principles of muscular system Flashcards
What are the 3 types of muscles?
- smooth muscle
- cardiac muscle
- skeletal muscle
What are some of the roles of skeletal muscles?
- moving organs/structures
- posture
- voluntary movement
What is the structure of skeletal muscles ?
contractile filaments called myofilaments are arranged as myofibrils
Describe the crosstructure of skeletal muscle
- elongated, multinucleated cells (form fibres)
- peripheral nuclei
- grouped into bundles called fascicles
- surrounded by connective tissue
What are the 3 types of connective tissue and what do they surround?
- ENDOMYSIUM: surrounds each fibre
- PERIMYSIUM: surrounds each fascicle
- EPIMYSIUM: surrounds each muscle
What are the two types of myofilaments found within a sarcomere?
- actin (thin)
- myosin (thick)
What is a sarcomere?
smallest functional unit of a skeletal muscle fibre
What is the end result of a muscle contraction?
- shortening of sarcomere
- shortening occurs between origin and insertion
- causes the movement of a bone or joint
What are the 4 parameters used to describe skeletal muscle?
- origin
- insertion
- action
- innervation/nerve supply
What are the 6 ways muscle fibres can be arranged?
- flat
- pennate
- fusiform
- quadrate
- circular
- multi-headed/bellied
What are satellite cells?
- myogenic cells located between the sarcolemma and basement membrane of muscle fibres
What do satellite cells do?
- usually dormant in adult muscle
- but act as a reserve population of cells which can proliferate in response to injury and give rise to regenerated muscle and to more satellite cells
Which are some of the main skeletal muscles in the body?
- pectoralis major
- pectoralis minor
- biceps brachii
- deltoid
- serratus anterior
Where are the origins of the pectoralis major?
- clavicle
- sternum
- costal cartilages
Where is the insertion of the pectoralis major?
humerus