Skeletal System
Osteology – the study/science of bones
Human Skeleton
• comprised of approximately 206 bones
• at birth approximate 270
• change due to fusion of separate bones during early growth
• divided into axial and appendicular
Axial
• skull 22 bones
• ear ossicles 6
• vertebrae 26
• hyoid 1
• rib cage 25
Appendicular
• pectoral girdle 4 bones
• upper extremities 60
• pelvic girdle 2
• lower extremities 60
**overhead and hand-out skeletal system
Functions of the Skeleton
• five functions of the human skeleton
1.
Support
•forms rigid framework to which the softer tissues and
organs of the body are attached
2.
Protection
•skull and vertebral column enclose central nervous system
(CNS)
•rib cage protects heart, lungs, liver spleen
•pelvic girdle protects pelvic viscera
•even RBC production factory protected within each
individual bone
1.
Body Movement
•serve as anchoring attachments for most skeletal muscles
•act as levers
2.
Hemopoiesis
•red bone marrow produces WBC, RBC, and platelets
•approximately 1,000,000 red blood cells/second produced
here
3.
Mineral Storage
•primarily calcium and phosphorus
•95% of these minerals found in bones and teeth
 Calcium
•important in muscle contraction
•blood clotting
•ion movement across the cell
 Phosphorus
•activities of nucleic acids (DNA/RNA)
•ATP utilization
AXIAL SKELETON
SKULL
• 8 bones
• joined rigidly
• protect brain and sense organs
FACIAL BONES
• framework for facial regoin and support of teeth
HYOID BONE
• supports tongue, and assists in swallowing
EAR OSSICLES (malleus, incus and stapes)
• transfer and amplify sound impulses to middle ear
VERTEBRAE (vertebral column)
• 26 vertebrae
• enclose and protect spinal cord
• support and permit movement of skull
• provide attachment for trunk muscles
RIB CAGE
• directly involved in mechanics of breathing
• protect vital organs
APPENDICULAR SKELETON
PECTORAL GIRDLE
Clavicle and Scapula
• serves as attachment for numerous muscles involved in
movement of arms
BRACHIUM
Humerous
• anatomically defined as the upper arm
• humerous is the only bone
FOREARM
Ulna and raduis
• ulna is the larger of the two bones in lower arm
• radius is the small bone, it is located on the thumb side and is
responsible for articulation of arm and wrist
WRIST AND HAND
• 27 bones
Carpus
• heel of hand
Metacarpus
• flat of hand
Phalanges
• fingers
PELVIC GIRDLE
Os coxae and symphysis pubis
• support weight of upper body
• protects and supports urinary bladder, reproductive organs,
and developing fetus
• shape of girdle differs in sexes
THIGH
Femur
• femur is the only lone bone in the thigh
• longest, heaviest and strongest bone in the body
• major center for blood cell production and mineral storage
Patella
• protects the knee joint
• also referred to as the “knee cap”
LOWER LEG
Tibia
• larger of the two bones in the lower leg
• found on medial side of the leg
• bears weight of the entire body
Fibula
• small of the two lower leg bones
• important for muscle attachment as opposed to support
Ankle
• 26 bones
Tarsus
• heel of the foot
Metarsus
• arch of the foot
Phalanges
• toes and distal flat portion of the foot
JOINTS
• The extent and type of movement determine the name applied to
a joint. Bone structure limits the kind and amount of movement in
each joint. Some joints are very limited whereas others have a
variety of movement ranges.
articulate
• the interaction between two or more bones, i.e. Bones moving
together
flexibility
• elasticity of the muscle tissue and tissue surrounding joints
Types of Joints
1. diarthrotic joints (majority of joints in the body)
2. suture joints (found in skull and pelvic area)
3. disc joints (found in vertebral column)
DIARTHROTIC JOINT GROUPS
Gliding Joint
• two plane or flat bony surfaces that butt against each other,
permitting limited gliding movement
• e.g. Carpal bones of the wrist
Biaxial Ball and Socket Joints
• the bones permit movement in two planes, without rotation
• e.g. Wrist between the radius and the proximal row of the carpal
bones
Multiaxial Ball and Socket Joints
• permits movement in all planes
• e.g. Shoulder and hip joints
Hinge Joints
• permits a wide range of movement in only one place
• e.g. Elbow, ankle, knee joints
Saddle Joint
• reciprocal reception is found only in the thumb at the
carpometacarpal joint and permits ball and socket movements with
the exception of rotation
Pivot Joint
• rotational movement around the long axis 18
• e.g. Rotation (pronation/suppination) of the radius at the radiolnar
joint
See page for handout
Joint Disorders
Injuries
• dislocation
• hyperextension
• capsule tears
• ligament tear
• bone fracture
• meniscus or cartilage damage
Osteomylithis
• infection due to bacteria or virus following an injury
Osteoarthritis
• due to aging/irritation, abrasion
• no known cure
Rheumatoid Arthritis
• sever pain
• affects women 3:1 over men
• synovial membrane becomes swollen and inflamed
• deformity → cartillage turns to calcium deposit
Demineralization
• due to lack of Vitamin D, aging and hormonal changes
• astronauts often obtain this disorder
Gout
• usually in the feet, especially big toe
Muscular System
Myology
• the science/study of muscles
Muscles
• contract when stimulated by electrical impulses
• only have power when contracting → cannot push
Functions of the Muscular System
• three functions of the muscular system
1.
•
•
•
•
Motion
skeletal movement
breathing
movement of body fluids
cardiac movement moves blood
2. Heat Production
• muscles constitute approximately 40% of the body’s weight
• the continuous fiber activity is important in producing heat in the body
3.
•
•
•
Posture and Support
maintain posture/offer support around joints
certain skeletal muscles even work without really knowing it
e.g. neck/head
 all muscles are:
• irritable → respond to stimulus
• contractible → works by shortening
• extensible → can be returned by opposing force
• elastic → can be stretched and returned to original length
 Over 600 skeletal muscles in the body (most are paired)
• the names suggest where the muscle is located
TYPES OF MUSCLES
I. Smooth Muscle
• involuntary, include blood vessels, intestines and lungs
II. Striated/Skeletal Muscle
• responsible for the voluntary movement of the body
III. Cardiac Muscle
• only one in body, the heart
Muscle System Actions
Origin – where the muscle meets the bone that doesn’t move
Insertion – where the muscle meets the bone that moves
Flexors – muscle that bends joints pulls limbs towards body
Extensors – straighten joints
Agonist – prime mover → initiates the action
Antagonist – relaxes or yields to agonist muscle
Synergists – fixators → hold limb/joint steady during the action
Hand-out diagrams of Muscle Types
FACIAL
Frontalis → over frontal bone (eyebrow movement)
Orbicularis occuli → surrounds the eyes (blinking)
Masseter → opens mouth
Temporalis → closes mouth
Zygomaticus → elevates the corner of the mouth (smiling)
Sternocleidomastoid → turns head
ABDOMINAL
External oblique, rectus abdominus, internal oblique, transverse
abdominus
• aid in breathing, defecation, and stabilize spine while lifting
PECTORAL GIRDLE
 Front
Pectoralis major → adduct, flexes and rotates the brachium medially
Serratus anterior → pulls scapula forward and down
 Back
Trapezius
→ adducts, elevates scapula
→ hyperextends the head
Latissimus dorsi →adducts arm, drawing it downward and back ward
 Brachia and Forearm
Deltoid →abduct, extend and flex brachium
Bicep brachi → two heads, flexes forearm
Brachialis → works with bicep to flex forearm
Brachioradialis → flexes forearm
Tricep brachi → three heads, extends forearm
 Legs
Gracilis, adductor longus, adductor magnus → adduct thigh and flex
leg
Sartorius → longest muscle in the body
→crosses legs
Quadricep femoris → four muscles in this group
→ rectus femoris, vastus lateralis, vastus medialis,
vastusintermedius
→ extend legs
Hamstrings
→ three muscles in this group
→ bicep femoris, semitendinosus, semimembranosus
→ flexion of leg at the knee
Tibialis anterior → dorsi flexes the foot
Peroneous Longus → plantar flexes the foot and eversion of foot
Gastrocnemius → flexes knee, plantar flexes foot
Soleus → plantar flexion of the foot
• Textbook
• p.40 Sliding Theory of Muscle Contraction
• p.41 Diagrams – reproduce and understand
• p.43 Reproduce
Sliding Filament Theory of Contraction
• stimulated muscle contracts as a result of the shortening of its
individual fibres
• shortening of these fibres is accomplished in turn by the shortening
of their own myofbrils
 which is actually the shortening of distance between “z” lines
• the thick myosin and thin actin filaments remain the same length
during contraction
→ instead, the think “slide” over the thick
MUSCLE TISSUE STRUCTURE
Epimysium – a fibrous outer sheath of connective tissue surrounding a skeletal
muscle
Perimysium – fascia (connective tissue) surrounding a bundle of muscle fibres
Endomysium – the connective tissue sheath the surrounds each skeletal muscle
fibre, separating the muscle cell from one another
Fasciculi – a small bundle of muscles or nerve fibres
MUSCLE CELL STRUCTURE
Sarcolemma – the cell membrane of a muscle fibre
Sarcoplasm – the cytoplasm within a muscle fibre
Myofibrils – a bundle of contractile fibres within a muscle cell (thick and thin)
SARCOMERE STRUCTURE
Sarcomere – the portion of a striated muscle fibre between the two adjacent “Z”
lines that is considered the functional unit of a myofibril
Myosin – “A” band – contain thick myofibrils – dark in appearance
Actin – “I” band – contain thin myofibrils – light in appearance
Z line – thin, dark center of each i-band. Basic sub-unit of striated muscle
contraction
Cross-bridge – sliding of the myofibrils produced by the action of cross-bridges that
extend from the myosin toward the actin
• pull actin from each side toward the middle of the cell
• extend from the axis of the thick myofilaments to form “arms” that terminate in
globular heads
Isotonic Contraction – the force of contraction remains relatively constant
throughout the shortening process
CIRCULATORY SYSTEM
Three functions of the circulatory system
1.
•
•
•
Transport
respiratory – O2 and CO2
nutritional – absorbs products through liver
excretory – waste processed through kidneys
2. Regulation
• hormones carried to target tissues
3. Protection
• clotting mechanisms
• leukocytes (WBC) attack disease
HEART
• four-chambered, muscular organ
• located in chest with 2/3 of the heart left of the midline with the
point downward
• upper right and left atria contract simultaneously and empty into
ventricles
• lower right and left ventricles also contract in synch to empty heart
Right Atrium
• collects venous blood from superior vena cava (upper body) and
inferior vena cava (lower body)
Left Atrium
• received oxygenated blood from lungs through pulmonary veins
(two from each lung)
Right Ventricle
• right atrial blood enters via tricuspid and is pumped to lungs
through pulmonary arteries
Left Ventricle
• blood from left atrium enters via bicuspid valve
• O2 blood leaves here via ascending aorta
Cardiac Cycle
contraction phase – systole, the “lub”
relaxation phase – diastole, the “dub”
 3/8 of time is spend in the “dub” phase
 above applies to ventricles, opposite is true for atrial systole and
diastole
Blood Vessels
• blood leaving heart passes through vessels
• these vessels diminish in size as they go
• arteries-arterioles-capillaries
Arteries
• very elastic – stretch with the hearts contraction
• carry oxygen rich blood
Capillaries
• “functional units” of the circulatory system
• gas and nutrient exchange takes place here
Veins
• low pressure is insufficient to return blood to heart without venous
valves
Venules
• performs similar function as capillaries
Cardiac Output
• measured in mL/min.=stroke vol/mL/beat X cardiac rat (beats/min)
• average stroke volume=70-80mL/beat
• average cardiac rate= 70 beats/min
RESPIRATORY SYSTEM
• Three functions of the respiratory system are all similar
1. Ventilation
• breathing
2. Gas exchange
• oxygen and carbon dioxide transfer in lungs
3. O2 utilization
Major Passages
Nasal Cavity – Nose
• warms, moistens and cleans air
• highly vascular, large surface area
• also contains olfactory cells
• provides sound resonance when speaking
Pharynx
• connects nasal cavity with larynx at the base of skull
• has both respiratory and digestive functions
Larynx
• connects to trachea
• prevents food and liquid from entering lungs
• permits air passage
Trachea (windpipe)
• connects larynx to primary bronchi
Bronchial Tree
• gas exchange passages branch apart like branches of a tree
Lungs
• hold air for gas exchange
• house the bronchi etc.
Alveoli
• functional units of respiration
• gas exchange takes place here
• enormous surface area