1
Q
Parts of skeletal system
A
- bones (osseous tissue)
- ligaments - dense regular CT, connect bone to bone
- tendons - dense regular CT, connect muscle to bone (technically part musculoskeletal system)
- cartilage - primary hyaline, fibrocartilage (between bone on bone joints)
- Connective tissue - periosteum (dense irregular)
2
Q
Give two general elevations and projections
A
process
Any projection or bump. (acromion process)
ramus
An extension of a bone making an angle with the rest of the structure (ramus of the mandible)
2
Q
Function of skeletal system
A
- support
- storage of minerals
- storage of lipids -> yellow marrow
- blood cell production -> red marrow
- protection
- Leverage (force of motion)
3
Q
What are the six classifications of bone
A
- Flat bones (bones of the skull, sternum, ribs, scapulae). Sandwich of compact bone with spongy bone (diploë) in the middle
- Sutural bones - only found in skull
- irregular bones (vertebra / pelvic bone) - primarily spongy bone that is covered with a thin layer of compact bone
- short bones (tarsal and carpal bones) - consist primarily of spongy bone, which is covered by a thin layer of compact bone
- sesamoid bone (patella, pisaform) - spongy bone covered by compact bone.
- long bones (humerus (upper arm), radius / ulna (forearm), tibia (shin bone), fibular, phalanges), clavicle- primarily compact bone (diaphysis) with spongy bone at the epiphysis covered by a layer of compact bone at epiphysis.
3
Q
Six processes where tendons or ligaments attach
A
trochanter
a large, rough projection. Found exclusively on the femur
greater / lesser trochanter of femur
tuberosity
a smaller, rough projection or a rounded prominance
deltoid tuberosity (humerus), radial tuberosity (radius), tibial tuberosity (tibia), ischial tuberosity (ischia)
tubercle
a small, rounded projection (abductor tubercle)
greater / lesser tubercle (humerus) / conoid tubercle (clavicle), costal tubercle (rib), abductor tubercle (femur)
crest
a prominent ridge (iliac crest)
iliac crest (ilia), anterior crest (tibia), intertrochanteric crest (femur)
line
A low ridge (nuchal lines of occipital bones)
mylohoid line (mandible), intertrochanteric line (femur)
spine
A pointed, narrow process (spinous process on vertebre, spine of scapula)
ischial spine (ischia), [anterior superior, anterior inferior, posterior superior, posterior inferior] + iliac spine
4
Q
Five processes formed for articulation with adjacent bones
A
Head
expanded articular end of an epiphysis, separated from the shaft by a neck.
head of femur, fibia, humerus, ulna, radius, rib (flat bone)
no head on tibia
head of ulna is distal
Neck
A narrow connection between the epiphysis and the diaphysis. Often considered part of metaphysis.
neck of femur, anatomical / surgical neck of humerus
Condyle
A smooth, rounded articular process. forms an articulation with another bone.
occipital condyle, mandibular condyle, medial / lateral condyle (femur), medial / lateral condyle (tibia), trochlea + capitulum = condyle (humerus)
Trochlea
A smooth, grooved articular process shaped like a pulley (trochlea of humerus)
trochlea of humerus. Forms condyle with capitulum
facet
a small, flat articular surface (costal facets in thoracic vertebrae)
costal facets (vertebral body / transverse process), superior / inferior articualting facet of vertebrae
5
Q
Two Depressions
A
Fossa
A shallow depression
- articulation, attachement, passageway
iliac fossa, mandibular fossa, olecranon fossa (humerus), coronoid fossa (medial humerus), infraspinous fossa, supraspinous fossa, subscapular fossa, intercondylar fossa (femur), lacrimal fossa, radial fossa (humerus lateral)
Ulna is medial
Sulcus
A narrow groove (intertubercular salculs (bicipital groove))
- nerve / blood vessel pasageway
6
Q
Four Bone openings
A
foramen
a rounded passageway for blood vessels or nerves
canal or meatus
a passageway through the substance of a bone. Natural opening or canal. (internal acoustic meatus)
fissure
a narrow, elongated opening or groove. often houses nerves or blood vessels
sinus or antrum
a chamber within a bone, normally filled with air
antra -> plural. Antrum -> singular
7
Q
Describe the structure of a long bone
A
- articular cartilage: found on the surfaces of bones that form synovial joints, such as the knees, hips, shoulders, and elbows. It covers the ends of bones where they come into contact with each other. Primarily hyaline
- epiphysis: rounded edge on long bone, primarily consists of spongy bone, thin external layer of compact bone.
- metaphysis: wide portion of a long bone, between epiphysis and diaphysis. Primarily spongy bone, thin external layer of compact bone. Where epiphyseal plate is
- diaphysis: The shaft or central part of a long bone, primarily composed of compact bone
- epiphyseal plate: A hyaline cartilage plate in the metaphysis of a growing bone, responsible for lengthwise growth. Region closest to diaphysis proximal face, region closest to epiphysis, distal face. Chondrocytes larger in proximal face. Bone invades proximal face, calcifying, killing cartilage. At the same time proliferation occurs at distal plate. Think of cartilage “outrunning” ossification, pushing out the epiphysis. The epiphysial plate closes when bone growth outpaces cartilage production.
- epiphyseal line: The remnant of the epiphyseal plate in adult bones, appearing as a line once bone growth has ceased
femur is the longest bone in the body
8
Q
What is the periosteum?
what are the layers in the periosteum
A
- The periosteum is a dense, fibrous membrane that covers the outer surface of all bones except at the joints, where it is covered by articular cartilage. Plays a critical role in bone health, growth, repair, and overall functionality of the skeletal system
Outer Fibrous Layer
Made up of dense irregular connective tissue, containing blood vessels, nerves, and lymphatic vessels.
Inner Cellular Layer (Cambium Layer)
Contains osteoprogenitor cells, osteoblasts, mesenchymal stem cells, osteoclasts (more on bone surface), nerve cells, fibroblasts, macrophages
The periosteum directly covers the outer surface of bones, but it does not directly cover the spongy bone
9
Q
What is the medullary cavity
A
- is the central cavity of long bones, located in the diaphysis of long bones
- houses bone marrow (red in children, yellow in adults)
- houses blood vessels
- lined by the endosteum
10
Q
Describe endosteum
A
- thin vascular layer or connective tissue (associated with reticular ct) which lines the medullary cavity and central canals, in compact bone and the trabeculae of spongy bone
- contains a layer of connective tissue and a cellular layer with osteoprogenitor cells, osteoblasts, and osteoclasts.
the endosteum consists of a layer of flattened osteoprogenitor cells and a type-III collagenous fibers (reticular fibers). The endosteum is noticeably thinner than the periosteum
The periosteum directly covers the outer surface of bones, but it does not directly cover the spongy bone. Instead, the periosteum covers the compact bone layer that encloses the spongy bone
11
Q
Spongy bone trabeculae
A
- Trabeculae are irregularly arranged, thin plates or struts. They form a porous network that provides structural support and strength to the bone while reducing its weight. Helps resist stresses and strains from various directions
- composed of lamellae, which are layers of bone matrix containing osteocytes (housed in lacunae). The trabeculae are surrounded by red bone marrow.
- canaliculi of spongy bone connect to the adjacent cavities, instead of a central haversian canal, to receive their blood supply
- lined by endeosteum.
- functional unit of spongy (cancellous) bone
contain trabecular lamellae
trabecula -> singular
12
Q
Four types of lamellae in bone
A
concentric lamellae
Found in compact bone, arranged in concentric rings around central (Haversian) canals. Form osteon.
interstitial Lamellae
Found between osteons in compact bone.
circumferential Lamellae
located on the outer surfaces of compact bone, encircling the entire bone shaft.
trabecular lamellae
Found in spongy bone, forming the trabeculae
Lamellae are composed of ground substance (collagen fibers + proteins + hydroxyapatite crystals), osteocytes, and canaliculi
13
Q
Components of Bone matrix
A
Organic Components
- collagen fibers (primarily type I). Provide tensile strength. Give bone ability to absorb shock.
- other proteins (proteoglycans and glycoproteins)
- 1/3 weight
Inorganic Components
- Hydroxyapatite crystals -> composed of calcium and phosphate and calcium hydroxide.
- small amounts of Mg (Magnesium contributes to the formation of bone matrix and plays a role in the regulation of calcium and phosphate balance), F(enhances stability / strength), Na+ (mineral balance / bone formation / structural integretiy),
- 2/3 of weight
ground substance
both organic and inorganic components of matrix.
Bones derive their flexibility from collagen fibers (Type I collagen) and their rigidity from the mineral content, primarily hydroxyapatite
14
Q
Cells in Osseous Tissue
A
- Osteoprogenitor cells. originate from mesenchymal stem cells. Become osteoblasts . Found in periosteum, endosteum, bone marrow.
- Osteoblast. Osteogenic cells. responsible for synthesizing and secreting the bone matrix, including collagen and other proteins (primary mineralization).
- Osteocytes. Maintain bone matrix, regulate bone remodeling in response to mechanical stress. Mature osteoblasts.
- Osteoclast. Osteoclasts are large, multinucleated cells responsible for bone resorption, breaking down bone tissue by secreting acids and enzymes that dissolve the mineral components and collagen. Process essential for bone remodeling.
- Hematopoietic stem cells. Become osteoclasts. Primarily found in bone marrow
bone mineralization has two phases, primary and secondary. Primary is orchestrated by osteoblasts (secret a large amount of collagen fibrils, non-collagenous proteins, and matrix vesicles, which are extracellular vesicles that trigger mineralization via membrane transporters and enzymes). Secondary mineralization is not well understood
15
Q
What is an osteon
A
The fundamental structural unit of compact bone. Each osteon is a cylindrical structure that helps maintain the strength and integrity of bone.
Contains:
- central canal which contains blood vessels, nerves, and lymphatic vessels. Provide nutrients. Remove waste
- Lamellae, concentric rings of bone matrix. Made of collagen fibers and mineralized ground substance (primarily hydroxyapatite)
- Lacunae: small spaces between lamellae, houses osteocytes.
- osteocyte: mature osteoblast, reside in lacunae, maintain matrix.
- canaliculi: channels radiating from lacunae, connect lacunae to each other and central canal. Allow exchange of nutrients, waste, and signals (gap junctions).
- endosteum, lines central canal
16
Q
Perforating fibers
A
- Perforating fibers, also known as Sharpey’s fibers, are strong, collagenous fibers (primarily type I collagen) that extend from the periosteum into the underlying bone matrix
- They run perpendicular to the surface of the bone, anchoring the periosteum to the bone
- Perforating fibers firmly anchor the periosteum to the outer surface of the bone, ensuring that the periosteum remains tightly attached
17
Q
Describe Endochondral Ossification
A
Interstitial growth Long bones
- Chondrocytes near the center of a hyaline cartilage template (which resembles the shape of the future bone) increase in size as the matrix calcifies. The chondrocytes die leaving cavities within the cartilage. This becomes the primary center of ossification.
- Blood vessels grow around the edges of the cartilage template, cells in the perichondrium convert to osteoblasts creating a superficial exterior layer of bone (bone colar).
- Blood vessels enter the central region of the calcified cartilage, bringing osteoprogenitor cells which differentiate into osteoblasts, producing spongy bone at the primary center of ossification. Bone formation spreads along the shaft towards both ends.
- As the bone remodels, the spongy bone in the primary center of ossification is resorbed by osteoclasts creating the medullary cavity.
- Capillaries and osteoblasts migrate into the epiphyses creating secondary ossification centers (normally one at each end).
- The epiphyses fills with spongy bone, hyalin cartilage persistes at end (articulating cartilage) and in epiphyseal plate. This is the site of interstitial growth.
18
Q
Describe intramembranous Ossification
6 steps
A
Development of flat bones
also called dermal ossification
- Differentiation of Mesenchymal Cells: Mesenchymal cells in the dermis differentiate directly into osteoblasts, initiating the process of ossification.
- Formation of Bone Spicules: The osteoblasts begin secreting bone matrix, which mineralizes to form spicules (small, needle-like structures) that spread into the surrounding tissues.
- Trapping of Blood Vessels: As the spicules grow and connect, they trap blood vessels within the developing bone, ensuring a good blood supply for continued growth and development.
- Development of Spongy Bone: Over time, the network of spicules expands and connects to form trabeculae, giving the bone a spongy structure.
- Formation of Periosteum: The outer layer of mesenchymal cells condenses to form the periosteum, a membrane that covers the bone and contains osteoprogenitor cells and osteoblasts.
- Formation of Compact Bone: Osteoblasts in the periosteum continue to produce bone matrix, which eventually forms layers of compact bone on the outer surfaces of the spongy bone, providing additional strength and structure.
19
Q
Describe Two types of Growth in Long Bones
A
Interstitial
- Growth in length.
- endochondral ossification at secondary ossifcation centers (epiphyseal plate) at the epiphysis.
- continues until epiphyseal closure.
Appositional Growth
- Growth in diameter.
- Compact bone thickens and strengthens long bone
- osteoclasts break down old tissue, osteoblasts deposit bone matrix, becomes surrounded by the matrix, become osteocytes. Occurs at endosteum or periosteum.
20
Q
Describe process of interstitial growth. Include zones.
A
The epiphyseal plate has hyaline cartilage in the middle with a transitional zone where cartilage is replaced by bone.
- Zone of resting cartilage, consistes of typical hyalin cartilage.
- Zone of proliferating cartilage, chondrocytes multiple, arrange themselves in longitudinal columns.
- Zone of hypertrophic cartilage, chondrocytes cease to multiple, undergo hypertrophy.
- zone of calcification, minerals are deposited between the columns of lacunae, calcifying the cartilage. Not the permanent mineral deposits, temporary.
- zone of ossification: Chondrocytes die, leaving empty channels. Blood vessels invade the channels, bringing with them osteoblasts. Osteoblasts start to lay down new bone matrix on the remnants of the calcified cartilage, creating a network of spongy bone (trabecular bone). Osteoclasts break down spongy bone in center elongating the marrow cavity. Osteoblasts convert exterior spongy bone into compact bone.
Region closest to diaphysis proximal face, region closest to epiphysis, distal face. Chondrocytes larger in proximal face. Bone invades proximal face, calcifying, killing cartilage. At the same time proliferation occurs at distal plate. Think of cartilage “outrunning” ossification, pushing out the epiphysis. The epiphysial plate closes when bone growth outpaces cartilage production.
21
Q
Four main sets of blood vessels in bones
A
- Nutrient vessels - Enter the bone through the nutrient foramen in the diaphysis of long bones. Supply inner layers of bone with nutrients.
- Metaphyseal Arteries and Veins
Found in the metaphysis, the region between the diaphysis and the epiphysis of long bones. Blood supply of the metaphyseal region and the adjacent areas of the growth plate (epiphyseal plate) - Epiphyseal Arteries and Veins:
located in the epiphysis. They provide blood to the epiphyseal regions, including the cartilage of the growth plate and the spongy bone in the epiphysis - Periosteal vessels - Located in the periosteum. Supply the outer layers of compact bone and the periosteum
Epiphyseal arteries and veins originate from periosteal arteries and veins, nutrient arteries and veins, and sometimes from metaphyseal arteries and veins. These vessels penetrate the epiphysis, supplying blood to the growth plate, spongy bone, and surrounding joint structures, ensuring the proper development and maintenance of bone tissue.
22
Q
Bone remodeling
A
- In bone remodeling osteoblasts create new bone by synthesizing and calcifying the bone matrix. At the same time osteoclasts break down old or damaged tissue, resorbing it. Bone remodeling is a dynamic process. If deposition is greater than removal bones get stronger, if removal is faster than replacement bones get weaker
- In the first year of life almost 100% of the skeleton is replaced
- In adults about 10% of the skeleton is remodeled each year.
23
What are the effects of exercise on Bone
- Wolff’s law of bone states that the architecture of a bone is determined by the mechanical stress placed on it.
- When bones are heavily stressed they will become thicker and stronger, when they are not used osteocytes remove the matrix to get rid of unnecessary mass. Up to one third of bone mass can be lost in a few weeks of inactivity. This rapid loss occurs because bones rely on mechanical stress and weight-bearing activities to maintain their density and strength
```
Mechanical Loading:
When you engage in weight-bearing activities, such as running, jumping, or resistance training, mechanical stress is applied to the bones. This stress leads to the deformation of bone tissue, which in turn stimulates the bone remodeling process. Bone remodeling involves the resorption of old bone by osteoclasts and the formation of new bone by osteoblasts
Exercise influences bone density, gemotetry, and quality
```
24
Six dietary requirements for bone growth
1. Calcium (primary mineral / structural support), phosphates (combine with calcium to create hydroxyapatite crystals in bone), small amounts of MG (Magnesium contributes to the formation of bone matrix and plays a role in the regulation of calcium and phosphate balance), F (enhances stability / strength), F (hemoglobin production)
2. Most active form of D3, calcitriol, behaves as a hormone, raising the blood/calcium levels by increasing calcium absorption in small intestines, increases calcium resorption from the skeleton, and weekly promotes reabsorption of calcium ions by the kidney.
3. Vitamin C is essential to make collagen and stimulate osteoblast differentiation.
4. Vitamin A helps regulates the activity of osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells), ensuring a balanced bone remodeling process.
5. Vitamin K is essential for bone mineralization and the regulation of calcium in the bones and blood
6. Vitamin B12 is involved in bone protein synthesis and overall bone health
25
Six hormones that affect bone grown
1. **Calcitriol**, the most active form of vit D, increases calcium and to a lesser extent phosphate absorption in the digestive tract, increases calcium resorption (in conjunction with PCTH), and weekly reduces calcium loss in urine.
2. **Calcitonin**: Is secreted by C cells in the *thyroid*, when blood calcium is too high, it inhibits osteoclasts and stimulates osteoblastsm, inhibits calcium absorption in intestines, Inhibits renal reabsorption increasing calcium excretion by kidneys.
3. **Parathyroid hormone**: Is released by *parathyroid glands* when blood calcium is to low and increases blood calcium levels. Increases calcium reabsorption in kidneys (reducing calcium in urine), increaces calcitriol production increasing calcium absorption in the digestive track, stimulates osteoclasts releasing calcium from the bones.
4. **Sex hormones**: Initially promotes ossification and eventually promotes epiphyseal closure. Estrogen has a stronger effect than testosterone.
5. **Growth hormones**: secreted by *pituitary gland*. Stimulate bone growth, ossification.
6. **thyroxine / TH / T3T4**: Thyroxine is a hormone produced by the *thyroid gland* that stimulates bone growth and development by promoting the metabolism and activity of osteoblasts
26
Why is calcium important
1. Calcium deficiency, hypocalcemia causes excitability of the nervous system can lead to muscle tremors, spasms and or tetany (in severe cases seizures). Can cause paresthesia (numbness particular around mouth and extremities)
2. Calcium excess, hypercalcemia, makes nerves and muscle cells less excitable than normal, can make them unresponsive.
3. Important for membranes, neurons, muscles cells (especially the heart)
*Regulation of Sodium Channels: Calcium ions are important in regulating the activity of voltage-gated sodium channels on the cell membrane. Calcium ions help to "stabilize" these channels, meaning that in normal conditions with adequate calcium levels, sodium channels require a stronger depolarization to open. When extracellular calcium levels are low, these sodium channels become more easily activated, which can lead to increased excitability. With higher levels of extracellular calcium, more calcium ions are available to bind to the extracellular sites on voltage-gated sodium channels. This binding further stabilizes the sodium channels, making them less likely to open in response to depolarization*
27
Describe function of parathyroid hormone
The parathyroid hormone (PTH) is produced in the parathyroid glands when calcium levels are low. It increases calcium levels by stimulating osteoclasts, increasing intestinal absorption of calcium by promoting calcitriol production, and decreasing calcium excretion in kidneys
*The parathyroid glands release parathyroid hormone (PTH) in response to a decrease in serum calcium. PTH acts on the kidneys to increase calcium reabsorption in the ascending loop of Henle, the distal convoluted tubule, and the collecting duct. The kidney also responds to PTH by increasing secretion of Vitamin D3, which in turn stimulates calcium absorption through the gut. PTH acts on the bones to stimulate osteoclasts involved in bone reabsorption and the release of free calcium. All of these processes contribute to the rise in serum calcium.*
28
Describe function of calcitonin
Calcitonin, secreted by **c cells in the thyroid** is secreted when calcium levels are high and decreases blood calcium levels. It inhibits osteoclast activity and increases osteoblast activity. Decreases intestinal absorption of calcium and increases calcium excretion in the kidneys
*Calcitonin is released by the thyroid parafollicular cells (C-cells) in response to an increase in serum calcium. Calcitonin acts on the bones to stimulate osteoblasts to deposit calcium in bones. Calcitonin also inhibits renal reabsorption of calcium, increasing urinary calcium excretion. Finally, calcitonin also inhibits calcium absorption in the intestines. These processes lead to a decrease in serum calcium*
29
What are the general steps in fracture repair?
1. Hematoma Formation: Bleeding occurs and produces a clot **fracture hematoma**, establishing a fibrous network as the basis for new bone growth. Bone cells in the area die. Blood capillaries grow into the clot, and fibroblasts, macrophages, and osteoclasts invade the tissue from both the endosteum and periosteum, forming **granulation tissue**.
2. Fibrocartilaginous Callus Formation: Osteogenic cells differentiate into chondroblasts and fibroblasts, producing fibrocartilage and collagen fibers. This creates an **internal and external soft callus**, which stabilizes the fracture.
3. Bony Callus Formation: Osteoblasts: differentiate from osteogenic cells and begin to replace the fibrocartilaginous callus with spongy bone, forming what is known as the **hard callus**. This spongy bone hard callus acts as a temporary splint, stabilizing the fracture further. This process typically takes about 4-6 weeks.
4. Osteoblasts and osteoclasts remodel the fracture for several months to a year, gradually replacing the spongy bone of the hard callus with compact bone, restoring the bone's original shape and strength.
*growth resembles intramembranous growth*
30
What are osteopenia and osteoporosis, and what are some of their effects?
Osteopenia is the precursor to osteoporosis, bone mineral density is lower than normal, bones are thinner and weaker. Osteoporosis is severe bone loss density, bones become fragile, height can be lost, teeth can be degraded.
Osteoporosis is more common in women, estrogens and androgens help maintain bone mass, the drop in estrogen after menopause increases the likelihood of severe DB loss.
One can reduce osteoporosis risk by adequate dietary intake of calcium and vitamin D. Weight bearing exercises promote bone density, and avoiding smoking and alcohol consumption will limit BD loss.
31
List differences between spongy and compact bones.
List similarities
**Differences**
- Spongy Bone: composed of network of trabeculae, found primarily at the ends of long bones, within the interior of short, irregular, and flat bones. Functional unit is the trabeculae, composed of irregularly arranged llamelae, primarily associated with red marrow in adults
- compact bone: osteon, central canal, concentric / circumferential / interstitial lamellae, primarily associated with yellow marrow in adults
**similarities**
osteocytes, lamellae, lacunae, canaliculi
*Compact bone has high compressive strength and rigidity, supporting weight and resisting bending and torsion. Spongy bone has less compressive strength but is more flexible, absorbing shock and distributing mechanical loads*
32
Give four growth disorders
**pituitary dwarfism**
Caused by insufficient growth hormone production from the pituitary gland, leading to proportionate but significantly shorter stature.
**achondroplasia**
A genetic disorder which affects the fibroblast growth factor receptor. Causes impaired conversion of cartilage to bone. Primarily affects endochondral ossification. This results in shorter limbs as the growth plates in long bones close prematurely. The trunk remains regular-sized because the axial skeleton is less affected by this process.
**gigantism**
Gigantism is caused by excessive secretion of growth hormone (GH), usually due to a pituitary adenoma. This excess GH stimulates the growth plates, leading to abnormal growth of long bones and overall body size. The excessive GH affects all parts of the body before the growth plates close, resulting in an overall increased stature with proportional body dimensions.
**acromegaly**
Acromegaly is caused by excessive secretion of growth hormone (GH) in adults, usually due to a pituitary adenoma. This excess GH leads to appositional growth, which is the thickening and enlargement of bones that have already fused, primarily affecting the hands, feet, and facial bones. The condition leads to disproportionate growth, with enlarged extremities and facial features
33
In the adult skeleton where is red bone marrow found? what about yellow?
**Red**
In adults, red bone marrow is found primarily in the central skeleton. In flat bones, such as the sternum, ribs, and skull, scapula, as well as in the irregular bones like the vertebrae and the pelvis (specifically the iliac crest). It can also found in the epiphyses (ends) of long bones such as the femur and humerus.
Red marrow is responsible for hematopoiesis, the production of blood cells.
**yellow**
medullary cavity of long bones. Yellow marrow primarily stores fat and can convert back to red marrow if necessary, such as in cases of severe blood loss or increased demand for blood cell production
34
List Six cranial bones
1. Frontal Bone: Flat bone
2. Left / Right Parietal Bones: Flat bones
3. Left / Right Temporal Bones: Irregular bones
4. Occipital Bone: Flat bone
5. Sphenoid Bone: Irregular bone
6. Ethmoid Bone: Irregular bone
35
List eight facial bones
1. Maxillae (2): Irregular bones *(maxilla -> singular)*
2. Mandible: Irregular bone
3. Palatine Bones (2): Irregular bones
4. Nasal Bones (2): Flat bones
5. Lacrimal Bones (2): Irregular bones
6. Inferior Nasal Conchae (2): Irregular bones
7. Vomer: Flat bone
8. zygomatic bone: irregular
36
What bone is not attached to other bones
The hyoid bone - irregular bone
- supports tongue is involved in swallowing and speech
- attachment site for muscles in throat
37
What are the five bones in the spine
1. Cervical vertebrae (1-7) - most movement. C1 = atlas, c2 = axis
2. thoracic vertebrae (1-12) - each articulate with one or more pairs of ribs (inferior / superior costal facets)
3. lumbar vertebrae (1-5) - 5th lumbar vertebra articulates with sacrum
4. sacrum (S1-S5) - articulates with the coccyx. protects reproductive, digestive, and urniary organs.
5. coccyx
*all irregular*
38
8 "arm" associated bones
1. Scapulae: Flat bone
2. Clavicles (2): Long Bone
3. Humerus: Long Bone. Articulates with pectoral girdle
4. Radius: Long Bone. Articulates with wrist and radius (ulnar notch)
5. Ulna: Long Bone articulates with humerus
6. Carpal bones / carpals: Short bones
7. Metacarpal bones / metacarpals: Long bones. Number I-V from lateral (thumb) to medial
8. Phalanges: Long bones. Pollex (two phalanges (proximal / distal)), fingers (three phalanges (proximal, middle, distal))
39
4. Pelvic Girdle Bones
1. Coxa: Irregular - entire hip bone, contains ilium, ischium and pubis. Also called pelvic or innominate bone.
2. Ilium: Flat Bone
3. Pubis: Irregualr
4. Ischium: Irregular Bone
*acetabulum (hip socket). Meeting point of the ilium, ischium, and pubis*.
*strong, bears weight of body, stress of movement*
*ilia, ischia, pubes, coxae -> plural*
40
"leg" associated bones
1. Femurs (2): Long Bones
2. Tibiae (2): Long Bones. Supports body weight
3. Patellae (2): Sesamoid bones
4. Fibulae (2): Long Bones. Attaches muscles of feet and toes but does not support wieght.
5. Tarsal bones / tarsals (14): Short bones
6. Metatarsal bones / metatarsals (10): Long Bones. Number 1-V medial to lateral
7. Phalanges (28): Long Bones/. Hallux (distal proximal), other four toes (distal, MIDDLE, proximal)
*phalanx is the singular of phalanges*
41
6 nerve locations in bone
1. Periosteum: The dense, fibrous outer layer of the bone that is richly innervated with sensory nerve fibers, making it sensitive to pain and pressure.
2. Haversian Canals (Central Canals): Found within compact bone, these canals run longitudinally through the osteons and contain blood vessels and nerve fibers, supplying nutrients and innervation to bone cells.
3. Perforating Canals (Volkmann's Canals): These transverse or diagonal canals connect the Haversian canals and allow blood vessels and nerves to penetrate from the periosteum into the deeper layers of the bone.
4. Nutrient Canals: Channels through which the nutrient artery and vein, along with accompanying nerves, enter the bone to supply the inner layers, including the bone marrow.
5. Endosteum: The thin vascular membrane lining the inner surfaces of the bone, including the medullary cavity, which contains nerves involved in the regulation of bone growth and remodeling.
6. Bone Marrow: Although the bone marrow itself is not innervated, nerves traveling through the nutrient canals can influence the marrow environment indirectly through their regulatory functions.
42
Axial Skeleton
Appendicular skeleton
**Axial**
1. skull
2. spine (vertebrae, sacrum, coccyx)
3. thoracic cage
4. hyoid bone
**Appendicular**
- all bones but axial. includes limbs, supportive girdles.
- allows movement
43
cervical vs thoracic vs lumbar vertebrae
**Cervical Vertebrae:**
- Size: Generally smaller and lighter (support only the head).
- Foramen: Each has a large vertebral foramen and transverse foramina (holes) in their transverse processes.
- Shape: The spinous process is often bifid (split into two parts) except for C7, which has a longer, non-bifid spinous process.
- Number: Seven cervical vertebrae (C1 to C7). C1 (*atlas* no spinous process / no body), c2 (*axis* has odontoid process, vertical process projecting superiorly). Most motion
**c7** - has a long and prominant spiny process. Normally has smaller transverse foramina. Is a transitional vertebrae, has characteristics of cervical and thoracic.
**Thoracic Vertebrae:**
- Size: Intermediate in size.
- Foramen: Smaller, round vertebral foramen.
- Shape: The spinous processes are long, pointed, and angled downward. They also have facets for rib articulation (costal facets) on their bodies and transverse processes. The transverse process are angled more medially. Look like the come from infront of superior articulating proceess instead of behind it.
- Number: Twelve thoracic vertebrae (T1 to T12).
**Lumbar Vertebrae:**
- Size: Largest and most robust to support more weight.
- Foramen: Triangular vertebral foramen.
- Shape: The spinous processes are short, thick, and more horizontal. The transverse processes are also larger and more robust.
- Number: Five lumbar vertebrae (L1 to L5).
```
transverse foramen: vertebral artery / vein. Blood supply to brain
intervertebral foramen: sensory nerves
```
44
List 4 major sutural joints
Immovable joints between skull bones, dense fibrous connective tissue.
1. **lambdoid**: between the parietal bones and the occipital bone
2. **coronal**: between the parietal bones and the frontal bone
3. **sagittal**: between the right and left parietal bones
4. **squamous**: between the parietal bone and the temporal bone
*sutural bones -> small islands of bone that fill gaps in sutures. Vary between individuals*
45
What is a fontanelle
What are the 4 major fontanelles
*Areas where cranial bones have not yet fused. Consist of fibrous connective tissue. Eases delivery and allows for quick brain growth. Disappear by age 2*
1. Sphenoidal fontanelles (2)
2. Mastoid fontanelles (2)
3. Anterior fontanelle
4. Occipital (posterior) fontanelle
*mastoid is the bony process of the temporal bone, sites behind ear*
46
Seven bones of the eye
1. **Frontal Bone**: Forms the superior part of the orbit.
2. **Zygomatic Bone**: Forms the lateral wall and part of the floor of the orbit.
3. **Maxilla**: Forms the majority of the floor of the orbit.
4. **Palatine Bone**: Contributes a small part to the floor of the orbit.
5. **Lacrimal Bone**: Located in the medial wall, it contains the lacrimal fossa for the lacrimal sac.
6. **Ethmoid Bone**: Forms a significant part of the medial wall.
7. **Sphenoid Bone**: Contributes to the posterior part of the orbit, including the superior orbital fissure and optic canal.
47
What are the functions of sinuses?
What are the major sinuses?
Sinuses:
1. lessen the weight of bone
2. Produce mucus to clean and moisten air
3. Serve as a resonating chamber for speech production
Major sinuses:
1. **frontal sinus**: within the frontal bone, situated above the eye.
2. **sphenoidal sinus**: Within the sphenoid bone.
3. **Maxillary sinus**: located within the maxillae.
4. **Ethmoidal sinus / ethmoid air cells**. Located within the ethmoid bone, between the eyes and behind the bridge of the nose.
48
What are the curves of the vertebral column
**primary / accommodation curves**
1. thoracic - CONVEX
2. sacral - CONVEX
- are present during fetal development and accommodate internal organs.
**secondary / compensation curves**
1. lumbar - CONCAVE
2. cervical - CONCAVE
- appear after birth, shift body weight for upright posture, fully formed by age ten
49
Name disc between vertebrae
**intervertebral disc**
Intervertebral discs are fibrocartilaginous structures located between the vertebral bodies of the spine. They act as shock absorbers and allow for flexibility and movement of the spine. Each intervertebral disc consists of two main components:
**nucleus pulposus**
The inner core of the intervertebral disc.
It is gel-like and primarily composed of water, collagen fibers, and proteoglycans.
Provides the disc with its elasticity and compressibility, allowing it to absorb and distribute pressure.
**annulus fibrosus**
The outer layer of the intervertebral disc.
Composed of several concentric layers of tough *fibrocartilage*.
Provides strength and structure to the disc, containing the nucleus pulposus and preventing it from bulging out.
50
Describe thoracic Cage
consists of: thoracic vertebrae, ribs, costal cartilage, sternum
functions:
1. protect heart, lungs, thymus
2. maintain position of vertebral column
3. attachment of muscles for breathing, maintaining posture, moving clavicles/scapulae, upper limbs
51
Describe pectoral Girdle
*also called shoulder girdle*
consists of:
1. clavicles / collarbones: originate at the manubrium (sternal end), articulate with the scapulae (acromial end)
2. scapulae / shoulder blades: articulate with humerus
connects with the axial skeleton only at the **manubrium** of the sternum.
function
1. connects arms to the body
2. positions the shoulders
3. provides a base for arm movement
52
Differences in female pelvis
- smoother and lighter. Less prominent muscle and ligament attachments
- enlarged pelvic outlet and outlet
- broad pubic angle - pelvic arch
- less curvature of sacrum and coccyx
- broad, low pelvis
- ilia project laterally not upwards
*ilium -> singular, ilia -> plural*
53
carpal bones
Proximal carpal bones
1. **scaphoid**: near styloid process of radius
2. **lunate**: medial to scaphoid
3. **Triquetrum**: medial to lunate bone
4. **pisiform** anterior to triquetrum. sesamoid bone.
Distal carpal bones
1. **trapezium**: lateral
2. **trapezoid**: medial to trapezium
3. **capitate**: largest
4. **hamate**: medial, distal, has a hook.
Allow wrist to bend and twist
```
proximal row (lateral to medial / thumb to pinky)
Some = Scaphoid
Lovers = Lunate
Try = Triquetrum
Positions = Pisiform
distal row (lateral to medial / thumb to pinky)
That = Trapezium
They = Trapezoid
Can't = Capitate
Handle = Hamate
```
54
True and False pelvis
**True Pelvis / lesser pelvis**
The true pelvis is located below the pelvic brim, which is the bony boundary formed by the sacral promontory, arcuate line of the ilium, pectineal line of the pubis, and the pubic symphysis.
it is enclosed by parts of the ilium, ischium, and pubis, as well as the sacrum and coccyx.
The true pelvis contains and protects the pelvic organs, such as the urinary bladder, rectum, and in females, the uterus and ovaries
**False pelvis**
The false pelvis is situated above the *pelvic brim*, lying between the iliac crests and the pelvic brim, formed by upper parts of ilium. The false pelvis primarily supports the weight of the abdominal organs and provides attachment points for muscles
*portions of the ilium, ischium, and pubis form the boundaries of the true pelvis, but not the entirety of these bones.*
55
What are the tarsal bones
1. Talus: carries weight from tibia across tochlea
2. calcaneous (heal bone): transfers weight from talus to ground.
3. cuboid: articulates with calcaneus
4. Navicular: articulates with talus
5. medial cuneiform
6. intermediate cuneiform
7. lateral cuneiform
```
Tiger: Talus
Cubs: Calcaneus
Need: Navicular
MILC:
M: Medial cuneiform
I: Intermediate cuneiform
L: Lateral cuneiform
C: Cuboid
```
56
What are the arches of the feet
Arches transfer weight from on part of the foot to another
**longitudinal arch**
- lateral longitudinal arch: runs along the outside of the foot from the heel to the little toe.
- medial longitudinal arch: runs along the inside of the foot from the heel to the big toe
**transverse arch**
formed by a difference in curvature between medial and lateral borders of the foot. This arch is located at the level of the tarsal bones and extends across the midfoot.
57
Identify Seven general characteristics of vertebrae
1. **body** - where vertebrae connect.
2. **vertebral foramen** - largest foramen, largest in cervical, round / oval in thoracic / triangular in lumbar. Where spinal column travels.
3. **spinous process** - projection in anterior part.
4. **transverse process** - most lateral projection.
5. **superior articulating process** - superior to transverse process and laminae. Creates a joint with inferior articulating process of higher vertebra. Have superior facets.
6. **inferior articulating process** - inferior to laminae. Have inferior facet
7. **vertebral arch**: made of laminae and pedicles. Laminae are medial to transverse process and lateral to spinous process. Pedicles two short cylindrical process which connect laminae to vertebral body.
8. **intervertebral foramen** - space between vertebrae. Where spinal nerves enter /exit
9. **transverse foramina** - foramen in transverse process. ONLY found in cervical vertebrae.
10. **superior and inferior facets**: superior facet is on the superior articulating process, inferior facet is on the inferior articulating process.
11. **costal facets**. superior, inferior and transverse costal facets. Not every vertebrae has all three. ONLY found in thoracic vertebrae.
58
Sacral Regions
Sacrum is **5** fused vertebrae
1. Base: broad superior surface. "horizontal" flat surface on superior side.
2. Ala: wings at either side of the base, attachment point for muscles. Still relatively horizontal.
3. **Sacral promontory**: On the anterior side at the center of the base
4. Apex: the narrow inferior (horizontal) portion, articulates with the coccyx.
5. **auricular surface**: articulate with the ilium of the pelvis forming the sacroiliac joint. Posterior and inferior to the ala. Form posterior "wings" shaped a bit like an ear.
7. **anterior and posterior sacral foramina**: Anterior foramina on pelvic surface, posterior on dorsal surface. Four anterior, four posterior.
*posterior side of sacrum has "spines" / medial sacral crest*
59
Describe the coccyx
Function: attaches ligaments and a constricting muscle of the anus
Structure: three to five fused coccygeal vertebrae
60
Bones and structures of sternum
1. **Body**
2. **Xiphoid process**
3. **Manubrium**: jugular notch, clavicalar notch
*sternum*
61
categorize ribs by type
**True Ribs: 7**
- Attach directly to the sternum via costal cartilage.
- pairs 1-7
**False Ribs: 5**
- Do not attach to sternum. Instead, their cartilages connect to the cartilage of the rib above them, creating an indirect attachment to the sternum.
- pairs 8-12
- last two pairs (11-12) ribs are **floating ribs**, do not attach to sternum at all
*costal cartilage -> hyaline cartilage*
*ribs -> flat bones*
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