Exam 2 Flashcards
When does the most significant growth if the skull occur
Age 5
The brain is 90-95% developed by nos
Appendicular skeleton
Bones of the upper and lower limbs
2) Bones that hold the limbs to the trunk of the body (pectoral girdle and pelvic
girdle)
Epicondyle
Projection adjacent to a Condyle
epiphyseal growth plate” is located in growing children and teenagers
(a) This growth plate is composed of hyaline cartilage and has intense mitotic activity
that helps bones increase in length.
(b) This mitotic activity is controlled by human growth hormone produced by the
pituitary gland located at the base of the brain.
(c) Fracture of a long bone in a growing child is especially serious if it results in
displacement of an epiphyseal growth plate. Such fractures can lead to a failure of the
damaged bone to elongate properly and a permanent shortening of the injured limb!
(d) In an adult when bone growth is completed the epiphyseal growth plate ceases its
activity and ossification occurs between the epiphysis and the diaphysis. The only
remnant is a defined area of compact bone called the “epiphyseal line”.
Outer ring of Fibrocartilage of intervertebral discs
Anulus fibrosus
TMJ movements
1) Depression and elevation of the lower jaw as a hinge joint.
2) Protraction and retraction of the lower jaw as a gliding joint.
3) Side-to-side lateral movements to grind food between the teeth as a gliding joint.
Compound (open)
Broken ends of bone protrude through the skin
Inversion
the movement of the sole (plantar surface) of the foot inward or
medially.
4 spinal curves
Cervical curve
Thoracic curve
Lumbar curve
Sacral curvature
Supination
occurs when the forearm rotates laterally so that the palm faces anteriorly or superiorly. In the anatomic position, the forearm is supinated and the radius and ulna are parallel
Crest
Narrow, prominent, ridge like projection
Lateral flexion
(d) “Lateral flexion” occurs when the trunk of the body moves in a coronal plane away
from the body.
- This type of movement occurs primarily between the vertebrae in the cervical
and lumbar regions of the vertebral column.
Condyloid joints
are biaxial joints with an oval, convex surface on one bone that articulates with a concave articular surface on the second bone of the joint.
(a) A good example are the metacarpophalangeal joints (commonly referred to as
“knuckles”) where fingers #2-#5 attach to the palm.
- Examine the metacarpophalangeal joint at the base of your finger #2 as an
example. You will note that it can flex and extend (one axis of movement) and
move side-to-side (second axis of movement).
(b) Another example is the radiocarpal joint were the distal end of the radius articulates
with the carpals.
3 types of fibrous joints
Gomphoses
Sutures
Syndesmoses
Alveolus
Deep pit or socket in the maxillae or mandible
Protraction
is the movement of a body part anteriorly in a horizontal plane.
- Examples are a jaw thrust, hunching the shoulders anteriorly, or moving the pectoral girdle forward (pelvic thrust).
Sutures
immoveable fibrous joints (synarthroses) that are
found only between certain bones of the skull.
1) Sutures form at about 15-24 months of age and replace the flexible fontanels of an
infant’s skull.
Rotational motion
pivoting motion in which a bone turns on its own
longitudinal axis (See Fig. at bottom of page 263).
(a) An example is turning the head from side to side (a “no” motion”) by rotation at the
atlantoaxial joint
Saddle joints
are biaxial joints that have a concave surface in one direction and
a convex surface in another. One is shaped like a saddle and the other is shaped like a rider sitting in the saddle.
(a) This arrangement allows a greater range of movement than either a condyloid or
hinge joint.
(b) The articulation of one of the carpal bones of the wrist (trapezium) with metacarpal
bone #1 in the meaty portion of the thumb forms the first carpometacarpal joint, which is a saddle joint.
- This joint permits the thumb to move toward the other fingers (opposable thumb)
so we can grasp objects.
- Having such opposable thumbs is most useful for grasping objects.
Step to bone healing
1) A “fracture hematoma” forms when blood vessels inside the bone and in the
periosteum are torn.
2) The traumatized area is cleaned up by phagocytic blood cells and by osteoclasts
that resorb the bone fragments. A soft “fibrocartilage callus” forms to bridge the
gap of the injured bones.
3) Osteoblasts begin ossifying the cartilage and soon a hard “bony callus” forms in
the injured area.
4) The final step is remodeling of the injured area. The excess callus is broken down,
a new vascular system is established, and compact bone develops around the periphery of the fracture.
Depressions, grooves, and tunnels
Blood vessels and nerves
Spongy (cancellous) bone
- This type of bone appears more porous, like a sponge.
- In a long bone, spongy bone is found primarily within epiphyses (See Fig. on
page 151). - In many of the flat bones of the skull there is spongy bone sandwiched between
two layers of compact bone. The spongy bone in this arrangement is referred to as “diploe” (See Fig. 6.7 on page 154). A blow to the head may fracture the outer compact layer of bone without harming the inner compact layer and the underlying brain. The central layer of spongy (cancellous) bone helps to distribute stresses and forces.
3 arches of the foot
(a) Medial longitudinal arch
(b) Lateral longitudinal arch
(c) Transverse arch
Sternoclavicular joint
a. The “sternoclavicular joint” is considered by your authors to be a saddle joint.
1) Some references agree that it is a saddle joint and some say it is a gliding joint.
b. The sternoclavicular joint is the articulation between the clavicle (collar bone) and the manubrium of the sternum.
c. An articular disc partitions the sternoclavicular joint into two parts and creates two separate synovial joint cavities.
d. A wide range of movements is possible: elevation, depression, and circumduction.
e. Support and stability are provided by the fibers of the articular capsule and by
reinforcing ligaments.
f. While dislocation of this joint is possible, typically when a person falls on an
outstretched hand the clavicle fractures before the joint dislocates.
Tempomandibular joint
The “temporomandibular joint” is the articulation formed at the point where the mandibular condyle of the lower jaw articulates with the mandibular fossa of the temporal bone.
1) This small, complex articulation located just anterior to the opening of the ear is
the only movable joint between skull bones.
Sulcus
Narrow groove
Third division nerve block
The mandibular teeth and gums can be desensitized by an injection of anesthetic near the mandibular foramen
Endochondral ossification
1) This is how the majority of the skeleton (the bones of the upper and lower limbs, the pelvis, the vertebrae, and the ends of the clavicles) develops.
Avulsion
Bone or bone fragments accompany soft tissues as it is pulled from its origin or insertion
Abduction
which means to “move away”, is a lateral movement of the body part away from the body midline.
- Examples are moving the leg or arm away from the midline of the torso or
spreading the fingers away from the midline of the hand.
Fibrous joints
Immoveable or slightly moveable
Lack a joint cavity
Purpose of skeletal system
form an internal framework to support soft tissues, protect vital organs, bear the weight of the body, and help us move
Planar (gliding) joints
are the simplest synovial articulations and are the least moveable type of diarthroses.
(a) They are uniaxial because they only allow side-to-side movements and the articular
surfaces are flat (planar). (b) Examples are:
- Intercarpal joints
- Intertarsal joints
- Joints between the articulating processes of adjacent vertebrae. Note that the
spine employs cartilaginous symphyses and synovial gliding joints!
Axial skeleton
The axial skeleton, which is composed of bones along the central axis of the body (See Fig. on page 174).
1) Skull and bones associated with the skull (auditory ossicles and hyoid bone) 2) Vertebral column
3) Rib cage (thoracic cage)
When does the squamoussal suture
By 60’s and might not ever ossify
2 types of ossification
Intramembranous
Endochondral
Trochanter
Massive, rough projection found only on the femur
Syndesmoses
Amphiarthroses
Between the shafts of the ulna and radius and between the tibia and fibula
Joined together by inter osseous membrane
Oblique
Diagonal fracture at an angle between linear and transverse
Arthrology
The study of joints
Pronation
the medial rotation of the forearm so that the palm of the hand is directed posteriorly or inferiorly. The radius and ulna are crossed to form an “x”
Common diarthotic synovial joints
shoulder (glenohumeral), jaw (temporomandibular), elbow, and knee (tibiofemoral).
Compact bone
- As its name implies, compact bone is solid and relatively dense.
- In a long bone, compact bone forms the solid external walls of the bone.
- In many of the flat bones of the skull compact bone forms both an inner and outer
layer
Line
Low ridge
Extension
which is the opposite of flexion, is movement in an anterior-posterior
plane that increases the angle between the bones.
- Examples are straightening the elbow, straightening of the knee, straightening the
fingers, or extending the neck so it is straight up.
- Extension typically returns a body part to the anatomical position.
Bones the develop by intramembranous ossification
flat bones of the skull, some of the facial bones (zygomatic bone, maxilla, and mandible), the central part of the clavicle (collarbone), and sesamoid bones (i.e.-kneecap)
Hollow paranasal sinuses
1) Sphenoidal 2) Maxillary 3) Frontal
4) Ethmoidal
Where does the glenohumeral joint get its strength
Rotator cuff
Head
Prominent, rounded epiphysis
Epiphyseal
Epiphysis is separated from the diaphysis at the Epiphyseal plate
Effects of hormones
a. Several hormones either directly, or indirectly, influence bone growth. A few will be discussed here.
1) “Growth hormone” (somatotropin) is produced by the anterior portion of the
pituitary gland and stimulates the activity of the epiphyseal growth plates.
2) Sex hormones (estrogen and testosterone), which begin to be secreted in great
amounts at puberty, dramatically accelerate bone growth at the epiphyseal growth
plates.
Depressed
Broken part of the bone forms a concavity (as in skull fracture)
Radiocarpal
a. The “radiocarpal articulation” is also called the “carpus”.
1) Three proximal carpal bones interface with the distal articular surface of the
radius to form the raiocarpal articulation.
2) A fibrocartilaginous articular disc separates the ulna from the radiocarpal joint,
which is why the ulna is not considered part of this joint.
Crepitus
Fracture of the maxillary sinus, a cracking sound caused by escaping air under the skin
Anatomic features of the TMJ
1) A loose “articular capsule” surrounds the joint and promotes an extensive range of motion.
(a) Consequently, the TMJ is poorly stabilized and thus a forceful anterior or lateral blow to the mandible can result in partial or complete dislocation of the lower jaw.
2) The TMJ contains an “articular disc”, which is a thick pad of fibrocartilage separating the articulating bones and extending horizontally to divide the synovial cavity into two separate chambers.
(a) As a result, the TMJ is really two synovial joints: one between the temporal bone and
the articular disc and a second between the articular disc and the mandible.
Impacted
One fragment of bone is firmly driven into the other
Synovial joints
Diarthotic, very mobile
Joints are separated by joint capsule
Classification of joints
Structure and function
Osteoblasts
secrete the initial semisolid form of bone matrix, called “osteoid”. This osteoid later calcifies and becomes bone. Once osteoblasts become entrapped in the matrix they produce and secrete, they differentiate into osteocytes
Fracture
Cracking of the bone
Fracture hematoma
blood vessels inside the bone and in the
periosteum are torn.
Inner core of intervertebral discs
Nucleus pulposus
Comminuted
Bone is splintered into several small pieces between the main parts
Displaced
Fractured bone parts are out of anatomic alignment
Aging of the skeletal system
- the tensile strength of bone decreases due to a reduced rate of protein synthesis that results in decreased ability to produce the organic of bone matrix.
1) Consequently, the percentage of inorganic minerals in the bone matrix increases,
and the bones of the skeleton become brittle and susceptible to fracture. - bone loses calcium and other minerals (demineralization).
1) The bones of the skeleton become thinner and weaker, resulting in insufficient ossification, a condition called “osteopenia”.
2) Aging causes all people to become slightly osteopenic
Cartilaginous joints
Lack a joint activity
Synchondroses
Symphyses
Gomphoses
- peg in socket
- only roots of teeth in socket
- held by periodontal ligament
- classified as synarthrosis
Functional joints
(a) “Synarthroses”, which are immovable joints.
(b) “Amphiarthroses”, which are slightly moveable joints. (
c) “Diarthroses”, which are freely moveable joints
Condyle
Large, smooth, rounded articulating oval structure
Process
Any marked bony prominence
Ball and socket
multiaxial joints in which the spherical articulating head of one bone fits into the rounded socket of a second bone.
(a) Examples are the:
- Hip joint (coxal joint or acetabulofemoral joint).
- -Shoulder joint (glenohumeral joint).
(b) Move your arm at your shoulder joint and you will note that it can move in three
planes (font and back, up and down, and rotate).
(c) Ball and socket joints are the most freely moveable type of synovial joint.
What are the most sexually dimorphism bones
Ossacoxae
Healing broken bones
Realigning bones, immobilizing
Depression
is the inferior movement of a part of the body.
- Examples include the opening of the mouth to chew food and the movement of your shoulders in an inferior direction
6 membranous areas of the skull
These areas are called “fontanels” (French for “little spring”).
2) Fontanels are sometimes referred to as “soft spots” on a baby’s head.
3) When a baby travels head-first through the birth canal, one parietal bone typically overlaps the other and the occipital bone slides under the parietals. This makes the delivery process easier.
(a) This shifting of bones during parturition is called “molding” and may cause a
temporary cone-like distortion in the shape of a newborn’s head!
4) The fontanels also allow for the rapid growth of the brain during infancy that was
mentioned earlier.
5) Ossification and disappearance of the fontanels is normally complete by 15-24
months of age.
6) Changes of the fontanels may be clinically important.
(a) Dehydration may lead to sunken fontanels.
(b) Meningitis and increased intracranial pressure may lead to bulging fontanel
Symphyses
Cartilaginous
have a pad of fibrocartilage between
the articulating bones.
1) The fibrocartilage resists compression and tension stresses and acts as a shock
absorber.
2) All symphyses are slightly moveable and are therefore classified as
amphiarthroses.
3) Examples are:
(a) Pubic symphysis
(b) Intervertebral joints formed by the bodies of adjacent vertebrae and the intervertebral
discs.
Glenohumeral joint ligaments
The glenohumeral joint has several major ligaments that strengthen the joint only
minimally.
1) The “coracohumeral ligament” is a thickening of the superior part of the joint
capsule and it runs from the coracoid process to the humeral head.
2) The “glenohumeral ligaments” are three thickenings of the anterior portion of the
articular capsule that may or may not be present and provide only minimal
support.
3) The “transverse humeral ligament” is a narrow sheet that extends between the
greater and lesser tubercles of the humerus.
Eversion
the movement of the sole (plantar surface) of the foot outward or
laterally.
Rotator cuff
1) The rotator cuff muscles (infraspinatus, subscapularis, supraspinatus, and teres
minor) work as a group to hold the head of the humerus in the glenoid cavity.
2) The tendons of these muscles encircle the joint (except for the inferior portion)
and fuse with the joint capsule.
(a) Because the inferior portion of the joint lacks rotator cuff muscles, this area is weak
and is the most likely site of injury.
Pivot joints
are uniaxial joints in which one articulating bone with a rounded surface fits into a ring formed by a ligament and another bone.
(a) The first bone rotates on its longitudinal axis relative to the second bone.
(b) Examples are:
- Proximal radioulnar joint, where the rounded head of the radius pivots along the ulna and permits the radius to rotate.
- Atlantoaxial joint between the first two cervical vertebrae. The rounded dens of the axis fits snugly against an articular facet on the anterior arch of the atlas, allowing it to pivot when you shake your head in a “no” movement.
Trochlea
Smooth, grooves, pulley like articular process
Osteoprogenitor cell
are located within both the periosteum and endosteum and give rise to cells that become osteoblasts
2 articulations found in vertebral column
symphyses and gliding joints
Classifying synovial joints
1) The shapes of their articulating surfaces 2) The types of movements they allow
(a) A joint is said to be “uniaxial” if the bone moves in just one plane. (b) A joint is said to be “biaxial” if the bone moves in two planes.
(c) A joint is said to be “multiaxial” if the bone move in multiple planes
Intramembranous ossification
1) This type of ossification produces the flat bones of the skull, some of the facial
bones [zygomatic (cheek) bone and maxilla (upper jaw bone)], the mandible
(lower jaw), and the central part of the clavicle (collarbone).
2) When sesamoid bones occur, they develop by intramembranous ossification
inside of tendons
Osteocytes
which develop from osteoblasts, maintain the bone matrix and detect mechanical stress on a bone. This information is communicated to osteoblasts, and may result in the deposition of new bone matrix at the surface
Angular motion
either increases or decreases the angle between two bones (See
Figs. on pages 261, 262, and top of page 263).
(a) “Flexion” is movement in an anterior-posterior plane of the body that decreases the
angle between the bones.
- Examples are bending of the elbow, bending the knee, bending of the fingers to
make a fist, or bending of the neck when the head falls forward
Circumduction
s a sequence of movements in which the proximal part of the body
remains relatively stationary while the distal part of the body makes a circular cone- like motion.
- An example is extending your arm at the shoulder and making circular drawings
on a blackboard.
- Circumduction can be easily done at the shoulder, wrist, trunk, hip, ankle, neck,
and metacarpophalangeal joints.
Spine
Pointed, slender process
Joint or articulatin
Lace of contact between bones, between bone and cartilage, or between bones and teeth
Ligaments of elbow
1) The “radial (lateral) collateral ligament” is responsible for stabilizing the joint at its lateral surface.
2) The “ulnar (medial) collateral ligament” stabilizes the medial side of the joint
3) The “anular (Latin for “ring-shaped”) ligament” surrounds the head of the radius
and binds the proximal head of the radius to the ulna. This ligament helps to hold the head of the radius in place.
Pott
Fracture at the distal end of the fibula and malleolis of the tibia
Causes of lumbar pain
1) Strained muscles (most common cause)
2) Herniation of the cartilage disc between lumbar vertebrae 3) Dislocation of articular facets between two vertebrae
Hairline
Fine crack in which sections of the bone remain aligned (common in the skull)
All types of synovial joints include:
Articular capsule Joint cavity Hyaline articular cartilage Ligaments Nerves and blood vessels Accessory structures
Plantar flexion
occurs when the talocrural joint (ankle) is bent such that the toes
move away from the head, like when a ballerina is standing on her tiptoes.
- Dorsiflexion and plantarflexion only occur at the talocrural joint (ankle
Gliding
simple movement in which two opposing surfaces slide slightly
back-and-forth or side-to-side to one another and the angle between the bones doesn’t change.
(a) Gliding motion typically occurs along planar joints (i.e.-between carpal bones and
between tarsal bones)
Effects of exercise
a. As was stated above, pulling stress on the periosteum by skeletal muscles stimulates nearby osteoblasts causing bone to increase in thickness.
b. It follows that exercise helps strengthen bones while the lack of exercise can weaken bones.
1) This is a real concern for astronauts and bed-ridden patients!
2) Even old persons with weak bones can strengthen them if they will just perform
moderate weight training exercises.
Blowout fracture
Blows to the eye and orbit may fracture the floor of the orbit amusing the eye or the muscles to droop
Transverse
Fracture at right angles to the long axis of the bone
Students elbow
Olecranal bursitis
Projection on elbow
4 types of cells in bone
Osteoprogenitor
Osteoblasts
Osteocytes
Osteoclasts
Incomplete
Fracture ends only partway across the bone
Two articulations of elbow joint
a. The elbow joint is composed of two articulations:
1) The humeroulnar joint where the trochlear notch of the ulna articulates with the
trochlea of the humerus.
(a) This is a hinge joint.
2) The humeroradial joint where the capitulum of the humerus articulates with the
head of the radius.
(a) This joint is currently poorly classified (my opinion is that it is a gliding joint)
Flail chest
a. Fractures of the ribs are common and most frequently occur between ribs 3-10.
b. When three or more adjacent ribs are fractured, each in two places, the segment of the
chest wall between the fractures becomes a free-floating segment.
1) This is called a “flail chest” and the injured area demonstrates “paradoxical
motion”.
c. It is a particularly dangerous injury because the underlying lungs may be damaged. d. Little can be done to assist the healing of broken ribs other than bandaging on the
injured side to provide firm support to the damaged area.
Coccyx
1) The coccyx is composed of four small vertebrae that become fused at about 25 years of age to form a triangular shaped structure.
2) It serves as an attachment site for several ligaments and some muscles.
3) In very old individuals the coccyx may fuse with the sacrum.
Opposition
” is the movement of the thumb toward the palmar tips of the fingers as it crosses the palm of the hand.
- As was stated above, this opposition is possible because of a saddle joint between
a carpal bone and the first metacarpal.
Effects of vitamins
a. Vitamin A activates osteoblasts
b. Vitamin C is required for normal synthesis of collagen, the primary organic
component in the bone matrix.
c. Vitamin D stimulates the absorption and transport of calcium and phosphate ions into
the blood for possible storage in the bone
Pathological fracture
spontaneous fracture) can occur when a bone is
weakened by disease (i.e.-cancer, osteoporosis, etc)
What is the most frequent large bone dislocation
The humerus from the glenoid cavity
Elevation
Opposite of depression
Intervertebral discs
Intervertebral discs make up approximately one-quarter of the height of the entire vertebral column.
3) They act as shock absorbers and allow for flexibility between vertebrae.
4) The length of your vertebral column diminishes after long hours of being in the
upright position and elongates when you lay down
Damage to elbow
1) The center of the trochlear notch may be broken when you fall on an outstretched
hand.
2) In children who fall on their outstretched hand there might be a fracture through
the epiphyseal growth plate at the distal end of the humerus.
3) The elbow may also be dislocated by pulling stresses, such as those experienced
by gymnasts.
Sphenoid bone
- bridging bone
- often fractured due to location and multiple foramina
Pseudoarthroses
false joints that occur when a fractured long bone (i.e.-humerus) heals as two separate bones.
Spiral
Fracture spirals around axis of long bone, results from twisting stress
Spina bifida
a. This is a congenital defect of the vertebral column resulting from a failure of the laminae of vertebrae to fuse, exposing the meninges, spinal cord, or both.
b. The lumbar area is mainly affected, often with only a single vertebra involved.
c. Over 50% of these defects can be prevented
Organic and inorganic make up of bones
The organic components make up one third of the bones mass and consist of cells,
collagen fibers, and ground substance, all of which provided some flexibility to bone. (b) The inorganic components provide bone with its compressional strength and consist
of calcium compounds, phosphorus, sodium, magnesium, sulfate, and fluoride.
Hinge joints
are uniaxial joints in which the convex surface of one articulating
bone fits into a concave depression on the other bone.
(a) Movement is confined to a single plane, like the hinge of a door. (b) Examples are:
- Humeroulnar articulation of the elbow
- Tibiofemoral joint (knee)
- Talocrural joint (ankle)
- Interphalangeal joints (between bones of fingers)
Which sutures become ossified in the 40’s
Sagittal and then the lambdoidal
Stress fracture
stress fracture” is a thin break caused by increased physical activity in which
the bone experiences repetitive loads, such as in running
When does the coronal suture become ossified
20’s to early 30’s
Projection
Where tendons and ligaments attach
Ossification (osteogenesis)
the formation and development of bone connective tissue. It begins in embryonic development and continues throughout a person’s life
Synchondroses
Cartilaginous
are joined together by hyaline cartilage.
1) Functionally, all synchondroses are immoveable and thus are classified as
synarthroses.
2) Examples are:
(a) Epiphyseal growth plates in children.
- As we know, epiphyseal growth plates are temporary, eventually ossify, and are
replaced by synostoses in adults.
(b) Costochondral articulations between most of the ribs and their respective costal
cartilage.
Ligamentum nuchae
that extends between C7 and the
base of the skull.
2) It is very thick and sturdy, and helps stabilize the skull on the cervical vertebrae.
3) You can palpate this thick ligament along the posterior midline of your neck.
Greenstick
Partial fracture, convex side of bone breaks, the other side is bent (think of bending a green stick)
Types of synovial joints
Planar Hinge Pivot Condyloid Saddle Ball and socket
Fossa
Flattened or shallow depression
2 types of bone connective tissue
Spongy bone
Compact bone
Cleft palate
If the palatine processes fail to join during the early prenatal development (10-12 weeks)
Dorsiflexion
occurs when the talocrural joint (ankle) is bent such that the superior
surface of the foot and the toes move towards the head
Hyper extension
- An example is extending your arm and hand with the palm facing inferiorly, and
then raising the back of your hand as if admiring a new ring on your finger, the
wrist is at this point hyperextended. - Another example is if you glance up at the ceiling while standing, you neck is
then hyperexteded. - A severe example of hyperextension of the spine is “opisthotonos”, which occurs
in tetanus.
Coles
Fracture of distal end of the radius; produces a dinner fork deformity
The axis
The axis is easily identified by the presence of a superior peg-like projection called the “odontoid process” (Greek for “tooth”) or “dens” (Latin for “tooth”).
b. This superior projection acts as a pivot for the rotation of both the atlas and the skull in a side-to-side “no” motion.
c. This articulation between the atlas and the axis is called the “atlanto-axial joint” (See Fig. (c) on page 210).
d. Since both the dens and the spinal cord occupy the vertebral foramen at the level of the axis, any trauma that fractures or dislocates the dens often damages the spinal cord or perhaps even the brain
Frontal sinuses
- lessen weight of skull
- moisten inhaled air
- resonance to voice
- appear after age 6 are more fully developed by 10
- unique pattern
Fracture to what bone leads to meningitis
Ethmoid
Endochondral step
(a) During the 8-12 week, of fetal development, chondroblasts secrete cartilage matrix
and a hyaline cartilage model forms.
(b) As the cartilage model grows, the cartilage cells in the center of the shaft increase in
size (hypertrophy) and minerals are deposited at the location by calcification.
- Calcification restricts the passage of nutrients to the cartilage cells causing them to die
- At the same time, some of the cells in the dense fibrous connective tissue surrounding the cartilage differentiate into bone cells (osteoblasts) which secrete the organic component of bone (osteoid).
- This gives rise to a thin plate of compact bone surrounding the outer surface of the cartilage (“periosteal bone collar”).
(c) Osteoblasts and blood vessels invade the disintegrating center of the cartilage model and the osteoblasts secrete osteoid.
- This region, where bone replaces cartilage in the center of the diaphysis of the
hyaline cartilage model, is called the “primary ossification center”.
- Bone development extends in both directions toward the epiphyses from the
primary ossification center, replacing the cartilage in the shaft.
- Most primary ossification centers have formed by the 12th week of fetal
development.
(d) This same basic process is repeated in both proximal and distal epiphyses, resulting
in “secondary ossification centers”.
(e) This process of calcification will continue until the only cartilage left is the articular
cartilage and the epiphyseal growth plates, both of which are composed of hyaline cartilage.
- Bone will continue to increase in length as long as the hyaline cartilage cells of
the epiphyseal growth plate continue to be mitotically active (See Fig. on page
161).
(f) When a person reaches adult size (approximately 18-20), the epiphyseal growth
plates will ossify leaving merely a thin layer of compact bone called the “epiphyseal line”
Linear
Fracture is parallel to the long axis of the bone
Acromioclavicular joint
a. The “acromioclavicular joint” is a gliding (planar) joint between the acromion of the scapula (shoulder blade) and the lateral end of the clavicle (collar bone).
1) If you palpate your clavicle in a lateral direction to the tip of your shoulder, you
can feel this joint.
2) A fibrocartilage articular disc lies within the joint cavity between these two bones.
b. Several ligaments provide great stability to this joint.
1) The fibrous joint capsule is strengthened superiorly by the “acromioclavicular
ligament”.
2) The “coracoclavicular ligament” binds the clavicle to the coracoid process of the
scapula.
(a) The coracoclavicular ligament is responsible for most of the stability of the joint
because it indirectly prevents the clavicle from losing contact with the acromion
Retraction
is the posterior movement of a protracted body part so the anatomic position is resumed
Complete
Bone is broken into two or more pieces
Facet
Small, flat, shallow articulating surface
Osteoclasts
are large, multinuclear, phagocytic cells and appear to be derived from bone marrow cells similar to those that produce monocytes in blood. Their role is to break down bone in a process called “osteolysis”
Structural joints
(a) “Fibrous joints” lack a joint cavity and are held together by dense (fibrous)
connective tissue.
(b) “Cartilaginous joints” lack a joint cavity and the bones are joined together by
cartilage.
(c) “Synovial joints” have a fluid-filled joint cavity that separates the articulating
surfaces of the bones and these articulating surfaces are enclosed within a capsule
and supported by ligaments.aa
Ramus
Angular extension of a bone relative to the rest of the structure
Compression
Bone is squashed (may occur in vertebra during a fall)
Adduction
which means to “move toward”, and is the medial movement of a body
part toward the body midline.
- Examples are moving the leg or arm back toward the body midline of the torso or
when the fingers are drawn back to the midline of the hand.
Simple (closed)
Bone does not break through the skin
