscles clear down to the package around muscle fibers… Deep Fascia ~ epimysium Perimysium Endomysium Purpose(s)?

Introduction to Muscles What other components do muscles have? Vessels necessary for transporting blood to and from muscle tissue travel through the connective tissue. Nerves necessary for conducting electrical signals to initiate muscle contraction also travel through the connective tissue

Introduction to Muscles What other components do muscles have? Contractile components… Muscles (whole) are comprised of: Fasciculi, which are… Many individual muscle cells (muscle fibers)… Each with a cell membrane (sarcolemma), cytoplasm (sarcoplasm), organelles and myofibrils… made ofmyofilaments See Fig. 10.2

Introduction to Muscles What are the components at the cellular level? The molecular machinery consists of myosin (thick) and actin (thin) myofilaments. Crossbridgesform and stored energy in mysosin heads is used to change conformation resulting in actin sliding

Introduction to Muscles Another View…

Introduction to Muscles How do limbs/structures move in 2 (or more) directions? Myofibrils CAN NOTexert a force in two directions!!! So in this sense relaxation is passive. It depends on: 1) Series-Elastic components (elasticity) 2) Antagonist muscle(s) 3) Gravity http://www.dailyhaha.com/_pics/big_muscles.htm However, relaxationDOESrequire energy!Where and Why? ?Rigor mortis?

Introduction to Muscles How do limbs/structures move in 2 (or more) directions? Skeletal muscles often work in pairs (or groups). If they generate force in same direction = Synergists Opposite directions = Antagonists Force is generally applied across the joint that will facilitate movement Immovable portion = OriginMoved part = Insertion

Introduction to Muscles http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__function_of_the_neuromuscular_junction__quiz_1_.html How do we get a whole muscle response based on individual muscle fibers? Muscle fibers contract in an “All-or-none” fashion. To control force of a whole muscle contraction, you must control the NUMBER of muscle fibers contracting. Each motor neuron and the muscle fibers it innervates is called a motor unit

What muscles are identified as axial? T3… those of tongue, trunk and tail Notice the complementary orientation of the abdominal fasciculi External Internal Transverse Axial Muscles

What muscles are identified as axial? They exhibit metamerism (primitive trait). This is a consequence of embryonic development from mesodermal segments or somites. Myomeresandmyosepta Absent in anurans and amniotes, but spinal nerves are segmental Axial Muscles

Where would you look for epibranchials and hypobranchials? How are myomeres of fishes organized? Dorsal and ventral bundles are separated by a sheet of connective tissue the horizontal septum Myomeres dorsal to this septum are epaxials and those ventral are hypaxials. Myomeres are arranged as “cones” that extend caudad. Generate great force that is maximal at tail Axial Muscles

How are myomeres of tetrapods organized? Horizontal septum has gone away since most tetrapods have lost hypaxial segmentation Some tetrapods have retained the “-paxials” such as urodeles. How would this facilitate locomotion? Axial Muscles

What adaptations facilitate terrestrial tetrapod locomotion? Increased vertebral mobility (dorsoventral) and unified muscle arrangement (sheets rather than myomeres) allows a variety of motions… for example “humping” or galloping Axial Muscles

What are the epaxial muscles of the trunk? 4 categories… Intervertebrals Longissimus Spinales Iliocostales Cause extension or lateral flexion of the trunk. How? Axial Muscles

What are the hypaxial muscles of the trunk? 4 categories… Subvertebrals Obliques Transverse Rectus abdominis What motion would these likely cause? Axial Muscles http://www.yorku.ca/earmstro/journey/images/extobliques.jpeg

What is special about the mammalian diaphragm? Central tendonsurrounded by a muscular sheet. Attaches sternally, costallyandvertebrally Axial Muscles

What are the functions of the hypobranchial muscles? Assist in depressing the mandible/lower jaw Expand the pharyngeal and branchial chambers For what purpose(s)? Axial Muscles

What are the functions of the hypobranchial muscles in tetrapods? Assist in depressing the mandible/lower jaw Moving the hyoid and laryngeal cartilages Moving the tongue (bats and people) Axial Muscles

Appendicular Muscles What is the significance of appendicular muscles? These muscles insert (as opposed to originate) on the girdles, fins and limbs… They can arise from blastemas within the body wall originating off axial skeleton or fascia are Extrinisic Those arising from blastemas within the limb and originating on the limb are Intrinsic

Appendicular Muscles What role do appendicular muscles play in fishes? Since most fish move by lateral undulations, the musculature of the appendicular skeleton is minimal. Fin fold is invaded by muscle buds from adjacent myomeres. Dorsal blastemas form extensors (elevators) Ventral blastemas form flexors (depressors) Would you expect blastemas of the median dorsal fins to arise from hypaxial or epaxialmyomeres?

Appendicular Muscles What are the extrinsic muscles of the pectoral girdle and forelimbs? A consistent muscle among taxa is the Latissimusdorsi It is more developed in taxa relying heavily on limbs for movement and spread from hypaxial region to insert on spinous processes Pharyngeal arches contribute to trapezius muscles. Cleidomastoideus and cleido-occipitalis actually move the head.

Appendicular Muscles What are the extrinsic muscles of the pectoral girdle and forelimbs on the ventral surface? Pectoralis and Supracoracoideus In birds the pectoralis are the primary adductors and the supracoracoideus are the abductors

Pectoralis and Supracoracoideus • In birds the pectoralis are the primary adductors and the supracoracoideus are the abductors

Appendicular Muscles What are the intrinsic muscles of the forelimbs? The dorsal group is comprised of the Deltoideus, Teres major, Teres minor, Subscapularis and long head of the Triceps Extensors of the hands and digits Which of the above would you expect to insert on the ulna?

Appendicular Muscles What are the intrinsic muscles of the forelimbs? The ventral group is comprised of the Biceps brachii, Brachialis Flexors of the hands and digits

Appendicular Muscles What are the muscles of the pelvic girdle and hindlimbs? Not much for pelvic girdle… Why? Iliopsoas group and the gluteal group arise from pelvic region and insert on what? Quadratusfemoris Adductor group “Hamstrings” Extensors and flexors of the foot and digits

Appendicular Muscles Branchiomeric muscles. Arising from the pharyngeal arches are several muscles including the masseter, temporalis and the pterygoids Digastric muscles Tensor tympani Platysma Stapedius

Appendicular Muscles

Muscle are the machines converting chemical energy to mechanical energy!