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TOPOGRAPHIC ANATOMY OF THE UPPER LIMB
The upper limb includes the following regions: the shoulder regions, the regions of
the arm, the cubital regions, the regions of the forearm, the regions of the hand and joints.
THE SHOULDER REGION
Is divided into four parts: the scapular region, the deltoid region, the subclavian
region, the axillary region.
Surface landmarks of shoulder regions. The clavicles is siÂtuated at the root of the
neck and can be palpated throughout its length. The deltopectoral triangle is a small
triangular depresÂsion situated below the outer third of the clavicle; it is bounÂded by the
pectoral major and deltoid muscles.
The tip of the coracoid process of the scapula can be felt on deep palpation in the
lateral part of the deltopectoral trianÂgle, it is covered by the anterior fibers of the deltoid.
The acromion process of the scapula forms the lateral extreÂmity of the spine of
the scapula. It is subcutaneous and easily located. Immediately below the lateral edge of
the acromion proÂcess, the smooth rounded curve of the shoulder is produced by the
deltoid muscle, which covers the greater tuberosity of the humeÂrus.
The inferior angle of the scapula can be palpated opposite the seventh thoracic spine
and the level of seventh rib. The anÂterior axillary fold, which is formed by the level
margin of the pectoralis major muscle, can be palpated between the finger and thumb.
The posterior axillary fold, which is formed by the tendon of latissimus dorsi
winding around the lower border of the teres major muscle, can be similarly palpated
between finger and thumb.
The axilla should be examined with the forearm supported and the pectoral muscles
relaxed. With the arm by the side, the inferior part of the head of the humerus can be easily
palpated through the floor of the axilla. The pulsation of the axillary artery may be felt high
up in the axilla.
The scapular region includes soft tissues which lie on posÂterior surface of
scapula. The skin is thick and less mobile. The skin is supplied by posterior supraclavicular
nerves and posteriÂor branches of the posterior intercostal nerves. The proper fasÂcia is
less developed. Beneath the proper fascia the trapezius and latissimus dorsi are located.
Under the trapezius and latisÂsimus dorsi the thick aponeurotic levels are located. They
are called the supraspinous fascia and infraspinous fascia. These fasciae and posterior
surface of the scapula form two osteofibroÂus beds. They are supraspinous and
infraspinous beds.
The posterior surface of the scapula is divided by the spine into the supraspinous
fossa and infraspinous fossa below. The supraspinous bed is formed by supraspinous fossa
– anteriorly and by supraspinous fascia – posteriorly. These beds contain the muscÂles, fat, vessels and nerve.
Supraspinatus arises from the supraspinous fossa of the scaÂpula and the tough
overlying supraspinous fascia. The belly fills the fossa and almost hides it, but with the
wasting of this muscÂle that is often associated with a painful shoulder joint the fossa can
soon be recognized. The tendon of supraspinatus passes under the acromion and over the
top of the shoulder joint to reÂach the highest of the facets on the greater tubercle of the
huÂmerus. The tendon fuses with the capsule of the shoulder joint and is separated from
the overlying acromion by the subacromial bursa.
Supraspinatus is supplied by the suprascapular nerve and its action is to stabilize the
shoulder joint, prevent the head of the depended humerus slipping down off the glenoid
cavity and with the deltoid muscle abduct the arm away from the body.
Infraspinatus arises from the infraspinatus fossa and the overlying infraspinous
fascia. Its fibers are directed up toward the shoulder joint and its tendon reinforces the
capsule before becoming inserted into the middle facet on the greater tubercle.
Infraspinatus is supplied by the suprascapular nerve through a branch that reaches it
through spinoglenoid notch. Its action is to rotate the arm laterally and with the other short
muscles staÂbilize the shoulder joint.
Teres minor is a slender muscle arising from the upper two-thirds of the dorsal
surface of the lateral margin of the scapula. Its fibers pass upward toward the posterior
aspect of the shoulder joint where they are replaced by a tendon which beÂcomes fused
with the capsule of the lowest of the three fasets on the greater tubercle of the humerus and
to the shaft for a short distance below this. Teres minor is supplied by a branch of the
axillary nerve. It joins the other short muscles in stabilizing the shoulder joint and, in
addition, will produce lateral rotatiÂon of the dependent arm.
Teres major arises from an area on the dorsal surface of the lateral border of the
scapula below teres minor and from angle of the scapula, and passes upward and laterally
into the anterior surface of the humerus where it is attached to the medial lip of the
intertubercular sulcus. It is supplied by the lower subscapuÂlar nerve and its action is to
adduct and medially rotate the arm.
The scapular region has two neurovascular bundles. One of bundle is composed by
the suprascapular nerve and vessels. The suprascapular nerve is an important and large
nerve which runs deep to trapezius to reach the supraspinous fossa by passing through the
scapular notch below the suprascapular ligament that bridges it. In the supraspinous fossa
it supplies supraspiatus and then passes with the suprascapular artery through the spinogÂlenoid notch to supply infraspinatus in the infraspinous fossa. The suprascapular artery is
branch of the thyrocervical trunk of the subclavian artery passes above the suprascapular
ligament. It is distributed to both the supraspinous and infraspinous fossa of the scapula
and forms anastomosis with circumflex scapular arteÂry. The circumflex scapular artery
is the large branch of the subscapular artery. It passes posteriorly around the lateral borÂder
of the scapula through the triangular space to reach the infÂraspinous fossa.
Anterior bundle consist of the deep branch of transverse cervical artery (branch of
the thyrocervical trunk of the subclaÂvian artery) and the dorsal scapular nerve. The deep
branch of transverse cervical artery runs down the medial border of the scapula in company
with the dorsal scapular nerve. This artery takes part in forming the arterial anastomosis
around the scapuÂla. The arterial anastomosis around the scapula is penitential collateral
anastomosis that may bypass obstruction or injuries of the first and second part of the
axillary artery.
Fat spaces of the scapular region communicate with fat spaÂces of adjacent region.
Upper part of the scapular region has suÂperficial fat space between the trapezius and
supraspinatus. It communicates with fat space of lateral triangle of the neck. The fat of
supraspinous bed communicates with fat of infraspinous bed along the suprascapular
vessels and nerve. Nearby of neck of scaÂpula the supraspinous and infraspinous fascia
are thinner and, heÂre fat of supraspinous and infraspinous beds communicates with fat of
subdeltoid space. Along the circumflex scapular through the triangular space the fat of
infraspinous bed with the fat of the axillary fossa.
Deltoid region
The deltoid region corresponds the disposition of the deltoÂid muscle. The deltoid
muscle forms the rounded contour of the shoulder and covers the shoulder joint. The skin
is supplied by supraclavicular nerves and by upper lateral cutaneous nerve (branch of
axillary nerve). The subcutaneous tissue contains the cutaneous nerves. The superficial
fascia is thing.
The proper fascia form sheath of deltoid muscle. The fascia gives off septa which
divided muscle into three parts: anterior fibers, middle fibers, posterior fibers. Anterior
fibers arise from the lateral third of the anterior border of the clavicle. Middle fibers arise
from the lateral border of the acromion proÂcess. Posterior fibers arise from the lower
border of the spine of the scapula. Its fibers converge to be inserted into the delÂtoid
tuberosity, on the middle of the lateral surface of the shaft of the humerus. The deltoid
muscle is supplied on its deep surface by the axillary nerve, a branch of the posterior cord
of the brachial plexus. It is this nerve that may be damage when the shoulder joint is
dislocated or while the dislocation is being reduced.
The V-shaped origin of the deltoid allows its fibers to appÂroach the humerus
anteriorly, laterally and posteriorly. This fact, coupled with freedom of movment at the
shoulder joint gives the muscle a wide range of actions. The anterior fibers are able to flex
the arm, that is swing it forward, and the posterior fiÂbers can extend it behind the body.
The intermediate fibers ariÂsing from the acromion are powerful adductors of the arm.
Beneath the deltoid muscle between the muscle and humerus the subdeltoid space is
located. This space contains fat, tendons of muscles, synovial bursae, vessels and nerve.
The axillary nerve is branch of the posterior cord of the passing posteriorly through
a quadranqular space in company the posterior circumflex humeral arteries. Then the nerve
and artery lie on surgical neck of the humerus in deltoid region. The anteÂrior circumflex
humeral artery and posterior circumflex humeral artery form an anastomotic circle around
the surgical neck of the humerus. The anterior is small. The arteries supply the shoulder
joint and surrounding muscles.
The fat of subdeltoid space communicates:
1) whit fat of axillary fossa along neurovascular bundle,
2) with fat of supraspinous and infraspinous beds of scapular region along fat around
tendons of supraspinatus and infraspinaÂtus. In phlegmon of subdeltoid space the pus
reach the deltopecÂtoral sulcus and triangle.
Infraclavicular region
This region include the soft tissues forming anterior wall of axillary fossa. The
boundaries of the region are: superiorly – clavicule, inferiorly – horizontal line,
passing through III rib in the male and through superior border of the mammary gland in
the female, medially – lateral border of the sternum, laterally – anterior margin of
the deltoid muscle.
The skin is thin and mobile and supplied by supraclavicular nerves and anterior and
lateral branches of the intercostal nerÂves. The subcutaneous tissue is good developed and
contains fiÂbers of platysma. The superficial fascia forms suspensory ligaÂment for
mammary gland. The deep fascia covers the pectoral major and serratus anterior muscles
and forms the sheath of the pectoÂralis major. This fascia is continuation of the second
fascia of the neck. Below it passes in deep fascia of the abdomen. In axilÂlary region it is
connected with axillary fascia. In deltoid reÂgion it passes in deltoid (proper) fascia.
Under deep fascia the pectoralis major muscle is located. It consist of three parts:
clavicular, sternocostal, abdominal. The muscle converges on the arm where it is inserted
into the outer lip of the intertubercular sulcus of the humerus. Pectoralis maÂjor is supplied
by both medial and lateral pectoral nerves. It adducts the arm and rotates it medially; the
clavicular fibers also flex the arm.
The deltoidopectoral sulcus is formed between deltoid and pectoralis major muscles.
It contains the cephalic vein which is directed into deltoidopectoral triangle and drained to
axillary vein.
Beneath the pectoralis major muscles the superficial subpecÂtoral fat space is
located. Before the pectoralis minor muscle the clavipectoral fascia is located. The
clavipectoral fascia is a strong sheet of connective tissue, which is split above to encÂlose
the subclavius muscle and is attached to the clavicle. Below it splits to enclose the
pectoralis minor muscle and then contiÂnues downward as the suspensory ligament of the
axilla and joints the fascial floor of the armpit. It protects the contents of the axilla by filling
in the internal between the clavicle and the pectoralis minor muscle. The suspensory
ligament of the axilla is responsible for raising the skin of the armpit when the clavicle is
elevated.
Pectoralis minor is found beneath pectoralis major arising from the third, fourth and
fifth ribs close to their costal carÂtilages. Its fibers converge on the coracoid process of the
scaÂpula. It is supplied by the medial pectoral nerve and its action is to help in pulling the
scapula forward around the chest wall. In acute respiratory difficulty its action may be
reversed and it is used to raise the ribs when the shoulder girdle is fixed. BetÂween the
posterior surface of pectoralis minor and deep layer of the clavipectoral fascia the deep
subpectoral space is located.
Deep layer of infraclavicular region is divided into tree triangles where the
neurovascular bungle including the axillary vessels, cords of the brachial plexus and their
nerves pass.
1) Clavipectoral triangle is limited superiorly – by clavicle and subclavius
muscle, inferiorly – by superior border of the pecÂtoralis minor muscle. The base of this
triangle is lateral border of sternum.
2) The pectoral triangle corresponds to contours of pectoraÂlis minor muscle.
3) The subpectoral triangle is limited by inferior border of the pectoralis minor
muscle – superiorly and by the inferior borÂder of the pectoralis major muscle –
inferiorly. The base of this triangle is limited by deltoid muscle.
Three parts of axillary artery correspond to these triangles. In
clavipectoral triangle the clavipectoral fascia is pierced by 1)the cephalic vein in order
that it may enter the axillaÂry vein; 2)the thoracoacromioal artery, a branch of the axillary
artery; 3)lymph vessels from the infraclavicular nodes and 4)the lateral pectoral nerve as it
passes to the pectoralis major muscÂle.
Along these vessels and nerves the fat of superficial subpecÂtoral space
communicates with fat of clavipectoral triangle. Along vessels and nerves piercing deep
layer of the clavipectoral fascia the fat of deep subpectoral space communicaties with fat
space of the axillary fossa. In both subpectoral spaces the subÂpectoral phlegmons may be
located. But in deep subpectoral space the phlegmons are rare as it is more closed.
Phlegmons may be formed as a result of suppurative lesion of an apical group or subclavian
lymph nodes. The pus passes under the pectoralis major muscle along vessels and nerve
piercing the clavipectoral fascia. However, subpectoral phlegmon is often developed as a
result of suppurative lesion of a pectoral group of lymph nodes.
In a neglicted cases pus (in subpectoral phlegmon) melting tissues may penetrate
through the intercostal space into pleural cavity or between fibers of the pectoralis major
muscle under the skin; also the pus passes between the pectoralis major and pectoÂralis
minor muscle and reaches of free border of the anterior wall of the axillary fossa.
Axillary region
Regions contains soft tissues, disposing between the shoulÂder joint with proximal
part of humerus and the thorax. The axilÂla or armput is a pyramidshaped space. It forms
an important pasÂsage for nerves, blood and lymph vessels as they travel from the root of
the neck to the upper limb. The upper end of the axilla, or apex, is directed into root of the
neck and is founded in front by the clavicle, behind- by the upper border of the scapula and
medially- by the outer border of first rib.
The lower end, or base, is bonded: in front- by the anterior axillary fold (formed by
two lower border of the pectoralis major muscle), behind- by the posterior axillary fold
(formed by the tendon of latissimus dorsi and the teres major muscle), medially – Âby
conditional line connecting these folds on thoracic wall and laterally – by conditional
line connecting these folds on the arm.
The axilla should be examined with the forearm supported and the pectoral muscles
relaxed. With the arm by the side, the infeÂrior part of the humerus can be easily palpated
through the floor of the axilla. The pulsation of the axillary artery may be felt high up in
the axilla and around the artery may be palpated the cord of the brachial plexus.
The skin of this region is thin and hair-bearing and contaÂins numerous sebaceous
and subdoriferous glands. The skin is supplied by the intercostobrachial nerve and the
medial cutaneous nerve of the arm. The subcutaneous tissue contains the superfici...
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