Thorax and Vertebra Flashcards
Where is the thorax located?
What are its parts and their functions?
Thorax located below neck and above abdomen.
It has 2 Parts:
1. Chest walls:
Composed of:
- Skeleton: ribs and vertebra
- Skeletal muscle and fascia (superficial and deep)
- Skin
Functions:
- Protect the heart & lungs
- Make the movements of breathing
- Breast tissue - lactation
2. Chest cavity:
- Within the chest walls
- Contains vital organs (known as viscera): heart and lungs
- Also contains major vessels and nerves: great vessels are also visceral structures
Label the diagram
How many thoracic vertebrae/ribs do we have?
12 thoracic vertebra, and associated with each is a pair of ribs
Label the diagram
Clavicle attaches to acromion of scapula
Caracoid of scapula is below it, hanging in the air (for muscle attachment), next to the ball joint for upper limb attachment
Which skeletal structures comprise the upper limb girdle? What is unique about it?
Scapula combined with the clavicle = shoulder girdle or upper limb girdle (scapula + clavicle)
There is no direct skeletal connection between the scapula and the thoracic cage (ribs) – all muscular, ligamentous, and tendon connection – gives a great range of movement to the upper limbs
How many vertebrae do we have in total?
What are the subdivisions?
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
Where are the sacral vertebrae located? When and why are they fused?
Sacral vertebrae are in between the two halves of the pelvis
The sacrum and the coccyx are fused vertebrae (fused around about puberty – before which they are individual vertebrae).
- The reason for the fusion of the sacrum is to provide stability – this area is all about transmission of forces through the lower limbs into the ground
- The coccyx is all about muscle attachment from the pelvic floor – no weight bearing element here
What are the two curvatures of the vertebrae?
Describe them and which vertebrae are associated with them, and when they develop
Vertebrae divided into primary and secondary curves
Primary = resembles embryonic curvature
- anterior cavity
- thoracic and sacral regions
Secondary = developed later in life
- posterior cavity
- cervical (develops at 3-4 months) and lumbar regions (develops at 6 months)
Label the diagram
List the functions of each part
- Pedicles – join the vertebral body with the arch behind
- Laminae – join the processes
Label the diagram
Which ribs are typical/atypical?
Ribs 3-9 are ‘typical’
1, 2, 10-12 are ‘atypical’
Label the diagram
Where does rib 1 sit and what at are its atypical characteristics?
Sits right below clavicle (collar bone):
- shortest, broadest, most sharply curved rib
- very strong and stout: least likely to fracture
- has 2 transverse grooves on superior surface: the anterior groove is for the subclavian vein, the posterior groove for the subclavian artery (subclavian because it goes below the clavicle)
Label the diagram
Describe how ribs articulate with vertebrae
Rule of thumb: A numbered rib will articulate with the same numbered vertebrae (its superior articular facet AND its transverse facet), PLUS the vertebrae above (its inferior articular facet): e.g. R2 with T2 and T1
- The head of the rib has 2 articular facets
- The tubercle of the rib articulates with the transverse facet (on the transverse process) of the same numbered vertebrae: R2 with T2
These joints are collectively known as costal vertebral joints
- All sinovialjoints that in part permit movement
NOTE: spinous processes slope downwards
NOTE: both the superior/inferior costovertebralfacets and transverse facets are joints of breathing. The facets lie on the processes bearing the same name.
NOTE: intervertebral foramen not shown here
What are the two types of anterior rib joints?
Describe their characteristics
What is the cartilage on rib called? What kind is it?
- Sternocostal (sternochondral) joints: synovial
- Chostocondral joints: not true joint but rather transition between cartilage and bone - does not allow any movement
The cartilage on ribs is called costal cartilage. It is hyaline cartilage.
Label the diagram
What can be felt at the top of the manubrium?
Why is the sternal angle an important landmark?
Jugular notch at the top of the manubrium is where we can palpate the trachea
Sternal angle important for
- counting ribs – since we know R2 articulates at the sternal angle. We count ribs by finding rib 2 and then counting down
- This is used to place stethoscope in the correct position to listen to breath sounds from the chest or heart sounds
- The curve of the aorta alse lies behind the sternal angle
- Trachea bifurcates at the level of the sternal angle
- Sternal angle is the border betwen the superior and inferior mediastinum
Label the diagram and list the functions of each part
Which structures change depending on the size of the cadaver?
Skin is the first layer
- Directly underlying it is the superficial fascia (yellow fatty substance) – depth of layer depends on how large cadaver is: more fat for big cadavers
- Under it is another layer of fascia – deep fascia – which is a very thin layer regardless of the size of the cadaver
- Under the deep fascia is skeletal muscl
Label the diagram with the function for each part
What is unusual about the nerve supply of one of these muscles? What can it result in?
What kind of procedure can cause this result? (and what is it called)
Which other muscle is responsible for anchoring the scapula? Where does it start and end?
The serratus anterior is unusual in terms of nerve supply – nerves supply the superficial aspect of the muscle (in contrast to most other muscles where the nerve is deep).
This is significant because this superficial nerve layout exposes it to injury:
If the thoracic nerve is temporarily impaired, the serratus anterior stops working, so the scapula is no longer anchored to the thoracic cage and looks like a winged scapula – temporary condition which corrects itself over the day.
- Can be caused temporarily by drunk student sleeping on the arm of the sofa
- Can by caused permanently by iatrogenic injury – surgeon’s injury e.g. during masectomy
Under pectoralis major is the pectoralis minor
- Extends from the coracoid process of the scapula to some of the ribs – so also partly responsible for anchoring the scapula
Label the diagram
What procedure is being shown? Describe it
Thoracocentesis: sampling fluid from pleural cavity
- via an intercostal space
- below intercostal NVB
- above collateral intercostal NVB
