Bones

Question 1

What are the two ways in which bone can develop ?

Answer 1

Endochondral ossification and intramembrane ossification

Question 2

Describe the structure of bone

Answer 2

Outer cortex
-dense, strong, heavy, thick
-compact (cortical) bone

Inner medulla
-more porous, weaker, lighter
-spongy (trabecullar/cancellous) bone

The medulla may contain bone marrow

Question 3

Where are different types of bone marrow found ?

Answer 3

The medulla may contain bone marrow:

Red marrow
-Red/white blood cell and platelet production
-Found in cancellous (spongy) material of proximal ends of femur and humerus and hip bone, breast bone, skull, ribs, vertebrae in adults

Yellow Marrow
-Fatty marrow mostly found in long bone shafts in adults

Active red marrow found in proximal cancellous long bones, in kids is fo

Question 4

What is endochondral ossification ?

Answer 4

-Process in which an initial small, hyaline cartilage version grows and turns into bone (ossifies)
-Develops long bones e.g. humerus, femur

At each end, each bone has:
-An epiphysis
-An epiphyseal growth plate
-Metaphysis
-Diaphysis is found between the two ends i.e. the shaft

When the growth plate of hyaline cartilage finally ossifies, bone growth ceases

Is the more common type, growth plate grrows until ossification catches up

Question 5

Zoom in a bit to a bone and describe the structure now

Answer 5

Periosteum
-fibrous connective tissue ‘sleeve’
-vascularised

Well innervated
-results in extreme pain during tearing of the periosteum as occurs during fractures - nerve damage

Nutrient vessels
-artery and vein
-carry blood to/from medullary cavity

Arteries, veins, lymph pass into marrow/medullary cavity through periosteum

Question 6

What are bony features ?

Answer 6

They develop during bone growth, due to;
-Functional (genetic) - best shape for the job of the bone. E.g. bones need to fit together well at eblow/shoulder so heads of bones develop.
-An adjacent structure applies a force to the developing bone. E.g. tendonds attach muscles to bone and muscle contraction pulls bone throuugh tendon. Where tendons attach are rough area or a raised bump (tuberosities)
-An adjacent structure is developing at the same time as the bone. E.g. might have a nerve/artery which needs to get thgrough so hole in bone will develop around it.

Ischial tuberosity is big attachment point for hamstring, tibial tuberosity is where patellar tendon joins

Question 7

What are bony features of the skull ?

Answer 7

The floor of the cranial cavity (the space inside the skull) is divided into 3 fossae:
-anterior cranial fossa
-middle cranial fossa
-posterior cranial fossa

The development of different parts of the brain moulded the floor of the cranial cavity into these 3 fossae (singular: fossa = space)

Foraminae (singular foramen) a “hole”for cranial nerves & the brain’s blood vessels to pass into/out of the cranial cavity

Brain and bone develop at same time to fossae created so cavities in this shape are made.
Cranial nerves developed at same time as bone so bone has foraminae to let them through

Question 8

Describe fracture healing

Answer 8

-Bones may look away because of trauma.
-Sometimes bone doesnt resume completely normal shape, may be a bit rough or has a wee bump but this can have no effect whatsoever but be visible.
-Callus is ring of new bone around the fractured part which has started to try and heal the bone
-Clavicles often dont need surgery
-Reducing a fracture means to realign/bring broken ends together back to normal position for healing

Question 9

What are the two skeletons ?

Answer 9

Axial skeleton and Appendicular skeleton

Note the diagramatic difference in colour

Question 10

What is the axial skeleton ?

Answer 10

Axial Skeleton:
-bones of the skull
-bones of the neck
- (including the cervical vertebrae & the hyoid bone)
-bones of the trunk (chest, abdomen & back)

Axial bones are more midline

Question 11

What is the appendicular skeleton ?

Answer 11

Appendicular Skeleton:
-bones of the pectoral girdle (attaches upper limbs to axial skeleton)
-bones of the upper limbs
-bones of the pelvic girdle (attaches lower limbs to axial skeleton)
-bones of the lower limb

Appendicular is mainly bones of limbs and which help attach limbs to trunk

Question 12

Describe bones of the skull

Answer 12

Skull can be divided into two areas, neurocranium and viscerocranium
-Neurocranium holds parts of nervous system; brain, spinal cord, cranial nerves
-Base of skull

Hole just above line is part of ear canal

Cranial nerves/vessels/spinal cord etc need to pass through base of skull, can also get tumours/trauma/etc here

Question 13

Name bones seen from left lateral view of cranial vault

Answer 13

Sphenoid bone goes through middle of skull from one side to the other

Question 14

Name structures seen from posterior view of cranial vault

Answer 14

Sutures are where skull bones come together (intramembrane ossification)

Question 15

Describe structures seen in a posterior view on the base of the skull

Answer 15

-Frontal bone makes up most of anterior cranial fossa
-Wee yellow bone is irregular shaped as you also see some of it in the nose and also helping to make walls of orbital
-Sphenoid bone looks like bat
-Foramen magnum is the biggest foramen

Cut is made along the base of skull (the line)

Question 16

Describe bones of the facial skeleton

Answer 16

Zygomatic bones are (main) part of cheek bones, forming its prominance
Left and right maxilla join together along midline

Question 17

What are the bones of the adult vertebral column ?

Answer 17

33 vertebrae in total
-7 cervical (C1-C7)
-12 thoracic (T1-T12)
-5 lumbar (L1-L5)
-5 sacral (fused to form 1 sacrum)
-4 coccygeal (fused to form 1 coccyx)

From superior to inferior:
- become larger as they bear more weight
- become smaller again once weight has transferred to hip bones

Vertebrae are the bones which make up spine, vertebral column is curved

Sacrum connects spine to pelvis so transfers upper body weight across pelvic onto lower limbs

Question 18

Describe curvature of vertebral column

Answer 18

-One directional curvature begins to develop as a foetus
-When begin to lift head, crawl, pull yourself up on things, walk, run etc, weight is held in different ways so new curvatures continue to develop until adulthood is reached

In adults;
Two parts curved as in foetus; thorasic and sacral - primary curvature
Two parts curved opposite as in foetus; cervical and lumber - secondary curvature

Curvatures can become too extreme, lateral curvature is scoliosis

Question 19

Describe features and funftions of a typical vertebra

Answer 19

-Mainly vertebral bodies which get bigger as you go down (processes get a bit bigger, foramen get a bit smaller esp lumbar)
-Spinous processes are bits of spine you can feel at back
-Articular processes are where the vertebra joins with superior and inferior vertebra - SAP of 1 articulates with the IAP of 1 above and vice versa
-Vertebral arch goes up and around vertebral foramen

Anterior aspect at bottom:

-Pedicles are like two wee feet sticking up from vertebral body, lamina are like two wee sheets which come up from pedicle

Question 20

How do adjacent vertebrae join together and what does this form ?

Answer 20

Intervertebral foramen
-forms between adjacent vertebrae
-spinal nerves emerge through

Facet joint
-between articular processes of 2 adjacent vertebrae
-affected by arthritis

Intervertebral foramen is just how spinal cord gets nerves out

Question 21

Describe features of general and specific cervical vertebrae

Answer 21

All have a foramen in each transverse process (transverse foramen)
-passage of vertebral arteries

C1 - Atlas
-does not have a body or spinous process, has a posterior arch and an anterior arch instead

C2 - Axis
-has an odontoid process, projects superiorly from body

C7
-vertebrae prominens
-has the largest and longest spinous process, can feel on back of neck

All cervical spinous process are bifid, bar C1 and C7

Cervical vertebrae identifiable by transverve foramen

Question 22

Describe bones of the chest (and back) - ribs

Answer 22

12 pairs of ribs:
-True Ribs, 1-7 (attach via their costal cartilage to the sternum)
-False Ribs, 8-10 (attach via the costal cartilage above to the sternum, don’t connect directly themselves, forms costal margin)
-Floating Ribs, 11 & 12 (no attachment to sternum)

-Rib 1 is protected by the clavicle and is less likely to fracture than the other ribs, is also a bit shorter and wider

-The sharp end of a fractured rib has the potential to pierce and damage the soft tissues or organs lying deep to it e.g. lung, liver (R), spleen (L)

Question 23

What are the pectoral and pelvic girdles ?

Answer 23

Parts of the appendicular skeleton
-the pectoral girdle (the 2 scapulae, 2 clavicles
-the pelvic girdle (the 2 hip bones & the sacrum)

A girdle refers to a ring or belt of bone that attaches a limb to the axial skeleton/trunk

Question 24

What are the bones of the limbs ?

Answer 24

Are parts of appendicular skeleton

Upper Limb
-Arm (between shoulder and elbow joint)
-Forearm (between elbow and wrist joint)
-Hand (distal to forearm, after wrist)

Lower limb
-Thigh (between hip and knee joint)
-Leg (between knee and ankle joint)
-Foot (distal to the ankle)

Question 25

Compare bones of the upper and lower limbs

Answer 25

## Footnote Both have 1 long bone proximal, 2 long bones distal part then wee collection of bones

Question 26

What makes up the skeleton ?

Answer 26

Bones and cartilage together make up the skeleton Bone Hard, connective tissue Functions include: - support & protection of the body organs - calcium metabolism -red blood cell formation -attachment for skeletal muscles Cartilage Less rigid and a bit softer than bone Located where mobility is required at articulations (joints)/movable joints (synovial ???)

Question 27

Where and how does movement occur ?

Answer 27

-Movement of the skeleton occurs at joints. -Skeletal muscles contract to move the bones, therefore without joints we couldn’t move. | Muscles and bones needed for movement ## Footnote Without bones, muscles wouldn’t have much to move or attach to

Question 28

What is what ?

Answer 28

Question 29

What is what ?

Answer 29

Bony features

Question 30

What is what ?

Answer 30