HESI ANATOMY & PHYSIOLOGY MUSCULAR SYSTEM Flashcards
Muscles
move bones by contracting and relaxing
heart is largely composed of muscles and the blood vessels contain a layer of muscles.
3 types of muscle tissue
skeletal, cardiac, and smooth muscle
Skeletal muscle
moves bones and generates heat.
cells in skeletal muscle are called myocytes and they contain a reddish pigment called myoglobin
Straiations
striations mark the contractile units called sarcomeres.
Cardiac muscle
it is also striated.
cells are called cardiomyoctyes which have 1 nucleus.
contains special cell junctions called intercalated discs which help the cells contract together which is important in moving blood through the heart.
contract on its own because it contains areas of special tissue called nodes
Smooth muscle
less organized structure than skeletal or cardiac muscle.
cells with only 1 nucleus and there are no striations
found in the digestive, reproductive, and urinary systems and in blood vessels.
involuntary control and can sustain contractions for long period of time
produce a wave like contraction called peristalsis - food moves through the digestive tract by way of peristalsis.
Skeletal muscle
arranged in bundles within bundles
most outer layer contains connective tissue called fascia
epimysium
Deep to the fascia we see a layer of dense connective tissue
fascicles.
contains an outer layer called the perimysium and inside each fascicle there are bundles of muscle fibers.
Describe the locations of skeletal muscles,
origin and insertion.
Origin of a muscle
less mobile end of a joint.
Insertion Muscle
more mobile end of a joint.
tendons.
Muscles connect to bones through dense connective tissue
broad and flattened.
Muscles of the neck
sternocleidomastoid - which is an important muscle for turning the head, and the trapezius which helps to shrug the shoulde
levator scapulae - elevates the scapula.
scalenes - deep muscles of the neck that assist in laeral flexion.
Muscles of the Arm
supraspinatus muscle - rotator cuff muscles and is the muscle most frequently injured in rotator cuff injuries.
below the supraspinatus - infraspinatus and teres minor muscles, both are rotator cuff muscles
One the **back of the arm we see the triceps brachii **which is a 3 headed muscles. The triceps allows you to straighten your elbow.
Muscles on the front of the arm include the biceps brachii and brachialis. Both allow you to flex your elbow
Muscles in the forearm
front of the forearm can be called flexors
back of the forearm can be called extensors.
muscles that allow for rotation - pronator teres and anaconeus.
Muscles of the hand
pollicis - thumb
brevis - short
Muscles of the Leg
Muscles on the front or anterior side of the leg include the sartorius or Tailor’s muscle
quadriceps muscles - rectus femoris, vastus medialis, and vastus lateralis
4th quad - beneath the rectus femoris and is called the vastus intermedius.
psoas major muscle - ombines with the iliacus to form the iliopsoas which is an important muscle in hip flexion
adductor group
muscles and gracilis that work to pull the leg inward (adduction)
gluteal muscles
located in the posterior hip region.
deepest gluteus muscle - gluteus mininus.
gluteus medius - pelvic stability and a site for injections.
gluteus maximus - gluteus medius muscle which is an important muscle in pelvic stability
hamstrings
3 hamstring muscles
lateral to medial we see the biceps femoris, semimembranosus and semitendinsosus
(Front) anterior lower leg
tibialis anterior, extensor digitorum and a group of muscles called the fibularis muscles
(Back) posterior of the lower leg
gastrocnemius (calf muscle)
soleus and the achilles or calcaneal tendon
small muscle here called the plantaris muscle as well that is absent in 8-12% of the population
Foot muscles
abductor hallucis - moves the big toe into abductio
flexor digitorum brevis - short muscle that flexes the toes.
neurotransmitters
bring the message from the nerve to the muscle
Other chemical messengers that tell the protein filaments to contract then pass on the message
energy comes from ATP.
ATP connects to one type of filament and extracts the energy so that it can pull the other filament along.
motor neuron
connects to a skeletal muscle at a special area called the motor end plate.
Process of Motor Neuron
1) in the motor neuron will cause the influx of calcium into the axon terminal
2) which promotes the release of the neurotransmitter acetylcholine from the axon terminal
3) Acetylcholine moves across the synaptic cleft to the motor end plate
4) romotes the opening of sodium channels causing sodium to rush into the skeletal muscle cell
5) keletal muscle is polarized and the movement of sodium causes it to depolarize.
6) effect on the sarcoplasmic reticulum
T-tubules.
reach into the muscle fiber and encircle the sarcomere
connects to the outside of the cell it is filled with extracellular fluid
sarcoplasmic reticulum
network of membranous channels called cisternae
transports calcium so it contains a high concentration of calcium
responds to the depolarization of the muscle cell by opening calcium channels in the terminal cisternae of the sarcoplasmic reticulum
Cisternae
T-tubules are wider and called terminal cisternae.
A tubule and the two adjacent terminal cisternae are called a triad.
Summary of sacriplasmic reticulm
To summarize, the sarcoplasmic reticulum is a network of tubules that wraps around the muscle cell. Think of a loosely knit winter sweater.
The sarcoplasmic reticulum will take calcium from the blood and store it until the muscle cell depolarizes. Once it does, the sarcoplasmic reticulum releases calcium into the muscle cell.
Actin
double helix protein and myosin has large globular protein heads.
Thin filament
Myosin
the thick filament.
large globular protein heads.
troponin-tropomyosin complex.
double helix protein complex wrapped around actin
m line
middle of this structure there is only myosin
z lines
called a sarcomere.
