Anatomy - Ch 10 Muscle Gross Anatomy

movement, stability, control of openings, heat production, and glycemic control

muscle functions include what?

moving from place to place; moving body parts; moving body contents in breathing, circulation, and digestion; in communication it is used for speech, writing, facial expression, and other nonverbal communications

examples of movement in muscles

maintain posture by preventing unwanted movements; antigravity muscles that prevent us from falling over; stabilizes joints by maintaining tension

examples of stability in muscles

the sphincters are internal muscular rings that control the movement of food, blood, and other materials within the body

examples of muscles controlling openings and passageways

they produce as much as 85% of our body heat; they are burning through ATP because of sodium potassium pumps and thick and thin filaments that slide past each other generate frictional heat

example of heat production by skeletal muscles

glycemic control

muscles absorb and store glucose which helps regulate blood sugar concentration within the normal range

600

about how many human skeletal muscles?

about half

how much of our body weight do muscles constitute?

skeletal, cardiac, smooth

what are the three kinds of muscle tissue?

converting the chemical energy in ATP into the mechanical energy of motion

what is the one major purpose muscles are specialized for?

myology

the study of the muscular system

sarcomeres

the unit that takes chemical energy and converts it into mechanical force

epimysium

the fibrous sheath surrounding the entire muscle; the outer surface grades into the fascia and the inner surface projections form the perimysium

fascia

the sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue

similarities: both are made of lots of collagen fibers; differences: the fascia connects muscle to bone while the epimysium holds the muscle together; the epimysium is much thinner than the fascia

what are the similarities and differences between the epimysium and the fascia?

endomysium

the thin sleeve of loose connective tissue around each fiber that insulates them; it allows room for capillaries and nerve fibers; it provides the chemical environment for muscle fiber

there would be problems with contraction since it is important for partial activation of skeletal muscle

what would happen if there was no endomysium?

perimysium

the thick layer of connective tissue that wraps fascicles; carries nerves, blood vessels, and stretch receptors

fascicles

bundles of muscle fibers wrapped together

yes

are all individual muscle cells electrically active?

the orientation of its fascicles

what is the strength of a muscle and the direction of its pull partly determined by?

fusiform muscles

muscles that are thick in the middle and tapered at each end; examples include the biceps brachii and triceps brachii

parallel muscles

muscles that have uniform width and parallel fascicles; examples include rectus abdominis and transverse abdominis

triangular (convergent) muscles

muscles that are broad at one end and narrow at the other; example is the deltoid

pennate muscles

feather shaped muscles; one big band of connective tissue with muscle fibers attached to it

unipennate

fascicles approach tendon from one side

bipennate

fascicles approach tendon from both sides

multipennate

bunches of feathers converge to a single point

circular muscles (sphincters)

form rings around body openings; example is orbicularis oculi

muscle compartment

a group of functionally related muscles enclosed by fascia ; also contains nerves and blood vessels that supply the muscle group

intermuscular septa

very thick fascia that separate one compartment from another

they isolate muscles so pathogens have a difficult time spreading; they efficiently group muscle nerves and blood vessels; they allow for better activation of muscle; group muscles with similar functions together

what is the purpose of muscle compartments?

tendons

example of indirect attachment to bone

tendons

connect muscle to bone

the collagen fibers of the endo-, peri-, and epimysium continue into the tendon and from there into the periosteum and matrix of bone; collagen fibers of the tendon merge with the collagen of the periosteum and the tendon is embedded in compact bone tissue

how does a tendon connect?

aponeurosis

tendon is a broad, flat sheet of connective tissue (large sheet of collagen that multiple muscles are anchored to)

retinaculum

connective tissue band that tendons from separate muscles pass under; makes sure movement of muscles and tendons past each other does not cause inflammation

direct (fleshy) attachment

attachment to bone in which there is little separation between the muscle and bone; the muscle seems to emerge directly from the bone; flat bones have lots of these attachments associated with them

some muscles attach on the fascia or tendon of another muscle or on collagen fibers of the dermis; example is many facial muscles attach to the skin

what is another place muscles attach besides to the bone?

origin

closer to heart

insertion

farther from heart

intrinsic muscle

entirely contained within a region, such as the hand so the muscle performs the action where it is located; examples are the flexor digitorum brevis and the muscles of the abdomen

extrinsic muscle

acts on a designated region, but has one attachment elsewhere so they send their force of contraction to a different part of the body; examples include the muscles of the forearm that help the wrist and hand move

action

effect produced by a muscle to produce or prevent movement

prime mover, synergist, antagonist, and fixator

what are the four categories of muscle action?

prime mover (agonist)

muscle that produces most of the force during a particular joint action

synergist

muscle that aids the primer mover; it may contribute additional force, modify the direction of the movement, or stabilize a nearby joint

antagonist

opposes the primary mover; prevents excessive movement; sometimes relaxes to give prime mover control over an action

antagonistic pairs

muscles that act on opposite sides of a joint; example: triceps brachii and biceps brachii

fixator

muscle that prevents movement of bone and keeps bones stable (built in shock absorber); examples: wrist and ankle (between the carpals and tarsals)

innervation of a muscle

refers to the identity of the nerve that stimulates it

enables diagnosis of nerve, spinal cord, and brainstem injuries from muscle tests

what does knowing innervation help us do?

they arise from the spinal cord; they emerge through intervertebral foramina and then immediately branch into posterior and anterior rami; they innervate the muscles below the neck

where do spinal nerves arise from?

plexus

web-like network of spinal nerves adjacent to the vertebral column

cranial nerves

these nerves arise from the base of the brain; they emerge through skull foramina and innervate the muscles of the head and neck

12; numbered CN 1 to CN XII

how many cranial nerves are there and how are they numbered?

about 1.24 L of blood per minute at rest which is one-quarter of the blood pumped by the heart

muscular system receives how much blood?

three-quarters

during heavy exercise, total cardiac output rises and the muscular system’s share is more than what amount of the blood supply?

endomysium

capillaries branch extensively through what to reach every muscle fiber?

latin names; or can describe distinctive aspects of the structure, location, or action of a muscle

how are muscles named?