Muscle Tissue (Ch 10) Flashcards
What are the types of muscle tissue?
- skeletal
- cardiac
- smooth
Skeletal Muscle
pulls on bones of skeleton
- striated
- voluntary
Cardiac Muscle
pushes blood through the circulatory system
- striated
- involuntary
Smooth Muscle
pushes fluids/solids along the digestive tract and regulates the diameters of small arteries
- not striated
- involuntary
What are the properties of skeletal muscle tissue?
- contractility: muscle cells can shorten
- excitability: very responsive
- extensibility: can increase in length
- elasticity: able to return to original length
What are the functions of skeletal muscle?
- produce movement
- maintain posture
- support
- generate heat
- storage and movement of materials
What does skeletal muscle contain?
skeletal muscle + CT + nerves + blood vessels
What are the subdivisons of skeletal muscle?
muscle –> fascicle –> muscle fiber
What are the connective tissue membranes?
- epimysium
- perimysium
- endomysium
Epimysium
- CT membrane
- surrounds entire “muscle,” separates muscle from surrounding tissues and organs
Perimysium
- CT membrane
- surrounds each fascicle –> divides skeletal muscle into compartments
Endomysium
- CT membrane
- surrounds muscle fibers within a fascicle
What are the muscle attachments?
tendons: muscle to bone
aponeurosis: flat sheets of tendons
Origin
proximal attachment to bone (fixed)
Insertion
distal attachment to bone (mobile)
What are the types of fascicle orientations?
- Circular
- Convergent
- Parallel
- Pennate
Circular Fascicle Orientation
- surround external body openings
- sphincter
- close when they contract
- -> ex. orbicularis oris, orbicularis oculi
Convergent Fascicle Orientation
- broad origin
- narrow insertion
- direction of pull can be changed because different groups of fibers can be activated
- ->ex. pectoralis major, latissimus dorsi, gluteus medius
Parallel Fascicle Orientation
- fascicles run parallel to long axis of muscle
- tapered at both ends
- strap
- high endurance, not very strong
- ->ex. sternocleidomastoid, brachioradialis, flexor digitorum superficialis (FDS)
Pennate Fascicle Orientation
- fascicles short
- attach obliquely to tendon or raphe
- uni-, bi-, multipennate
- stronger than parallel muscle of same size
- ->ex. rectus femoris (bi-), extensor digitorum longus (uni-), deltoid (multi)
Muscle Compartments
- dense, fibrous CT divides muscles into compartments
- same compartment? = similar actions
- different compartment? = opposite actions
- usually muscles in same compartment are innervated by a single nerve
Compartment Syndrome
- damaged muscle swells –> surrounding fascia (inelastic) constricts
- puts pressure on vessicles and nerves (=PAIN), also prevents blood from entering/draining
- -> acute vs. chronic
Acute Compartment Syndrome
- from accident/injury
- can lead to tissue loss in muscle or limb due to loss of blood supply
Chronic Compartment Syndrome
caused by overuse
–> rest until it heals
How do we name muscles?
- Location (ex. biceps brachii)
- Shape (ex. deltoid = triangular)
- Relative Size (ex. gluteus maximus = largest)
- Direction of Fascicles/Fibers (ex. external oblique)
- Direction of Attachments (ex. coracobrachialis = corocoid process and brachium)
- Number of Origins/Heads (ex. biceps brachii = two heads)
- Action (ex. flexor digitorum longus)
Myofibril
- ->contractile portion of muscle fiber
- there are 100s-1000s of myofibrils in each skeletal muscle fiber
- along length of myofibril are sarcomeres (repeating segments)
Sarcomere
- ->basic functional unit of skeletal muscle
- contraction = contraction of muscle
- extends from Z disc to Z disc (A band)
- up to 10,000 per myofibril
- center = M line
- made of thick (myosin) filaments and thin (actin) filaments
Sliding Filament Mechanisms
thin (myosin) and thick (actin) filaments slide past each other
