Muscular System (lecture I-III) Flashcards
Function of muscle
- Produce movement
- Maintain posture
- Generates heat
- Stores minerals
- Provide protection
Three types of muscle
- Smooth
- Cardiac
- Skeletal
-1 cell = 1 muscle fibre
-bundle of muscle fibres (covered with perimysium) = fascicle
-Group of fascicles (covered by epimysium) = muscle
-Muscles consist of fleshy parts = belly and a connective tissue
attachment = tendon
SMOOTH MUSCLE
-Variable intermediate length single nucleus -Spindle shaped (thick middle with tapered edges) -Thin diameter (3-8um) -located in walls of vessels and found in some organs -Only endomysium -Gap junctions found in some areas -Has capacity to regenerate -Slow contraction -Involuntary
CARDIAC MUSCLE
-Long branched cylindrical fibre
-Large diameter (10-20um)
-Endomysium and perimysium
-Attached to each other at
intercalated discs have
desmosomes and gap junctions
-Moderate speed of contraction
-Involuntary
-Limited capacity for regeneration
SKELETAL MUSCLE
- Long cells with multiple nuclei
- Large diameter (10-100um)
- Striated
- Attached to bone via tendons
- No junctions between fibres
- Under voluntary control
- Limited capacity for regeneration
- Fast reacting
- Endo-, peri- and epimysium
SKELETAL MUSCLE CONTRACTION
-Muscles contract toward their origin
-They change their origin and insertion to produce different
actions
-PRIME MOVER Produces a movement -ANTAGONIST Relaxes to allow movement -SYNERGISTS Stabilize intermediate joints -FIXATORS Stabilizes the origin of the prime mover
Muscles are grouped together
• These groups are called compartments • Each compartment share a common: – Action – Innervation – Attachment – Embryologic origin • Learn muscles in groups then add the exceptions
The naming of muscles
Shape – deltoid • Size – magnus • Attachment – carpi • Movement – flexor • Length – brevis • Depth – superficialis • Number of bellies – triceps
Muscle response to stress
When you exercise your muscles they get
bigger
• How?
• Because the muscle cells increase in size = This is called hypertrophy
• In some cases more muscle cells may form = hyperplasia
• It can also be physiological
– Pregnant uterus
Appendicular muscles
• Upper and lower limbs share a common arrangement • But they are opposite due to rotation during embryologic development • The patterns and layers are generallycomparable – Quick hints • The extensors are where the nails are • Special actions: – Wrist = supination/pronation – Ankle = Inversion and eversion
Muscles of the hands and feet
• Arranged in layers
– 3 hand, 4 foot
• Change the shape of the extremity
• Thenar and hypothenar eminence
Combination movements
• Left shoulder – Abducted – Muscles? • Left elbow – Extended – Muscles? • Forearm – Pronated – Muscles? • Fingers – Extended and abducted – Muscles?
Combination movements
• Right hip – Flexed – Muscles? • Right knee – Flexed – Muscles? • Ankle – Plantar flexed – Muscles? • Toes – Extended? – Muscles?
MUSCLES OF THE NECK AND BACK
PRODUCE DIFFERENT ACTIONS
WHEN CONTRACTING BI- VS UNILATERALLY
BACK AND NECK MUSCLES
- The muscles of the back and neck are not only divided by depth but also by location and action
• Intrinsic muscles have both their attachments on the back and produce movements the mainly change the shape and position of the back and neck
• Errector spinae
• Extrinsic muscles are muscles which have one of their attachments on the back but act on another part of the body such as the upper limb
• Lattisimus dorsi
