Skeletal System Flashcards
joints, car- tilages, and ligaments
fibrous cords that bind the bones together at joints
The skeleton is divided into two parts what are these?
the AXIAL skeleton, the bones that form the longitudinal axis of the body and APPENDICULAR skeleton, the bones of the limbs and girdles that attach them to the axial skeleton.
what is hematopoiesis?
Blood cell formation, or hematopoiesis (hem′′ah-to-poi-e′sis), occurs within the marrow cavities of certain bones.
The adult skeleton is composed of 206 bones. There are two basic types of osseous, or bone, tis- sue: what are these?
Compact bone is dense and looks smooth and homogeneous, whereas
Spongy bone has a spiky, open appearance like a sponge
Long bones are mostly compact bone but also contain spongy bone at the ends. All the bones of the limbs, except.
the patella (kneecap) and the wrist and ankle bones, are long bones
Bones that are thin, flattened, and usually curved. They have two thin layers of compact bone sandwiching a layer of spongy bone between
them. Most bones of the skull, the ribs, and the sternum (breastbone) are
Flat bones.
Bones that are generally cube-shaped and contain mostly spongy bone with an outer layer of compact bone. The bones of the wrist and ankle are?
Short bones
The vertebrae, which make up the spinal column, fall into this group. Like short bones, they are mainly spongy bone with an outer layer of compact bone.
Irregular bones
In a long bone ______ or shaft, makes up most of the bone’s length and is composed of compact bone
the diaphysis (di-af′ ̆ı-sis),
The diaphysis is covered and protected by a fibrous connective tissue membrane, what is it called?
the perios- teum (per-e-os′te-um).
Hundreds of connective tissue fibers, called __________ secure the periosteum to the underlying bone.
perforating fibers, or Sharpey’s fibers,
The _______ are the ends of long bones. Each epiphysis consists of a thin layer of compact bone enclosing an area filled with spongy bone.
epiphyses (e ̆-pif′ ̆ı-seˉz)
Instead of a periosteum, articular cartilage covers its external surface. Because the articular cartilage is glassy hyaline cartilage, it pro- vides a smooth surface that decreases friction at the joint when covered by lubricating fluid. Imagine how slick a marble floor (the articular cartilage) is when wet; this is analogous to the lubrication of a joint
articular cartilage has it’s own lubrication
In adult bones, there is a thin line of bony tissue spanning the epiphysis that looks a bit differ- ent from the rest of the bone in that area.
This is the epiphyseal line.
The inner bony surface of the shaft is covered by a delicate connective tissue called
endosteum
In infants, the cavity of the shaft, called the med- ullary cavity, is a storage area for ________ , which produces blood cells.
red marrow
Children’s bones contain red marrow until the age of 6 or 7, when it is gradually replaced by ______ which stores adipose (fat) tissue.
yellow marrow,
There are two categories of bone markings:
(a) projections, or processes, which grow out from the bone surface, and
(b) depressions, or cavities, which are indentations in the bone.
There is a lit- tle trick for remembering some of the bone mark- ings listed in the table: All the terms beginning with T are “projections”, and the terms beginning with F (except facet) are depressions.
that spongy bone is composed of small needlelike pieces of bone called _______ and lots of “open” space filled by marrow, blood vessels and nerves
trabeculae
In compact bone, the mature bone cells, osteocytes (os′te-o-sˉıtz′′), are found within the bone matrix in tiny cavities called
lacunae (lah- ku′ne).
Tiny canals are called _____ radiate outward from the central canals to all lacunae. The canaliculi form a transportation sys- tem that connects all the bone cells to the nutrient
supply and waste removal services through the hard bone matrix.
canaliculi (kan′′ah- lik′u-li),
most bones develop using hyaline car- tilage structures as their “models.” This process of bone formation,is called?
ossification
(os′′ ̆ı-f ̆ı-ka′shun), involves two major phases
First, the hyaline cartilage model is completely covered with bone matrix (a bone “collar”) by bone-building cells called OSTEOBLAST. So, as the embryo develops into a fetus, for a short period it has cartilage “bones” enclosed by actual bone matrix.
When the blood calcium ion level drops below its homeostatic level, the parathyroid glands (located in the throat) are stimulated to release parathyroid hormone (PTH) into the blood. PTH activates OSTEOCLAST, giant bone-destroying cells in bones, to break down bone matrix and release calcium ions into the blood. When the blood cal- cium ion level is too high (hypercalcemia [hi′′per- kal-se′me-ah]), calcium is deposited in bone matrix as hard calcium salts by osteoblasts.
A fracture type that Bone breaks into three or more fragments - Particularly common in older people, whose bones are more brittle
Comminuted
a fracture type that is Bone is crushed- Common in porous bones (i.e., osteoporotic bones of older people)
Compression
Fracture type that is Broken bone portion is pressed inward - Typical of skull fracture
Depressed
Broken bone ends are forced into each other - Commonly occurs when someone attempts to break a fall with outstretched arms
Impacted
Ragged break occurs when excessive twisting forces are applied to a bone - Common sports fracture
Spiral
Bone breaks incompletely, much in the way a green twig breaks - Common in children, whose bones are more flexible than those of adults
Greenstick
Blood vessels are rup- tured when the bone breaks. As a result, there is a blood-filled swelling, or bruise, called a
__________forms.
hematoma (he-mah-to′mah)
Two early
events of tissue repair are the growth of new capillaries (granulation tissue) into the clottedblood at the site of the damage and disposal of
dead tissue by phagocytes.
A fibrocartilage callus forms.
As more osteoblasts 2 and osteoclasts migrate into the area and multi- 4 ply, the fibrocartilage callus is gradually replaced by the _______ made of spongy bone.
bony callus
Over the next few 6 weeks to months, depending on the bone’s size and site of the break, the bony callus is
remodeled in response to the mechanical
stresses placed on it, so that it forms a strong, permanent “patch” at the fracture site.
Bone remodeling occurs
Axial skeleton can be divided into three parts—
the skull, the vertebral column, and the thoracic cage.
The skull is formed by two sets of bones. what are these?
The cranium encloses and protects the fragile brain tissue.
The facial bones form a cradle for the eyes that is open to the anterior and allow the facial muscles to show our feelings through smiles or frowns.
All but one of the bones of the skull are
joined together by sutures, which are interlocking, immovable joints.
Only the _______ is attached to the rest of the skull by a freely movable joint.
mandible (jawbone)
Cranium
The boxlike cranium is composed of eight large flat bones. Except for two sets of paired bones (the parietal and temporal), they are all single bones.
Cranium
The _______ forms the forehead, the bony projections under the eye- brows, and the superior part of each eye’s orbit
Frontal Bone
The _________ form most of the superior and lateral walls of the cra- nium. The sagittal suture is formed at the midline where the two ______ meet and the coronal suture is formed where the paired _______ meet the frontal bone.
Parietal Bones
The ________ lie inferior to the parietal bones and join them at the squamous sutures.
temporal bones
Several important bone markings appear on the temporal bones - dont answet justs study
• The external acoustic meatus is a canal that leads to the eardrum and the middle ear. It is the route by which sound enters the ear.
• The styloid process, a sharp, needlelike pro- jection, is just inferior to the external auditory meatus. Many neck muscles use the styloid process as an attachment point.
• The zygomatic (zi′′go-mat′ik) process is a thin bridge of bone that joins with the cheek- bone (zygomatic bone) anteriorly.
• The mastoid (mas′toid) process, which is full of air cavities (the mastoid sinuses), is a rough projection posterior and inferior to the external acoustic meatus. It provides an attachment site for some muscles of the neck.
The mastoid sinuses are so close to the middle ear—a high-risk spot for infections— that they may become infected too, a condi- tion called mastoiditis. Also, this area is so close to the brain that mastoiditis may spread to the brain.
The ________ is the most posterior bone of the cranium. It forms the base and back wall of the skull. This joins the parietal bones anteriorly at the lambdoid (lam′doyd) suture. In the base of it is a large opening, the foramen magnum
occipital (ok-sip′ ̆ı-tal) bone
The butterfly-shaped _______ spans the width of the skull and forms part of the floor of the cranial cavity
sphe- noid (sfe′noid) bone
In the midline of the sphenoid is a small depression, ________ ,or Turk’s saddle, which forms a snug enclosure for the pituitary gland.
sellaturcica(sel′ahtur′s ̆ı-kah)
The _________, a large oval opening in line with the posterior end of the sella turcica
foramen ovale
the optic canal, which allows the optic nerve to pass to the eye, and the slitlike superior orbital fissure, through which the cranial nerves controlling eye movements - dont answer just study
the optic canal, which allows the optic nerve to pass to the eye, and the slitlike superior orbital fissure, through which the cranial nerves controlling eye movements
The______bone is very irregularly shaped and lies anterior to the sphenoid. It forms the roof of the nasal cavity and part of the medial walls of the orbits.
Ethmoid Bone
The two _______ fuse to form the upper jaw. All facial bones except the mandible join the ______ ; thus they are the main, or “keystone,” bones of the face.
maxillae (mak-s ̆ı′le), or maxillary bones,
The maxillae carry the upper teeth in the
alveolar process.
Extensions of the maxillae called the ________ processes form the anterior part of the hard palate of the mouth
palatine (pal′ah-tˉın)
The ________ are commonly referred to as the cheekbones. They also form a good-sized portion of the lateral walls of the orbit
Zygomatic Bones
The _______ are fingernail-sized bones forming part of the medial, wall of each orbit.
lacrimal (lak′r ̆ı-mal) bones
The small rectangular bones forming the bridge of the nose are the nasal bones. (The lower part of the skeleton of the nose is made up of hyaline cartilage.)
Nasal Bones
The single bone in the median line of the nasal cavity . (means “plow,” which refers to the bone’s shape.) The ___ the inferior part of the bony nasal septum, which separates the two nostrils.
Vomer Bone
The _________ are thin, curved bones projecting medially from the lateral walls of the nasal cavity
inferior nasal con- chae (kon′ke)
The ______, is the largest and strongest bone of the face. It joins the temporal bones on each side of the face, forming the only freely movable joints in the skull.
mandible, or lower jaw
Though not really part of the skull, is closely related to the mandible and temporal bones. The ______ is unique in that it is the only bone of the body that does not articulate (form a joint) with any other bone. Instead, it is suspended in the midneck region
the hyoid (hi′oid) bone
Serving as the axial support of the body, the _______extends from the skull, which it supports, to the pelvis, where it transmits the weight of the body to the lower limbs. Instead, the ___ is formed from 26 irregular bones connected and reinforced by ligaments in such a way that a flexible, curved structure results
verte- bral column, or spine,
Before birth, the spine consists of 33 separate bones called ______, but 9 of these eventually fuse to form the two composite bones, the sacrum and the coccyx,
vertebrae
The individual vertebrae are separated by pads of flexible fibrocartilage—
intervertebral discs
▪ Bones grow in width
▪ Osteoblasts in the periosteum add bone matrix to the outside of the diaphysis
▪ Osteoclasts in the endosteum remove bone from the inner surface of the diaphysis
Appositional growth
▪Bones are remodeled throughout life in response to two factors
STUDY ONLY
- Calcium ion level in the blood determines when bone matrix is to be broken down or formed
- Pull of gravity and muscles on the skeleton determines where bone matrix is to be broken down or formed
(high blood calcium levels) prompts calcium storage to bones by osteoblasts
Hypercalcemia
▪ Released when calcium ion levels in blood are low
▪ Activates osteoclasts (bone-destroying cells)
▪ Osteoclasts break down bone and release calcium ions into the blood
Parathyroid hormone
Bone fractures are treated by reduction and immobilization
eeks
▪ Closed reduction: bones are manually coaxed into position by physician’s hands
▪ Open reduction: bones are secured with pins or wires during surgery
▪Healing time is 6–8 w
Repair of bone fractures involves four major events
STUDY ONLY
▪ Hematoma (blood-filled swelling, or bruise) is formed ▪ Fibrocartilage callus forms
▪ Cartilage matrix, bony matrix, collagen fibers splint the broken bone
▪ Bony callus replaces the fibrocartilage callus ▪ Osteoblasts and osteoclasts migrate in
▪ Bone remodeling occurs in response to mechanical stresses
▪Forms the longitudinal axis of the body
▪Divided into three parts
1. Skull
2. Vertebralcolumn
3. Bonythorax
Axial Skeleton
Two sets of bones form the skull
- Cranium bones enclose the brain
- Facialbones
▪ Hold eyes in anterior position
▪ Allow facial muscles to express feelings
▪Bones are joined by sutures
▪Only the mandible is attached by a freely
movable joint STUDY ONLY
▪Bones are joined by sutures
▪Only the mandible is attached by a freely
movable joint STUDY ONLY
▪8 cranial bones protect the brain
1 Frontal bone
2 Occipital
3 Ethmoid
4 Sphenoid
5, 6 Parietal bones
7, 8 Temporal bones
Outside covering of the diaphysis
Periosteum
▪ Covers the external surface of the epiphyses
▪ Made of hyaline cartilage
▪ Decreases friction at joint surfaces
Articular cartilage
▪ Remnant of the epiphyseal plate
▪ Seen in adult bones
Epiphyseal line
▪ Flat plate of hyaline cartilage seen in young, growing
bone
▪ Causes lengthwise growth of a long bone
Epiphyseal plate
▪ Lines the inner surface of the shaft ▪ Made of connective tissue
Endosteum
▪ Cavity inside the shaft
▪ Contains yellow marrow (mostly fat) in adults
▪ Contains red marrow for blood cell formation in infants until age 6 or 7
Medullary cavity
▪ Mature bone cells situated in bone matrix
Osteocytes
▪ Cavities in bone matrix that house osteocytes
Lacunae
▪ Concentric circles of lacunae situated around the
central (Haversian) canal
Lamellae
▪ A unit of bone containing central canal and matrix rings ▪ Structural and functional unit of compact bone
Osteon (Haversian system)
▪By birth, most cartilage is converted to bone except for two regions in a long bone
- Articularcartilages
- Epiphysealplates
▪ Hollow portions of bones surrounding the nasal cavity ▪ Functions of paranasal sinuses
Paranasal sinuses
26 vertebral bones are separated by intervertebral discs: STUDY ONLY
▪ 7 cervical vertebrae are in the neck
▪ 12 thoracic vertebrae are in the chest region
▪ 5 lumbar vertebrae are associated with the lower back ▪ Sacrum (formed by fusion of 5 vertebrae)
▪ Coccyx (formed by fusion of 3–5 vertebrae
study only
▪ Spinal curvatures of the thoracic and sacral regions
▪ Present from birth
▪ Form a C-shaped curvature in newborns
Primary curvatures
▪ Spinal curvatures of the cervical and lumbar regions
▪Develop after birth
▪ Form an S-shaped curvature in adults
Secondary curvatures
Bony thorax, or thoracic cage, protects organs of the thoracic cavity
▪Consists of three parts
- Sternum
- Ribs
▪ True ribs (pairs 1–7)
▪ False ribs (pairs 8–12)
▪ Floating ribs (pairs 11–12) - Thoracicvertebrae
Appendicular Skeleton
▪Composed of 126 bones
▪ Limbs (appendages)
▪ Pectoral girdle
▪Pelvic girdle
▪Also called pectoral girdle
▪Composed of two bones that attach the upper limb to the axial skeletal
1. Clavicle 2. Scapula
▪Light, poorly reinforced girdle
▪Allows the upper limb a exceptional flexibility
Bones of the Shoulder Girdle
▪Composed of 126 bones
▪ Limbs (appendages)
▪ Pectoral girdle ▪Pelvic girdle
Appendicular Skeleton
▪Also called pectoral girdle
▪Composed of two bones that attach the upper limb to the axial skeletal
1. Clavicle 2. Scapula
▪Light, poorly reinforced girdle
▪Allows the upper limb a exceptional flexibility
Bones of the Shoulder Girdle
▪ Humerus
▪ Forms the arm
▪ Single bone
▪ Proximal end articulation
▪ Head articulates with the glenoid cavity of the scapula
▪Distal end articulation
▪ Trochlea and capitulum articulate with the bones of the
forearm
Bones of the Upper Limbs
▪The forearm has two bones
- Ulna—medial bone in anatomical position
▪ Proximal end articulation
▪ Coronoid process and olecranon articulate with the
humerus - Radius—lateral bone in anatomical position
▪ Proximal end articulation
▪ Head articulates with the capitulum of the humerus
Bones in Hand
▪ Carpals—wrist bones
8 bones arranged in two rows of 4 bones in each hand
▪ Metacarpals—palm bones
5 per hand
▪ Phalanges—fingers and thumb
14 phalanges in each hand
In each finger, there are 3 bones
In the thumb, there are only 2 bones
Bones of the Pelvic Girdle
Formed by two coxal (ossa coxae) bones
▪Composed of three pairs of fused bones
- Ilium
- Ischium
- Pubis
▪Pelvic girdle = two coxal bones, sacrum
▪Pelvis = two coxal bones, sacrum, coccyx
▪ The heaviest, strongest bone in the body
▪ Proximal end articulation
▪ Head articulates with the acetabulum of the coxal (hip) bone
▪Distal end articulation
▪ Lateral and medial condyles articulate with the tibia in
the lower leg
Femur—thigh bone
The lower leg has two bones
- Tibia—shinbone; larger and medially oriented
▪ Proximal end articulation
▪ Medial and lateral condyles articulate with the femur to
form the knee joint ▪ Distal end articulation
▪ Medial malleolus forms the inner part of the ankle - Fibula—thin and sticklike; lateral to the tibia
▪ Has no role in forming the knee joint ▪ Distal end articulation
▪ Lateral malleolus forms the outer part of the ankle
▪Tarsals—7 bones
▪ Two largest tarsals are the: ▪ Calcaneus (heel bone) ▪Talus
▪ Metatarsals—5 bones form the sole of the foot ▪ Phalanges—14 bones form the toes
Bones of Foot
Two ways joints are classified
▪ Functionally
▪ Structurally
Functional joint classifications
▪ Synarthroses-Immovable joints
▪ Amphiarthroses -Slightly movable joints
▪ Diarthroses - Freely movable joints
Structural joint classifications
▪ Fibrous joints - Generally immovable
▪ Cartilaginous joints-Immovable or slightly movable
▪Synovial joints - Freely movable
Study only
Birth to adulthood
▪ First “long bones” of a fetus are hyaline cartilage
▪ Earliest “flat bones” of the fetal skull are fibrous membranes
▪ As fetus grows, all bone models are converted to bone
Birth to adulthood
▪ First “long bones” of a fetus are hyaline cartilage
▪ Earliest “flat bones” of the fetal skull are fibrous membranes
▪ As fetus grows, all bone models are converted to bone
▪ Fontanels are fibrous membranes connecting the
cranial bones
▪ Known as “soft spots”
▪ Allow skull compression during birth
▪ Allow the brain to grow during later pregnancy and infancy
▪ Usually ossify by 2 years of age
Fetal skull
Study Only
▪Size of cranium in relationship to body
▪ 2 years old—skull is three-fourths the size of adult
skull
▪ 8 or 9 years old—skull is near adult in size and proportion
▪ Between ages 6 and 11, the face grows out from the skull
▪Size of cranium in relationship to body
▪ 2 years old—skull is three-fourths the size of adult
skull
▪ 8 or 9 years old—skull is near adult in size and proportion
▪ Between ages 6 and 11, the face grows out from the skull
STUDY ONLY
Older adults
▪ Osteoporosis
▪ Bone-thinning disease afflicting:
▪ 50 percent of women over age 65 ▪ 20 percent of men over age 70
▪ Disease makes bones fragile, and bones can easily fracture
▪ Vertebral collapse results in kyphosis (also known as “dowager’s hump”)
▪ Estrogen aids in health and normal density of a female skeleton
▪Older adults
▪ Osteoporosis
▪ Bone-thinning disease afflicting:
▪ 50 percent of women over age 65 ▪ 20 percent of men over age 70
▪ Disease makes bones fragile, and bones can easily fracture
▪ Vertebral collapse results in kyphosis (also known as “dowager’s hump”)
▪ Estrogen aids in health and normal density of a female skeleton
