MUSCULAR SYSTEM

is responsible for all types of body movement. Additional functions of this system include providing support, stabilizing joints, and generating heat for the body

muscular system

what do all muscles consist of?

muscle fibers

these contract to facilitate body movement

muscle fibers

what are muscle attached to?

attached to bones and to internal organs and blood vessels

how many muscles are there in the body?

over 600

3 types of muscle

cardiac, smooth, skeletal

muscle is striated, short, and branched. Contains one nucleus, are branched, and rectangular.

Involuntary process and under the control of the autonomic nervous system.

Found in the walls of the heart

cardiac muscle

muscle is striated, long and cylindrical. Many nuclei in a cell.

Attached to bones in the body, contracts voluntarily - under conscious control

skeletal muscle

muscle consists of non-striated muscle cells that are spindle-shaped. Contain one nucleus.

Found in the walls of internal organs like the bladder and stomach.

Contraction is involuntary and controlled by the autonomic nervous system

smooth muscle

what do all the muscles share in common

excitability, contractility (muscle shortening), extensibility (muscle stretching), and elasticity

what muscle is excited by the nervous system

skeletal

what muscle are stimulated by the nervous system and by circulating hormones (dont got to think about it !)

cardiac and smooth

what muscles do skeletal muscles have?

endomysium, perimysium, epimysium

endomysium

encases individual skeletal muscle fibers

perimysium

muscle fibers are bundled together by a connective tissue

fasciculi

Bundles of skeletal muscle fibers

epimysium

Each fascicle is bundled together by a strong connective tissue

sarcolemma

cell membrane that surrounds a skeletal muscle fiber

sarcoplasm

cytoplasm of the skeletal muscle fiber

myofibrils

One muscle fiber is filled with several long, cylindrical protein, are the contractile units of the fiber

sarcomere

smallest contractile unit in a myofibril

myofilaments

they make up a myofibril

2 types of myofilaments

thick bands and thin bands

thick bands

made of several protein molecules called myosin

thin bands

several protein molecules, called actin, link together to form these bands

are attached to a Z-disk (or Z-line).

what color are the I-bands

light-colored bands

what color are the A-bands

dark-colored bands

where is the Z line found?

middle of the I-bands

where is the H zone found

middle of the A-bands

what is in the middle of the H zone

M line, which is the center of the sarcomere

which band is thick and thin filaments

A band

what band is thin filament only

I band

what band is actin filament attachment site

Z line

which band is thick filament only

H band

what does slide filament theory explain?

muscle contraction

actin filaments slide past myosin filaments, pulling the actin filaments closer to the center of the sarcomere, or M line

what attachments do head of myosin form with the actin myofilaments?

crossbridges

what is the head of actin

a round protein shaped like a ball. Several of these round proteins link together to form a long chain, or thin myofilament

with the help of ATP, what do myosin heads do?

attach to binding sites in actin and form a crossbridge. After energy in the myosin head is released, the myosin pulls actin myofilaments closer to the M line. This head can only form another crossbridge when another molecule of ATP attaches to the head, reenergizing it

how does calcium play a role?

determining when contraction happens

where is calcium found in?

sarcoplasmic reticulum

ligaments

attach bones to bones, they form a joint

3 type of joints

immovable, partly movable, synovial

immovable joint

known as fibrous joints, these consist of bones held together by connective tissues. The bones are in very close contact.

ex: intersection of cranial bones in the skull.

partly moveable joint

known as cartilaginous joints, these consist of bones held together by cartilage. These joints allow some degree of movement.

ex: vertebral discs in the spine.

synovial joint

allow the largest freedom of movement because the bones are separated by a joint cavity.

ex: hip and shoulder

6 types of synovial joints

pivot, hinge, saddle, condyloid, plane, ball/socket

pivot joint

a type of freely moveable, uniaxial synovial joint that allows only rotational movement around a single axis

Allow turning, twisting, pronation, and supination

ex of pivot joint

• Atlanto-axial joint: Located between the first (atlas) and second (axis) cervical vertebrae, this joint allows the head to turn from side to side.

• Proximal Radioulnar Joint: Located near the elbow, where the head of the radius rotates against the ulna, enabling the forearm to twist.

• Distal Radioulnar Joint: Located near the wrist, working in conjunction with the proximal joint for forearm rotation

hinge joint

a type of synovial joint allowing movement in only one plane, enabling flexion and extension like a door hinge

ex of hinge joint

• Elbow: Articulation between the humerus and ulna.

• Knee: Between the femur and tibia (note: allows slight rotation when flexed).

• Ankle: Between the tibia/fibula and the talus.

• Interphalangeal Joints: Fingers and toes.

saddle joint

a highly flexible, biaxial synovial joint where one bone is concave and the other convex, fitting together like a rider on a saddle

ex of saddle joint

• Trapeziometacarpal Joint (Thumb): Connects the trapezium and the metacarpal of the thumb, allowing complex, opposable movements.

• Sternoclavicular Joint (Shoulder): Connects the sternum (breastbone) and clavicle (collarbone).

• Incudomalleolar Joint (Ear): Connects the incus and malleus, part of the ossicle chain

condyloid joint

a biaxial synovial joint featuring an oval-shaped condyle that fits into an elliptical cavity, allowing movement in two planes: flexion/extension and abduction/adduction

ex of condyloid joint

• Wrist (Radiocarpal joint): Between the radius and carpal bones.

• Knuckles (Metacarpophalangeal joints): Between the metacarpals and phalanges.

• Foot (Metatarsophalangeal joints): Between metatarsals and phalanges.

• Jaw (Temporomandibular joint): Although often considered a complex hinge, it functions as a condyloid joint.

• Head/Spine (Atlanto-occipital joint): Allows nodding,.

plane joint

a type of synovial joint with flat or slightly curved bone surfaces that permit limited, non-axial gliding movements

ex plane joint

• Acromioclavicular Joint: Connects the scapula to the clavicle.

• Intercarpal/Intertarsal Joints: Joints between the small bones of the wrist and ankle.

• Zygapophyseal Joints: The facet joints connecting vertebrae in the spine.

• Sternocostal Joints: Joints connecting the ribs and sternum.

• Sacroiliac Joint: Connects the sacrum to the pelvis.

ball socket joint

a type of synovial joint where a spherical bone end fits into a cup-like cavity, allowing multi-axial movement, including rotation, flexion, extension, abduction, and adduction

ball socket joint ex

hip and shoulder joints

tendons

attach muscle to bone

consist of tough connective tissue that is found on either side of the joint where two bones are connected

work with skeletal muscles to move bones

flexor muscle

muscle that causes a joint to bend

extension muscle

muscle that contracts and causes a joint to straighten

what happens when one of the flexor or extension muscles contracts

the other remains elongated.

ex of flexor and extension muscle

Biceps and triceps muscles in the arm work together to bend and lengthen the elbow. As a biceps muscle contracts, the triceps muscle remains elongated, or relaxed. Thus, the biceps is the flexor and the triceps is the extensor of the elbow joint.