Musculoskeletal System
I. Anatomy and Physiology of the Musculoskeletal System
A.Components
1.Skeleton
2.Muscles
3.Ligaments – Connect bone to bone
4.Tendons – Connect muscle to bone
B.Function
1.Gives the body shape
2.Protects vital internal organs
3.Provides for body movement
C.Bone Structure
1.Diaphysis
a.The central portion (shaft) of the long bone.
b.Consists of a very dense and relatively thin layer of compact bone.
2.Epiphysis
a.The end of a long bone.
b.Much larger in diameter than the diaphysis.
3.Metaphysis
a.The intermediate region between the epiphysis and diaphysis.
b.The epiphyseal (or growth) plate is in this region.
D.Joint Structure
1.Types of Joints
a.Fibrous Joints
(1)Bones joined by fibrous tissue that have little or no movement.
(2)Example: the bones of the skull.
b.Cartilaginous Joints
(1)Bones joined by cartilage.
(2)Examples: the connection between the ribs and the sternum, and the symphysis pubis.
c.Synovial (Diarthrosis) Joints
(1)These joints contain synovial fluid (a thin, lubricating film).
(2)The synovial fluid is contained within the joint capsule (a sac-like structure that encloses the ends of bones).
(3)Types of Synovial Joints:
(a)Hinge – elbow and knee.
(b)Pivot – connection of C1 and C2.
(c)Condyloid (Gliding) – junction of the clavicle and sternum.
(d)Ball-and-socket – hip and shoulder.
2.Ligaments
a.Connective tissue that holds bones together at joints.
b.Are able to stretch and permit motion while holding the bone ends in position.
3.Bursa
a.A fluid-filled, pad-like sac usually found in the vicinity of joints.
b.It acts to reduce friction between tendons, ligaments, and bones that are in close proximity to each other.
4.Types of Motion
a.Flexion/extension
(1)Flexion – reduces the angle between the bones of a joint.
(2)Extension – increases the angle between the bones of a joint.
b.Abduction/adduction
(1)Abduction – movement away from the body.
(2)Adduction – movement towards the body.
C.Muscular Tissue
1.Cardiac
2.Smooth (Involuntary)
3.Skeletal (Voluntary) (also called striated muscle)
a.Sternocleidomastoid
b.Trapezius
c.Deltoid
d.Biceps
e.Triceps
f.Latissimus dorsae
g.Gluteus maximus
h.Hamstring group
i.Quadriceps group
D.Bones of the Skeleton
1.Skull - houses and protects the brain
a.Cranium
b.Face
(1)Mandible (jaw)
(2)Maxilla
(3)Zygomatic bones (cheeks)
(4)Nasal bone
(5)Orbit
2.Spinal Column – 33 vertebrae
a.Cervical (neck) - 7
b.Thoracic (upper back) - 12
c.Lumbar (lower back) - 5
d.Sacral (back wall of the pelvis) - 5
e.Coccyx (tailbone) - 4
3.Thorax
a.Ribs
(1)12 pair
(2)Attached posterior to the thoracic vertebrae.
(3)Pairs 1-10 are attached anterior to the sternum.
(4)Pairs 11 and 12 are floating.
b.Sternum (Breastbone)
(1)Manubrium (superior portion of sternum)
(2)Body (middle)
(3)Xiphoid process (inferior portion of sternum)
4.Pelvis
a.Ilium (top edge is the iliac crest)
b.Ischium (inferior portion of pelvis)
c.Pubis (anterior portion of pelvis)
d.Hip (hip joint)
(1)Acetabulum (socket of hip joint)
(2) Greater trochanter (or femur head)(sometimes called the “hip bone”)
5.Lower extremities
a.Femur (thigh)
b.Patella (kneecap)
c.Tibia (shin – larger bone of the lower leg)
d.Fibula (smaller bone of the lower leg)
e.Lateral Malleolus and Medial Malleolus - the surface landmarks of the ankle
f.Tarsals (bones in ankle)
g.Metatarsals (bones in foot)
h.Calcaneus (heel)
i.Phalanges (toes)
6.Upper extremities
a.Clavicle (collar bone)
b.Scapula (shoulder blade)
c.Acromion process (tip of shoulder)
d.Humerus (superior portion of upper extremity)
e.Olecranon (elbow)
f.Radius (lateral bone of forearm)
g.Ulna (medial bone of forearm)
h.Carpals (bones of wrist)
i.Metacarpals (bones of hand)
j.Phalanges (fingers)
7.Shoulder Girdle
a.Proximal portion of the upper extremity
b.Consists of three bones:
i.Clavicle
ii.Scapula
iii.Humerus
E.Joints
1.Where bones connect to other bones
2.Types
a.Ball and socket
b.Hinged
F.Muscles
1.Voluntary (skeletal)
a.Under conscious control of the brain via the nervous system. Can be contracted and relaxed by the will of the individual.
b.Attached to the bones.
c.Form the major muscle mass of the body.
d.Responsible for movement.
2.Involuntary (smooth)
a.Found in the walls of the tubular structures of the gastrointestinal tract, lungs,
blood vessels and urinary system.
b.Controls the flow through these structures.
c.Carry out the automatic muscular functions of the body.
d.Individuals have no direct control over these muscles.
e.Respond to stimuli such as stretching, heat, and cold.
3.Cardiac
a.Found only in the heart.
b.A specialized form of involuntary muscle.
c.Has its own supply of blood through the coronary artery system and can
tolerate interruption of blood supply for only very short periods.
d.Automaticity – has the ability to generate and conduct its own electrical
impulses so it is able to contract on its own.