Case 6- lung anatomy Flashcards
What is in the thoracic cage
Thoracic vertebra, sternum, ribs and costal cartilage
What is the thoracic wall
Contains the bone structures of the thoracic cage as well as muscle, connective tissue and neurovascular structures.
Sternum
Split into the Manubrium, sternal body and xiphoid process (T9/T10).
Location of suprasternal (jugular) notch
T2
Location of sternal angle
T4/T5 also where the second rib is
Location of ribs
The thoracic vertebra are between T1-T12
True ribs T1-7
False ribs T8-10
The floating ribs are T11-12
Difference between true and false ribs
The true ribs have cartilage which directly attaches to the sternum. The false ribs attach to the sternum via the costal cartilage of the rib above
Costal cartilage
Connects the ribs to the sternum anteriorly
How the thoracic vertebra are split from top to bottom
- 7 cervical vertebra- neck
- 12 thoracic vertebra- thorax
- 5 Lumbar vertebra- abdomen
- The Sacrum and then the Coccyx- around the pelvis and hip bone
Body of vertebra
Bares the weight, is where the vertebra articulate, have the interverbal disk above and below it
Vertebra- neural arch
The vertebra is split into the body and the neural arch. The neural arch contains the pedicle, the Lamina, the spinous process and the transverse process.
Vertebra- vertebral foramen
Between the body and the neural arch, transports the spinal cord
Vertebra- superior and inferior articular processes
Facet articulates with adjacent superior and inferior vertebra. How the different vertebra connect with each other
Superior and inferior demifacet
Where the vertebra articulates with the superior and inferior facet on the head of the rib
Atypical ribs
Ribs 1, 2, 10, 11 and 12. Atypical shape and articulates with its own vertebra only
Typical rib
Curved shaft with both anterior and posterior parts. They will have a head, neck and tubercle. It articulates with their own vertebra and the one above, so rib 4 would articulate with T4 and T3.
Anatomy of typical rib
- Head- articular facets which connect with the vertebra bodies. Contains both the superior and inferior facets, the inferior connects with its own vertebrae and the superior connects to the rib above.
- Neck- contains the tubercle facet which articulates with the transverse process
- Angle- where the rib curves.
- Costal groove- a depression in the rib which transports the neurovascular bundle.
Costovertebral joint
Head of a typical rib articulates between its own thoracic vertebra and the one above
Costotransverse joint
Head of typical rib articulates between its own thoracic vertebra and the one above. The inferior facet of the head of the rib articulated with the superior demi-facet of the body of the same vertebra. The superior facet of the head of the rib articulates with the inferior facet of the above vertebra.
Costotransverse joint
Articulation of rib tubercle with the costal facet on the transverse process of the corresponding vertebra
Manubiosternal joint
Between the manubrium and the sternal body. It is a symphysis joint.
Xiphisternal joint
Between the sternal body and the Xiphoid process. It is a synchondrosis joint
Sternocostal joints
Between the costal cartilage and the sternum.
The Costochondrial joint
Between the ribs and the cartilage
The interchondrial joints
Between the different joints of the cartilage
How do the joints help in respiration
Allow changes in thoracic volume so are useful in inspiration and expiration. They allow for the bucket handle and pump handle movement
Cartilaginous joints
When structures are attached by cartilage. The two types:
• Primary cartilaginous joints (synchondrosis) – Connected by hyaline cartilage.
• Secondary cartilaginous joints (symphysis) – Connected by fibrocartilage.
Synovial joints
Between structures that aren’t directly joined but are surrounded by a joint capsule that contains synovial fluid
Openings in the thoracic wall
There are two openings of the thoracic wall: the superior and inferior thoracic apertures
Muscle in the intercostal space
The intercostal space is the space between the ribs, there are 11 intercostal spaces. The muscles in the interoctsal space are the external, internal and innermost intercostal muscle. The intercostal muscles keep the intercostal space (ICS) rigid and prevent the spaces being blown out during expiration or in during inspiration. They provide structure to the thoracic wall and have a role in respiration.
The neurovascular bundle in the intercostal space
The neurovascular bundle is between the inner intercostal muscle and the innermost intercostal muscle. The main part of the vein, artery and nerve travels in the costal groove, the collateral branch sits inferiorly in the intercostal space. Superiorly to inferiorly it goes vein, artery and nerve.
Spinal nerve
The nerve supply to the thoracic wall and parietal pleura is from the anterior division of the spinal nerves T1-T11. Each spinal nerve gives rise to a intercostal nerve and collateral branch.
Intercostal nerve
It is an extension of the ventral rami of segmental nerves leaving the spinal cord at the thoracic vertebral levels. Between the inner and innnermost intercostal muscle. The collateral parts travel across the inferior parts of the intercostal space. The lateral and anterior cutaneous branch provides sensation to the skin of the thoracic wall and the parietal pleura and the muscles of the thoracic wall.
Blood supply of the thoracic wall
Through intercostal arteries which are in the neurovascular bundle. The posterior intercostal artery comes of the thoracic aorta, the anterior intercostal artery comes of the internal thoracic artery. These arteries anastome, meaning they fuse together and form a continuous blood supply around the thoracic wall. Though the blood supply looks continuous they are two separate vessels
Blood supply to the first and second posterior intercostal space
The subclavian artery gives of the costocervical trunk which then gives off the posterior intercostal artery.
Blood supply to the majority of the posterior intercostal space
Branches of the thoracic aorta (3-11)
Blood supply to the anterior intercostal arteries
Internal thoracic artery (1-6) which is a branch of the subclavian artery. The musculophrenic artery (7-9) is a branch of the internal thoracic which runs around the costal margin. Ribs 11-12 are floating ribs so dont have anterior arteries
Azygos vein- intercostal space
Comes from the ascending lumbar veins which have drained the posterior abdominal wall. The 4-11th right posterior intercostal veins drain into here
Accessory hemiazygos vein
Drains into the Azygos vein. The 4th-7th left posterior intercostal veins drain into the accessory hemiazygos.
Hemiazygos vein
Comes from the ascending lumbar veins then drains into the Azygos vein. The 8-11th left posterior intercostal veins drain into the Hemiazygos vein
What drains the first intercostal space
The supreme intercostal vein which drains into the vertebral or brachiocephalic vein
What drains the 2nd and 3rd intercostal space
Drains into the intercostal veins, on the right it drains into the Azygos vein and on the left it drains into the Brachiocephalic
Where do the anterior intercostal veins drain into
The internal thoracic and musculophrenic vein following the arterial supply
The diaphragm
Separates the thorax from the abdomen and allows for structures to move between them. It increases intrabdominal pressure to expel vomit, faeces and urine
What’s the diaphragm made of
It is made of skeletal muscle, 60% of which is slow-twitch fibres which have are resistant to fatigue and has a lot of endurance. The skeletal muscle has a higher oxidative capacity and larger blood-flow than limb muscles so it can work continuously.
Diaphragm- central tendon
Where the fibrous pericardium attaches to the diaphragm
Diaphragm attachments
The inferior attachments of the diaphragm are: the costal margin, posterior abdominal wall and lumbar vertebra. It attaches to the xiphoid process of the sternum, the costal cartilages of ribs 7-10, ribs 11 and 12, and the lumbar vertebrae. The attachments are the right crus (L1-3) and the left crus (L1-2) and the 4 arcuate ligaments: Median (travels over the aorta), Medial (passes over the psoas major) and Lateral (travels over the quadratus lumborum muscle of the posterior abdominal wall). The left and right crus are the posterior attachments
The caval hiatus
At T8 where the inferior vena cava and the terminal bronchus of the right phrenic nerve travel from the abdomen into the thorax
Oesophageal hiatus
At T10, the oesophagus and right and left vagus nerve travel through this hiatus to the abdomen
Aortic hiatus
At T12. Where the descending aorta travels into the abdomen becoming the abdominal aorta. The thoracic duct and the azygos vein travel from the abdomen to the thorax through the aortic hiatus also.
Diaphragm nerve supply
The phrenic nerves supply the diaphragm and are from the spinal routes C3, C4 and C5
The intercostal muscles
Within the intercostal space. The muscles run in different directions, the external muscles run medially and down, the internal and innermost intercostal muscles run medially and up.
Subcostalis muscle
Attach to the posterior ribs
Transversus thoracic muscle
Attach to the anterior ribs
The innermost muscle layer
Consists of the innermost intercostal muscles, the subcostalis muscle and the transversus thoracis. They are the accessory muscles of expiration. They are primarily responsible for changing the volume of the thoracic cavity during respiration along with the diaphragm.
What is different about interchondrial muscles
The interchondrial part of the internal intercostal muscles have the same role as the external intercostal muscles.
The abdominal wall muscles
• External oblique muscle
• Internal oblique
• Transverse abdominus
• Rectus abdominus- the only layer posteriorly
The muscles are from the outside in. They are accessory muscles which may be used in recovery from strenuous exercise or in individuals with respiratory disorders
Sternocleidomastoid muscle
Attaches to the sternum and the clavicle, when it contracts it elevates them increasing the thoracic volume
Scalene muscles
In the back of the neck attached to ribs 1 and 2. They contract to elevate the ribs and increase the thoracic volume
Pectoralis minor and major
Attach to the superior ribs, contract to elevate them
Serratus anterior
On each side of the ribs, elevate them
Quadratus lumborum
A muscle of expiration and inspiration, it attaches to the lower ribs and depresses them when they contract. It stabilises the diaphragm so it has more force on inspiration
