ch. 11 - skeletal muscle tissue

the 4 functional properties of muscle tissue

1. contractibility

2. excitability

3. extensibility

4. elasticity

What are the two kinds of myofilaments that make up muscle myofibrils?

actin and myosin

sarcomeres

a structural unit of a myofibril in striated muscle

sliding filament model

describes how muscles contract through the action of actin filaments sliding past myosin filaments, shortening the sarcomere without changing the filaments length.s

myosin head

the myosin heads bind and hydrolyze ATP, which provides the energy to drive filament slidings.

tropomyosin

an actin binding protein that blocks the myosin binding sites on actin to prevent myosin actin interaction and sarcomeric contraction

troponin

a protein located on the actin filaments of the sarcomere, acting as the calcium dependent switch for muscle contraction. Moves tropomyosin upon binding calcium, allowing myosin heads to attach and start the cross bridge cycle.

sarcolemma

plasma membrane of muscle cells

sarcoplasm

cytoplasm of muscle cells

epimysium

outer layer of dense, irregular connective tissue surrounding the whole skeletal muscle

perimysium

surrounds each fascicle

endomysium

each muscle fiber is surrounded by this fine sheath of loose connective tissue consisting mostly of reticular fibers

tendons

formed by the convergence of the three connective tissue sheaths

function of muscle contraction with skeletal movement

when muscle fibers contract, they pull on the surrounding endomysium. because of the continuity between sheaths, this pull exerts the perimysium, epimysium, and tendon. this sequence transmits the force of contraction to the bone being moved

fascicles

small, organized bundles of muscle fibers surrounded by perimysium. arrangements differ in muscle functions

circular fascicle

Fascicles are arranged in concentric rings surrounding external body openings.

sphincter muscles

ring-shaped muscles that relaxes or tightens to open or close bodily passages

orbicularis oris

• O: muscle fibers around mouth

• I: mucous membrane of lips

• N: CN VII

orbicularis oculi

convergent fascicles

origin of the muscle is broad and converge toward the tendon of insertion. ex: pectoralis major

pectoralis major

parallel fascicles

fascicles run parallel to the long axis of the muscle. fusiform vs straplike

fusiform parallel fascicles

run parallel to the long axis of the muscle with an expanded central belly. ex: biceps brachii

biceps brachii

straplike parallel fascicles

straight parallel muscle formation

sartorius muscle

sternocleidomastoid

• O: clavicle, manubrium

• I: mastoid process

• N: CN XI

pennate fascicles

fascicles are short and attach obliquely to a tendon that runs the whole length of the muscle

multipennate fascicle

looks like many feather situated side by side, with all their quills inserting into one large tendon. ex: deltoid

deltoid muscle

bipennate fascicles

fascicles insert into the tendon from both sides. ex: rectus femoris

rectus femoris

unipennate fascicles

fascicles insert into only one side of the tendon. ex: extensor digitorum longus

Extensor digitorum longus

lever system

a lever is is a rigid bar that moves on a fixed point called the fulcrum, when a force is applied the lever. the applies force, effort, is used to move a resistance, or load

mechanical advantage with a power lever

in moving a heavier load, if the load to be moved is close to the fulcrum and the effort is applied far from the fulcrum, a small effort can move a large load.

mechanical disadvantage with a speed lever

in moving a load farther and faster, if the effort is applied closer to the fulcrum than the load to be moved, greater effort is required to move the load. Due to the load arm being longer than the effort arm, the load is move dover a greater distance and greater speed

prime mover / agonist

muscle that has a major responsibility for producing a specific movement

antagonist

muscles that oppose or reverse a particular movement

synergists

help the prime movers, either by adding a little extra force to a movement or reducing undesirable extra movement that the prime mover may produce

flexion

makes the joint angle smaller bringing two body parts closer together

extension

makes the joint angle larger, moving two body parts farther away from each other

Which muscle is the primary mover in chewing (mastication) and elevates the mandible?

Masseter

Which muscle is involved in inspiration by expanding the thoracic cavity downward?

Diaphragm

The gluteus medius muscle is primarily involved in:

Medial rotation and abduction of the thigh

The flexor carpi ulnaris is located:

In the anterior forearm and flexes the wrist on the ulnar side

Which muscle is NOT part of the quadriceps femoris group?

Biceps femoris

Cranial Nerve No. 1

Olfactory. Function for smell

Cranial Nerve No. 2

optic nerve. function in visual acuity

Cranial Nerve No. 3

oculomotor nerve. function in opening of eyelids, eye movement

Cranial Nerve No. 4

trochlear nerve. Function in eye movement (downward/medial)

Cranial Nerve No. 5

trigeminal nerve. function in facial sensation, chewing movements

Cranial Nerve No. 6

abducens nerve. Function in lateral eye movement

Cranial Nerve No. 7

facial nerve. function in facial muscle movement (except chewing muscles) and eyelid closing

Cranial Nerve No. 8

vestibulocochlear nerve. function in hearing and balance

Cranial Nerve No.9

glossopharyngeal nerve. function in taste on the posterior third of the tongue

Cranial Nerve No. 10

vagus nerve. function in uvula and swallowing

Cranial Nerve No. 11

accessory nerve. function in shoulder shrug

Cranial Nerve No. 12

hypoglossal nerve. function in tongue movement

what muscles consist within the rotator cuff?

• supraspinatus

• infraspinatus

• teres minor

• subscapularis