Download musculoskeletal system

MUSCULOSKELETAL SYSTEM
SKELETAL SYSTEM
Read pages 159-165 and stop before you get to the skeletal muscles section; we’ll do that
next time. However, you should be able to answer questions 1-6 on the last page of the
lab today. Don’t turn in this lab until after we finish the muscles, and just turn in the
whole chapter at once.
A long bone has a DIAPHYSIS (the long part) which contains COMPACT BONE.
The heads of a long bone are called the EPIPHYSIS and contains SPONGY BONE,
which is red bone marrow (where red blood cells are made). There is a tough connective
tissue covering the entire bone called the PERIOSTEUM, which has nerves and blood
vessels that supply the oxygen to the bone cells (OSTEOCYTES). HYALINE
CARTILAGE is where two bones articulate (touch each other); this area is smooth to
decrease the friction. The MEDULLARY CAVITY is the hollow part inside a long bone
and contains yellow marrow, which is mostly fat.
The human skeleton is divided into these two regions:
AXIAL SKELETON
1. Skull (with skull bones, and the maxilla and mandible)
2. Vertebral column (with cervical, thoracic, lumbar, and sacral vertebrae, and
the coccyx) sternum, true ribs, false ribs, and floating ribs). When someone
has a hunchback, it is called KYPHOSIS. When they have a swayback (lower
back is swayed so the buttocks sticks out) it is called LORDOSIS.
APPENDICULAR SKELETON
1. Pectoral girdle (clavicle and scapula)
2. Upper limb (humerus, radius, ulna, carpals, metacarpals, phalanges)
3. Pelvic girdle (hip bones)
4. Lower limb (femur, patella, tibia, fibula, tarsals, metatarsals, phalanges)
NOTE: The LEG is below the knee only. Above the knee it is called the THIGH.
The ARM is above the elbow only. Below the elbow it is the FOREARM.
Look at the bones.
MUSCULAR SYSTEM
Finish reading the rest of the lab and answer all the questions. We are not doing the
experiment on page 171, but read it because you will need to understand it to answer
questions 10 and 16 on the last page.
Muscles are named according to one of the following characteristics:
1. size (GLUTEUS MAXIMUS is the largest muscle)
2. shape (DELTOID) is triangle shaped like the Greek letter delta.
3. direction of fibers (RECTUS means “straight”)
4. location (FRONTALIS is in front of the frontal bone of the forehead)
5. number of attachments (BICEPS means there are two heads)
6. action (EXTENSOR DIGITORUM extends the digits)
MOVEMENTS OF MUSCLES
FLEXION: reducing the angel of the joint
EXTENSION: increasing the angel of the joint
ADDUCTION: moving a body part towards the midline
ABDUCTION: moving a body part away from the midline
ROTATION: moving a body part around its own axis
CIRCUMDUCTION: moving a body part in a circle
This is the list of muscles to identify and the functions you need to know for the exam:
ANTERIOR VIEW
FRONTALIS (moves eyebrows)
ORBICULARIS OCULI (blinks eyes)
ORBICULARIS ORIS (moves mouth)
ZYGOMATICUS (smile muscle)
MASSETER (for chewing)
PECTORALIS (pulls arm across chest)
DELTOID (abducts arm)
BICEPS BRACHII (flexes forearm)
RECTUS ABDOMINUS (abdominal muscles)
QUADRICEPS FEMORIS (flexes hips and extends the legs)
TIBIALIS ANTERIOR (shin splint muscle)
POSTERIOR VIEW
TRAPEZIUS (shrugs shoulders)
LATISSIMUS DORSI (pulls arm across back)
TRICEPS BRACHII (extends forearm)
EXTENSOR DIGITORUM (extends fingers)
GLUTEUS MAXIMUS (extends thigh, forms the buttocks)
HAMSTRINGS (flexes leg and extends hip)
GASTROCNEMIUS (flexes leg and foot as in tip-toeing)
ACHILLES TENDON
MUSCLE CONTRACTION
ISOTONIC contraction is when a muscle contracts when you are not lifting a load.
ISOMETRIC contraction is when a muscle contracts and SHORTENS when you are
either lifting a load or are trying to, such as when you lift an object that is too heavy to
move. Your muscle will become MORE FIRM as it contracts.
Skeletal muscles are STRIATED, meaning that they have dark and light bands. These
bands are two kinds of PROTEINS called ACTIN and MYOSIN. When a muscle
contracts, these two protein strands slide toward each other, causing the muscle to
shorten.
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
ACTIN
MYOSIN
ACTIN
They form repeating patterns, giving the striped appearance of skeletal muscle (striated).
When a muscle contract, the actin and myosin move but neither one shortens; the entire
muscle fiber is what shortens.
NOTE
Be able to identify the muscles from a body builder photo, because that’s actually where
you will be seeing muscles in real life. The photos are on the exam.