Week 1: Muscle Flashcards
Describe smooth muscle:
- Non-striated muscle - actin & myosin not organised into sarcomere
- Involuntary
Describe cardiac muscle:
- Striated muscle - actin & myosin arranged into regular repeating structures (sarcomere)
- Involuntary
Describe skeletal muscle:
- Striated muscle - actin & myosin arranged into regular repeating structures (sarcomere)
- Voluntary
Name the different structures of the muscle from biggest to smallest:
- Muscle
- Fascicles/ bundles
- Muscle cell/ fibre
- Myofibrils
- Protein filaments/ myofilaments (actin & myosin)
Describe the organisation of muscle and fascia:
- Fascia
– Loose, areolar connective tissue
– Promotes movement - Whole muscle
– Surrounded by EPIMYSIUM - Bundle of muscle fibres (fascicles)
– Surrounded by PERIMYSIUM - Individual muscle fibres
– Surrounded by ENDOMYSIUM
What is the function of the epimysium?
To separate muscles from their neighbours and at the same time permit frictionless movement between them
What are the 3 main functions of the extensive connective tissue organisation of the muscle?
- Resists passive stretching of the muscle and ensures that forces are distributed in such a way as to minimise damage to the muscle fibres
- Provides a pathway for nerves, blood vessels and lymphatic vessels
- Transmits the forces generated within the muscle cells to the tendon
What are the 2 architectures of muscle? Give examples of each.
- Parallel:
Strap - Sartorius
Fan-shaped - Pectoralis major
Fusiform - Biceps brachii - Pennate:
Uni - Extensor digitorum longus
Bi - Rectus femoris
Mult - Deltoid
What are tendons and ligaments composed of?
Dense regular connective tissue
Describe the role of ligaments and the joint capsule:
- Connect bone to bone
- Stabilize and guide joint motion
- Preventing abnormal or excessive movements
Describe the role of tendons:
- Connect muscle to bone
- Interlocking of muscle fibres and tendinous collagen.
- Transmit tensile loads to the bone when a muscle contracts – thereby creating joint motion
Define fusiform (parallel) muscles:
Fibres extend parallel to the muscle’s line of pull e.g. Biceps brachii, brachialis, sartorius
Define unipennate muscles:
Fibres are oriented at a single angle relative to the line of pull, attached to one side of the tendon only e.g. Flexor pollicis longus, soleus, vastus lateralis, palmar interosseous muscles (hand)
Define bipennate muscles:
Fibres are oriented at two angles relative to the line of pull, i.e. they attach to both sides of the tendon e.g. Rectus femoris, dorsal interosseous muscles (hand)
Define multipennate muscles:
Fibres are oriented at several angles relative to the line of pull e.g. Gluteus medius, gluteus minimus, deltoid
Which type of muscle is likely to generate most force – a fusiform or multipennate muscle? Why?
Multipennate – a larger number of shorter fascicles are able to attach to the tendon (larger cross-sectional area)
