Thorax I Flashcards
anterior posterior dorsal ventral lateral medial proximal distal
All body planes
True Ribs
1-7
False Ribs
8-10
Floating Ribs
11-12
The Thoracic Cage
Inferior Thoracic Aperture
Posterior Anterior of Thoracic vertebrae
Lateral View of Vertebrae
Costovertebral joint
Features of Typical Ribs
Which of the ribs is atypical?
Ribs 1, 2, 10 11 and 12
Note how all contains the numbers 1, 2
1 is important clinically because of its close relationship to lower nerves of the brachial plexus and main vessels of arm
True & False Ribs
How do all ribs articulate? and with what structure?
All ribs articulate posteriorly with the thoracic vertebrae
What can happen if the first rib/clavicle is damaged…
The nerves of the brachial plexus can be compressed between the first rib and clavicle which can cause pain in the forearm, hand, wrist and can comprimise circulation in the upper limb
Where are fractures most likely to occur in the ribs?
The weakest point in adult ribs vulnerable to fractures is the angle
Clinical case: Cervical Rib
A rib arising from anterior tubercle of transverse process (TP) of C7
Can cause pressure on lower brachial plexus or subclavian artery
The black boxes are fibres
Muscles of the chest wall: Pectoralis Major
Deltoids _____ arm
Pectoralis Major ______ arm
Deltoids abduct arm
Pectoralis Major adducts arm
Muscles of the chest wall: Pectoralis Minor
Function?
Depression of Scapula
Muscles of the chest wall: Serratus anterior
Function?
Protraction and rotation of scapula
Intercostal muscles
Intercostal Membranes
Intercostal muscle fibre direction
Subcostalis
Internal surface of one rib to internal surface of another
Transversus thoracis
From xiphoid process and lower body of sternum to lower border of CCs 3-6
(costal cartilages?)
Functions of intercostal muscles
•External intercostal muscles most active during inspiration (A)
•Interchondral portion of internal intercostal also involved (C)
o Elevate ribs and sternum
•Internal intercostal muscles most active during expiration (B)
o Interosseous portion - the portion between the ribs
o Depress ribs and sternum
Most activity of intercostal muscle is to maintain tone in the intercostal space: ‘isometric’
The Diaphragm & structure
Most important muscle of respiration
Thin muscular & tendinous septum
Separates the thoracic cavity above & the abdominal cavity below
Dome shaped
Diaphragm consists of…
Peripheral muscular part & Centrally placed tendon
On contraction the diaphragm…
pulls down its central tendon & increases the vertical diameter of the thorax
Diaphragm Structure question
Answer in Picture
There are three main apertures in the diaphragm:
Vena Caval foramen (T8)
Oesophageal hiatus (T10)
Aortic hiatus (T12) (not a true aperture)
Mechanism of respiration
- Two phases of Inspiration & Expiration
- Alternate increase & decrease of capacity of thoracic cavity
- As there is only a single entrance (trachea), an increase in capacity of the thoracic cavity, results in air moving into the lungs under atmospheric pressure
Vertical diameter
Changes in thoracic cage diameter
changes are achieved through the diaphragm
Anteroposterior diameter
Changes in thoracic cage diameter
Downward sloping ribs raised at sternal end
First rib is fixed, intercostals contract bringing ribs closer together
External intercostals & interchondral part of internal intercostals and innermost intercostals
Transverse diameter
Changes in thoracic cage diameter
- Ribs articulate in front with the sternum & behind with vertebral column
- Curve downward & resemble bucket handles
The interchondral joints
small articulations between the apposed costal cartilages of the ribs 7-10.
The intercostal artery, vein & nerve (the neurovascular bundle) run along between the…
Intercostal neurovascular bundle
Internal & innermost intercostal muscles
Protected by the costal groove of the superior rib
V - Vein
A - Artery
N - Nerve
How many intercostal spaces are there?
11 intercostal spaces: name according to the rib superior
Intercostal nerve enters space between
Intercostal nerves
parietal pleura & internal intercostal membrane
Intercostal nerves originates segmentally from…
Intercostal Nerves
Anterior Rami T1-T11 of spinal nerve:
- 1-6 intercostal spaces
- 7-9 pass deep to Costal Cartilages to enter anterior abdominal wall
- 10-11 pass directly to anterior abdominal wall
‘Subcostal nerve’
Intercostal nerves
T12 intercostal nerve
T1 intercostal nerve has branch that joins to..
Intercostal nerves
Brachial Plexus
It also has:
No lateral cutaneous branch
No anterior cutaneous branch
Intercostal Nerve Diagram question
Blood supply via the anterior & posterior intercostal arteries originate from…
Intercostal arteries
…the internal thoracic artery (branch of the subclavian - anterior) & descending thoracic aorta (posterior) respectively
Each intercostal artery gives off branches to the…
…muscles, skin, parietal pleura & in the region of the breast in the female. The branches to the superficial structures are particularly large
Intercostal Artery & Vein Diagram
The azygous and hemi-azygous system of veins drains…
Intercostal veins
the intercostal spaces, as well as the pericardium & parts of the posterior abdominal region
Posterior intercostal veins drain into…
Intercostal veins
the azygous & hemi-azygous systems
Main azygous vein on _____
Superior (accessory) & Inferior hemiazygous (proper) on _____
Intercostal veins
Main azygous vein on right,
Superior (accessory) & Inferior hemiazygous (proper) on left
Azygous & Hemi-zygous veins are also important as they can be an…
Intercostal Veins
anastomotic pathway for venous return if IVC becomes blocked
- Azygous formed by union of right ______ _____& right ______ ____
- Inferior hemiazygous formed by union of left ______ _____ & left _____ ____
Intercostal Vein
- Azygous formed by union of right ascending lumbar & right subcostal veins
- Inferior hemiazygous formed by union of left ascending lumbar & left subcostal veins
Breast structure, where it overlies and parts rest
- Overlies the 2nd–6th rib
- Two-thirds of it rests on pectoralis major, one-third on serratus anterior
- Lower medial edge just overlaps the upper part of the rectus sheath
Structure of the Breast (go over lecture in this bit)
- Modified sweat gland
- It is conical in shape
- It lies in superficial fascia of the front of chest
- It has a base, apex and tail (axillary tail)
- It extends from the lateral margin of the sternum to the midaxillary line
- It has no capsule
Blood supply to the Breast (Arterial)
Arterial
From the axillary artery, principally via its lateral thoracic and acromiothoracic branches:
- Perforating branches of internal thoracic (internal mammary) artery
- Mammary branches of lateral thoracic artery
- Mammary branches of Intercostal arteries
Blood supply to the Breast (Venous)
Venous
- Circular venous plexus are found at the base of nipple.
- Veins of this plexus drain into axillary & internal thoracic veins.
Diagram
The largest lymph nodes are located where….
Breast Lymphatics
peripheral lymphatics connect with the trunk , such as the groin, axillae and base of the neck
Particular importance to the lymph nodes in the axilla…
Breast Lymphatics
- Frequent development of cancer in the mammary gland
- Subsequent dissemination of the malignant cells along lymph vessels to the nodes
5 breast lymphatic groups which lie in the axillary fat:
Breast lymphatic
- Pectoral (Anterior) group: which lies on Pectoralis Major along lateral thoracic vessels
- Subscapular (Posterior) group: which lies on posterior wall of axilla on lower border of subscapularis along subscapular vessels
- Brachial (Lateral) group: lies on lateral wall of axilla along the axillary vessels
- Central group: lies in at the Center (base of axilla)
- Apical group: lies at apex of axilla
Subclavian lymph trunk is formed by union of…
Breast lymphatic
…efferent lymph vessels of apical group.
- It usually opens in subclavian vein.
- On the left side it usually opens into thoracic duct.
