Human Anatomy: Bone and Joint Structure

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Questions and Answers

What is the primary difference between spongy and compact bone in terms of structure?

Spongy bone has a porous structure with trabecular patterns, while compact bone is dense and provides strength and support.

List the types of cells found in cartilage and their primary functions.

The main cells of cartilage are chondrocytes, which produce and maintain the cartilaginous matrix.

What are the components that make up the basic structure of the axial skeleton?

The axial skeleton consists of the skull, rib cage, and vertebral column.

Explain the difference between true ribs and false ribs.

True ribs (1-7) attach directly to the sternum, while false ribs (8-12) do not attach directly to the sternum. Signup and view all the answers

What are the main functions of ligaments in joints?

Ligaments connect bones to other bones and provide stability to joints. Signup and view all the answers

How are bones classified based on their shapes?

Bones are classified into four categories: long, short, flat, and irregular. Signup and view all the answers

How many bones are typically present in an adult human skeleton?

An adult human skeleton typically consists of about 206 bones. Signup and view all the answers

Which section of the vertebral column contains the most vertebrae, and how many are there?

The thoracic section contains the most vertebrae, with 12. Signup and view all the answers

What type of cartilage is found in symphyses joints, like intervertebral discs?

Fibrocartilage Signup and view all the answers

Describe the structure and movement permitted by a pivot joint.

It has a cylindrical shape and allows rotation, typically seen in the radioulnar joint. Signup and view all the answers

Which type of synovial joint allows for flexion and extension?

Hinge joint Signup and view all the answers

What is the main characteristic of a saddle joint?

It features both convex and concave surfaces, allowing for biaxial movement. Signup and view all the answers

Name one intra-articular ligament of the knee.

Anterior cruciate ligament (ACL) Signup and view all the answers

What is the function of capsular ligaments in synovial joints?

They enhance the strength of the joint capsule. Signup and view all the answers

Identify a feature that distinguishes a ball and socket joint.

It has an obvious convex ball and concave socket, allowing multiaxial movement. Signup and view all the answers

What is the role of synovial fluid in synovial joints?

It lubricates the joint and nourishes the articular cartilage. Signup and view all the answers

What are the two primary sections of a long bone?

The two primary sections of a long bone are the diaphysis and the epiphysis. Signup and view all the answers

What is the role of osteocytes in bone structure?

Osteocytes are mature bone cells that lie in lacunae and help maintain bone tissue. Signup and view all the answers

Explain the difference between red and yellow bone marrow.

Red bone marrow produces red blood cells, platelets, and white blood cells, while yellow bone marrow stores fat cells. Signup and view all the answers

What are trabeculae, and where are they found in bone?

Trabeculae are the struts and plates forming the network in spongy bone, primarily found in the epiphysis. Signup and view all the answers

Describe the function of the periosteum in bone structure.

The periosteum is the outer layer of bone that protects and nourishes the bone tissue. Signup and view all the answers

How does the Haversian canal contribute to bone health?

The Haversian canal allows the passage of blood, nerves, and lymph vessels, supporting bone health. Signup and view all the answers

What is the significance of the epiphyseal line in long bones?

The epiphyseal line indicates where growth plates were located, marking areas of bone growth in adolescence. Signup and view all the answers

What is the primary difference between intramembranous and endochondral ossification?

Intramembranous ossification involves the direct transformation of mesenchyme into bone, while endochondral ossification involves a pre-existing cartilage model that is converted into bone. Signup and view all the answers

What initiates the process of ossification in bone development?

Ossification is initiated when bone replaces cartilage and other connective tissues. Signup and view all the answers

During which embryonic phase does most endochondral ossification occur?

Most endochondral ossification occurs when we are a foetus. Signup and view all the answers

What role do osteoblasts play in bone formation?

Osteoblasts secrete osteoid, facilitating the formation of bone by depositing minerals and creating the bone collar. Signup and view all the answers

What is the epiphyseal plate and its significance in bone growth?

The epiphyseal plate is the cartilage region between primary and secondary ossification centres that allows for the lengthening of bones until about 20 years of age. Signup and view all the answers

Describe the process that occurs at the primary ossification center.

In the primary ossification center, bone formation begins with the deposition of bone collar, calcification of the matrix, and the formation of the medullary cavity as osteoclasts break down spongy bone. Signup and view all the answers

What happens around the time of birth regarding endochondral ossification?

Around the time of birth, a secondary ossification center appears at the epiphyses of long bones, allowing for continued growth in length. Signup and view all the answers

How does appositional growth contribute to bone diameter?

Appositional growth occurs by the deposition of new bone beneath the periosteum, which increases the diameter of bones. Signup and view all the answers

At what age is it typical for all cartilage in the epiphyseal plate to be replaced by bone?

All cartilage in the epiphyseal plate is typically replaced by bone by around 20 years of age. Signup and view all the answers

What structures are classified as intra-articular discs and what is their primary function?

Intra-articular discs are fibrocartilaginous structures located in joints such as the temporomandibular joint, sternoclavicular joint, and ulnocarpal joint. Their primary function is shock absorption and increasing joint congruency. Signup and view all the answers

Explain the relationship between mobility and stability in joints.

Joints with greater mobility typically have less stability, as their range of motion compromises their stability. Stability depends on factors such as articular shape, ligament strength, and muscle control. Signup and view all the answers

Define the roles of agonists, antagonists, and synergists in muscle movement.

Agonists are the primary muscles responsible for a movement, while antagonists oppose the action of the agonists to control and slow the movement. Synergists assist the agonist by stabilizing joints and aiding in the execution of the movement. Signup and view all the answers

What distinguishes bi-articular muscles from mono-articular muscles?

Bi-articular muscles produce actions over two joints, such as the rectus femoris, while mono-articular (or uni-articular) muscles only produce action over one joint. Signup and view all the answers

What are ligaments and tendons, and give an example of each?

Ligaments are connective tissue that connects bones to other bones, like the medial collateral ligament (MCL) of the knee, while tendons connect muscles to bones, such as the Achilles tendon. Signup and view all the answers

What shape do parallel muscles have in terms of their fascicle arrangement?

The fascicles run parallel to the long axis of the muscle. Signup and view all the answers

Describe the main characteristic of fusiform muscles and give an example.

Fusiform muscles have fibers arranged parallel to the line of pull and a wider muscle belly than origin and insertion; an example is the biceps brachii. Signup and view all the answers

What distinguishes pennate muscles from other types of muscle shapes?

Pennate muscles have fibers that are arranged obliquely to the line of pull. Signup and view all the answers

What is the function of circular muscles, and where are they typically found?

Circular muscles function to close external body openings by contracting and are found in structures like the mouth and gastrointestinal tract. Signup and view all the answers

Explain the feature of convergent muscles and provide an example.

Convergent muscles have fibers that spread over a broad area and converge at a common attachment site, such as the pectoralis major. Signup and view all the answers

What is the distinction between the origin and insertion of a muscle?

The origin is the fixed bone where the muscle attaches, while the insertion is the moving bone. Signup and view all the answers

Define concentric contraction and describe the muscle's behavior.

Concentric contraction occurs when a muscle develops sufficient tension to overcome resistance, resulting in shortening. Signup and view all the answers

What occurs during eccentric muscle contraction?

During eccentric contraction, the muscle cannot overcome the resistance, leading to net lengthening as the muscle contracts. Signup and view all the answers

Study Notes

Bone, Cartilage, and Joint Anatomy

The adult human skeleton has approximately 206 bones.
Babies have around 300 bones that fuse together as they grow.
Bones are present in the majority of hands and feet.
Cartilage is also part of the skeletal system.
The lecture aims to explain bone and cartilage, classify them, describe their structures (spongy/compact), the cells and their matrix components, and functions, detail the skeletal anatomy, classify joint types, detail the role of capsular ligaments and intra-articular discs, and describe structures that determine joint stability along with the composition and roles of bones.

Skeleton

Skull: Cranium, Mandible
Thoracic cage: Clavicle, Scapula, Sternum, Ribs
Vertebral column: Cervical (7), Thoracic (12), Lumbar (5), Sacral (5 fused), Coccyx (3-5 fused)
Upper limb: Humerus, Radius, Ulna, Carpals, Metacarpals, Phalanges
Lower limb: Femur, Patella, Tibia, Fibula, Tarsals, Metatarsals, Phalanges
Pelvic girdle: Ilium, Ischium, Pubis, Sacrum

Axial and Appendicular Skeleton

Axial: Skull, vertebral column, thoracic cage (ribs and sternum)
Appendicular: Limbs, shoulder girdle, pelvic girdle
The diagram in the notes shows the axial and appendicular skeleton.

Bone Composition

Organic: Mostly collagen (33%)
Inorganic: Primarily calcium phosphate (67%).
Calcium makes up 99% of the total calcium in the body.

Bone Cells

Osteocytes: Mature bone cells in lacunae
Osteoblasts: Bone deposition
Osteoprogenitor cells: Mesenchymal stem cells
Osteoclasts: Bone resorption, remodeling

Bone Development

Intramembranous ossification: Bone forms directly in mesenchymal tissue, without a cartilage precursor (e.g., skull bones).
Endochondral ossification: Bone forms from a pre-existing hyaline cartilage model (e.g., most of the bones in the body).

Endochondral Ossification

Bone growth occurs at the epiphyseal plate, and the length of the bone increases in early childhood and adolescence.
Eventually, the epiphyseal plate entirely turns into bone, and bone growth stops.

Growth (Epiphyseal) Plates

Crucial for bone lengthening
Located between the diaphysis and the epiphysis.

Bone Growth and Remodeling

Growth in length occurs through cartilage in the epiphyseal plates.
Bone is continuously remodeled through the actions of osteoblasts (depositing) and osteoclasts (resorbing).

Bone Remodeling

A continuous process of bone formation and resorption to maintain skeletal homeostasis and repair damage.
Crucial for maintaining bone health, and restoring damaged bone is important as part of bone remodeling.
Bone remodeling needs to be in balance. The rates of bone formation and resorption are key if done too quickly you get osteoporosis.

Types of Bones

Flat (e.g., sternum)
Long (e.g., femur)
Short (e.g., carpals)
Irregular (e.g., vertebrae)
Sesamoid (e.g., patella)

Lumps and Bumps

Anatomical landmarks include tuberosities, tubercles, lines, processes, and spines.

Grooves and Holes

Anatomical landmarks include fossae, foramina, sulci, and notches.

Articular Surfaces

Condyles, facets, epicondyles, and trochlea.
Surfaces for articulation (interaction between bones at joints).

Cartilage

Soft, slightly elastic tissue consisting of a matrix of chondrin (protein).
Three types: hyaline, elastic, and fibrocartilage.
Lacks blood vessels, relying on diffusion for nutrients.

Cartilage Locations

Found throughout the body. Present in the respiratory tract, joint surfaces, vertebrae, and the intervertebral discs.

Growth of Cartilage

Appositional growth: Cartilage increases in width due to chondroblasts in the perichondrium differentiating into chondrocytes and producing matrix material.
Interstitial growth: Cartilage increases in length due to the proliferation and hypertrophy of chondrocytes.

Joints

A joint is where two or more bones meet.
Joints allow movement and connect bones in the body.
Classification of joints based on connecting tissue include: fibrous, cartilaginous, and synovial.

Fibrous Joints

Connect bones with fibrous connective tissue.
Examples: sutures (skull), syndesmoses (tibiofibular ligament), gomphoses (teeth).
Little to no movement.

Cartilaginous Joints

A joint where the bones are connected by cartilage.
Examples: synchondroses and symphyses.
Little or moderate movement.

Synovial Joints

The most common joint type.
Encased with a joint capsule filled with a synovial fluid.
Surrounded with ligaments connected inside and outside the joint capsule.
Movement is usually significant
Have synovial fluid, cartilage, and ligaments.
Six types: pivot, plane/gliding, hinge, condyloid, saddle, ball-and-socket.

Specialized Features of Synovial Joints

Ligaments: Connect bone to bone, enhance stability.
Tendons: Connect muscles to bone, enabling movement.
Bursae: Fluid-filled sacs that cushion joints and reduce friction.
Articular discs: Pads that improve joint congruency and provide stability.

Capsular Ligaments

Important for stability; can be intracapsular (within the joint capsule) or extracapsular (outside).
Examples from the notes include those of the knee (ACL, PCL, transverse ligament), and hip (iliofemoral, pubofemoral, ischiofemoral).
Notes contains discussion questions.

Intra-articular Discs

Fibrocartilaginous structure located within synovial joints.
Improve joint stability, congruency, reduces friction and provides cushioning
Functions include shock absorption, increase congruence, and improve joint stability.

Stability versus Mobility

Trade-off between joint mobility and stability.

Tendons and Ligaments

Tendons connect muscle to bone. Ligaments connect bone to bone to stabilize joints.
Examples from the notes are the Achilles tendon and the Medial Collateral Ligament (MCL) of the knee.

Muscles

The human body has over 600 muscles.
The shape and arrangement of the muscles determine the degree of contraction and force they can generate.
Five categories of muscle shapes included in the notes are parallel, fusiform, pennate, circular and convergent.
Muscles move the skeleton based on contraction.
Muscle functions, terms regarding muscle contraction included in the notes are agonist (prime mover), antagonist, synergist/stabilizer, fixators, bi-articular, mono-articular.

Types of Muscle Contraction

Concentric: Muscle shortens (e.g., lifting a weight).
Eccentric: Muscle lengthens (e.g., lowering a weight).
Isometric: Muscle length remains constant (e.g., holding a weight).

Origins and Insertions

The origin of a muscle is the fixed point of attachment.
The insertion is the movable point of attachment.

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Description

This quiz covers essential topics related to human bone and joint anatomy. Participants will explore the differences between types of bones, cartilage cells, and important features of synovial joints. Perfect for students studying human anatomy in a biology class.