Skeletal Muscle and Movement Flashcards
Describe Smooth (Visceral) muscle
- Involuntary
- Not striated
- Irregular fibre arrangement
- 1 nuclei per fibre
- Responds to nerve impulses, hormones, local stimuli
Describe Cardiac muscle
- Involuntary
- Striated
- Regular fibre arrangement
- 1-2 nuclei per fibre
- Responds to nerve impulses, hormones and local stimuli
Describe Skeletal muscle
- Voluntary
- Striated
- Regular fibre arrangement
- Multinucleated
- Responds to nerve impulses
What are the functions of skeletal muscle?
- Generate movements
- Maintain posture
- Protection
- Storage
- Promote blood flow
- Heat production
What are the properties of muscle?
- Excitability
- Conductive
- Contractibility
- Extensibility
- Elasticity
Describe the histology of building muscle
-Hierarchical
-Muscle
=Tissue-level
=Surrounded by epimysium (connective tissue)
-Fascicle
=Small ‘packets’ of muscle cells
-Surrounded by perimysium
=Arranged in many forms
=Blood vessels (larger arterioles)
-Muscle fibres
=Myocytes
=Multinucleated cells, periphery (contractile proteins push them to sides)
=Packed with contractile proteins
=Surrounded by endomysium
What is the Sarcomere?
-Each muscle fibre / cell contains numerous myofibrils
=Cylindrical contractile structures
-Each myofibril comprised of sarcomeres
=Contractile unit of muscle
=Repeating protein pattern
-Gives striated muscle its ‘striped’ appearance
What are the features of the Sarcomere?
- Red: actin fibres (thin)
- Blue: myosin fibres (thick)
- I band: Actin only (light)
- A band: Actin + myosin (dark)
- H band / line: myosin only
- M line: middle of sarcomere (hypothetical)
- Z line: anchor of actin between sarcomeres
Describe the innervation of skeletal muscle
Skeletal muscle is voluntary
- Responds to nerve impulses
- Neuron releases neurotransmitter
- Binds to receptors on motor end plate
- Changes voltage (via Na+)
- Sarcoplasmic reticulum releases Ca2+ ions
- Sarcomere contracts
What do muscles attach to?
-Muscles attach via tendons (or an aponeurosis)
-Usually muscle – bone
-Some exceptions
=e.g. muscles of facial expression attach to skin
-Tendon: regular dense fibrous connective tissue
=Tough, inelastic
-Ligaments (connects bones)= flexible, highly elastic
What is Muscle Attachment?
Anchorage point (both ends)
What is Origin?
Attachment to the stationary (or less mobile) bone in a joint
What is Insertion?
Attachment to the moveable (or more mobile) bone in a joint
How do muscles attach?
-Muscles blend into tendons at myotendinous junctions
-Muscular fibres and connective tissues interdigitate
=‘FLP’ – ‘finger like projections’
-Muscles blend into bone via the enthesis (where tendon meets bone)
-Transition from soft tissue to bone
-Usually fibrocartilaginous
-Important site for current research
=Repair of tendon damage (e.g. rotator cuff tears)
Describe muscle shape
- Myofibrils arranged in parallel within fascicle
- Fascicles may be arranged in a number of ways
- Affects magnitude + direction of force
- Maximum force: muscle mass
- Maximum range: length of fibres
What are the muscle shapes?
- Strap/ parallel (linear)
- Quadrilateral (linear)
- Intersected
- Fusiform (common)
- Digastric
- Tricipital
- Unipennate
- Bipennate (multiple bellies, more feathered than Tricipital)
- Circular
- Multipennate
Describe the deltoid muscle
- Multipennate
- Limited range of movement, adduction
- Powerful= short, well anchored, large mass
Describe the Sartorius
- Strap/ parallel
- Increased range of movement= long
- Relatively weak= thin, less mass
Describe lever systems
- Muscles, bones and joints act together as lever systems
- Allow movements to occur in set planes
- Lever = bone
- Fulcrum / Axis = joint
- Applied force/ effort = muscle attachment (distal muscle insertion)
- Load= weight of body part being moved
What are the roles in muscle coordination?
- Agonist
- Synergist (supporting movement)
- Antagonist
- Fixators (does not directly act on joint)
What is compartmentalisation?
-Muscles can be grouped together:
-Broad groupings are regional:
=Head and Neck
=Trunk
=Upper Limb
=Lower Limb
-Regions do interact
=(e.g. trunk muscles move upper limb
What are the compartments of the upper limb?
-Arm =Anterior compartment =Posterior compartment -Forearm =Anterior compartment =Posterior compartment -Hand
What are the compartments of the lower limb?
-Thigh =Anterior compartment =Posterior compartment =Medial compartment -Leg =Anterior compartment =Posterior compartment =Lateral compartment -Foot
What are the functions of the skeleton?
Provide support / facilitate movement
Protection
Haematopoiesis
Mineral storage
What are the bones are functions of the Axial skeleton?
Protection and posture
- Skull
- Vertebrae
- Ribs
- Sternum
What are the bones and functions of the Appendicular skeleton?
Movement
- Girdles
- Long bones
- Extremities
What are the types of bone?
Flat= sternum, skull Irregular Long= most common Short= rectangular Sesamoid= in tendon, patella
Describe the anatomy of a bone
-Not a static tissue =Metabolically active =Undergoing constant remodelling (1/10th bone mass renewed per year) -Organic and inorganic components =Hydroxyapatite (calcium phosphate) =Collagen (mainly type 1)
What are the layers of the bone?
- Periosteum= outer membranous connective tissue covering bone
- Bone tissue= mineralised tissue, formed from cortical and trabecular bone
- Endosteum= inner membranous connective-tissue lining marrow cavity
- Bone marrow
Describe the two types of bone
-Cortical/ compact =Tightly packed =Formed of cylindrical sub-units (osteons) =Rigid so resists compression -Trabecular/ Spongy/ Cancellous =Loosely arranged struts/ trabeculae =Highly porous, filled with marrow =Adaptable- stronger in multiple directions
Describe bone histology of cortical bone
-Cortical bone: osteons =Central (Haversian) Canal =Contains artery, vein and nerve =Surrounded by concentric bone lamellae -Sectioned bone: osteons easily identified =Bone cell present: osteocytes =Reside within lacunae =Communicate via canaliculi small channels
Describe bone histology of trabecular bone
-Trabecular bone has similar structure =Rounded layers of bone =Osteocytes residing in lacunae -Does not have central canal -Nutrients diffuse directly from bone marrow -Tiny= 100-150 micrometres
