Cartilage, joints and bones Flashcards
What is a joint?
Junctions/articulations between 2+ bones
Some joints permit movement, others don’t
What is the pectoral girdle?
Bones which connect the arms to the torso
What is a synovial joint?
Found between bones that move against eachother
What are the two joints in the pectoral girdle?
Sternoclavicular joint
Acromioclavicular joint
What is the sternoclavicular joint?
Joins the sternum and the clavicle
What is the acromioclavicular joint?
Joins the scapula and the clavicle
What is the glenohumeral joint?
Shoulder joint
Ball and socket joint between scapula and humerus
What is the scapulothoracic joint?
Scapula meets with ribs at back of chest
What type of joint is the elbow joint?
Synovial joint
What bones are connected in the elbow joint?
The trochlea and capitulum of humerus with the trochlear notch of ulna and head of radius respectively
Which two articulations are present in the elbow?
Humero-ulnar and humero-radial
Which joint isn’t part of the elbow joint?
The proximal radio-ulnar joint
Which bone doesn’t participate in the wrist joint?
Ulna
What type of joint is the wrist?
Condyloid/ellipsoid type of synovial joint
Which bones are joined together in the wrist joint?
Connects wrist with forearm proximally and with the metacarpals distally
Proximal part is formed by distal end of radius and articular disc of distal radio-ulnar joint and the proximal row of carpal bones
What is the pelvic girdle made out of?
Two hip bones and sacrum
Connects vertebral column to femoral bones
Which joints are present in the pelvic girdle?
Two sacroiliac joints and pubic symphysis
What is another name for the ankle joint?
Talocrural joint
What bones are connected at the ankle joint?
Distal ends of tibia and fibula and superior part of talus
What does the hip joint connect?
Pelvic girdle and lower limbs
What is the hip joint formed by?
Connection of femur head to socket of hip bone
What is the knee joint formed of?
Connections of prominences of distal end of femur and proximal end of tibia, and femur with patella
Which bone isn’t involved in the knee joint?
Fibula
Why is the knee joint weak?
Incongruent structure
Which areas of the body make up the axial skeleton?
Head/bones/neck/trunk
Which areas of the body make up the appendicular skeleton?
Limbs/shoulder/pelvic girdle
Where is cartilage founding adults?
At almost all junctions between bones
Characteristics of cartilage
Weight bearing connective tissue
Capacity for rapid growth
What happens to the blood supply of cartilage after childhood?
Cartilage becomes avascular - no blood vessels
Does cartilage have either lymphatic vessels or nerves?
No
What is cartilage surrounded by?
Fibrous perichondrium
What are the two areas where cartilage isn’t surrounded in perichondrium?
Bone junctions and articular surface of synovial joints
How many layers is the perichondrium made of and what are they?
2 - one outer fibrous layer and one liner cellular layer
What is the perichondrium?
A collagenous tissue sheath
What does the inner layer of the perichondrium do?
Secretes cartilage matrix
How are the areas of the cartilage not surrounded with perichondrium nourished?
Synovial fluid
Is the perichondrium vascularised?
Yes
What does the cartilage matrix do?
Provides tensile strength
What is the cartilage matrix composed of?
Collagen, elastic fibres, dissolved salts, glycoproteins and non-collagenous proteins
What are chondrogenic cells?
Embryonic cartilage cells - can differentiate into chondroblasts and osteoprogenitor cells
What are chondroblasts?
Synthesise extracellular matrix in growing cartilage
How do chondroblasts become chondrocytes?
Become trapped in lacunae within the matrix they secrete and become less active
Function of chondrocytes
Diffusion of nutrients and other substances and repair matrix
Are chondroblasts or chondrocytes more active?
Chondroblasts
What are the three types of cartilage?
Hyaline cartilage
Yellow elastic cartilage
White fibrocartilage
What colour is hyaline cartilage?
Bluish and semi-translucent
Where is hyaline cartilage found?
It is very abundant
Nose/larynx/rib ends/tracheal rings/bronchi
Function of hyaline cartilage
Forms cartilage template for long bone development and the epiphyseal plate
What does hyaline cartilage contain?
Type ii collagen fibres/proteoglycans/glycoproteins/ECF
Where doe hyaline cartilage function and why?
Articular joint - it is smooth and resists tension
What happens to hyaline cartilage as you age?
Degenerates
What colour is yellow elastic cartilage?
Yellow and opaque - due to elastic fibres
Where is yellow elastic cartilage found?
Pinna of ear/epiglottis/auditory tubes/cuneiform cartrtilage of larynx
Does yellow elastic cartilage or hyaline cartilage have more chondrocytes?
Yellow elastic cartilage
What is yellow elastic cartilage made of?
Type I and ii collagen fibres
Its matrix and perichondrium contain elastic fibres
Does white fibrocartilage have a perichondrium?
No
It is bundles of collagen fibres
What does the matrix of white fibrocartilage contain?
Type I collagen fibres, chondroitin sulphate and dermatan sulphate
Where is white fibrocartilage found?
Intervertebral disks/attached to bones/pubic symphysis
What is calcitonin?
Opposite of PTH
Produced during hypercalcaemia
Where is calcitonin produced?
Clear/C/parafollicular cells
What does calcitonin do?
Binds to receptors on osteoblasts, which inhibit osteoclasts dissolving bone
This allows osteoblasts to form hydroxyapatite crystals
What does PTH do during hypocalcemia?
Stimulates dissolution of bone
PTH binds to receptors on osteoblasts, which secrete a ligand called RANKL
RANKL binds to osteoclasts and stimulates dissolution of bone
What crystal constitutes the main mass of bone?
Hydroxyapatite
Where in bone is calcium readily available?
In the bone fluid
What do osteoblasts do?
Phosphate + calcium - hydroxyapatite
What do osteocytes do?
Used to be osteoblasts - trapped in surrounding mineralised bone
What are osteoclasts?
Specialised macrophages that can destroy mineralised bone
What is bone resorption?
Dissolving mineralised bone
Why must phosphate be removed from the body immediately when bone is dissolved?
Equal concentrations of calcium and phosphate leads to the formation of hydroxyapatite
What effect does PTH have on the distal convoluted tubule?
Excrete excess phosphate in urine
What are the two types of bone?
Compact and spongy bone
Where is the bone marrow contained?
The marrow cavity
What type of organ is bone marrow?
Haemopoetic
What is the outer layer of bone called?
Periosteum
What is the marrow cavity lined with?
Endosteum - connective tissue composed of a single layer of osteoprogenitor cells and osteoblasts
What are the two types of bone marrow?
Red and yellow
What is red bone marrow?
Haemopoetic tissue and site of RBC production
What is a haemopoetic organ?
Elements of blood and lymph produced
What is yellow bone marrow?
Fat/adipose tissue, can convert to red bone marrow especially after severe blood loss
What is compact bone made of?
A Haversian/osteon system (repeating structures in compact bone)
What is a Haversian system?
Concentric lamellae of bones enclosing a Haversian central canal
Osteogenic cells located in lining of canal
What are the only surfaces not covered by periosteum?
Articular surfaces
What are trabeculae?
Fork-like projections which enclose the space for red bone marrow
Where are trabeculae found?
Spongy bone
Is there a Haversian system in spongy bone?
No
Function of trabeculae?
Provide compressive and tensile strength
What is the epiphyseal line?
Divides spongy bone and articular (Hyaline) cartilage
Why do bones need a rich blood supply?
Calcified matrix doesn’t allow for diffusion - it is supported by blood, nerves and lymphatic vessels
Characteristics of long bone
End is epiphysis, shaft is diaphysis
