INFRACLAVICULAR SEGMENT
(regio infraclavicularis)
is
determined: by clavicle – from above; by the 3rd rib – from
below; in the middle – by linea sternalis; sidewise – by anterior
edge of deltoid muscle.
The skin of the segment is thin and flexible. Subcutaneous
layer has nn. supraclaviculares, rr. cutanei anteriores et
rr. cutanei laterales (these are
branches of the intercostal
nerves). The superficial fascia lies deeper which encases
platysma muscle (m. platysma).
The
fascia pectoralis
is located, under the superficial fascia.
It forms a fascial sheath for
m. pectoralis major.
The sulcus deltoideopectoralis passes, between anterior
edge of deltoid muscle and upper external edge of pectoralis
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major muscle, where v. cephalica is located. V. cephalica
penetrates fascia clavipectorale and goes into v. axillaris.
Sulcus
deltoideopectoralis
goes
up
to
trigonum
deltoideopectorale
(or
fossa
deltoideopectorale,
Mohrenheim’s fossa).
Between the deep lamina of fascia pectoralis and deeper is
located fascia clavipectorale. There is superficial subpectoral
space, filled with adipose tissue, where we see
branches of
a.
thoracoacromialis, nn. pectorales medialis et lateralis and
Rotter’s lymph nodes (nodi lymphoidei interpectorales).
Fascia clavipectorale is located between scapula coracoid
process, clavicle and the 3rd – 5th ribs. It forms the sheath for m.
pectoralis minor, m. subclavius, a. et v. axillaris and plexus
brachialis.
Between the posterior surface of m. pectoralis minor and
thoracic wall is located a deep subpectoral space, where axilla
neurovascular fascicle passes (Fig. A. 1).
Superfacial and deep subpectoral spaces join together via
cellular tissue, which surrounds the neurovascular fascicle,
with axilla, cellular tissue of lateral cervical region and
subdeltoid cellular space.
Subpectoral phlegmons should be cut through the line
which goes along the posterior edge of pectoralis major
muscle.
Two triangles can be considered in this segment:
1. Trigonum clavipectorale – between the clavicle and
upper edge of m. pectoralis minor.
2. Trigonum pectorale – complies with the position of m.
pectoralis minor.
These triangles have neurovascular fascicle: a. et v. axillaris
and plexus brachialis, which come here from the lateral
cervical segment while passing between the clavicle and the
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1st rib, and move to axilla.
V. axillaris passes in trigonum clavipectorale downward, up
to the middle and forward from a. axillaris. It is bedded to
fascia clavipectorale and attaches to it. That is why air epiboly
occurs
(frequent and dangerous complication of clavicle
fracture).
The axillary vein (v. axillaris) is followed by a group of lymph
nodes, which are amputated in mastectomy. The v. subclavia is
a direct continuation of v. axillaris.
The surgical anatomy of subclavian vein is very important,
because it is often needled and catheterized for introducing
medications, vein blood pressure measuring, and diagnostic
manipulation in the heart cavity.
The border between v. axillaris and v. subclavia is located
on the inferior margin of the 1st rib. The vein lays on the
upper surface of the 1st rib in spatium antescalenum, then
goes to the level of sternoclavicular joint, where it combines
with internal jugular vein while creating a brachiocephalic
vein.
Subclavian vein goes in obliquity from down to top and
from outside to inside. It does not change its position when
we move upper limbs, because it is solidly connected to
surrounding tissues.
As a result of adhesion of subclavian vein sheath with
clavicle periosteum, the 1st rib and fascia clavipectoral, its
lumen remains constant even in case of acute fall of circulating
blood volume (CBV), when all other circumferential veins are
stuck together.
The subclavian vein can be divided into three segments.
First segment is located in trigonum clavipectorale, second –
behind the clavicle, and third – in spatium antescalenum.
Postclavicular segment of
v. subclavia is located on upper
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surface of the 1st rib, which separates the vein from cupula of
the pleura. Here the vein is located between the clavicle and
anterior scalene muscle, which separates it from a. subclavia
and trunk of brachial plexus.
Then v. subclavia goes to spatium antescalenum, passes
above cupula of pleura while covering a. subclavia.
V. cephalica, v. suprascapularis, v. transversa colli, v.
jugularis externa, v. cervicalis profunda, v. vertebralis, and
chest or jugular lymphatic trunk fall into v. subclavia from
above.
If long-standing fluid maintenance is necessary (peritonitis,
major combustion, craniocerebral trauma, heavy loss of blood, etc)
when superficial veins are absent, we use a puncture and
catheterization of v. subclavia according to the method of
Seldinger.
The puncture of v. subclavia is performed by means of
subclavian or supraclavicular approach. The vein puncture
according to Abanіak technique (1 cm down from the border
of middle and internal third of the clavicle) is more useful at
subclavian approach. The angle formed by upper edge of the
clavicle and lateral crus of sternocleidomastoid muscle is a
reference point during the vein puncture when using
supraclavicular approach. The needle enters Ioffe’s point, a bit
upper from the top of the angle.
The puncture of the right vein with subclavian access is
more dangerous, because:
a) large veins and lymphatic trunks fall into upper wall of
v. subclavia;
b) above the clavicle the vein is located near to cupula of the
pleura, and damage of the latter could result in pneumothorax.
Below the clavicle the vein is separated from pleura with the 1st
rib;
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c) in the middle parts of infraclavicular region the vein
covers a. subclavia and protects it.
The choice of v. subclavia for catheterization can be
explained by its anatomic-functional peculiarities:
1) the vein has its permanent position and clear
topographic-anatomical points of reference;
2) the vein lumen is big enough (12 – 25 mm in adults);
3) the vein’s wall is fixed with muscular-fascial formations,
what ensures its relative immovability and prevents it from
collapse even in unexpected hypovolemia (decrease of blood
circulation);
4) the high speed of blood circulation is a factor which
prevents thrombosis.
Compression of v. subclavia in spatium costoclavicularis on
exertion induces hypertrophy of valve wall and results in vein
thrombosis. Thus Paget – Schroetter syndrome occurs. The
symptoms of Paget – Schroetter syndrome are: progressive
limb edema, sharp pain, cyanosis and affection of blood
circulation in the limb.
There is a valve in the part of v. subclavia passage, between
clavicle and the
1st rib. The damage of cups of the valve results in
their thickening and parafunction. The balloon dilatation causes
the destruction of thickened cups and improves the vein blood
circulation. Thus, the Paget – Schroetter syndrome is successfully
treated by means of endovascular surgery (thrombolytic therapy,
balloon dilatation and aspiration thrombectomy).
A. thoracica superior springs from a. axillaris in trigonum
clavipectorale and provides blood supply of the 1st and the 2nd
intercostal spaces, and of a. thoracoacromialis, which penetrates
fascia clavipectorale near the internal edge of m. pectoralis minor
and gives off:
● rr. pectorales – provide blood supply of major and minor
pectoralis muscles;
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● r. acromialis – provides blood supply of acromioclavicular
joint and participates in forming rete acromiale;
● r. deltoideus – provides blood supply of m. deltoideus.
V. axillaris is located downwards and up to the middle in
trigonum pectorale, and a. axillaris is located upwards and
outwards.
At this level plexus brachialis bifurcates into 3 fascicles.
Fasciculus lateralis is located outwards and upwards from the
arteria, fasciculus posterior – behind the arteria, fasciculus
medialis – up to the middle and downwards from the arteria,
and behind the vein.
Plexus brachialis is formed by anterior branches of four
lower cerebrospinal nerves (С5 – С8). The part of anterior
branch (C4 and Th1) also participates in forming plexus
brachialis. They join together like this: the anterior branch of
C5 joins with anterior branch of C6 while forming a truncus
superior; the anterior branch of C8 joins with anterior branch
of Th1 while forming a truncus inferior; and between them the
anterior branch of C7 is located. The anterior branch of C7
forms a truncus medius. Superior, inferior and middle trunks
with their short branches form pars supraclavicularis of
brachial plexus (Fig. A.2).
Each of abovementioned trunks bifurcate into 2 branches:
anterior and posterior one. Due to these branches the fascicles
of plexus brachialis are formed at the level of inferior edge of
the clavicle, or just in trigonum clavipectorale.
The process of their formation is explained by
K. A. Hryhorovych the next way: the posterior divarications are
joined together in one trunk and form a posterior cord of brachial
plexus (fasciculus posterior). The frontal divarications of upper
trunk are joined together with frontal divarications of the middle
trunk and form a lateral cord of brachial plexus (fasciculus
lateralis).
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The frontal divarications of inferior trunk form a medial
fascicle of brachial plexus (fasciculus medialis). Fasciculus
posterior gives off n. axillaris and then passes into n. radialis.
Fasciculus lateralis and fasciculus medialis bifurcate into
2 branches. The middle branch of fasciculus lateralis and lateral
branch of fasciculus medialis join almost at the right angle,
encircling a. axillaris and forming n. medianus. The outer branch
of fasciculus lateralis forms n. musculocutaneus, which enters m.
coracobrachialis. Medial branch of fasciculus medialis forms n.
ulnaris, n. cutaneus antebrachii medialis and n. cutaneus brachii
medialis.
The damage of plexus brachialis in adults is observed as
complication from inflammation in the result of direct trauma,
or during the treatment of dislocation of glenohumeral joint.
The damage of plexus brachialis quite often occurs in obstetric
practice during childbirth: in case of fetus head, hand or leg
traction, when fetus is overweight (more than 4000 g), or if fetus
is in abnormal position (pelvic presentation, breech birth).
Depending on the level of brachial plexus damage we can
distinguish the following types of paralysis:
Erb – Duchenne paralysis (superior type) – С5 – С6 – С7
rami or trunks of plexus brachialis;
Dejerine-Klumpke paralysis (inferior type) – С8 – Th1 rami
or inferior trunk formed by them.
In case of Erb – Duchenne paralysis the function of m.
deltoideus, m. biceps brachii and m. brachioradialis is affected,
i. e. n. axillaris and n. musculocataneus are damaged. A patient
is not able to lift and shift his shoulder back, or bend his
brachium in elbow joint.
In case of Dejerine – Klumpke paralysis we can observe
paralysis phenomena, sensory anesthesia, and pupillary
disorders. Dysfunction and atrophy of small muscles of the
hand (thenar and hypothenar muscles, musculi interossei
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dorsales,
musculi
interossei
palmares
and
musculi
lumbricales). Sensory anesthesia of skin of the hand
(cutaneous branches of n. radialis, ulnaris et medianus),
medial surface of shoulder and brachium (n. cutaneus brachii
medialis, n. cutaneus antebrachii medialis) occur.
A. thoracica lateralis originates from a. axillaris in trigonum
pectorale and follows n. thoracicus longus till m. serratus anterior.
Anteriorly a. axillaris is crossed by nn. intercostobrachiales. Having
reached the exterior surface of m. serratus anterior, a. axillaris
supplies this muscle with blood, and gives off lateral rami
(rr. mammarii laterales).
Compression of neurovascular fascicle is possible within
trigonum pectorale, which results in syndrome of pectoralis
minor muscle (Wright syndrome). The symptoms of Wright
syndrome are muscle-tonic neurodystrophic disorders of the
pectoralis minor muscle and compression of neurovascular
fascicle which passes below the muscle. Neurovascular fascicle
is pressed behind the pectoralis minor muscle below the
processus coracoideus to caput humeri. Compression of these
formations may appear in cases of excessive shoulder
abduction (immobilization after humerus fracture, sleeping
with arms put behind the head). A patient complains of pain in
pectoralis minor muscle area when he raises or abducts his
arm. We can observe paresthesia, weakness of arm muscles,
skin blanching, hand swelling, decrease of pulse in a. radialis.
The axillary vessels and plexus brachialis are surrounded by
cellular tissue and located in fascial compartment formed by
fascia clavipectorale. The cellular tissue of trigonum
clavipectorale while the neurovascular fascicle upwards, joins the
deep cellular tissue of trigonum cervicalis lateralis, and fissure
anterscalenum. Downwards it joins the cellular tissue of axilla,
and along a. et v. axillaris and nerves of plexus brachialis – with
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subpectoral cellular space.
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