Each lung is divided into lobes and each lobe is divided into segments. Each segment is supplied by its own bronchus, which is called a segmental bronchus. We will learn the anatomy of the tracheobronchial tree and the segments together.
1
Study Figure S1-1 . You should be familiar with this anatomy already. The trachea bifurcates at the carina, into the right and left main bronchi. The right has _________________ lobar bronchi, and the left has _________________ lobar bronchi.
A.
one
B.
two
C.
three
D.
four
1
C. three
B.
two
2
Let’s start with the right upper lobe (RUL). In Figure S1-2 , the RUL bronchus comes off at approximately the level of the carina. It divides into _________________ segmental bronchi.
A.
one
B.
two
C.
three
D.
four
2
C. three
Over the years, several numbering systems have been used to describe the segmental bronchi. They are difficult to remember and seldom used. I prefer the anatomic names. They are logical and one less thing to memorize. Understanding lasts longer than memorization. Remember that!
In Figure S1-2 , the diagram shows the three RUL segmental bronchi described by location: apical (#1), anterior (#2), and posterior (#3). The numbers are the Boyden system, for those who prefer numbers to names.
CLINICAL PEARL: Reactivation (postprimary) tuberculosis (TB) is usually in the apical (#1) or posterior (#3) segments of the upper lobes. In the anterior segment (#2), postprimary TB is rare, whereas cancer is not uncommon in older adults.
4
In Figure S1-4 , the bronchus intermedius is a continuation of the right ____________ bronchus after the takeoff of the RUL bronchus. In reality, the right main bronchus bifurcates into the RUL and bronchus intermedius.
A.
anterior segmental
B.
posterior segmental
C.
apical segmental
D.
right main stem
4
D. right main stem
5
In Figure S1-4 , the right middle lobe (RML) bronchus arises from the bronchus intermedius. It courses anteriorly and divides into two segmental bronchi: the lateral segment (#4) and the ____________ segmental (#5) bronchi.
E ____________________________ F ______________________
A.
anterior
B.
medial
C.
lateral
D.
apical
6
E= B. medial
F
= C. lateral
7
In Figures S1-5 A and S1-5 B , the lateral segment (#4) is bordered superiorly by the _____________________ fissure on both the PA and lateral. The __________________ segment (#5) lies against the right heart border, medially, and against the ________________ fissure, posteriorly.
A.
minor
B.
major
C.
azygous
D.
medial
E.
lateral
7
A. minor
D.
medial
B.
major
Figures S1-6 A and S1-6 B show a segmental pneumonia in the right middle lobe. The sharp upper margin is the minor fissure. The right heart border is vague. Figure S1-6 C is a coronal computed tomography (CT) scan through the middle lobe.
8
The right lower lobe (RLL) bronchus is the direct continuation of the bronchus intermedius after the takeoff of the ____________ bronchus ( Figures S1-7 A and S1-7 B ).
A.
RML
B.
RUL
C.
medial segment
D.
lateral segment
8
A. RML
9
In Figure S1-7 B , the lateral view shows the first segmental bronchus of the RLL arises posteriorly, just opposite the _____ bronchus. It runs posteriorly to supply the superior segment (#6) of the RLL.
A.
RUL
B.
RML
C.
RLL
9
B. RML
Husband: I just killed three male and two female flies. Wife: How can you tell one from the other? Husband: Three were on the beer can and two were on the phone.
10
Figures S1-8 A and S1-8 B show the anatomic position of the superior segment of the RLL. On the frontal view ( Figure S1-8 A ), the superior segment of the RLL overlaps __________________ lobe(s).
A.
the RUL
B.
the RLL
C.
both
D.
neither
10
C. both
On the lateral view ( Figure S1-8 B ), test yourself by identifying:
E _______________________ F ________________________ G _______________________
A.
superior segment RLL
B.
inferior segment RML
C.
medial segment RML
D.
lateral segment RML
E.
C. medial segment RML
F.
D. lateral segment RML
G.
A. superior segment RLL
11
The four remaining segmental bronchi supply the four basal segments of the RLL. They are named for their location at the lung base (see Figure S1-7 A ). Two basal segments are located ventrally (anteriorly), the medial (#7) and the anterior (#8) segments. Two basal segments are located dorsally (posteriorly), the _______________ (#9) and ___________________ (#10) segments.
A.
posterior basal
B.
superior
C.
lateral basal
D.
inferior basal
11
A. posterior basal
C.
lateral basal
12
The two basal segments that contact the major fissure sit ____________________.
A.
anteriorly
B.
posteriorly
12
A. anteriorly
They are the ____________________ and the ____________________ segments.
A.
anterior basal
B.
inferior basal
C.
lateral basal
D.
posterior basal
E.
medial basal
A.
anterior basal
E.
medial basal
The two that contact the posterior thoracic wall are the _________________ and the ___________________ segments.
A.
anterior basal
B.
inferior basal
C.
lateral basal
D.
posterior basal
E.
medial basal
D.
posterior basal
C.
lateral basal
13
Figures S1-9 A and S1-9 B show the position of the medial basal (#7) and the lateral basal (#9). In the lateral view ( Figure S1-9 B ), test yourself by identifying H and I.
A.
medial basal
B.
posterior basal
C.
anterior basal
D.
lateral basal
E.
superior basal
13
H. A. medial basal
I.
D. lateral basal
14
Figures S1-10 A and S1-10 B show the remaining basal segments: the anterior basal (#8) and posterior basal (#10). In the lateral ( Figure S1-10 B ), test yourself by identifying J and K.
A.
posterior basal
B.
anterior basal
C.
superior basal
D.
inferior basal
14
J. A. posterior basal
K.
B. anterior basal
15
Which RLL segments border on the major fissure? __________, __________ and __________. None border on the minor fissure.
Figures S1-11 A and S1-11 B show consolidation in the __________ segment of the __________ lobe.
A.
posterior
B.
superior
C.
apical
D.
interior basal
E.
right upper
F.
right middle
G.
right lower
16
B. superior
G.
right lower
CLINICAL PEARL: The posterior segment (#3) of the upper lobes and the superior segments (#6) and posterior basal segments (#10) of the lower lobes are the most gravity-dependent segments in supine patients. Aspiration pneumonitis, foreign body aspiration, and abscess often occur in these segments. In Figures S1-11 A and S1-11 B there is an air/fluid level caused by an aspiration abscess. Figure S1-11 C is a sagittal CT through the abscess.
If you know the right lung segments, the left segments are easy. The differences between the two lungs are minor, so don’t get discouraged. (There are basically two types of people, optimists and pessimists. The optimists are usually happy and the pessimists are usually right.)
17
First of all, there are only two lobes on the left, the ______________ lobe and the _______________ lobe. The homologue of the ________________ is called the lingula. (Now whose bright idea was that?)
A.
left upper lobe (LUL)
B.
left lower lobe (LLL)
C.
left middle lobe (LML)
D.
right lingula
E.
RML
17
A. left upper lobe (LUL)
B.
left lower lobe (LLL)
E.
RML
18
Figure S1-12 shows that the first lobar bronchus arising from the left main bronchus is the ________________ bronchus. It branches into an upper division and lower division, which is called the ________________.
A.
LUL
B.
left lower lobe
C.
left lower lobe
D.
lingula
18
A. LUL
D.
lingula
19
Figure S1-12 shows that the upper division bronchus divides only twice—into the combined _____________ segment and the _____________ segment. The LUL apical-posterior segment is the equivalent of the apical and posterior segments of the RUL.
The RML bronchus arises from the _________________________. There is no similar bronchus on the left. The lingula is the continuation of the ____________ bronchus just distal to the upper division bronchus.
A.
right main bronchus
B.
bronchus intermedius
C.
RLL
D.
left main
E.
LUL
F.
left middle lobe
G.
LLL
20
B. bronchus intermedius
E.
LUL
Most call the LUL upper division the “left upper lobe” and the LUL lower division “the lingula.”
21
Figure S1-14 shows that the lower or lingula division of the LUL is subdivided into two segments: the superior (#4) and the inferior (#5). These are similar in location to the lateral and medial segments of the RML. One more quirk of anatomic nomenclature to have to deal with!
21
The lingula segments are shown in Figures S1-15 A and S1-15 B . The _________________ segment (#5) of the lingula and the _________________ segment (#5) of the RML contact the heart medially
A.
superior
B.
inferior
C.
lateral
D.
medial
The inferior segment contacts the major fissure posteriorly.
B. inferior
D.
medial
The lateral segment of the RML contacts the minor fissure from below. The superior segment of the lingula would contact the left minor fissure, if one existed. (Note: It does exist in <5% of patients.)
Figure S1-16
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