anatomy lab exam 4 yay

what type of skeletal muscles function under involuntary control?

smooth and cardiac

what type of muscles are under voluntary control?

skeletal

what feature do cardiac muscles have that skeletal muscles don’t?

intercalated discs

what do skeletal and cardiac muscles both have in common?

striations

what does the smooth muscle line?

internal organs like inside blood vessels, stomach, large intestine, trachea

function of skeletal muscle

movement of skeleton

function of cardiac muscle

forms the heart

what do all muscle types do?

contract and cause movement

what components do muscle cells contain?

actin, myosin, and proteins

what nervous system stimulates skeletal muscles?

somatic nervous system

what nervous system stimulates cardiac and smooth muscles?

autonomic nervous system

what are skeletal muscle cells often referred to as? what are their function?

skeletal muscle fibers; extend from one end of a muscle cell all the way to the other end

what does multinucleated mean? what is an example of this?

containing many nuclei of the cells that fused together, skeletal muscle fibers are multinucleated

what are myofibrils?

bundles of actin and myosin

what gives skeletal muscle its striated appearance?

the orderly arrangement of actin and myosin in the myofibrils

use the terms striated or smooth and involuntary or voluntary to describe the three types of muscle tissue

skeletal: voluntary and striated

cardiac: involuntary and striated

smooth: involuntary and smooth

both axons and skeletal muscle cells are often referred to as fibers. what do both of these structures have in common that leads them to being called fibers?

both skeletal muscle cells and axons tend to be long and thin.

An enzyme called acetylcholinesterase is found in the neuromuscular junction. This enzyme breaks down acetylcholine. If the action of this enzyme, acetylcholinesterase , was blocked, then what would happen to the muscle? Would it be unable to properly contract or would it be unable to properly relax? explain your answer

acetylcholine would remain in the synapses longer that it should, stimulating the muscle to contract. the muscle would be unable to relax properly

Why is the surface of the motor end plate ruffled, rather than smooth?

increases the surface area at the neuromuscular junction

What is the strong sheet of tissue that acts as a tendon to attach muscles to bone

aponeurosis

What is the attachment of a muscle that remains relatively fixed during muscular contraction

origin

What is the attachment of a muscle tendon to a moveable bone or the end opposite the origin

insertion

skeletal muscle image

cardiac muscle image

smooth muscle image

what do intercalated discs contain?

desmosomes and gap junctions

what do gap junctions allow?

allow action potentials to spread quickly from one cell to the next

how does the structure of a cardiac muscle cell help its function?

they are branched, allowing rapid spread of action potential across heart

what is the sarcolemma? what is it capable of?

plasma membrane of a muscle fiber; excitable and capable of conducting action potentials

what is the connective tissue that wraps around the muscle fiber called?

endomysium

what does a skeletal muscle fiber synapse with? what is this synapse called?

somatic motor neuron; neuromuscular junction (NMJ)

what happens when a somatic motor neuron fires an action potential?

the action potential propagates along the axon and causes the release of a neurotransmitter, acetylcholine, from the synaptic bulb.

what does acetylcholine do once it enters the synaptic cleft?

it binds to nicotinic receptors on the motor end plate, stimulating a muscle fiber to fire its own action potential, spreading it to the sarcolemma, causing contraction of the muscle.

belly

the thickest, fleshy part of a muscle, where most of the muscle fibers are located

tendon

muscle to bone

aponeurosis

connective tissue that connects muscle to muscle

origin

the attachment point of a muscle to a bone that doesn’t move during contraction

insertion

the attachment point where a muscle connects to a bone that moves during a muscle's action

synergist

muscle that assists the main muscle (agonist) performing a joint action

antagonist

one that opposes or resists the action of an agonist muscle

how many skeletal muscles does the human body contain?

over 600

what forms the neuromuscular junction (NMJ)?

synapse between motor neuron axon and skeletal muscle fiber

function of frontalis muscle

to raise eyebrows

function of orbicularis oculi

blinking and closing eyelids

function of orbicularis oris

closes mouth area and does kissing

function of zygomatic major and minor

goes to corner of mouth and helps you smile

where does the zygomatic major originate from? where is its insertion?

originates on the zygomatic bone and inserts on the skin at superolateral region of mouth

function of masster

allows elevation of mandible

where does the masseter originate and where is its insertion?

originates on the zygomatic arch and maxilla and inserts on the angle and ramus of mandible

function of temporalis

to elevate the mandible

what is the origination and insertion of the temporalis

originates on the parietal bone and inserts on the coronoid process of mandible

function of platysma

depresses the mandible

what is the function of the four eye muscles? what are their names

superior rectus: rotates eye superiorly, to look up

inferior rectus: rotates eyeball inferiorly, to look down

medial rectus: rotates eyeball medially, toward the nose

lateral rectus: rotates the eyeball laterally

name two synergist muscles on the face

temporalis and masseter

name three antagonistic pairs on the face

temporalis and platysma
masseter and platysma
lateral and medial rectus

if you are looking to your left, which muscle is responsible for getting your left eye into position? what about your right?

lateral rectus; medial rectus

function of sternocleidomastoid muscle

allows you to bend your neck and turn or tilt your head

what is the origination and insertion of sternocleidomastoid muscle?

originates on the manubrium and the clavicle; inserts on the mastoid process

what happens if both splenius capitis muscles contract?

the head extends and works as antagonist of sternocleidomastoid muscle

what happens if ONE of the splenius capitis muscles contract?

head rotates ipsilaterally and muscle works as a synergist with one of sternocleidomastoid muscles

which muscles contract and which ones relax when you turn your head to the right?

contracted: left sternocleidomastoid and right splenius capitis
relaxed: right sternocleidomastoid and left splenius capitis

what are certain situations in which the abdominal muscles work together to compress the abdomen?

urination, defecation, vomiting, childbirth, and coughing

function of diaphragm

inhalation

function of external intercostals

elevate rib cage and aid inhalation

function of internal intercostals

depress the rib cage to aid exhalation

function of erector spinae

extend the vertebral column

function of rectus abdominis

flex vertebral column

what is the origin and insertion of the rectus abdominis?

origin is on the pubis, insertion is on the xiphoid process and some of the costal cartilages

function of external and internal oblique

rotate trunk of body

function of transverse abdominis

compress the abdomen

which muscle is antagonist to the rectus abdominis?

erector spinae

Place a finger on your right side, between your iliac crest and your rib cage. If you were to stick a needle into your abdominal cavity at this point, it would pass through three layers of skeletal muscle. What are they? List them in order from superficial to deep.

external oblique, internal oblique, transverse abdominis

function of pectoralis minor

protract and depress the scapula

what is the origin and insertion of the pectoralis minor?

originates on ribs 3-5, inserts on coracoid process of scapula

function of serratus anterior

protract the scapula and hold is close to the rib cage

function of the trapezius

superior fibers: elevates scapula

middle fibers: retract scapula

inferior fibers: depress scalpula

how did the trapezius get its name?

from its trapezoid shape

function of pectoralis major

flexes and adducts the arm, ex. bench press

function of latissimus dorsi

extends and adducts the arm, ex. rowing

function of deltoid

abducts the arm

what’s the origin and insertion of the deltoid muscle

originates on the clavicle, and the acormion and spine of the scapula; inserts on the deltoid tuberosity of humerus

function of tres major

adducts and extends the arm

function of subscalpularis

rotates arm medially

function of supraspinatus

abducts the arm

function of infraspinatus

adducts arm and laterally rotates arm

function of tres minor

adducts and laterally rotates arm

what are the two large superficial muscles visible on the back?

trapezius and latissimus dorsi

The military press is an exercise in which weights are lifted straight up and over the head. What is the main muscle acting to move the arm during exercise?

the deltoid

function of biceps brachii

flex the forearm

where is the origin and insertion of the biceps brachii?

origin is coracoid process of scapula and inserts into radial tuberosity

function of brachialis and brachioradialis

flex the forearm

function of triceps brachii

extend the forearm

what is the origination and insertion of the triceps brachii

originates on the scapula and posterior shaft of the humerus, inserts on the olecranon process

what two pair of muscles in the superior appendages are antagonistic?

biceps brachii and triceps brachii

deltoids and latissimus dorsi

why do muscles have “brachi” in their name?

indicates the location of the muscle

function of flexor carpi radialis

flex and abduct the hand

what is the origination and insertion of the flexor carpi radialis?

originates on the medial epicondyle of the humerus and inserts onto the second and third metacarpals

function of the flexor carpi ulnaris

flexes and abducts the hand

function of extensor carpi radialis longus? what does it work with to do?

extends the hand, works with flexor capri radialis to abduct the hand

extensor carpi ulnaris function? what does it work with?

extends the hand, works with flexor carpi ulnaris to abduct the hand