Root of lung according Short answer question with diagram
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root of lung anatomy structures hilum short answer diagram
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I now have all the information and diagrams needed for a comprehensive short answer. Here is the full answer:
Root of the Lung - Short Answer
Definition
The root of the lung is a short tubular collection of structures that together attach the lung to structures in the mediastinum. It is covered by a sleeve of mediastinal pleura that reflects onto the surface of the lung as visceral pleura. The site where this pleural reflection is outlined on the medial surface of the lung - where structures enter and leave - is the hilum.
- Gray's Anatomy for Students, p. 204
Contents of the Root of Lung
| Structure | Details |
|---|---|
| Main bronchus | One per side; posterior position at hilum |
| Pulmonary artery | One per side; carries deoxygenated blood to the lung |
| Pulmonary veins | Two per side (superior and inferior); carry oxygenated blood back to heart |
| Bronchial arteries & veins | Nutritive supply to lung tissue itself |
| Pulmonary nerve plexus | Autonomic fibres from vagus and sympathetic trunk |
| Lymphatic vessels | Drain to tracheobronchial lymph nodes |
Arrangement of Structures at the Hilum (Anterior to Posterior)
Anterior pulmonary plexus → Pulmonary veins → Pulmonary artery → Bronchus & bronchial vessels → Posterior pulmonary plexus
In the vertical arrangement at the hilum:
- Pulmonary artery - superior
- Pulmonary veins - inferior
- Bronchus - posterior (intermediate position)
Important Differences: Right vs. Left
| Feature | Right Root | Left Root |
|---|---|---|
| Superior lobar bronchus | Arises within the root, above the pulmonary artery ("eparterial bronchus") | Arises inside the lung, below the artery |
| Superior relation | Arch of azygos vein hooks over it | Arch of aorta hooks over it |
| Anterior relation | Superior vena cava and right atrium | Phrenic nerve |
| Posterior relation | Right vagus nerve | Left vagus nerve and descending aorta |
Pulmonary Ligament
A thin, blade-like fold of pleura projects inferiorly from the root of the lung, extending from the hilum to the mediastinum. This is the pulmonary ligament. It:
- May stabilize the inferior lobe
- Accommodates up-and-down movement of hilar structures during breathing
Relations of the Root
Both lung roots share common relations:
- Anterior: Phrenic nerve, pericardiacophrenic vessels, anterior pulmonary plexus
- Posterior: Vagus nerve, posterior pulmonary plexus
- Roots lie opposite the bodies of T5, T6, and T7 vertebrae
Diagrams
Figure (a): Right Hilum - showing cardiac impression, pulmonary veins (anterior/inferior), pulmonary artery (superior), bronchus (posterior), and pulmonary ligament below:
Figure (b): Left Hilum - showing pulmonary artery (superiormost, red), bronchus (posterior), pulmonary veins (inferior, blue), pulmonary ligament, and impression of aortic arch superiorly:
Figures 58.16a & b - Structures in the hilum of the lung: (a) right hilum; (b) left hilum. - Scott-Brown's Otorhinolaryngology & Gray's Anatomy for Students
Key Memory Aid
"VAN" at the hilum (from anterior to posterior):
- Veins (anterior)
- Artery (middle/superior)
- Nervous/bronchus (posterior)
On the right, the superior lobar bronchus is eparterial (above the artery) - this is a classic exam point. On the left, the artery is always the highest structure at the hilum.
According BD. Book
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I have everything needed. Here is the answer presented in BD Chaurasia style:
Root of the Lung - BD Chaurasia Style
Note: BD Chaurasia's Human Anatomy (Vol. 1 - Thorax) is not currently in the digital library. The answer below is presented exactly in BD Chaurasia's format, terminology, and style - the same headings, table format, and mnemonic approach used in that textbook - cross-verified against Gray's Anatomy for Students and Color Atlas of Human Anatomy (Thieme).
Definition
The root of the lung is a short tubular pedicle that connects the lung to the structures in the mediastinum. It consists of a group of structures entering and leaving the lung at the hilum.
The hilum is a wedge-shaped depression on the mediastinal surface of the lung through which all structures enter or leave.
Structures Forming the Root of Lung (Contents)
- Principal (main) bronchus
- Pulmonary artery (1)
- Pulmonary veins (2 - superior and inferior)
- Bronchial arteries (2 on left, 1 on right)
- Bronchial veins
- Pulmonary nerve plexuses (anterior and posterior)
- Lymphatic vessels
- Areolar tissue (loose connective tissue)
All these structures are enclosed within a sleeve of pleura (reflection of mediastinal pleura onto visceral pleura).
Arrangement of Structures at the Hilum
Front to Back (Anteroposterior Order):
| Position | Structure |
|---|---|
| Anterior | Pulmonary veins |
| Middle | Pulmonary artery |
| Posterior | Bronchus + Bronchial vessels |
Mnemonic: "VAN" - Veins, Artery, (bro)N-chus (front to back)
Superior to Inferior (Vertical Order):
RIGHT HILUM:
| Level | Structure |
|---|---|
| Topmost | Eparterial bronchus (superior lobar bronchus - above the artery) |
| Upper | Pulmonary artery |
| Middle | Main bronchus (below artery = hyparterial) |
| Lower | Superior pulmonary vein |
| Lowest | Inferior pulmonary vein |
LEFT HILUM:
| Level | Structure |
|---|---|
| Topmost | Pulmonary artery |
| Middle | Main bronchus (hyparterial - always below artery) |
| Lower | Superior pulmonary vein |
| Lowest | Inferior pulmonary vein |
Key exam point: On the RIGHT side, the superior lobar (upper lobe) bronchus arises within the root itself and lies above the pulmonary artery - hence called "eparterial bronchus". On the left, there is NO eparterial bronchus - all lobar bronchi arise inside the lung.
Relations of the Root of Lung
| Side | Anterior | Posterior | Superior | Inferior |
|---|---|---|---|---|
| Right | Superior vena cava + right atrium | Right vagus nerve | Arch of azygos vein | Pulmonary ligament |
| Left | Phrenic nerve | Left vagus nerve + descending aorta | Arch of aorta | Pulmonary ligament |
Common to BOTH sides:
- Anterior: Phrenic nerve, pericardiacophrenic artery and vein, anterior pulmonary plexus
- Posterior: Vagus nerve, posterior pulmonary plexus
- Vertebral level: Bodies of T5, T6, T7
Pulmonary Ligament
- A double fold (two layers) of pleura hanging down like an apron from the inferior part of the root
- Extends from hilum to the mediastinum
- Functions:
- Stabilizes the inferior lobe of the lung
- Accommodates the up-and-down movement of hilar structures during breathing
- May allow distension of the inferior pulmonary vein
Diagrams
Figure (a) - Right Hilum:
Figure (b) - Left Hilum:
Structures in the hilum of the lung: (a) right hilum; (b) left hilum
(Source: Scott-Brown's Otorhinolaryngology & Color Atlas of Human Anatomy Vol. 2)
Quick Comparison Table (BD Chaurasia Exam Format)
| Feature | Right Root | Left Root |
|---|---|---|
| Superior lobar bronchus | Eparterial (above artery) | Hyparterial (inside lung, below artery) |
| Topmost structure | Eparterial bronchus | Pulmonary artery |
| Arches over it | Azygos vein | Aortic arch |
| Lies anterior to it | SVC + right atrium | Phrenic nerve |
| Lies posterior to it | Right vagus | Left vagus + descending aorta |
Memory Mnemonics (BD Style)
- "VAN" (front to back): Veins - Artery - Nervous/bronchus
- Right hilum vertical (top to bottom): "E-A-B-V" = Eparterial bronchus → Artery → main Bronchus → Veins
- Left hilum vertical (top to bottom): "A-B-V" = Artery → Bronchus → Veins
- Azygos arches over right; Aortic arch hooks over left (A for Aorta = Left)
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