Week 1 Flashcards
What are the functions of the skeleton?
Maintain body shape
Support and protection of tissues and organs
Movement and storage of calcium triphosphate in bone
Haemopoiesis
Lipid storage
Describe endochondral ossification
Primary ossification centre in the diaphysis of hyaline cartilage model. Here, the cartilage calcifies and a nutrient artery penetrates
Secondary ossification centres form at the epiphyses
Epiphyseal growth plates develop
Epiphyses ossify
Growth plates move further apart to lengthen bone
Epiphyseal growth plates are replaced by bone
Describe intramembranous ossification
Begins in a highly vascularised connective tissue
Mesenchymal cells differentiate into osteoblasts which are surrounded by collagen fibres and ground substance
Osteoblasts secrete osteoid, which becomes calcified
Osteoblasts become osteoclasts
What is osteogenesis imperfecta caused by?
A defect in collagen synthesis by osteoblasts and fibroblasts.
Which type of collagen in present in bone, skin and tendons?
Type 1
What are features of osteogenesis imperfecta?
Multiple fractures in long bones
Bone deformities due to fracture healing with poor alignment and weak callus
How does osteoporosis occur?
Bone density is reduced because osteoclast activity is more than osteoblasts activity
Leads to medullary canals in the centre of the bone becoming enlarged and gaps develop in the lamellae
Features of rickets?
Bone is softened due to calcium deficiency - matrix does not calcify
Children have slow growing bones which are often deformed
Epiphyseal plate becomes distorted
Features of osteomalacia?
Occurs during bone remodelling
There is deficient calcification of recently formed bone
Bone softening
Symptoms of Paget’s disease?
Bone pain
Osteoarthritis
Fractures
Deafness/headaches
Pathology of Paget’s disease?
Increased number of osteoclasts, and often over active osteoblasts
An accelerated rate of bone turnover and new bone formation
Bones increase in size and are more brittle so more prone to fracture
Which hormones increase calcium plasma concentration?
PTH and calcitrol
How does PTH work?
Decreases osteoblasts activity
What innervates the pec major and the spinal root values?
Medial and lateral pectoral nerves
Derived from the brachial plexus so C5-T1
What is the action of the pec major?
Adducts and medially rotates the humerus
Draws scapula anteriorly and inferiorly
Clavicular head performs flexion of the humerus
What is the innervation of the pec minor? Spinal root values?
Medial pectoral nerve
C8, T1
Action of the pec minor?
Draws scapula inferiorly and anteriorly against thoracic wall
Innervation of the subclavius? Spinal root values?
Nerve to subclavius
C5 and C6
Attachments of the subclavius?
Junction of first rib and its costal cartilage
Inferior surface of middle third of clavicle
Action of the subclavius?
Anchors and depresses clavicle
Innervation of serratus anterior? Spinal root values?
Long thoracic nerve
C5, C6, C7
Attachments of the serratus anterior?
1st-8th ribs
Medial border of scapula
Action of the serratus anterior?
Rotates the scapula, abducting arm above 90*
Holds scapula against rib cage
What is winged scapula?
Injury to long thoracic nerve, paralysing serratus anterior
Medial border of scapula moves laterally and posteriorly away from the thoracic wall
Can be seen when someone leans on their hands against a wall
