Bone Cells and Tissue Quiz

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Questions and Answers

What is the primary function of osteoblasts?

Break down old bone tissue

Communicate with osteocytes

Maintain mineral concentration

Create new bone tissue (correct)

Where do osteocytes reside within bone tissue?

Canaliculi

Lacunae (correct)

Trabeculae

Haversian canals

What is the role of osteoclasts in the skeletal system?

Produce collagen

Transform cartilage into bone

Resorb old bone (correct)

Secrete enzymes

Which type of bone tissue is primarily dense and structured in layers?

Compact bone Signup and view all the answers

Which vitamin is crucial for promoting calcium absorption and bone health?

Vitamin D Signup and view all the answers

What occurs immediately after a bone fracture?

A hematoma forms Signup and view all the answers

How does exercise affect bone density?

It increases bone density Signup and view all the answers

What role does Parathyroid hormone (PTH) play in calcium homeostasis?

It stimulates osteoclasts to break down bone and release calcium. Signup and view all the answers

What type of matrix do osteocytes reside in within spongy bone?

Lattice-like matrix Signup and view all the answers

Which hormones are known to stimulate osteoblast activity and promote bone formation?

Thyroid hormones and Sex hormones Signup and view all the answers

What are trabeculae in the context of bone structure?

The small bony structures that provide strength to bones Signup and view all the answers

What is the first step in the healing process after a fracture?

Formation of a hematoma Signup and view all the answers

Which of the following is NOT a component of the axial skeleton?

Humerus Signup and view all the answers

What structure is primarily responsible for allowing the head to nod?

C1 Vertebrae Signup and view all the answers

Which vertebrae are characterized by having transverse foramen?

Cervical vertebrae Signup and view all the answers

Which part of the intervertebral disc allows for flexibility and compression?

Nucleus Pulposus Signup and view all the answers

What is the function of the anterior longitudinal ligament?

Prevent excess posterior movement Signup and view all the answers

At what age do the bones that form the sacrum typically fuse?

By age 20 Signup and view all the answers

What is the role of costal facets in the thoracic vertebrae?

Attach to ribs Signup and view all the answers

Which vertebral region carries the most weight and has large, thick bodies?

Lumbar vertebrae Signup and view all the answers

What primarily happens to intervertebral discs in the lumbar spine?

They are most often herniated Signup and view all the answers

Which bone houses the middle and inner ears and includes the mastoid process?

Temporal bone Signup and view all the answers

What structure allows for the entry and exit of the spinal cord in the occipital bone?

Foramen magnum Signup and view all the answers

Which bone formation primarily contributes to the nasal septum?

Vomer Signup and view all the answers

Which cranial fossa contains the optic canal crucial for the optic nerve?

Middle cranial fossa Signup and view all the answers

Which bone forms the lateral portion of the orbit and the zygomatic arch?

Zygomatic bone Signup and view all the answers

What is the primary function of the nasal conchae?

Warm and moisturize incoming air Signup and view all the answers

Which structure is responsible for muscle attachment and contributes to the nasal cavity?

Pterygoid plates Signup and view all the answers

What type of bone is the hyoid classified as?

Not a bone of the skull Signup and view all the answers

Which of the following bones has a sella turcica that houses the pituitary gland?

Sphenoid bone Signup and view all the answers

Which bone contributes to the structure of the hard palate?

Palatine bone Signup and view all the answers

What is the total number of cranial bones in the human skull?

8 Signup and view all the answers

The mandible is unique among skull bones because it is:

The only mobile skull bone Signup and view all the answers

Which suture is located at the junction between the right and left parietal bones?

Sagittal suture Signup and view all the answers

What is primarily contained within the posterior cranial fossa?

Cerebellum Signup and view all the answers

What is the role of the supraspinous ligament in the spinal structure?

Connects spinous processes Signup and view all the answers

Which part of the sternum attaches to ribs 1-7 via cartilage?

Sternal body Signup and view all the answers

How many pairs of ribs are in the thoracic cage?

12 pairs Signup and view all the answers

What type of ribs are classified as 'true ribs'?

Ribs 1-7 Signup and view all the answers

Which part of the scapula articulates with the humerus?

Glenoid fossa Signup and view all the answers

What is a characteristic feature of the humerus?

Three fossa at the distal end Signup and view all the answers

Where is the olecranon process located?

On the ulna Signup and view all the answers

What is the primary function of the pelvic girdle?

Bear the weight of the torso Signup and view all the answers

Which bone forms the knee joint by articulating with the femur?

Tibia Signup and view all the answers

What is the function of the carpal tunnel?

Houses tendons and the median nerve Signup and view all the answers

What is unique about the first digit of the foot compared to the other digits?

Has only two phalanges Signup and view all the answers

Which part of the femur articulates with the acetabulum of the hip bone?

Head Signup and view all the answers

What distinguishes false ribs from true ribs?

Attachment via rib cartilage Signup and view all the answers

How is the clavicle classified in terms of skeletal structure?

A long bone Signup and view all the answers

Study Notes

Bone Cells

Osteoblasts: Found in growing bone portions, create new bone tissue using collagen and calcium salts.
Osteocytes: Mature osteoblasts that have surrounded themselves with hydroxyapatite, neither can replicate.
Osteocytes: Sit in lacunae (little spaces) surrounded by bone tissue and secrete enzymes to maintain mineral concentration in the matrix
Osteocytes: Communicate and receive nutrients via canaliculi.
Osteoclasts: Breakdown old or damaged bone (“resorption”) releasing calcium (bone is dynamic!).
Osteoclasts: Found on bone surfaces, multinucleated, originate from a monocyte/macrophage lineage (different cell line than the other 3).

Bone Tissue

Compact bone (cortical): Dense bone tissue found under the periosteum in the diaphysis (shaft) of long bones.
Osteons: Structural units of compact bone, composed of lamellae (concentric rings of calcified matrix) with a central canal (Haversian canal) containing blood vessels and nerves.
Spongy bone (cancellous/trabecular): Less dense, lighter, osteocytes are found in a lattice-like matrix called trabeculae.
Spongy bone: More trabeculae form under high stress areas in the bone for support and strength.
Spongy bone: In some bones (e.g., femur), red or yellow marrow is found within.

Bone Formation and Repair

Skeletal formation: In embryos and fetus, bone starts as cartilage, slowly converted to calcified bone.
Fracture: A break in a bone, bones have excellent healing ability due to blood vessels.
Fracture repair: Hematoma (blood collection) forms first, followed by an internal callus (cartilage), followed by an external callus (bone).
Fracture repair: Osteoclasts break down dead bone, new osteoblasts replace old osteocytes

Effects of Exercise, Nutrition, and Hormones on Bone

Exercise: Makes bones more dense, physical stress stimulates osteoblasts to reinforce certain areas with more calcium salts.
Calcium: Must be in the diet for bone growth and maintenance.
Vitamin D: Promotes calcium and phosphate absorption from the small intestine and kidneys.
Vitamin D: Can be made from cholesterol and UV light in the skin using a pathway involving the liver and kidneys.
Vitamin D: Promotes Ca+2 deposition onto bone and Ca+2 homeostasis in the body.
Vitamin K: Works with Vitamin D to promote bone growth.
Magnesium and Fluoride: Also contribute to bone density and strength.
Growth Hormone: Stimulates chondrocyte (cartilage cells) mitosis in the epiphyses of long bones, enhances calcium mineralization of bones and increases osteoblast activity.
Thyroid hormones (T3, T4) and Sex hormones (Estrogen, Testosterone): Stimulate osteoblasts to create new bone tissue.
Parathyroid hormone (PTH): Released due to low Ca+2 in the bloodstream, stimulates osteoclasts to break down bone, releasing Ca+2.
Calcitonin: Inhibits osteoclasts, stimulates osteoblasts to deposit Ca+2 onto bones.
Calcium Homeostasis: Vitamin D, Parathyroid Hormone (PTH), Calcitonin regulate calcium homeostasis.

Axial Skeleton

Axial skeleton: Head, neck, chest, and back, comprises 80 of the 206 bones in adults.
Skull: 28 bones (22 skull bones & 6 ossicles).
Hyoid: 1 bone.
Vertebrae, Sacrum, Coccyx: 26 bones.
Ribs: 24 bones.
Sternum: 1 bone.

Ossicles

Malleus, Incus, Stapes: Three small bones in each middle ear.

The Skull

Cranium: Divided into Facial bones and Brain case (Cranial bones).
Mandible: Only mobile skull bone.

Cranial Bones

Parietal bones (2): Form the lateral walls and top of the skull.
Temporal bones (2): Join the zygoma to form an arch (cheek), house the middle and inner ears.
Frontal bone: Single bone in the front, forms the superior part of the orbit.
Occipital bone: Single bone at the posterior of the skull, contains the foramen magnum where the spinal cord enters/exits the skull.
Sphenoid bone: Single, bat-shaped, central skull bone, divided into “wings”, forms much of the skull base.
Ethmoid bone: Single, midline bone, forms the roof and lateral walls of the upper nasal cavity.

Sutures

Sutures: Where the bones of the skull meet.

Facial Bones

Maxillary bones (2): Form the upper jaw, hard palate, part of the orbit, and the lateral base of the nose.
Palatine bones (2): Form part of the nasal cavity, orbits, and the posterior portion of the hard palate.
Zygomatic bones (2): Form the lateral portion of the orbit and the zygomatic arch.
Nasal bones (2): Join together at the bridge of the nose and support the nasal cartilage.
Lacrimal bones (2): Contribute to the medial wall of the orbit, form the nasolacrimal canal for tear drainage.
Inferior Nasal Conchae (2): Curved bony plates projecting inferiorly into the nasal cavity, warm and moisturize incoming air.
Vomer: Single, midline, triangular bone, forms the posterior portion of the nasal septum.
Mandible: Forms the lower jaw, the only mobile skull bone.

Important Skull Features

Orbit: Formed by seven bones, surrounds and protects the eye and associated structures.
Nasal Septum: Bony portion made up of the Ethmoid and Vomer, the rest is septal cartilage.
Nasal Conchae (Turbinates): Three curved projections in the nasal cavity that warm and moisturize incoming air.
Cranial Fossa: Anterior, Middle, and Posterior.
Anterior Cranial Fossa: Shallowest fossa, overlies orbits, houses the frontal lobes of the brain.
Middle Cranial Fossa: Made of sphenoid and temporal bones, houses the temporal lobes of the brain.
Posterior Cranial Fossa: Deepest fossa, houses the cerebellum, formed by the temporal and occipital bone.
Paranasal Sinuses: Communicate with the nasal cavity, give resonance to voice, found in frontal, maxillary, sphenoid, and ethmoid bones.

The Hyoid

Not part of the skull, doesn't contact other bones.
Attached to tongue, larynx, and pharynx muscles, involved in speaking and swallowing.
Has a central body, greater and lesser horns for muscle attachment.

The Vertebral Column

Protects the spinal cord, supports the neck, provides rib attachment, and carries weight.
Three major regions: Cervical (7), Thoracic (12), Lumbar (5).
Sacrum and Coccyx located inferior to the vertebrae.
Four curvatures provide strength and flexibility: Cervical, Thoracic, Lumbar, Sacral

The Vertebral Structure

Body: Thick, rounded portion in the anterior portion of the vertebrae.
Pedicles: Extend posterior from the body, form the vertebral arch and foramen with the lamina, where the spinal cord passes through.
Spinous, Transverse Processes: Important attachment points for muscles and ligaments.
Superior, Inferior Articular Processes: Connect to vertebrae above and below.

The Cervical Vertebrae

C1 (Atlas): Ring-shaped, allows head nod.
C2 (Axis): Has an upward projection called the Dens (ontoid process) allowing head shaking from side to side.
C3-C7: Unnamed, small bodies, have transverse foramen for the vertebral arteries.

Thoracic Vertebrae

Larger than cervical vertebrae.
Have costal facets to attach to ribs.
Spinous processes angle inferiorly.

Lumbar Vertebrae

Large and thick bodies, carry the weight of the thorax.
Intervertebral discs are often displaced (herniated) in the lumbar spine.

Sacrum

Triangular-shaped bone, forms from the fusion of 5 bones by age 20.
Attached to L5 superiorly, the coccyx inferiorly, and the ilium bones laterally.
Has many foramina for nerve passage.

Coccyx

Tailbone, formed by the fusion of 4 small bones.

Intervertebral Discs

Fibrocartilage pads between vertebral bodies providing flexibility and allowing movement.
Anulus Fibrosus: Thick, fibrous outer layer anchored to the vertebral body.
Nucleus Pulposus: Soft, gel-like inside the disc, allows compression.

Spinal Ligaments

Anterior longitudinal ligament: Runs the length of the spinal column on the anterior vertebral bodies’ surfaces, prevents excessive posterior movement.### Supraspinous Ligament
Connects spinous processes along posterior aspect of the spine
Becomes Nuchal ligament in cervical spine, attaching to occipital skull

Thoracic Cage

Composed of 12 pairs of ribs (24 bones), sternum, and costal cartilage
Ribs anchored to thoracic vertebrae (T1-T12)
Protects the heart and lungs

Sternum

Found in anterior thoracic cage, has 3 parts:
- Manubrium - superior portion, contains jugular notch/depression
- Sternal body - long central portion, attaches to ribs 1-7 via cartilage
- Xiphoid process - inferior tip of sternum

Ribs

12 pairs (24 bones) numbered 1 through 12 (superior to inferior), left and right
Articulate with respective thoracic vertebrae via their heads (e.g., rib 1 with T1)
Costal groove on underside contains blood vessels and nerves
Ribs 1-7 are "true ribs," attaching directly to sternum via costal cartilage
Ribs 8-12 are "false ribs" and don't attach directly to sternum but to the rib cartilage above
Ribs 11 & 12 are "floating" and have cartilages attaching to the lateral abdominal wall

Appendicular Skeletal System

Composed of 126 bones

Pectoral (Shoulder) Girdle

Consists of clavicle and scapula
Clavicle connects arm to body via scapula, divided into 3 regions:
- Medial (sternal) end - articulates with manubrium
- Shaft
- Lateral (acromial) end - articulates with acromion of scapula
Protects nerves and blood vessels beneath
Highly mobile, prone to fractures

Scapula

Triangular, dense bone surrounded by muscle
Glenoid fossa on lateral aspect articulates with humerus forming the shoulder joint
Coracoid process - bony projection for chest/arm muscles
Spine of scapula runs along posterior side, ending at the acromion which articulates with the clavicle (AC joint)
Has three fossa:
- Supraspinous fossa - above the spine
- Infraspinous fossa - below the spine
- Subscapular fossa - entire anterior surface

Humerus - Proximal

Single bone of upper arm
Humeral head articulates with glenoid fossa of scapula, forming shoulder joint (prone to inferior/anterior dislocation)
Greater/lesser tuberosities are important for muscle attachments
Anatomic (proximal) and surgical neck (distal)

Humerus - Distal

Medial and lateral epicondyles for tendon attachments (golf vs. tennis elbow)
Trochlea articulates with ulna
Capitulum articulates with radius
Has 3 fossa for radius and ulna when fully flexed (coronoid, radial) or extended (olecranon fossa)

Ulna

Medial forearm bone
Proximal end has a large curved trochlear notch articulating with humerus (elbow joint)
Forms joints with radius proximally and distally
Olecranon process forms the "elbow"
Linked to radius along shaft by a thick fibrous interosseous membrane
Styloid process is distal at the wrist

Radius

Lateral forearm bone
Disc-shaped head articulates with capitulum of humerus
Forms joints with ulna proximally and distally
Articulates with two carpal bones at the wrist
Styloid process at wrist

Carpals

8 bones in 2 rows
Proximal row: Scaphoid, Lunate, Triquetrum, Pisiform
Distal row: Trapezium, Trapezoid, Capitate, Hamate