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Structural Support and Movement
Chapter 36 Part 1
Impacts, Issues
Pumping Up Muscles
 Increasing muscle size and strength with drugs
such as “andro” has unwanted side effects and
can damage other organ systems
36.1 Invertebrate Skeletons
 Hydrostatic skeleton
• An enclosed fluid that contracting muscles act
upon (as in sea anemones, earthworms)
 Exoskeleton
• A hardened external skeleton found in some
mollusks and all arthropods
 Endoskeleton
• An internal skeleton, as in echinoderms
Hydrostatic Skeleton: Sea Anemone
mouth
gastrovascular
cavity; the
mouth can
close and trap
fluid inside
this cavity
Fig. 36-2a, p. 618
Animation: Hydrostatic skeleton
Hydrostatic Skeleton: Earthworm
Exoskeleton: Fly
thorax
longitudinal
muscle contracts
longitudinal
muscle relaxes
vertical muscle
relaxes
vertical muscle
contracts
A Wings pivot down as the
relaxation of vertical muscle and
the contraction of longitudinal
muscle pulls in sides of thorax.
B Wings pivot up when the
contraction of vertical muscle
and relaxation of longitudinal
muscle flattens the thorax.
Fig. 36-4, p. 619
Animation: Fly wing action
Exoskeleton: Spider
36.1 Key Concepts
Invertebrate Skeletons
 Contractile force exerted against a skeleton
moves animal bodies
 In many invertebrates a fluid-filled body cavity is
a hydrostatic skeleton
 Others have an exoskeleton of hard structures at
the body surface
 Still others have a hard internal skeleton, or
endoskeleton
36.2 The Vertebrate Endoskeleton
 All vertebrates have an endoskeleton
• Usually consists primarily of bones
• Supports the body, site of muscle attachment
• Protects the spinal cord
 The vertebral column (backbone) is made up of
individual vertebrae separated by
intervertebral disks made of cartilage
Axial and Appendicular Skeleton
 Axial skeleton
• Skull
• Vertebral column
• Ribs
 Appendicular skeleton
• Pectoral girdle
• Pelvic girdle
• Limbs
Skeletal Elements: Fish and Reptile
vertebral column
pectoral girdle
pelvic girdle
Fig. 36-7a, p. 620
vertebral
column
skull bones
rib cage
pelvic girdle
pectoral
girdle
Fig. 36-7b, p. 620
The Human Skeleton
 Some features of the human skeleton are
adaptations to upright posture and walking
• Foramen magnum at the base of the skull allows
brain and spinal cord to connect
• Vertebrae stacked one above the other in an S
curve
Bones of the Human Skeleton
A Skull bones
CRANIAL BONES
FACIAL BONES
D Pectoral girdle
and upper limb bones
CLAVICLE (collarbone)
B Rib cage
STERNUM (breastbone)
RIBS (twelve pairs)
C Vertebral column,
or backbone
VERTEBRAE
INTERVERTEBRAL
DISKS
SCAPULA (shoulder blade)
HUMERUS (upper arm bone)
RADIUS (forearm bone)
ULNA (forearm bone)
CARPALS (wrist bones)
1
2
3
54
METACARPALS
(palm bones)
PHALANGES
(thumb, finger
bones)
E Pelvic girdle and lower limb bones
PELVIC GIRDLE (six fused bones)
FEMUR (thighbone)
PATELLA (kneebone)
ligament bridging
a knee joint,
side view,
midsection
TIBIA (lower leg bone)
FIBULA (lower leg bone)
TARSALS (ankle bones)
METATARSALS (sole bones)
PHALANGES (toe bones)
Fig. 36-8, p. 621
Animation: Human skeletal system
36.3 Bone Structure and Function
 Bones have a variety of shapes and sizes
• Long bones (arms and legs)
• Flat bones (skull, ribs)
• Short bones (carpals)
 The human skeleton has 206 bones ranging
from tiny ear bones to the massive femur
Bone Anatomy
 Bones consist of three types of living cells in a
secreted extracellular matrix
• Osteoblasts build bones
• Osteocytes are mature osteoblasts
• Osteoclasts break down bone matrix
 Bone cavities contain bone marrow
• Red marrow in spongy bone forms blood cells
• Yellow marrow in long bones is mostly fat
Bone Anatomy: Long Bone
Fig. 36-9a, p. 622
space occupied
by living bone cell
blood
vessel
nutrient canal
location of
yellow marrow
compact
bone tissue
spongy
bone
tissue
55 µm
Fig. 36-9a, p. 622
Fig. 36-9b, p. 622
spongy
bone
tissue
compact
bone tissue
blood vessel
outer layer
of dense
connective tissue
Fig. 36-9b, p. 622
Animation: Structure of a femur
Bone Functions
Bone Formation and Remodeling
 The embryonic skeleton consists of cartilage
which is modeled into bone, grows until early
adulthood, and is constantly remodeled
 Bones and teeth store the body’s calcium
•
•
•
•
Calcitonin slows release of calcium from bones
Parathyroid hormone releases bone calcium
Sex hormones encourage bone building
Cortisol slows bone building
Long Bone Formation
Embryo:
cartilage model
of bone forms
Fetus:
blood vessel invades
model; osteoblasts start
producing bone tissue;
marrow cavity forms
Newborn:
remodeling and growth
continue; secondary
bone-forming centers
appear at knobby
ends of bone
Adult:
mature bone
Fig. 36-10, p. 623
About Osteoporosis
 Osteoporosis (“porous bones”)
• When more calcium is removed from bone than is
deposited, bone become brittle and break easily
 Proper diet and exercise help keep bones
healthy
Osteoporosis
36.4 Skeletal Joints—Where Bones Meet
 Joint
• Area of contact or near contact between bones
 Three types of joints
• Fibrous joints (teeth sockets): no movement
• Cartilaginous joints (vertebrae): little movement
• Synovial joints (knee): much movement
Synovial Joints
 In synovial joints, bones are separated by a fluidfilled cavity, padded with cartilage, and held
together by dense connective tissue (ligaments)
 Different synovial joints have different movements
• Ball-and-socket joints (shoulder)
• Gliding joints (wrist and ankles)
• Hinged joints (elbows and knees)
Three Types of Joints
Three Types of Joints
fibrous joint attaches
tooth to jawbone
synovial joint (ball and
socket) between humerus
and scapula
cartilaginous joint
between rib and sternum
cartilaginous joint
between adjacent
vertebrae
synovial joint (hinge type)
between humerus and
radius
synovial joint (ball and
socket) between pelvic
girdle and femur
Fig. 36-12a, p. 624
femur
patella
cartilage
ligaments
menisci
tibia
fibula
Fig. 36-12b, p. 624
36.5 Those Aching Joints
 We ask a lot of our joints when we engage in
sports, carry out repetitive tasks, or strap on a
pair of high heels
Joint Injuries and Diseases
 Common joint injuries
• Sprained ankle; torn cruciate ligaments in knee;
torn meniscus in knee; dislocations
 Arthritis (chronic inflammation)
• Osteoarthritis; rheumatoid arthritis; gout
 Bursitis (inflammation of a bursa)
36.2-36.5 Key Concepts
Vertebrate Skeletons
 Vertebrates have an endoskeleton of cartilage,
bone, or both
 Bones interact with muscles to move the body;
they also protect and support organs, and store
minerals
 Blood cells form in some bones
 A joint is a place where bones meet; there are
several kinds
36.6 Skeletal–Muscular Systems
 Muscle fibers
• Long, cylindrical cells with multiple nuclei that
hold contractile filaments
 Tendons attach skeletal muscle to bone
• Muscle contraction transmits force to bone and
makes it move
 Muscles and bones interact as a lever system
• Many skeletal muscles work in opposing pairs
Skeletal–Muscular Action
C The first muscle
group in the upper
hindlimb contracts
again and draws it
back toward body.
B An opposing muscle
group attached to the
limb forcefully contracts
and pulls it back. The
contractile force, applied
against the rock, now
propels the frog forward.
A A muscle attached
to each upper hindlimb
contracts and pulls it
slightly forward relative
to main body axis.
Fig. 36-14, p. 626
Opposing Muscle Groups
Triceps relaxes.
Biceps contracts at
the same time, and
pulls forelimb up.
Triceps
contracts,
pulls the
forelimb
down.
At the same
time, biceps
relaxes.
A When the triceps
relaxes and its
opposing partner
(biceps) contracts,
the elbow joint flexes
and the forearm is
pulled upward.
B When the triceps
contracts and the
biceps relaxes, the
forearm is extended
downward.
Fig. 36-15, p. 626
Animation: Opposing muscle action
Muscles and Tendons
Muscles and Tendons
TRICEPS BRACHII
Straightens the
forearm at elbow
PECTORALIS MAJOR
Draws the arm forward
and in toward the body
SERRATUS ANTERIOR
Draws shoulder blade
forward, helps raise arm,
assists in pushes
EXTERNAL OBLIQUE
Compresses the abdomen,
assists in lateral rotation of
the torso
RECTUS ABDOMINIS
Depresses the thoracic
(chest) cavity, compresses
the abdomen, bends the
backbone
ADDUCTOR LONGUS
Flexes, laterally rotates,
and draws the thighs
toward the body
SARTORIUS
Bends the thigh at the hip,
bends lower leg at the
knee, rotates the thigh in
an outward direction
QUADRICEPS FEMORIS
Set of four muscles that
flex the thigh at the hip,
extend the leg at knee
TIBIALIS ANTERIOR
Flexes the foot toward
the shin
BICEPS BRACHII
Bends the forearm
at the elbow
DELTOID
Raises the arm
TRAPEZIUS
Lifts the shoulder blade,
braces the shoulder,
draws the head back
LATISSIMUS DORSI
Rotates and draws the
arm backward and
toward the body
GLUTEUS MAXIMUS
Extends and rotates the
thigh outward when
walking, running, and
climbing
BICEPS FEMORIS
(Hamstring muscle)
Draws thigh backward,
bends the knee
GASTROCNEMIUS
Bends the lower leg at
the knee when walking,
extends the foot when
jumping
Achilles tendon
Fig. 36-16a, p. 627
muscle
tendon
bursae
synovial
cavity
Fig. 36-16b, p. 627
Animation: Human skeletal muscles
36.6 Key Concepts
The Muscle–Bone Partnership
 Skeletal muscles are bundles of muscle fibers
that interact with bones and with one another
 Some cause movements by working as pairs or
groups; others oppose or reverse the action of a
partner muscle
 Tendons attach skeletal muscles to bones
Animation: Long bone formation
Animation: Vertebrate skeletons