Lecture 13 - Musculoskeletal system 3: Muscle Flashcards
(33 cards)
What are 3 types of muscle tissue
- skeletal (striated, voluntary) aprox 40% body mass
- cardiac (striated, involuntary)
- smooth (visceral)(non-striated, involuntary)
What are 4 functions of muscles
- Movement: locomotion, manipulation, circulation)
- Stabilization of body position: gravity
- Regulation of organ volume: stomach, bladder
- Release of heat: during contraction
What are 4 characteristics of muscles
- Excitability or irritability: can transmit, produce & react to a stimulus (electric current, neurotransmitter)
- Contractility: shortening & widening of the cells ( force production, generated by an action potential)
- Extensibility: can be stretched
- Elasticity: retakes its form either after the contraction or the extension.
What is fascia
Connective tissue layer that covers muscles and organs
What is superficial fascia
(Under the skin)
Loose areolar CT and adipose tissue
What is Deep fascia
- dense CT
- surrounds deeper organs, including muscles
- makes strong fibrous framework
- bound to capsules, tendons, ligaments
What are other names for superficial fascia
Subcutaneous layer or hypodermis
What is subserous fascia
- betwn serous membrane and deep fascia
- areolar tissue
What are 3 layers of skeletal muscle
- Epimysium: envelopes all of the muscle
- Perimysium: surrounds the fascicles of myocytes 10-100
- Endomysium: isolate each myocyte
The epimysium and perimysium fuse and elongate to form
Part of the tendons
What is a tendon
- extension of CT
- interfaces with bone to produce strong anchor for contraction
What is aponeurosis
- broad flat sheet of CT
- typically merges with fibrous tissue from nearby muscle
What is tendon sheath
- double-walled tube that encloses tendons
- contains synovial membrane, reduces friction
What are the 6 type of muscle arrangements
- Parallel
- Fusiform
- Convergent
- Circular
- Spiral
- Pennate
Describe parallel muscle fibres arrangement
- long axis of the fascicles are oriented parallel to the long axis of the muscle
- straplike (ex. Sartorius / thigh muscle)
Describe fusiform muscle fibres arrangement
- long axis of the fascicles are oriented parallel to the long axis of the muscle but have expanded belly
- ex. Biceps brachii
Describe convergent muscle fibres arrangement
- broad origin (fixed point)
- fascicles leading to a single tendon at the insertion end (mobile point)
- ex. Pectoral
Describe circular muscle fibres arrangement
- fascicles in concentric circles
- ex. Orbicularis occuli or oris (eye or mouth), sphincter
Describe spiral muscle fiber arrangement
- fascicles twist btw points of attachment
- ex. Lassimus dorsi
Describe pennate muscle fibre arrangement
- shorter fascicles, attach diagonally on the central tendon on the axis of the muscle
- resemble feathers
What are the 3 types of pennate muscle fibre arrangement
- unipennate: single feather like extensor digitorum longus
- bipennate: 2 rows of muscle fibers, facing in opposite directions like rectus femoris
- multipennate: multiple rows of diagonal fibers like deltoid
When muscle contraction occurs what usually happens to the two attached bones and what is the origin and insertion
When contraction happens, one bone usually remains fixed while the other moves (not always but usually)
Origin = point of attachment that doesn’t move
insertion = point of attachment the moves when muscle contracts
What are 4 main muscle action groups
- Prime mover
- Antagonist
- Synergist
- Fixator
what is muscle action prime mover (agonist)
- Muscle that directly performs a specific movement
- The movement produced is the action
- Agonist can refer to it, or any other muscle directly contributing to the same action