06 Bones Cartilage And Fracture

Question 1

Define endochondral ossification. Label the parts of a long bone and describe the epiphyseal plate and its function.

Answer 1

Endochondral ossification is a process in which an initial small hyaline cartilage grows and turns(ossifies) into bone. Long bones e.g. Humerus and Femur

At each end, each bone contains

• epiphysis
• epiphyseal growth plate
• metaphysis
• diaphysis (which is the portion between both ends and is called the shaft)

The epiphyseal growth plate is where longitudinal growth of the bone takes place and when it ossified, bone growth ceases and the bone attains it’s final height.

Question 2

What does the bone consist of?

Answer 2

The bone has a

• outer cortical layer of compact bone which is dense, strong and heavy
• inner Medulla of spongy bone(trabecular/cancellous) which is porous, weak and light
• central medullary cavity which contains red marrow in the hematapoietic bone (site of white blood cell and red blood cell production) and fatty marrow in the non- blood cell forming bone
• eg of bones which have bone marrow- hip bone, skull, breast bone , ribs, vertebrae, and the spongy bone at the proximal ends of the Long bones humerus and femur

Question 3

Outline the blood supply to bone and comment on the presence of sensory nerves within the periosteum

Answer 3

The periosteum is a fibrous connective tissue that is vascularised and mainly supply blood to the compact bone.

It is also well innervated with sensory nerves and this results in extreme when the periosteum tears as occurs during fractures.

Nutrient vessels(arteries and veins) carry blood to and from the medullary cavity. They mainly supply the bone marrow, spongy bone and deep compact bone

Question 4

List the stages in the healing of a fracture defining “callus”. Understand what is meant by the term “surgical reduction and fixation”.

Answer 4

1. Normal clavicle
   >trauma
2. Fractured clavicle
3. Initial healing - callus(bony healing tissue which forms around the ends of the broken bone)of New bone surrounds the fracture line
4. Callus remodelling (into lamellar bone which is much stronger) (reassuming normal shape)
5. Healed left clavicle (more or less normal shape)

Question 5

List the bones of the axial and appendicular skeletons

Answer 5

Bones of the axial skeleton

• bones of the skull
• bones of the neck (which includes the cervical vertebrae and hyoid bone)
• bones of the trunk ( which includes the chest, abdomen and back)

Bones of the appendicular skeleton

• bones of the pectoral girdle which attaches the upper limbs to the axial skeleton
• bones of the upper limb
• bones of the pelvic girdle which attaches the lower limbs to the axial skeleton
• bones of the lower limb

Question 6

Define the terms “cranial vault”, “bones of the face”, “base of the skull”, and “Le Fort fracture”

Answer 6

Cranial vault- neurocranium
Bones of the facial skeleton -
Viscerocranium

Bones of the cranial vault- occipital bone (posterior), temporal bone, parietal bone, frontal bone, sphenoid bone
Joints- coronal suture, Sagittal suture

Base of the skull- occipital bone, temporal bone, sphenoid bone, frontal bone, cribriform plate of the ethmoid bone, foreamen magnum

Bones of the viscerocranium - Nasal bone, zygoma (zygomatic bone which forms the prominence of the cheek), maxilla, right and left sides of the jaw(separate in children and fuse at 1st year of age)

Le Fort 1- upper teeth set
Le Fort 2- along the borders of the nasal bone and maxilla
Le Fort 3- along the borders of the nasal bone, maxilla and zygoma

Question 7

Identify the bony features of the mandible.

Answer 7

Condylar process head and neck, coronoid process, Remus, angle, lower border of the side of the mandible, mental foramen, mental process

Question 8

Describe the vertebral column or spine in terms of regions and curvatures

Answer 8

The human body has 33 vertebrae in total.

It has 7 cervical, 12 thoracic, 5 lumbar, 5 sacrum (fused to form 1 sacrum- fuses at 1 year of age) and 4 coccygeal (fused to form 1 coccyx)

From superior to inferior, they become larger as they bear more weight. They become smaller again once the weight has been transferred to the hip bones.

Secondary curvature- cervical region
Primary curvature- thoracic
Secondary- lumbar
Primary- sacrum

Question 9

Describe the features and functions of the typical vertebra.

What is a facet joint.

Answer 9

Spinous process (x1) - ligament and muscle attachments
Transverse processes (x2) - ligament, muscle and rib articulations
Inferior and superior articular processes (x2 each) - Ensure mobility with adjacent vertebrae via synovial facet joints
Vertebral arch- protects the spinal cord and consists of pedicle (x2) and lamina (x2)
Vertebral foramen- transmits and protects the spinal cord
Weight bearing vertebral body

A fact joint is between the articular processes of two adjacent vertebrae and can be affected by arthritis.

Question 10

State and identify the features shared by all cervical vertebrae, shared by vertebrae C2-C6 and the unique features of c1,C2, and C7

Answer 10

All cervical vertebrae have a foreamen in each transverse process for the passage of vertebral arteries

C1- atlas- bears the weight of the skull on its shoulders

• has no body or spinous process
• has a posterior and anterior arch instead

C2- axis bone
- has an odontoid process which projects superiority from the body and articulates with the anterior arch of the atlas bone to form a pivot joint for the skull

C7- vertebrae prominens

• has the first palpable spinous process in 70% of people
• can be palpated at the midline of the posterior aspect of the neck

Question 11

Define pectoral Girdle, pelvic girdle, arm, forearm, thigh and leg

Answer 11

Pectoral girdle- 2 scapulae and 2 clavicles
Pelvic girdle- 2 hip bones and sacrum
Hand- distal to forearm
Foot- distal to ankle