Week 3: Axial Skeleton Flashcards
(87 cards)
1
Q
Describe the skeletal system
A
- System of protection and support composed primarily of bone and cartilage
- Also consists of joints and ligament
- Accounts for about 20% of body mass
- Bones make up most of the skeleton.
- Cartilages occur only in isolated areas, such as the nose, parts of the ribs, and the joints.
- Ligaments connect bones and reinforce joints, allowing required movements while restricting motions in other directions.
- Joints provide for the remarkable mobility of the skeleton.
2
Q
Describe cartilage (11 points)
A
- The human skeleton is initially made up of cartilages and fibrous membranes but bone soon replaces most of these early supports.
- A skeletal cartilage is made of some variety of cartilage tissue sculpted to fit its body location and function.
- Cartilage consists primarily of water. It is very resilient—it has the ability to spring back to its original shape after being compressed.
- Cartilage contains no nerves or blood vessels. It is surrounded by a layer of dense irregular connective tissue called the perichondrium, which contains blood vessels that nourish the cartilage cells.
- The perichondrium also acts as reinforcement to resist outward expansion when the cartilage is compressed.
- The thickness of cartilage is limited by the distance nutrients can diffuse through the matrix to reach the cells.
- Three types of cartilage:
1. Hyaline cartilage: the most abundant cartilage type in the body; provides firm support with some pliability
2. Elastic cartilage: cartilage with abundant elastic fibers; more flexible than hyaline cartilage
3. Fibrocartilage: the cartilage most resistant to compression and stretch. Forms vertebral discs and knee joint cartilages - All three types have the same basic components—cells called chondrocytes, enclosed in small cavities (lacunae) within an extracellular matrix containing a jellylike ground substance and fibers.
3
Q
Describe Hyaline Cartilages (8 points)
A
- provide support with flexibility and resilience.
- They are the most abundant skeletal cartilages.
- Their chondrocytes are spherical and the only fiber type in their matrix is fine collagen fibers (which are undetectable microscopically).
- Types of skeletal hyaline cartilages include:
- Articular cartilages, which cover the ends of most bones at movable joints
- Costal cartilages, which connect the ribs to the sternum (breastbone)
- Respiratory cartilages, which form the skeleton of the larynx (voice box) and reinforce other respiratory passageways
- Nasal cartilages, which support the external nose
4
Q
Describe Elastic Cartilages (2 points)
A
- Resembles hyaline cartilages, but they contain more stretchy elastic fibers and so are better able to stand up to repeated bending.
- They are found in only two skeletal locations—the external ear and the epiglottis (the flap that bends to cover the opening of the larynx each time we swallow)
5
Q
Describe Fibrocartilage (3 points)
A
- Highly compressible with great tensile strength
- Consists of roughly parallel rows of chondrocytes alternating with thick collagen fibers
- Fibrocartilages occur in sites that are subjected to both pressure and stretch, such as the padlike cartilages (menisci) of the knee and the discs between vertebrae
6
Q
Locate the major cartilages of the adult skeleton (20 points)
A
7
Q
Describe how cartilage grows (6 points)
A
- Unlike bone, which has a hard matrix, cartilage has a flexible matrix that can accommodate mitosis.
- It is the ideal tissue to use to rapidly lay down the embryonic skeleton and to provide for new skeletal growth.
- Cartilage grows in two ways.
1. Appositional growth: cartilage-forming cells in the surrounding perichondrium (the surrounding connective tissue) secrete new matrix against the external face of the existing cartilage tissue.
2. Interstitial growth: the lacunae-bound chondrocytes divide and secrete new matrix, expanding the cartilage from within. Typically, cartilage growth ends during adolescence when the skeleton stops growing. - Under certain conditions—during normal bone growth in youth and during old age, for example—cartilage can become calcified (hardened due to deposit of calcium salts). Note, however, that calcified cartilage is not bone; cartilage and bone are always distinct tissues.
8
Q
Describe the differences between cartilage and bone (5 points)
A
- Connective tissue: cartilage is surrounded by perichondrium, bone is surrounded by periosteum
- Blood vessels and nerves: cartilage has no blood vessels or nerves while bone has both throughout
- Composition : cartilage is composed of chondrocytes in lacunae, bones is made up of osteocytes in lacunae
- Extracellular Matrix: cartilage has a flexible extra cellular matrix made by chondroblasts, bone has rigid extracellular matrix (due to inorganic calcium salts) whose organics part is made by osteoblasts
- Growth: cartilage grows through appositional growth and interstitial growth, bones grows only through appositional growth
9
Q
Describe the functions of the skeleton and of bone tissue. (12 points)
A
- Bones perform seven important functions
1. Support: Bones provide a framework that supports the body and cradles its soft organs. - For example, bones of lower limbs act as pillars to support the body trunk when we stand, and the rib cage supports the thoracic wall.
2. Protection: The fused bones of the skull protect the brain. - The vertebrae surround the spinal cord, and the rib cage helps protect the vital organs of the thorax.
3. Anchorage: Skeletal muscles, which attach to bones by tendons, use bones as levers to move the body and its parts. As a result, we can walk, grasp objects, and breathe. - The design of joints determines the types of movement possible.
4. Mineral Storage: Bone is a reservoir for minerals, most importantly calcium and phosphate. - The stored minerals are released into the bloodstream in their ionic form as needed for distribution to all parts of the body. Indeed, “deposits” and “withdrawals” of minerals to and from the bones go on almost continuously.
5. Blood cell formation: Most blood cell formation, or hematopoiesis, occurs in the red marrow of certain bones
6. Triglyceride (fat) storage. Fat, a source of energy for the body, is stored as yellow marrow in the cavities of long bones.
7. Hormone production. Bones produce osteocalcin, a hormone that helps to regulate insulin secretion, glucose homeostasis, and energy expenditure
10
Q
Describe the classification of bones (4 points)
A
- Bones are divided into two major groups
1. The axial skeleton forms the long axis of the body and includes the bones of the skull, vertebral column, rib cage, hyoid bone and ossicles. Generally speaking these bones protect, support, or carry other body parts.
2. The appendicular skeleton consists of the bones of the upper and lower limbs and the girdles (shoulder bones and hip bones) that attach the limbs to the axial skeleton. Bones of the limbs help us move from place to place (locomotion) and manipulate our environment. - Bones are also classified by their shape as long, short, flat, or irregular
11
Q
Describe long bones (5 points)
A
- Long bones, as their name suggests, are considerably longer than they are wide.
- A long bone has a shaft plus two ends, which are often expanded.
- All limb bones except the patella (kneecap) and the wrist and ankle bones are long bones.
- Notice that these bones are named for their elongated shape, not their overall size.
- The three bones in each of your fingers are long bones, even though they are small.
12
Q
Describe short bones (4 points)
A
- Short bones are roughly cube shaped. The bones of the wrist and ankle are examples.
- Sesamoid bones a special type of short bone that form in a tendon (for example, the patella).
- They vary in size and number in different individuals.
- Some sesamoid bones act to alter the direction of pull of a tendon. Others reduce friction and modify pressure on tendons to reduce abrasion or tearing. Many influence the action of muscles.
13
Q
Describe flat bones (2 points)
A
- Flat bones are thin, flattened, and usually a bit curved.
- The sternum (breastbone), scapulae (shoulder blades), ribs, and most cranial bones of the skull are flat bones
14
Q
Describe irregular bones (2 points)
A
- Irregular bones have complicated shapes that fit none of the preceding classes.
- Examples include the vertebrae and the hip bones
15
Q
Describe the gross anatomy of bones (3 points)
A
- Every bone has a dense outer layer that looks smooth and solid to the naked eye. This external layer is compact bone.
- Internal to this is spongy bone (also called trabecular bone), a honeycomb of small needle-like or flat pieces called trabeculae.
- In living bones the open spaces between trabeculae are filled with red or yellow bone marrow.
16
Q
Describe the gross anatomy of a flat bone (5 points)
A
- Short, irregular, and flat bones share a simple pattern: They all consist of thin plates of spongy bone (diploë) covered by compact bone.
- The compact bone is covered outside and inside by connective tissue membranes, respectively the periosteum and endosteum.
- However, these bones are not cylindrical and so they have no shaft or expanded ends.
- They contain bone marrow (between their trabeculae), but no well-defined marrow cavity.
- Where they form movable joints with their neighbors, hyaline cartilage covers their surfaces.
17
Q
Describe the gross anatomy of a long bone. (8 points)
A
- With few exceptions, all long bones have the same general structure: a shaft, bone ends, and membranes
- Components of a long bone are:
1. Diaphysis: elongated shaft of a long
2. Epiphyses: the end part of a long bone
3. Epiphyseal line: an epiphyseal plate that has been ossified
4. Periosteum: fibrous connective tissue membrane that covers the external surface of all bones
5. Endosteum: fibrous connective tissue membrane that covers the internal surface of all bones
6. Blood vessels and nerves
18
Q
Describe the diaphysis (4 points)
A
- A tubular diaphysis, or shaft, forms the long axis of the long bone.
- It is constructed of a relatively thick collar of compact bone that surrounds a central medullary cavity, the central cavity of a long bone.
- Also known as the marrow cavity, this cavity contains no bone tissue. Instead, the medullary cavity contains yellow marrow (fat) in adults and so is called the yellow marrow cavity.
- Between the marrow and the compact bone, there is often a thin layer of spongy bone.
19
Q
Describe the epiphyseal line (3 points)
A
- Between the diaphysis and each epiphysis of an adult long bone is an epiphyseal line, a remnant of the epiphyseal plate.
- The epiphyseal plate, commonly called the growth plate, is a disc of hyaline cartilage that grows during childhood to lengthen the bone.
- The flared portion of the bone where the diaphysis and epiphysis meet, whether it is the epiphyseal plate or line, is called the metaphysis
19
Q
Describe the epiphysis (3 points)
A
- The epiphyses are the bone ends.
- An outer shell of compact bone forms the epiphysis exterior and the interior contains spongy bone.
- A thin layer of articular (hyaline) cartilage covers the joint surface of each epiphysis, cushioning the opposing bone ends during movement and absorbing stress.
20
Q
Describe the periosteum (7 points)
A
- A glistening white, double-layered membrane called the periosteum covers the external surface of the entire bone except the joint surfaces.
- The outer fibrous layer of the periosteum is dense irregular connective tissue.
- The inner osteogenic layer next to the bone surface contains osteoprogenitor cells (primitive stem cells that give rise to most bone cells).
- It also has bone-destroying cells (osteoclasts) and bone-forming cells (osteoblasts).
- The periosteum is richly supplied with nerve fibers and blood vessels, which is why broken bones are painful and bleed profusely.
- Perforating fibers—bundles of collagen fibers that extend into the bone matrix—secure the periosteum to the underlying bone.
- The periosteum also provides anchoring points for tendons and ligaments. At these points the perforating fibers are exceptionally dense.
21
Q
Describe the endosteum (3 points)
A
- A delicate connective tissue membrane called the endosteum covers internal bone surfaces.
- The endosteum covers the trabeculae of spongy bone and lines the canals that pass through the compact bone.
- The endosteum contains the same cell types as the inner layer of the periosteum.
22
Q
Describe the blood vessels and nerves in the long bone (6 points)
A
- Unlike cartilage, bones are well vascularized.
- The main vessels serving the diaphysis are a nutrient artery and a nutrient vein.
- Together these run through a hole in the wall of the diaphysis, the nutrient foramen.
- The nutrient artery runs inward to supply the bone marrow and the spongy bone. Branches then extend outward to supply the compact bone.
- Several epiphyseal arteries and veins serve each epiphysis in the same way.
- Nerves accompany blood vessels through the nutrient foramen into the bone.
23
Q
Label the image (18 points)
A
24
Describe hematopoietic tissue in bones (9 points)
- Hematopoietic tissue is also called red marrow.
- It is found in different locations in infants and adults.
- In infants, the medullary cavity of the diaphysis and all areas of spongy bone contain red bone marrow.
- In adults, much of the red marrow, particularly in long bones, has been replaced by yellow marrow. In most adult long bones, the fat-containing yellow marrow extends well into the epiphysis, and little red marrow is present in the spongy bone cavities.
- As a result, red marrow in adults is only found in the cavities between trabeculae of spongy bones in:
1. The flat bones of the skull, as well as the sternum, ribs, clavicles, scapulae, hip bones, and vertebrae
2. The heads of the femur (thigh bone) and humerus (long bone of the arm)
- Compared to long bones (femur and humerus), the red marrow found in the spongy bone of flat bones (such as the sternum) and in some irregular bones (such as the hip bone) is much more active in hematopoiesis.
- However, yellow marrow in the medullary cavity can revert to red marrow if a person becomes very anemic (has low oxygen-carrying capacity) and needs more red blood cells.
25
Describe bone markings (5 points)
- The external surface of a bone is rarely smooth and featureless. Instead, it has distinct bone markings that provide a wealth of information about how that bone and its attached muscles and ligaments work together.
- Bone markings fit into three categories:
1. projections that are sites of muscle and ligament attachment
2. surfaces that form joints
3. depressions and openings for blood vessels and nerves.
26
List and briefly describe the key projection bone markings (8 points)
1. Tuberosity: Large rounded projection; may be roughened
2. Crest: Narrow ridge of bone; usually prominent
3. Trochanter: Very large, blunt, irregularly shaped process (the only examples are on the femur)
4. Line: Narrow ridge of bone; less prominent than a crest
5. Tubercle: Small rounded projection or process
6. Epicondyle: Raised area on or above a condyle
7. Spine: Sharp, slender, often pointed projection
8. Process: Any bony prominence
27
List and briefly describe the key bone marking surfaces that help to form joints (3 points)
1. Head: Bony expansion carried on a narrow neck
2. Facet: Smooth, nearly flat articular (joint) surface
3. Condyle: Rounded articular projection; often articulates with a corresponding fossa
28
List and briefly describe the key depressions and openings bone markings (9 points)
- For passage of blood vessels and nerves
1. Groove: Furrow
2. Fissure: Narrow, slitlike opening
3. Foramen: Round or oval opening through a bone
4. Notch: Indentation at the edge of a structure
- Others
1. Meatus: Canal-like passageway
2. Sinus: Cavity within a bone, filled with air and lined with mucous membrane
3. Fossa: Shallow, basinlike depression in a bone, often serving as an articular surface
29
Describe the cells of bone tissue (10 points)
- Five major cell types populate bone tissue:
1. osteoprogenitor cells
2. osteoblasts
3. osteocytes
4. bone lining cells
5. osteoclasts
- Some osteoprogenitor cells become osteoblasts.
- Some osteoblasts become osteocytes
- All of these except for the osteoclasts originate from embryonic connective tissue cells.
- The presence of bone cells is what makes bone a dynamic living tisue because these cells continuously resorb (break down) and deposit bone in a process called remodeling.
30
Describe osteoprogenitor cells (4 points)
- Also called osteogenic cells or bone stem cells
- are mitotically active stem cells found in the membranous periosteum and endosteum.
- In growing bones they are flattened or squamous cells.
- When stimulated, these cells differentiate into osteoblasts, while others persist as osteoprogenitor cells.
31
Describe osteoblasts (7 points)
- are bone-forming cells that secrete the bone matrix.
- Like their close relatives, the fibroblasts and chondroblasts, they are actively mitotic.
- The unmineralized bone matrix they secrete includes collagen (90% of bone protein) and calcium-binding proteins that make up the initial unmineralized bone, or osteoid.
- also play a role in matrix calcification.
- When actively depositing matrix, osteoblasts are cube shaped.
- When inactive, they resemble the flattened osteoprogenitor cells or may differentiate into bone lining cells.
- When the osteoblasts become completely surrounded by the matrix being secreted, they become osteocytes.
32
Describe osteocytes (4 points)
- are mature bone cells that occupy spaces (lacunae) that conform to their shape. Osteocytes monitor and maintain the bone matrix.
- They also act as stress or strain “sensors” and respond to mechanical stimuli (bone loading, bone deformation, weightlessness).
- Osteocytes communicate this information to the cells responsible for bone remodeling (osteoblasts and osteoclasts) so that bone matrix can be made or degraded as mechanical stresses dictate.
- Osteocytes can also trigger bone remodeling to maintain calcium homeostasis as we will see shortly.
33
Describe bone lining cells (2 points)
- are flat cells found on bone surfaces where bone remodeling is not going on.
- Like osteocytes, they are thought to help maintain the matrix.
34
Describe osteoclasts (5 points)
- are giant multinucleate cells located at sites of bone resorption.
- They are derived from the same white blood cell lineage that gives rise to macrophages.
- When actively resorbing (breaking down) bone, the osteoclasts lie in a shallow depression they have carved out.
- They have a distinctive ruffled border that directly contacts the bone.
- The deep plasma membrane infoldings of the ruffled border tremendously increase the surface area for enzymatically degrading the bones and seal off that area from the surrounding matrix.
35
Describe the histology of compact bone (5 points)
- Although compact bone looks solid, a microscope reveals that it is riddled with passageways that serve as conduits for nerves and blood vessels
- Composed of:
1. Osteon
2. Canals and Canaliculi
3. Interstitial and Circumferential Lamellae
36
Describe the osteon (10 points)
- The structural unit of compact bone is called the osteon
- Also called the Haversian system
- System of interconnection canals in the microscopic structure of adult compact bone
- Each osteon is an elongated cylinder oriented parallel to the long axis of the bone.
- Functionally, osteons are tiny weight-bearing pillars.
- an osteon is a group of hollow tubes of bone matrix, one placed outside the next like the growth rings of a tree trunk.
- Each matrix tube is a lamella, and for this reason compact bone is often called lamellar bone.
- Although all of the collagen fibers in a particular lamella run in a single direction, the collagen fibers in adjacent lamellae always run in different directions.
- This alternating pattern withstands torsional stresses—the adjacent lamellae reinforce one another to resist twisting.
- Collagen fibers are not the only part of bone lamellae that are distinctly ordered. The tiny crystals of bone salts align between the collagen fibers and also alternate their direction in adjacent lamellae.
37
Describe the Canals and Canaliculi (13 points)
- Running through the core of each osteon is the central canal or Haversian canal
- Contains small blood vessels and nerve fibers that serve the osteon’s cells.
- Canals of a second type called perforating canals or Volkmann’s canals
- These canals lie at right angles to the long axis of the bone and connect the blood and nerve supply of the medullary cavity to the central canals.
- Unlike the central canals of osteons, the perforating canals are not surrounded by concentric lamellae, but like all other internal bone cavities, these canals are lined with endosteum.
- Spider-shaped osteocytes occupy lacunae at the junctions of the lamellae.
- Hairlike canals called canaliculi radiate from the lacunae, connecting them to each other and to the central canal.
- The manner in which canaliculi are formed is interesting.
- As bone forms, the osteoblasts maintain contact with one another and existing osteocytes by gap junctions in their tentacle-like extensions.
- The osteoblasts secrete bone matrix, and are trapped within it as it hardens, becoming osteocytes.
- This leaves a system of tiny canals—the canaliculi—filled with tissue fluid and containing the osteocyte extensions.
- The canaliculi tie all the osteocytes in a mature osteon together, allowing them to communicate and permitting nutrients and wastes to be relayed from one osteocyte to the next throughout the osteon.
- Although bone matrix is hard and impermeable to nutrients, the canaliculi and gap junctions allow bone cells to be well nourished.
38
Describe Interstitial and Circumferential Lamellae (5 points)
- Not all the lamellae in compact bone are part of complete osteons.
- Lying between intact osteons are incomplete lamellae called interstitial lamellae.
- They either fill the gaps between forming osteons or are remnants of osteons that have been cut through by bone remodeling extend around the entire circumference of the diaphysis and effectively resist twisting of the long bone.
- Circumferential lamellae extend around the entire circumference of the diaphysis and effectively resist twisting of the long bone.
- These are located just deep to the periosteum and just superficial to the endosteum
39
Label the image (21 points)
40
Label the image (7 points)
41
Describe the histology of spongy bone (5 points)
- The trabeculae in spongy bone align precisely along lines of stress and help the bone resist stress.
- These tiny bone struts are as carefully positioned as the cables on a suspension bridge.
- Only a few cells thick, trabeculae contain irregularly arranged lamellae and osteocytes interconnected by canaliculi.
- No osteons are present.
- Nutrients reach the osteocytes of spongy bone by diffusing through the canaliculi from capillaries in the endosteum surrounding the trabeculae.
42
Describe the chemical composition of bone (4 points)
- Bone contains both organic and inorganic substances.
- When these two substances are present in the right proportions, bone is extremely strong and durable without being brittle.
- Its soft organic components—including bone cells and osteoid—allow it to resist tension (stretch).
- Its hard inorganic components—mineral salts—allow it to resist compression.
43
Describe the organic components of bone (7 points)
- The organic components of bone include its cells and osteoid, the organic part of the matrix.
- Osteoid makes up approximately one-third of the matrix
- includes ground substance and collagen fibers, both of which are secreted by osteoblasts.
- These organic substances, particularly collagen, contribute both to a bone’s structure and to the flexibility and tensile strength that allow it to resist stretch and twisting.
- Bone’s resilience is thought to come from sacrificial bonds in or between collagen molecules.
- These bonds stretch and break easily on impact, dissipating energy to prevent the force from rising to a fracture value.
- In the absence of continued or additional trauma, most of the sacrificial bonds re-form.
44
Describe the inorganic components of bone (5 points)
- The balance of bone tissue (65% by mass) consists of inorganic hydroxyapatites
- Also known as mineral salts, they are largely calcium phosphates present as tiny, tightly packed, needle-like crystals in and around collagen fibers in the extracellular matrix.
- The crystals account for the most notable characteristic of bone—its exceptional hardness, which allows it to resist compression.
- Because of the mineral salts they contain, bones last long after death.
- In fact, skeletal remains many centuries old reveal the shapes and sizes of ancient peoples, the kinds of work they did, and many of the ailments they suffered, such as arthritis.
45
Describe the skull (10 points)
- Bony protective encasement of the brain and the organs of hearing and equilibrium
- Includes cranial and facial bones (total of 22 bones). The anterior aspect of the skull is formed by facial bones, and the remainder is formed by a cranium.
- Most skull bones are flat bones
- All skull bones of the adult skull are firmly united by interlocking joints called sutures, except for the mandible, which is connected to the rest of the skull by freely movable joints
- The skull possesses several cavities, which are:
1. Cranial cavity
2. Middle and internal ear cavities
3. The nasal cavity
4. Orbits, which house the eyeballs
- The skull also has about 85 named openings (foramina, canals, fissures, etc.). The most important of these provide passageways for the spinal cord, the major blood vessels serving the brain, and the 12 pairs of cranial nerves (numbered I through XII) that transmit information to and from the brain.
46
Describe suture (8 points)
- An immovable joint
- The suture lines have a saw-toothed or serrated appearance.
- The major skull sutures connect cranial bones. They are:
1. the coronal sutures
2. sagittal sutures
3. squamous sutures
4. lambdoid sutures
- Most other skull sutures connect facial bones and are named according to the bones they connect.
47
Describe the cranial bones (6 points)
- Also known as the cranium
- Encloses and protects the brain
- Furnish attachment sites/anchors for head and neck muscles
- The cranium is divided into a vault and a base. The space enclosed by the cranial vault and cranial base is called the cranial cavity and is occupied by the brain.
- The cranium consists of eight strong, superiorly curved bones. Together, these construct the brain’s protective bony “helmet.”
- Because its superior aspect is curved, the cranium is self-bracing. This allows the bones to be thin, and, like an eggshell, the cranium is remarkably strong for its weight.
48
List the 8 cranial bones (6 points)
1. Two parietal bones
2. Two temporal bones
3. Frontal bone
4. Occipital bone
5. Sphenoid bone
6. Ethmoid bone
49
Describe the cranial vault (2 points)
- also called the calvaria
- forms the superior, lateral, and posterior aspects of the skull, as well as the forehead
50
Decribe the cranial base (6 points)
- forms the skull’s inferior aspect.
- Internally, prominent bony ridges divide the base into three distinct “steps” or fossae
- anterior cranial fossa
- middle cranial fossa
- posterior cranial fossae
- The brain sits snugly in these cranial fossae, completely enclosed by the cranial vault.
51
Describe the purpose of the facial bones (7 points)
- Form the framework of the face
- Contain cavities for the special sense organs of sight, taste, and smell
- Provide openings for air and food passage
- Secure the teeth
- Anchor the facial muscles of expression, which we use to show our feelings
- Made up of 14 bone, of which only the mandible and the vomer are unpaired.
- The maxillae, zygomatics, nasals, lacrimals, palatines, and inferior nasal conchae are paired bones.
52
Describe the hyoid bone (6 points)
- The hyoid bone lies inferior to the mandible in the anterior neck.
- It looks like a miniature version of the mandible.
- It is the only bone that does not articulate directly with any other bone.
- Though not directly connected to the skull, the hyoid bone is considered to be part of the skull.
- The hyoid bone acts as a movable base for the tongue.
- Its body and greater horns are attachment points for neck muscles that raise and lower the larynx during swallowing and speech.
53
Label the image (5 points)
54
Label the image (3 points)
55
Label the image (7 points)
56
Label the image (12 points)
56
Label the image (25 points)
56
Label the image (27 points)
57
Label the image (28 points)
58
Label the image (27 points)
59
Label the image (10 points)
60
Label the image (31 points)
61
Label the image (13 points)
62
Describe the vertebral column (7 points)
- Formed of a number of individual bones called vertebrae and two composite bones (sacrum and coccyx)
- Consists of 26 irregular bones, forming a flexible, curved structure
- The spine extends from the skull to the pelvis, where it transmits the weight of the trunk to the lower limbs.
- It also surrounds and protects the delicate spinal cord and provides attachment points for the ribs and for the muscles of the back and neck.
- The curvatures of the spine increase resiliency and flexibility of the spine.
- The major supporting ligaments of the spine are the anterior and posterior longitudinal ligaments, which run as continuous bands down the front and back surfaces of the spine, supporting the spine and preventing hyperflexion and hyperextension.
- Intervertebral discs are cushion-like pads that act as shock absorbers and allow the spine to flex, extend, and bend laterally.
63
Describe the divisions of the vertebral column (8 points)
- The vertebrae of the spine fall in five major divisions:
1. cervical vertebrae: the seven vertebrae of the vertebral column that are located in the neck
2. thoracic vertebrae: the 12 vertebrae that are in the middle part of the vertebral column and articulate with the ribs
3. lumbar vertebrae: five vertebrae of the lumbar region of the vertebral column, commonly called the small of the back
4. sacrum: five fused vertebrae which articulates with the hip bones
5. coccyx: the four fused vertebrae which are the terminus of the vertebral column
- The cervical and lumbar curvatures are concave posteriorly, and the thoracic and sacral curvatures are convex posteriorly.
- These four curvatures give the spine its S, or sinusoid, shape.
64
Label the typical vertebra structures (9 points)
65
Label the divisions of the vertebral column (9 points)
66
Describe the cervical vertebra (7 points)
- C1 and C2 differ from the other cervical vertebra.
- C1 (the atlas) has no body or spinous process and superior facets receive the occipital condyles of the skull and "carry the skull" just as Atlas carried the heavens in Greek Mythology.
- This joint allows you to nod your head to say 'yes'.
- C2 (the axis) has a dens that acts a pivot for rotation of the atlas, consequently it allows you to rotate your head to say 'no'.
- C3-C7 have a spinous process that project posteriorly and are bifid (except C7).
- The body is wide side to side, the vertebral foramen is large and triangular, and they contain transverse foramen (in transverse processes) to allow vertebral arteries to supply blood to the brain.
- C3-C7 are the most movement accommodating vertebra allow all general back movements - flexion, extension, lateral flexion and rotation.
67
Label the components of the Atlas (9 points)
68
Label the components of the Axis (8 points)
69
Label the components of the cervical vertebra (9 points)
70
Describe the thoracic vertebra (3 points)
- Thoracic vertebra spinous processes are long and face inferiorly and they have facets for ribs (except T11 and T12).
- They have a circular vertebral foramen and large heart shaped body. Movements allowed include rotation, but flexion and extension is largely limited.
- Lateral flexion is restricted by the ribs.
71
Label the components of the thoracic vertebra (8 points)
72
Describe the lumbar vertebra (2 points)
- Lumbar Vertebra have a large kidney shape body, short blunt spinous process, a triangular vertebral foramen and the transverse processes are thin and tapered.
- Movements allowed include flexion and extension, some lateral flexion, but no rotation
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Label the components of the lumbar vertebra (6 points)
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Describe the Sacrum and coccyx (3 points)
- The Sacrum is 5 fused vertebra (S1-S5).
- Superiorly it articulates with L5. Laterally it attaches to the pelvic bones.
- Inferiorly it articulates with the coccyx (3 to 5 fused vertebrae)
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Label the components of the Sacrum and coccyx (15 points)
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Label the components of the cervical vertebra from a superior view (7 points)
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Label the components of the thoracic vertebra from a superior view (7 points)
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Label the components of the lumbar vertebra from a superior view (5 points)
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Describe herniated disc (6 points)
- Intervertebral discs are a cushion-like pads that absorb shock when we walk, run and jump.
- They are composed of two parts.
1. The inner gelatinous like nucleus pulposus acts like a rubber ball giving the disc its elasticity and compressibility.
2. Its is surrounded by the annulus fibrosus, which is composed of collagen fibers and fibro-cartilage that acts to prevent limit the expansion of the nucleus pulposus, and to bind vertebra together to help withstand torsion and tension in the spine.
- Herniated or prolapsed disc from severe physical trauma to the spine (like bending forwards while lifting a heavy weight) involves rupture of the annulus fibrosus followed by protrusion of the spongy nucleus pulposus.
- If the protrusion impinges on the spinal cord, intense pain may result.
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Describe abnormal spinal curvatures (7 points)
- Abnormal spinal curvatures include:
- scoliosis
- kyphosis
- lordosis.
- Scoliosis (literally twisted disease) is abnormal lateral curvature of the spine (most often the thoracic spine).
- Kyphosis or "hunchback" is dorsally exaggerated thoracic curvature commonly seen in people with osteoporosis.
- Lordosis is sway-back and is accentuated lumbar curvature.
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Describe thoracic cage (8 points)
- Also known as the bony thorax
- Bones and costal cartilage that form the frame-work of the thorax
- Consists of the thoracic vertebrae dorsally, the ribs laterally, and the sternum and costal cartilages anteriorly
- The costal cartilages secure the ribs to the sternum
- The bony thorax:
- forms a protective cage around the vital organs of the thoracic cavity (heart, lungs, and great blood vessels)
- supports the shoulder girdles and upper limbs
- provides attachment points for many muscles of the neck, back, chest, and shoulders.
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Describe the sternum (7 points)
- The sternum lies in the anterior mid-line of the thorax.
- It is a flat bone approximately 15 cm long and consist of 3 bones fused
- the manubrium (most superior)
- the body
- xiphoid process (most posterior).
- The sternum is an important structure when administering compressions during cardio-pulmonary resuscitation (CPR).
- It is important to identify the xiphoid process to not compress it during compressions as it is relatively fragile and prone to fracture
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Describe the ribs (5 points)
- 12 pairs of ribs form the thoracic cage.
- All ribs attach posteriorly to the thoracic vertebrae and curve inferiorly to the anterior body surface.
- The superior 7 ribs attach directly to the sternum by individual costal cartilages. These are true ribs.
- The remaining 5 pairs of ribs are called false ribs that either attach indirectly or not at all to the sternum.
- The last 2 ribs (11 and 12) are called floating ribs as they have no anterior attachments
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Label the thoracic cage (14 points)
