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
What actions can the pectoralis major perform?
- flexion
- adduction
- internal rotation of the shoulder joint
What nerves generate the nerve supply for the pectoralis major?
- lateral pectoral nerve
- medial pectoral nerve
Where are the origins of the pectoralis minor?
ribs 3, 4 and 5
Where is the insertion of the pectoralis minor?
coracoid process of the scapula
Which actions can the pectoralis minor perform?
- protraction of the scapula
- elevation of ribs
Which nerve supplies the pectoralis minor?
medial pectoral nerve
Where are the origins of the biceps brachii for the long head and short head?
- LONG HEAD: supraglenoid tubercle of the scapula
- SHORT HEAD: coracoid process of the scapula
Where is the insertion of the biceps brachii?
radius
Which actions can the biceps brachii perform?
- flexion of the shoulder joint
- flexion of the elbow joint
- supination of the radio-ulnar joints
Which nerves supply the biceps brachii?
musculocutaneous nerve
Where are the origins of the deltoid?
- clavicle
- acromion
- spine of scapula
Where is the insertion of the deltoid?
deltoid tuberosity of the humerus
Which nerve supplies the deltoid?
axillary nerve
Where are the origins of the serratus anterior?
the upper 8/9 ribs
Where is the insertion of the serratus anterior ?
the scapula
Which actions can the serratus anterior perform?
- protraction for the scapula
- holds the scapula flat against the thoracic cage
Which nerve supplies the serratus anterior
long thoracic nerve
Which action can the deltoid perform?
abduction of shoulder joint
