7.1 Bones of the Limbs Flashcards
- What is an example of a disease where one tissue type turns into another?
Fibrodysplasia ossificans progressive, this is where a mutation in the gene that controls bone growth results in the uncontrolled bone growth after injury, resulting in an extra heterotropic skeleton. Body eventually becomes fused and movement near impossible, attempts to remove abnormal growth just triggered repair mechanisms an caused more abnormal growth.
How many bones are there in the human skeleton?
206, but this number can vary due to variable numbers of sesamoid bones and coccygeal vertebrae (and other small bones). Homeotic bones may increase number of ribs or alter digits.
What makes up the axial skeleton?
- Cranium
- Vertebral column
- Ribs and sternum
What makes up the appendicular skeleton?
- Pectoral girdle
- Upper limb bones
- Pelvic girdle
- Lower limb bones
What are the functions of the skeleton?
- Movement and muscle attachment
- Protection of soft tissues
- Calcium storage (variable and vital - through negative feedback system using hormones from the thyroid and parathyroid)
- Resistance to forces (incl gravity)
- Haematopoiesis (blood cell production in red blood cell marrow)
What are the main constituents of bone?
Collagen and calcium hydroxyapatite - they balance strength and weight of the skeleton
How can collagen be removed from bones and what is the effect of this?
Collagen can be removed through heat treatment (denatures the protein), causes bone to become very brittle and hard, so shatters easily.
How can calcium hydroxyapatite be removed from bones and what is the effect of this?
Calcium hydroxyapatite can be removed through treatment with acid, leaving the collagen intact. Bone loses its rigidity and strength, so becomes extremely flexible.
What is the function of collagen in bones?
Organic component
- Increases flexibility
- Some elasticity
(- Is the most common protein in the body and bones)
What is the function of calcium hydroxyapatite in bones?
Inorganic component (along with calcium carbonate and magnesium carbonate)
- Mainly calcium phosphate
- Crystals impregnate collagen matrix
- Provides hardness and rigidity
How is bone a composite material?
Because it is made up of multiple components
What are the two histological types of bone?
- Woven (immature)
- Lamellar (mature)
Where is woven bone seen?
- Development/immature bones
- Fracture repair
- Pathology (excess seen in some tumours)
Temporary type of bone, will be made into lamellar
What is considered to be lamellar bone?
- Compact bone
- Spongy bone
- MATURE BONE
Permanent bone, made up of lots of layers
What are the different morphological classifications (shapes) of bones, with examples?
- Flat (e.g. parietal)
- Short (e.g. carpals)
- Long (e.g. femur)
- Sesamoid (e.g. patella)
- Irregular (e.g. vertebrae)
What are diaphyses?
Primary ossification centres of bones, will usually make up the main body (e.g. shaft of femur).
Will contain more compact or cortical bone and possibly yellow marrow.
What are epiphyses?
Areas of secondary ossification/growth plate, at the ends/extensions of bones.
Will be made up of mostly spongy bone, collagen running in different directions allowing the bone to be able to withstand high tensile stress.
What is the metaphysis?
This is the region adjacent to the growth/epiphyseal plate during development, will ossify and connect the diaphysis to the epiphysis.
Often where the bones ‘flare’.
What is endochondral ossification?
Endo = in, chondral = cartilage, ossification = turn into bone
This is where hyaline cartilage is converted into bone during osteogenesis in embryonic development.
What is the benefit of secondary ossification centres?
Allows long bones to grow along with the person - birth would be extremely difficult if bones were always full size.
What is intramembranous ossification and where does it occur?
This is where fibrous membranes are converted straight into bone, with no intermediate steps. Occurs in the flat bones of the skull and irregular ones such as the mandible - the head is relatively full-sized at birth.
What are the primary ossification sites in a 12 week old foetus?
- Frontal bone of skull
- Parietal bone of skull
- Occipital bone of skull
- Mandible
- Clavicle
- Scapula
- Radius
- Ulna
- Humerus
- Femur
- Tibia
- Ribs
- Spinal vertebra
- Ilium
(In areas where bones WILL be - for example, in the wrist - no bone will currently exist but their ‘ghosts’ of deposited cartilage will in a similar shape)
- What effect could dislocations or fractures along growth plates in children have?
Disruption of growth, resulting in uneven development of bone and even necrosis if blood supply is compromised
Go revise the spine flashcards
Do it!
What are features of the sternum?
Aka the breastbone
- Formed of three main parts, manubrium, body and xiphoid process (top -> bottom)
- Suprasternal notch on manubrium, aka jugular notch, is at the level of the T2 vertebrae
- Sternal angle/manubriosternal joint is lower than the T4 vertebrae
- Xiphoid process is at the level of T9 or T10
How are ribs 1-7 attached anteriorly and what is their simple classification?
To the sternum via costal cartilage, ‘vertebrosternal’
How are ribs 8-10 attached anteriorly and what is their simple classification?
Through costal cartilage attaching to the rib above, ‘vertebrocostal’
How are ribs 11-12 attached anteriorly and what is their simple classification?
No anterior attachment, ‘floating’
What are the bones of the upper limb?
Humerus, radius and ulna
- What are cervical ribs?
Congenital abnormality where a rib emerges from above the normal ‘first rib’ from the C7 vertebrae, may present as chest pain
What does the pectoral girdle enable?
A wide range of movement, unlike the fused bones of the pelvic girdle. This is partly due to the shallow shoulder joint, so has a relatively high risk of dislocation.
Compare the pectoral and pelvic girdles.
- Pelvic has far less movement, as deeper socket and fused bones - pectoral girdle has far more mobile joints, allowing for greater range of movement and a shallow socket
- Pelvic is inherently more stable because of the deeper socket, the shallow shoulder joint of the pectoral girdle makes this joint far more prone to dislocation.
What is a unique feature of the forearm?
The bones are capable of pronation and supination, adding dexterity - the lower limb is unable to do this
What is a unique feature of the hand?
Specialised thumb joint allows opposition which increases manual dexterity
What makes up the arm?
The shoulder to the elbow/upper arm in layman’s terms
What makes up the forearm?
The elbow to the wrist
What are the three types of bones in the hand and wrist?
Carpals, metacarpels and phalanges
What are the 8 carpals?
Proximal row, lateral to medial (from anatomical position) - Scaphoid - Lunate - Triquetrum - Pisiform Distal row, lateral to medial - Trapezium - Trapezoid - Capitate - Hamate
What makes up the pectoral girdle?
Clavicle and scapula
What joints are within the pectoral girdle?
- Sternoclavicular joint (only one between the upper limb and the axial skeleton)
- Acromioclavicular joint (AC, acromion process is on the scapula)
- Coracoclavicular joint (coracoid process is on the scapula also)
- Where do fractures frequently occur on the clavicle?
In the middle third/shaft of the bone
How does the clavicle appear from a superior view?
Convex medially (near joint with manubrium) and concave laterally (near joint with acromion)
What are different features present on the scapula?
- Acromion process (joint with clavicle, palpable above shoulder)
- Coracoid process (joint with clavicle, palpable below lateral clavicle)
- Subscapular fossa (where subscapularis sits)
- Supraspinous fossa (where supraspinatus sits, above spine of scap)
- Spine of scapula (posterior projection of bone)
- Infraspinous fossa (where infraspinatus and teres minor sit, below spine of scap)
- Glenoid fossa (distal fossa, where humerus articulates, has fibrous labrum)
What is a fossa?
An indentation or depression into the bone
