Muscular(System( - Mt. SACfaculty.mtsac.edu/mpresch/35_lecture_files_unit_2/6 Anat...Types(of(Muscle(Fibers(• Classified(based(on(the(speed(of(contrac7on(1. Slow((Type(I,(SO)(2.
Post on 20-Jun-2020
0 Views
Preview:
Transcript
Muscular System
Anatomy 35 Unit 2
Func7ons Movements of bones and so. body parts
Movements of fluids through a tube (blood, diges:ve)
Func7ons
Maintain posture Support so. organs
Func7ons Control movement through a passage or opening Control body temperature
Muscle Fascia
Muscle Tissue
• Connec7ve 7ssue layers are con7nuous with each other – Tendon – Perios7um – Epimysium – Perimysium – Endomysium
Fascicle Orienta7on 5 Muscle Types
• Fusiform • Parallel • Convergent • Pennate • Circular
Fusiform Muscles
• Thick in middle • Tapered at ends • Moderately strong contrac7ons
• Examples: – Biceps brachii – Gastrocnemius
Parallel Muscles
• Straplike with parallel fascicles
• Uniform width • Contract more than other muscle types
• Weaker than fusiform • Examples: – Rectus abdominis – Sartorius
Pennate Muscles • Feather-‐shaped • Fascicle inserts into tendon running through muscle
• Unipennate – Semimembranosus
• Bipennate – Rectus femoris
• Mul7pennate – Deltoid
Circular and Convergent Muscles
• Circular – Sphincters – Ex) Obicularis oris
• Convergent – Fan shaped – Narrow at inser7on – Strong – Ex) Pectoralis major
Macrostructure of skeletal muscle
• Origins – aQachment of a muscle to a sta7onary bone
• Inser7ons – aQachment of a muscle to a movable bone
Characteris7cs of Origins and Inser7ons
• Indirect aQachments (most common) – Tendons
• cordlike structures of fibrous, regular connec7ve 7ssue – Aponeuroses
• a wide, thin, tendon • Direct aQachments – the muscle surface is aQached directly to the periosteum of bone
Naming Muscles
• By fiber arrangement • Rectus – Fascicles (fibers) run parallel to the muscle longitudinal midline axis (LMA)
• Example – Rectus abdominis
Naming Muscles
• By fiber arrangement • Transverse
– Fascicles are perpendicular to the LMA
– Transverse abdominis – Transversus costarum
• Oblique – Fascicles are at an angle different than parallel or perpendicular
– Internal/external oblique
Naming Muscles
• By loca7on • Rela:ve loca:on – Tibialis anterior – Vastus lateralis – Serratus dorsalis – Scalenius dorsalis
• Profundus – a deep muscle – Flexor digitorum profundus
Naming Muscles
• By size – maximus – minimus – medius – brevis – longus – magnus
Naming Muscles
• By the number of origins – biceps – triceps – quadriceps
Naming Muscles
• By shape • Deltoideus – Triangular – AQached at side
• Trapezius – Quadrilateral – 2 sides that are parallel
• Rhomboideus – parallelogram
Naming Muscles
• By origin and inser7on – Sternocleidomastoid – Sternohyoid
Naming Muscles
• By ac7on • flexor pollices longus (pollux = thumb)
• pronator teres (teres = round)
• extensor digitorum
Func7onal Groups of Muscles
1. Prime movers (agonists) 2. Synergists 3. Antagonists 4. Fixators
Prime Movers
• Muscle produces most of force during movement across a par7cular joint
• 11 types – Flexor Abductor – Extensor Adductor – Levator Depressor – Supinator Pronator – Rotator Sphincter – Tensor
Types of Muscle Fibers
• Classified based on the speed of contrac7on 1. Slow (Type I, SO) 2. Intermediate (Type IIA, FO: fast oxida77ve) 3. Fast (Type IIB, FG: fast glycoly7c)
• Other characteris7cs – Primary source of fuel – Myoglobin content – Diameter of fiber – Blood supply – Time to fa7gue
Slow Twitch Fibers Type I: SO Fibers
• Small diameter • Fa7gue resistant – Very good blood supply – Myoglobin (red meat) – Many mitochondria
• Take a long 7me to contract aber s7mula7on • Develop less tension • Primarily aerobic metabolism – Lipids, carbohydrates, amino acids
Intermediate Twitch Fibers Type IIA: FO Fibers
• Fast twitch • Intermediate – Diameter – Fa7gue resistance
• Blood supply • Number of mitochondria • Myoglobin content
– Tension • Primarily anaerobic metabolism – Carbohydrates – High [glycoly7c enzymes] in sarcoplasm
Fast Twitch Fibers Type II, FG Fibers
• Large diameter • Fa7gue quickly – Poor blood supply – No myoglobin (white meat) – Few mitochondria
• Generates a lot of tension (Force) • Primarily anaerobic metabolism – Crea7ne phosphate – High [glycoly7c enzymes] in sarcoplasm
Fiber Type Distribu7on
top related