Upper limb
OVERVIEW
Ø The
upper limb is characterized by its mobility and ability to grasp, strike, and
conduct fine motor skills (manipulation).
The upper limb consists of four major segments, which are
further subdivided into regions for precise description.
Regions of the upper limb
Ø 1.
Shoulder: proximal segment of the limb that overlaps parts of the trunk (thorax
and back) and lower lateral neck.
Ø It
includes the pectoral, scapular, and deltoid regions of the upper limb, and the
lateral part (greater supraclavicular fossa) of the lateral cervical region.
The pectoral (shoulder) girdle is a bony ring, incomplete
posteriorly, formed by the scapulae and clavicles and completed
anteriorly by the manubrium of the sternum (part of the axial skeleton).
SHOULDER _
The shoulder is
the region of upper limb attachment to the trunk and neck.
The bone framework
of the shoulder consists of: the clavicle and scapula, which form the pectoral
girdle (shoulder girdle); and the proximal end of the humerus.
2. Arm: first segment of the free upper limb (more
mobile part of the upper limb independent of the trunk) and the longest segment
of the limb.
It extends between and connects the shoulder and the
elbow and consists of anterior and posterior regions of the arm, centered
around the humerus.
3. Forearm (L. antebrachium): second longest segment
of the limb. It extends between and connects the elbow and the wrist and
includes anterior and posterior regions of the forearm overlying the radius and
ulna.
Ø 4.
Hand: part of the upper limb distal to the forearm that is formed around
the carpus, metacarpus, and phalanges.
Ø It is composed of the wrist, palm, dorsum of
hand, and digits and is richly supplied with sensory endings for touch, pain,
and temperature.
BONES OF UPPER LIMB
Ø The
pectoral girdle and bones of the free part of the upper limb form the superior
appendicular skeleton.
Ø The
superior appendicular skeleton articulates with the axial skeleton only at the
sternoclavicular joint, allowing great mobility.
Ø The
clavicles and scapulae of the pectoral girdle are supported, stabilized, and
moved by axioappendicular muscles that attach to the relatively fixed ribs,
sternum, and vertebrae of the axial skeleton.
Bones of the shoulder girdle
Clavicle
Ø The
clavicle (collar bone) connects the upper limb to the trunk.
Ø The
shaft of the clavicle has a double curve in a horizontal plane.
Clavicle
Ø Its
medial half is convex anteriorly, and its sternal end is enlarged and
triangular where it articulates with the manubrium of the sternum at the sternoclavicular
(SC) joint.
Ø Its
lateral half is concave anteriorly, and its acromial end is flat where it articulates
with the acromion of the scapula at the acromioclavicular (AC) joint.
Ø The
clavicle: Serves as a moveable, allows the scapula to move on the thoracic wall
at the “scapulothoracic joint,” increasing the range of motion of the limb.
Ø Forms
one of the bony boundaries of the cervico-axillary canal (passageway between
the neck and the arm), affording protection to the neurovascular bundle
supplying the upper limb.
Ø The
superior surface of the clavicle, lying just deep to the skin and platysma
muscle in the subcutaneous tissue, is smooth.
Ø The
inferior surface of the clavicle is rough because strong ligaments bind it to
the 1st rib near its sternal end
Ø The
conoid tubercle, near the acromial end of the clavicle gives attachment to the conoid
ligament, the medial part of the coracoclavicular ligament
Scapula
Ø The
scapula (shoulder blade) is a triangular flat bone that lies on the
posterolateral aspect of the thorax, overlying the 2nd–7th ribs.
scapula
Ø The
convex posterior surface of the scapula is
divided by a thick projecting ridge of bone, the spine of the scapula,
into a small supraspinous fossa and a much larger infraspinous fossa.
Ø The
concave costal surface of most of the scapula forms a large subscapular fossa.
Ø The
broad bony surfaces of the three fossae provide attachments for fleshy
muscles.
Ø The
triangular body of the scapula is thin and translucent superior and inferior to
the scapular spine;
Ø The
deltoid tubercle of the scapular spine is the prominence indicating the medial
point of attachment of the deltoid.
Ø Superolaterally,
the lateral surface of the scapula has a glenoid cavity , which receives and
articulates with the head of the humerus at the glenohumeral joint.
Ø The
glenoid cavity is a shallow, concave, oval fossa (L. fossa ovalis), directed
anterolaterally and slightly superiorly—that is considerably smaller than
the ball (head of the humerus) for which it serves as a socket.
Ø The
beak-like coracoid process is
superior to the glenoid cavity and projects anterolaterally.
The scapula has medial, lateral, and superior borders and
superior, lateral, and inferior angles.
Humerus
Ø The
humerus (arm bone), the largest bone in the upper limb, articulates with the
scapula at the glenohumeral joint and the radius and ulna at the elbow
joint.
Ø The
proximal end of the humerus has a head, surgical and anatomical necks, and
greater and lesser tubercles.
Ø The
spherical head of the humerus articulates with the glenoid cavity of the
scapula.
Ø The
anatomical neck of the humerus is formed by the groove circumscribing the head
and separating it from the greater and lesser tubercles.
Ø It
indicates the line of attachment of the glenohumeral joint capsule.
The surgical neck of the humerus, a common site of
fracture, is the narrow part distal to the head and tubercles
Ø The
junction of the head and neck with the shaft of the humerus is indicated by the
greater and lesser tubercles, which provide attachment to some scapulohumeral
muscles.
Ø The
greater tubercle is at the lateral margin of the humerus, whereas the lesser
tubercle projects anteriorly from the bone.
Ø The
intertubercular (bicipital) groove separates the tubercles and provides
protected passage for the slender tendon of the long head of the biceps muscle.
Ø The
shaft of the humerus has two prominent features:
ü the
deltoid tuberosity laterally, for attachment of the deltoid muscle,
ü oblique radial groove (groove for radial
nerve, spiral groove) posteriorly, in which the radial nerve and deep artery of
the arm (profunda brachii artery ) lie.
Ø The
inferior end of the humeral shaft widens as the sharp medial and lateral
supraepicondylar (supracondylar) ridges form and then end distally in the
especially prominent medial epicondyle and the lateral epicondyle, providing
for muscle attachment.
The distal end of the humerus—including the trochlea; the
capitulum; and the olecranon, coronoid, and radial fossae— makes up the condyle
of the humerus.
Ø The
condyle has two articular surfaces:
Ø a lateral capitulum for articulation with the
head of the radius
Ø medial, spool-shaped or pulley-like trochlea
for articulation with the proximal end (trochlear notch) of the ulna.
Humerus of the Arm
Ø Two
hollows, or fossae, occur back to back superior to the trochlea,making the
condyle quite thin between the epicondyles. Anteriorly, the coronoid fossa
receives the coronoid process of the ulna during full flexion of the elbow.
Posteriorly, the olecranon fossa accommodates the
olecranon of the ulna during full extension of the elbow.
Bones of Forearm
The two forearm bones serve together to form the second
unit of an articulated mobile strut (the first unit being the humerus), with a
mobile base formed by the shoulder, that positions the hand.
Bones of the forearm
ULNA
Ø The
ulna is the stabilizing bone of the forearm and is the medial and longer of the
two forearm bones.
Ø Its
more massive proximal end is specialized for articulation with the humerus
proximally and the head of the radius laterally.
Ø For
articulation with the humerus, the ulna has two prominent projections:
(1) the olecranon,
which projects proximally from its posterior aspect (forming the point of the elbow) and serves as a
short level for extension of the elbow,
(2) the coronoid process,
which projects anteriorly.
Ø The
articulation between the ulna and the humerus primarily allows only flexion and
extension of the elbow joint, although a small amount of abduction– adduction
occurs during pronation and supination of the forearm.
Ø Inferior
to the coronoid process is the tuberosity of the ulna for attachment of the
tendon of the brachialis muscle.
RADIUS
Ø The
radius is the lateral and shorter of the two forearm bones.
Ø Its
proximal end includes a short head, neck, and medially directed tuberosity.
Ø The
head also articulates peripherally with the radial notch of the ulna.
Ø The
neck of the radius is a constriction distal to the head.
Ø The
oval radial tuberosity is distal to the medial part of the neck and demarcates
the proximal end (head and neck) of the radius from the shaft.
Ø The
shaft of the radius, in contrast to that of the ulna, gradually enlarges as it
passes distally.
Ø Its
medial aspect forms a concavity, the ulnar notch (Fig. 6.8C & D), which
accommodates the head of the ulna.
Projecting dorsally, the dorsal tubercle of the radius
lies shallow grooves for the passage of the tendons of forearm muscles.
Bones of Hand
Ø The
wrist, or carpus, is composed of eight carpal bones (carpals) arranged in
proximal and distal rows of four.
Ø These
small bones give flexibility to the wrist.
Ø The
carpus is markedly convex from side to side posteriorly and concave anteriorly.
Ø From
lateral to medial, the four bones in the proximal row of carpals are the:
ü Scaphoid:
a boat-shaped bone that articulates proximally with the radius and has a
prominent scaphoid tubercle; it is the largest bone in the proximal row of
carpals.
ü Lunate
: a moon-shaped bone between the scaphoid and the triquetral bones; it
articulates proximally with the radius and is broader anteriorly than
posteriorly.
ü Triquetrum
: a pyramidal bone on the medial side of the carpus; it articulates
proximally with the articular disc of the distal radio-ulnar joint.
ü Pisiform
, a small, pea-shaped bone that lies on the palmar surface of the
triquetrum.
From lateral to medial, the four bones in the distal row
of carpals (green in Fig. 6.9A & B) are the:
Ø Trapezium
: a four-sided bone on the lateral side of the carpus; it articulates
with the 1st and 2nd metacarpals, scaphoid, and trapezoid bones.
Ø Trapezoid:
a wedge-shaped bone that resembles the trapezium; it articulates with the 2nd
metacarpal, trapezium, capitate, and scaphoid bones.
Capitate: a head-shaped bone with a rounded
extremity and the largest bone in the carpus; it articulates primarily with the
3rd metacarpal distally and with the trapezoid, scaphoid, lunate, and hamate.
Hamate: a wedge-shaped bone on the medial side of
the hand; it articulates with the 4th and 5th metacarpal, capitate,
and triquetral bones; it has a distinctive hooked process, the hook of the
hamate, that extends anteriorly.
Surface Anatomy of Upper Limb Bones
AXILLA
AXILLA
Ø The
axilla is the pyramidal space inferior to the glenohumeral joint and
superior to the axillary fascia at the junction of the arm and thorax.
Ø axilla
is the gateway to the upper limb, providing an area of transition between the
neck and the arm.
Ø The
axilla provides a passageway, or “distribution center,” usually protected by
the adducted upper limb, for the neurovascular structures that serve the upper
limb.
Ø From
this distribution center, neurovascular structures pass.
Ø •
Superiorly via the cervico-axillary canal to (or from) the root of the neck.
Ø •
Anteriorly via the clavipectoral triangle to the pectoral region.
Ø •
Inferiorly and laterally into the limb itself.
Ø •
Posteriorly via the quadrangular space to the scapular region.
Ø • Inferiorly and medially along the thoracic
wall to the inferiorly placed axioappendicular muscles (serratus anterior and
latissimus dorsi).
Ø The
shape and size of the axilla varies, depending on the position of the arm; it
almost disappears when the arm is fully abducted—a position in which its
contents are vulnerable.
Ø The
axilla has an apex, a base, and four walls (three of which
are muscular):
Ø The
apex of axilla is the cervico-axillary canal, the
passageway between the neck and the axilla, bounded by: the 1st
rib, clavicle, and superior edge of the scapula.
Ø The
arteries, veins, lymphatics, and nerves traverse this superior opening of the
axilla to pass to or from the arm (Fig. 6.37A).
Ø •
The base of axilla is formed by the concave skin, subcutaneous tissue,
and axillary (deep) fascia extending from the arm to the thoracic wall
(approximately the 4th rib level), forming the axillary fossa (armpit).
Ø The
base of the axilla or axillary fossa is bounded by the anterior and
posterior axillary folds, the thoracic wall, and the medial aspect of the arm.
• The anterior wall of axilla has two layers, formed by
the pectoralis major and pectoralis minor and the pectoral and
clavicopectoral fascia associated with them.
The anterior
axillary fold is formed by the pectoralis major, as it bridges from
thoracic wall to humerus, and the overlying integument.
The posterior wall of axilla is formed chiefly by the
scapula and subscapularis on its anterior surface and inferiorly by the
teres major and latissimus dorsi.
The posterior axillary fold is the inferiormost part of
the posterior wall is formed by
latissimus dorsi, teres major, and overlying integument.
• The medial wall of axilla is formed by the thoracic
wall (1st–4th ribs and intercostal muscles) and the overlying serratus
anterior.
• The lateral wall of axilla is a narrow bony wall formed
by the intertubercular groove in the humerus.
Ø The
axilla contains axillary blood vessels (axillary artery and its branches,
axillary vein and its tributaries), lymphatic vessels, and several groups of axillary
lymph nodes, all embedded in a matrix of axillary fat (Fig. 6.37C).
The axilla also contains large nerves that make up the cords
and branches of the brachial plexus, a network of interjoining nerves that
pass from the neck to the upper limb.
Axillary Artery
Ø The
axillary artery begins at the lateral border of the 1st rib as the
continuation of the subclavian artery and ends at the inferior border of the
teres major.
Ø It passes posterior to the pectoralis minor
into the arm and becomes the brachial artery when it passes the inferior border
of the teres major, at which point it usually has reached the humerus.
the axillary artery is divided into three parts by the
pectoralis minor:
1. The first part of the axillary artery is located
between the lateral border of the 1st rib and the medial border of the
pectoralis minor; it is enclosed in the axillary sheath and has one
branch—the superior thoracic artery.
2. The second part of the axillary artery lies posterior to
pectoralis minor and has two branches—the thoracoacromial and
lateral thoracic arteries—which pass medial and lateral to
the muscle, respectively.
3. The third part of the axillary artery extends from the
lateral border of pectoralis minor to the inferior border of teres major
and has three branches.
The subscapular artery is the largest branch of the
axillary artery, the anterior circumflex humeral and posterior circumflex
humeral arteries
The superior thoracic artery is a small, highly variable vessel
that arises just inferior to the subclavius.
It commonly runs inferomedially posterior to the axillary
vein and supplies the subclavius, muscles in the 1st and 2nd intercostal
spaces, superior slips of the serratus anterior, and overlying pectoral
muscles. It anastomoses with the intercostal and/or internal thoracic arteries.
The thoraco-acromial artery, a short wide trunk, pierces the
costocoracoid membrane and divides into four branches (acromial,
deltoid, pectoral, and clavicular), deep to the clavicular head of the
pectoralis major (Fig. 6.40).
The lateral thoracic artery has a variable origin. It
usually arises as the second branch
of the second part of the axillary artery and descends along the lateral border
of the pectoralis minor, following it onto the thoracic wall (Fig. 6.38B and
6.39A);
The lateral thoracic artery supplies the
pectoral, serratus anterior, and intercostal muscles, the axillary lymph nodes,
and the lateral aspect of the breast.
Ø The
subscapular artery, the branch of the axillary artery with the greatest
diameter but shortest length descends along the lateral border of the
subscapularis on the posterior axillary wall.
Ø It is dividing into the circumflex scapular
and thoracodorsal arteries.
Ø The
circumflex scapular artery, often the larger terminal branch of the subscapular
artery, curves posteriorly around the lateral border of the
scapula, passing posteriorly between the subscapularis and the teres
major to supply muscles on the dorsum of the scapula.
Ø It
participates in the anastomoses around the scapula.
The thoracodorsal artery continues the general course of
the subscapular artery to the inferior angle of the scapula and supplies
adjacent muscles, principally the latissimus dorsi. It also participates in
the arterial anastomoses around the scapula.
v The
circumflex humeral arteries encircle the surgical neck of the humerus,
anastomosing with each other.
v The smalleranterior circumflex humeral
artery passes laterally, deep to the coracobrachialis and biceps brachii.
It gives off an ascending branch that supplies the shoulder.
Ø The
larger posterior circumflex humeral artery passes medially through the
posterior wall of the axilla via the quadrangular space with the
axillary nerve to supply the glenohumeral joint and surrounding muscles (e.g.,
the deltoid, teres major and minor, and long head of the triceps).
Axillary Vein
The axillary vein lies initially (distally) on the anteromedial
side of the axillary artery, with its terminal part anteroinferior to the
artery.
Ø This
large vein is formed by the union of the brachial vein (the accompanying
veins of the brachial artery) and the basilic vein at the
inferior border of the teres major.
Ø The
axillary vein is described as having three parts, which correspond to the three
parts of the axillary artery.
Ø Thus
the initial, distal end is the third part, whereas the terminal, proximal end
is the first part.
Ø The
axillary vein (first part) ends at the lateral border of the 1st rib, where it
becomes the subclavian vein.
Ø The axillary vein receives tributaries that
generally correspond to branches of the axillary artery with a few major
exceptions:
Axillary Lymph Nodes
Ø The
fibrofatty connective tissue of the axilla (axillary fat) contains many lymph
nodes.
Ø The axillary lymph nodes are arranged in five
principal groups: pectoral, subscapular, humeral, central
and apical.
Ø The
pectoral (anterior) nodes consist of three to five nodes that lie along
the medial wall of the axilla, around the lateral thoracic vein and the
inferior border of the pectoralis minor.
Ø The
pectoral nodes receive lymph mainly from the anterior thoracic
wall, including most of the breast (especially the superolateral [upper outer]
quadrant and subareolar plexus .
Ø The
subscapular (posterior) nodes consist of six or seven nodes that lie
along the posterior axillary fold and subscapular blood vessels. These nodes
receive lymph from the posterior aspect of the thoracic wall and scapular
region.
Ø The
humeral (lateral) nodes consist of four to six nodes that lie along the
lateral wall of the axilla, medial and posterior to the axillary vein.
Ø These
nodes receive nearly all the lymph from the upper limb, except
that carried by the lymphatic vessels accompanying the cephalic vein, which
primarily drain directly to the apical axillary and infraclavicular nodes.
Ø Efferent
lymphatic vessels from these three groups pass to the central nodes.
Ø There
are three or four of these large nodes situated deep to the pectoralis
minor near the base of the axilla,in association with the second part of the
axillary artery.
Ø Efferent
vessels from the central nodes pass to the apical nodes, which are
located at the apex of the axilla along the medial side of the axillary vein
and the first part of the axillary artery.
Ø The
apical nodes receive lymph from all other groups of axillary
nodes as well as from lymphatics accompanying the proximal cephalic vein.
Ø Efferent
vessels from the apical group traverse the cervico-axillary canal.
Ø These
efferent vessels ultimately unite to form the subclavian lymphatic trunk,
although some vessels may drain through the clavicular (infraclavicular
and supraclavicular) nodes.
Ø Once
formed, the subclavian trunk may be joined by the jugular and
bronchomediastinal trunks on the right side to form the right lymphatic
duct, or it may enter the right venous angle independently.
Ø On the left side, the subclavian trunk
commonly joins the thoracic duct.
Brachial Plexus
Ø Most
nerves in the upper limb arise from the brachial plexus, a major
nerve network (Fig 6.43) supplying the upper limb; it begins in the neck
and extends into the axilla.
Ø Almost
all branches of the brachial plexus arise in the axilla (after the plexus has
crossed the 1st rib).
Ø The
brachial plexus is formed by the union of the anterior rami of the
last four cervical (C5–C8) and the first thoracic (T1) nerves, which
constitute the roots of the brachial plexus.
The roots of the plexus usually pass through the gap between
the anterior and the middle scalene (L. scalenus anterior and medius)
muscles with the subclavian artery (Fig. 6.45).
Ø In
the inferior part of the neck, the roots of the brachial plexus unite to form
three trunks:
1. A superior trunk, from the union of the C5 and C6
roots.
2. A middle trunk, which is a continuation of the C7
root.
3. An inferior trunk, from the union of the C8 and T1
roots.
Ø Each
trunk of the brachial plexus divides into anterior and posterior divisions as
the plexus passes through the cervicoaxillary canal posterior to the
clavicle.
Ø Anterior
divisions of the trunks supply anterior (flexor) compartments of the upper
limb, and posterior divisions of the trunks supply posterior
(extensor) compartments.
Ø The
divisions of the trunks form three cords of the brachial plexus:
1. Anterior divisions of the superior and middle trunks
unite to form the lateral cord.
2. Anterior division of the inferior trunk continues as the medial
cord.
3. Posterior divisions of all three trunks unite to form the
posterior cord.
Ø The
brachial plexus is divided into supraclavicular and infraclavicular
parts by the clavicle.
Ø Four
branches of the supraclavicular part of the plexus arise from the
roots (anterior rami) and trunks of the brachial plexus (dorsal scapular
nerve, long thoracic nerve, nerve to subclavius, and suprascapular nerve) and
are approachable through the neck.
Ø Branches
of the infraclavicular part of the plexus arise from the cords of the brachial
plexus and are approachable through the axilla.
ARM
Ø The
arm extends from the shoulder to the elbow.
Ø Two
types of movement occur between the arm and the forearm at the elbow joint:
flexion–extension and pronation–supination
Ø The
muscles performing these movements are clearly divided into anterior and
posterior groups, separated by the humerus and medial and lateral
intermuscular septae
Muscles of Arm
Ø Of
the four major arm muscles, three flexors (biceps brachii, brachialis,
and coracobrachialis) are in the anterior (flexor) compartment,
supplied by the musculocutaneous nerve, and one extensor (triceps brachii)
is in the posterior compartment, supplied by the radial nerve
BICEPS BRACHII
Ø As
the term biceps brachii indicates, the proximal attachment of this
fusiform muscle usually has two heads (bi, two + L. caput, head).
Ø The two heads of the biceps arise proximally by
tendinous attachments to processes of the scapula, their fleshy bellies uniting
just distal to the middle of the arm
Ø Approximately
10% of people have a third head to the biceps.
Ø Although
the biceps is located in the anterior compartment of the arm, it has no
attachment to the humerus.
Ø The
biceps is a “three-joint muscle,” crossing and capable of effecting movement at
the glenohumeral, elbow, and radio-ulnar joints,
although it primarily acts at the latter two.
Ø Its
action and effectiveness are markedly affected by the position of the elbow and
forearm.
Ø Distally,
the major attachment of the biceps is to the radial tuberosity via the biceps
tendon.
Ø a triangular membranous band, called the bicipital
aponeurosis, runs from the biceps tendon across the cubital fossa and
merges with the antebrachial (deep) fascia covering the flexor muscles in the
medial side of the forearm.
Ø It
attaches indirectly by means of the fascia to the subcutaneous border of the
ulna. The proximal part of the bicipital aponeurosis can be easily felt where
it passes obliquely over the brachial artery and median nerve (Fig. 6.52A).
Ø The
bicipital aponeurosis affords protection for these and other structures in the
cubital fossa.
BRACHIALIS
Ø The
brachialis is a flattened fusiform muscle that lies posterior (deep) to
the biceps.
Ø Its distal attachment covers the anterior part
of the elbow joint.
Ø The
brachialis is the main flexor of the forearm.
Ø It
is the only pure flexor, producing the greatest amount of flexion force.
CORACOBRACHIALIS
Ø The
coracobrachialis is an elongated muscle in the superomedial part of the
arm. It is a useful landmark for locating other structures in the arm
Ø The
coracobrachialis helps flex and adduct the arm and stabilize
the glenohumeral joint.
Ø With
the deltoid and long head of the triceps, it serves as a shunt
muscle, resisting downward dislocation of the head of the humerus.
TRICEPS BRACHII
Ø The
triceps brachii is a large fusiform muscle in the posterior compartment
of the arm.
Ø As
indicated by its name, the triceps has three heads: long, lateral,
and medial.
Ø The
triceps is the main extensor of the forearm.
ANCONEUS
Ø The
anconeus is a small, triangular muscle on the posterolateral aspect of
the elbow; it is usually partially blended with the triceps (Fig. 6.49G;
Table 6.9).
Ø The anconeus helps the triceps extend the
forearm and tenses of the capsule of the elbow joint, preventing its being
pinched during extension.
Ø It is also said to abduct the ulna during
pronation of the forearm.
Brachial Artery
Ø The
brachial artery provides the main arterial supply to the arm and is the
continuation of the axillary artery.
Ø It
begins at the inferior border of the teres major and ends in the cubital fossa opposite the
neck of the radius where, under cover of the bicipital aponeurosis, it divides
into the radial and ulnar arteries.
During its course through the arm, the brachial artery gives
rise to many unnamed muscular branches and the humeral nutrient artery, which
arise from its lateral aspect.
The main named branches of the brachial artery arising from
its medial aspect are the deep artery of the arm and the superior and
inferior ulnar collateral arteries.
The collateralarteries help form the periarticular arterial
anastomoses of the elbow region (Fig. 6.51).
DEEP ARTERY OF ARM
Ø The
deep artery of the arm (L. arteria profunda brachii) is the
largest branch of the brachial artery and has the most superior origin.
Ø The
deep artery accompanies the radial nerve along the radial groove as it passes
posteriorly around the shaft of the humerus (Figs. 6.50 and 6.53).
HUMERAL NUTRIENT ARTERY
The main humeral nutrient artery arises from the brachial
artery around the middle of the arm and enters the nutrient canal on the
anteromedial surface of the humerus. The artery runs distally in the canal toward
the elbow. Other smaller humeral nutrient arteries also occur.
SUPERIOR ULNAR COLLATERAL ARTERY
Ø The
superior ulnar collateral artery arises from the medial aspect of the
brachial artery near the middle of the arm and accompanies the ulnar nerve
posterior to the medial epicondyle of the humerus.
Ø it anastomoses with the posterior ulnar
recurrent artery and the inferior ulnar collateral artery, participating in the
periarticular arterial anastomoses of the elbow.
INFERIOR ULNAR COLLATERAL ARTERY
Ø The
inferior ulnar collateral artery arises from the brachial artery
approximately 5 cm proximal to the elbow crease.
Ø It then passes inferomedially anterior to
the medial epicondyle of the humerus and joins the anastomoses of the elbow
region by anastomosing with the anterior ulnar recurrent artery.
Veins of Arm
Ø Two
sets of veins of the arm, superficial and deep, anastomose freely with
each other. The superficial veins are in the subcutaneous tissue, and the deep
veins accompany the arteries. Both sets of veins have valves, but they are more
numerous in the deep veins than in the superficial veins.
Nerves of Arm
Four main nerves pass through the arm: median, ulnar,
musculocutaneous, and radial. The median and ulnar nerves supply no
branches to the arm.
MUSCULOCUTANEOUS NERVE
Ø The
musculocutaneous nerve begins opposite the inferior border of the
pectoralis minor, pierces the coracobrachialis, and continues distally between
the biceps and the brachialis.
Ø After
supplying all three muscles of the anterior compartment of the arm, the
musculocutaneous nerve emerges lateral to the biceps as the lateral
cutaneous nerve of the forearm.
RADIAL NERVE
Ø The
radial nerve in the arm supplies all the muscles in the posterior
compartment of the arm (and forearm).
Ø The
radial nerve enters the arm posterior to the brachial artery, medial to the
humerus, and anterior to the long head of the triceps, where it gives branches
to the long and medial heads of the triceps.
Ø Anterior
to the lateral epicondyle, the radial nerve then divides into deep and
superficial branches.
ü •
The deep branch of the radial nerve is entirely muscular and articular
in its distribution.
ü •
The superficial branch of the radial nerve is entirely cutaneous in its
distribution, supplying sensation to the dorsum of the hand and fingers.
MEDIAN NERVE
The median nerve in the arm runs distally in the arm on the
lateral side of the brachial artery until it reaches the middle of the arm,
where it crosses to the medial side and contacts the brachialis.
Ø The
median nerve then descends into the cubital fossa, where it lies deep to the
bicipital aponeurosis and median cubital vein (Fig. 6.52).
Ø The
median nerve has no branches in the axilla or arm, but it does supply articular
branches to the elbow joint.
ULNAR NERVE
The ulnar nerve in the arm passes distally from the
axilla anterior to the insertion of the teres major and to the long head of
the triceps, on the medial side of the brachial artery.
Around the middle of the arm, it pierces the medial
intermuscular septum with the superior ulnar collateral artery and descends
between the septum and the medial head of the triceps (Fig. 6.53).
The ulnar nerve passes posterior to the medial epicondyle
and medial to the olecranon to enter the forearm (Fig. 6.46C).
} FOREARM
Ø The
forearm is the distal unit of the articulated of the upper limb.
Ø It
extends from the elbow to the wrist and contains two bones, the radius
and ulna, which are joined by an interosseous membrane
} Compartments
of Forearm
Ø As
in the arm, the muscles of similar purpose and innervation are grouped within
the same fascial compartments in the forearm.
} Muscles
of Forearm
Ø There
are 17 muscles crossing the elbow joint, some of which act on the elbow
joint exclusively, whereas others act at the wrist and fingers.
Ø In
the proximal part of the forearm, the muscles form fleshy masses extending
inferiorly from the medial and lateral epicondyles of the humerus.
Ø The
tendons of these muscles pass through the distal part of the forearm and
continue into the wrist, hand, and fingers.
Ø The
flexor muscles of the anterior compartment have approximately twice the bulk
and strength of the extensor muscles of the posterior compartment.
Ø The
tendons of these muscles pass through the distal part of the forearm and
continue into the wrist, hand, and fingers.
} FLEXOR–PRONATOR
MUSCLES OF FOREARM
} The
flexor muscles of the forearm are in the anterior (flexor–pronator)
compartment of the forearm and are separated from the extensor muscles of
the forearm by the radius and ulna and, in the distal two thirds of the
forearm, by the interosseous membrane that connects them.
Ø The
tendons of most flexor muscles are located on the anterior surface of the wrist
and are held in place by the palmar carpal ligament and the flexor
retinaculum transverse carpal
} ligament),
thickenings of the antebrachial fascia.
} The
flexor muscles are arranged in three layers or groups:
Ø A
superficial layer or group of four muscles (pronator teres, flexor carpi radialis, palmaris longus, and
flexor carpi ulnaris).
Ø These
muscles are all attached proximally by a common flexor tendon to the medial
epicondyle of the humerus, the common flexor attachment.
Ø 2.
An intermediate layer, consisting of one muscle (flexor digitorum
superficialis).
Ø 3.
A deep layer or group of three muscles (flexor digitorum profundus,
flexor pollicis longus, and pronator quadratus).
} The
five superficial and intermediate muscles cross the elbow joint; the three deep
muscles do not
} All muscles in the anterior compartment of the
forearm are supplied by the median and/or ulnar nerves (most by the median;
only one and a half exceptions are supplied by the ulnar).
} Functionally,
the brachioradialis is a flexor of the forearm, but it is located in the
posterior (posterolateral) or extensor compartment and is thus supplied by the
radial nerve.
} Therefore,
the brachioradialis is a major exception to the rule that:
(1) the radial nerve supplies only extensor muscles
(2) that all flexors lie in the anterior (flexor)
compartment.
} The
long flexors of the digits (flexor digitorum superficialis and flexor
digitorum profundus) also flex the metacarpophalangeal and wrist joints.
} The
flexor digitorum profundus flexes the fingers in slow action; this action is
reinforced by the flexor digitorum superficialis when speed and flexion against
resistance are required.
} Tendons
of the long flexors of the digits pass through the distal part of the forearm,
wrist, and palm and continue to the medial four fingers.
} The
flexor digitorum superficialis flexes the middle phalanges, and the flexor
digitorum profundus flexes the middle and distal phalanges.
} the
muscles of the superficial and intermediate layers
} Pronator
Teres:
} The
pronator teres, a fusiform muscle, is the most lateral of the
superficial forearm flexors. Its lateral border forms the medial boundary of
the cubital fossa.
} Flexor
Carpi Radialis
} The
flexor carpi radialis (FCR) is a long fusiform muscle located medial to
the pronator teres.
} The
FCR produces flexion (when acting with the flexor carpi ulnaris) and abduction
of the wrist (when acting with the extensors carpi radialis longus and brevis).
} Palmaris
Longus.
} The
palmaris longus, a small fusiform muscle, is absent on one or both sides
(usually the left) in approximately 14% of people
} Flexor
Carpi Ulnaris
} The
flexor carpi ulnaris (FCU) is the most medial of the superficial flexor
muscles.
} The
FCU simultaneously flexes and adducts the hand at the wrist if acting alone. It
flexes the wrist when it acts with the FCR and adducts it when acting with the
extensor carpi ulnaris.
} Flexor
Digitorum Superficialis
} The
flexor digitorum superficialis (FDS) is sometimes considered one of the
superficial muscles of the forearm,
} the
FDS gives rise to four tendons, which pass deep to the flexor retinaculum
through the carpal tunnel to the fingers. The four tendons are enclosed (along
with the four tendons of the flexor digitorum profundus) in a synovial common
flexor sheath (Fig. 6.57C).
} The
FDS flexes the middle phalanges of the medial four fingers at the proximal
interphalangeal joints.
} Flexor
Digitorum Profundus
Ø The
flexor digitorum profundus (FDP) is the only muscle that can flex the distal
interphalangeal joints of the fingers
} Flexor
Pollicis Longus.
} The
flexor pollicis longus (FPL), the long flexor of the thumb (L. pollex,
thumb), lies lateral to the FDP, where it clothes the anterior aspect
of the radius distal to the attachment of the supinator.
} Pronator
Quadratus
Ø The
pronator quadratus, as its name indicates, is quadrangular and pronates
the forearm.
Ø The
pronator quadratus is the only muscle that attaches only to the ulna at one end
and only to the radius at the other end.
} EXTENSOR
MUSCLES OF FOREARM
Ø The
extensor muscles are in the posterior (extensor–supinator) compartment
of the forearm, and all are innervated by branches of the radial nerve (Fig.
6.57B).
Ø These
muscles can be organized physiologically into three functional groups:
Ø 1.
Muscles that extend and abduct or adduct the hand at thewrist joint (extensor carpi radialis longus, extensor
carpi radialis brevis, and extensor carpi ulnaris).
Ø 2.
Muscles that extend the medial four fingers (extensor digitorum,
extensor indicis, and extensor digiti minimi).
3. Muscles that extend or abduct the thumb (abductor
pollicis longus, extensor pollicis brevis, and extensor
pollicis longus).
Ø The
extensor tendons are held in place in the wrist region by the extensor
retinaculum, which prevents bowstringing of the tendons when the
hand is extended at the wrist joint.
Ø the
tendons pass over the dorsum of the wrist, they are provided with synovial
tendon sheaths that reduce friction for the extensor tendons.
Ø Four
of the superficial extensors (extensor carpi radialis brevis,
extensor digitorum, extensor digiti minimi, and
extensor carpi ulnaris) are attached proximally by a common
extensor tendon to the lateral epicondyle
} Brachioradialis.
Ø lies
superficially on the anterolateral surface of the forearm (Figs. 6.58 and
6.61A).
Ø It
forms the lateral border of the cubital fossa (Fig. 6.56C)
} Extensor
Carpi Radialis Longus.
} The
extensor carpi radialis longus (ECRL), a fusiform muscle, is partly
overlapped by the brachioradialis, its tendon is crossed by the abductor
pollicis brevis and extensor pollicis brevis.
} Extensor
Carpi Radialis Brevis
Ø The
extensor carpi radialis brevis (ECRB), as its name indicates, is a shorter muscle
than the ECRL .
Ø it attaches adjacent to the ECRL in the hand
(but to the base of the 3rd metacarpal rather than the 2nd)
Ø The
ECRB and ECRL pass under the extensor retinaculum together within the tendinous
sheath of the extensor carpi radiales
} Extensor
Digitorum.
Ø The
extensor digitorum, the principal extensor of the medial four digits,
occupies much of the posterior surface of the forearm.
} Extensor
Digiti Minimi
} The
extensor digiti minimi (EDM) .The tendon of this extensor of the
little finger runs through a separate compartment of the extensor retinaculum,
posterior to the distal radio-ulnar joint, within the tendinous sheath of
the extensor digiti minimi.
} Extensor
Carpi Ulnaris
} The
extensor carpi ulnaris (ECU), a long fusiform muscle located on the medial
border of the forearm, has two heads:
} a humeral head from the common extensor tendon
and an ulnar head that arises by a common aponeurosis attached to the posterior
border of the ulna and shared by the FCU, FDP, and deep fascia of the forearm.
} Supinator.
} The
supinator lies deep in the cubital fossa and, along with the brachialis,
forms its floor.
} Abductor
Pollicis Longus
Ø The
abductor pollicis longus (APL) has a long, fusiform belly that lies just
distal to the supinator and is closely related to the extensor pollicis
brevis.
Ø The
APL acts with the abductor pollicis brevis during abduction of the thumb and
with the extensor pollicis muscles during extension of this digit.
} Extensor
Pollicis Brevis
} The
belly of the extensor pollicis brevis (EPB), the fusiform short extensor of
the thumb, lies distal to the APL and is partly covered by it. When the
thumb is fully extended, a hollow called the anatomical snuff box, can be
seen on the radial aspect of the wrist (Fig. 6.65).
} Extensor
Pollicis Longus
} The
extensor pollicis longus (EPL) is larger and its tendon is longer than that
of the EPB.
} The
tendon passes under the extensor retinaculum in its own tunnel, within the tendinous
sheath of the extensor pollicis longus, medial to the dorsal tubercle of the
radius.
} Extensor
Indicis.
} The
extensor indicis has a narrow, elongated belly that lies medial to and
alongside that of the EPL (Figs. 6.61 and 6.62).
} Arteries
of Forearm
} The
main arteries of the forearm are the ulnar and radial arteries,which usually
arise opposite the neck of the radius in the inferior part of the cubital fossa
as terminal branches of the brachial artery (Fig. 6.66).
} ULNAR
ARTERY
} Pulsations
of the ulnar artery can be palpated on the lateral side of the FCU
tendon, where it lies anterior to the ulnar head.
} The ulnar nerve is on the medial side of the
ulnar artery. Branches of the ulnar artery arising in the forearm participate
in the periarticular anastomoses of the elbow and supply muscles of the medial
and central forearm, the common flexor sheath, and the ulnar and median nerves.
} The
anterior and posterior ulnar recurrent arteries anastomose with the
inferior and superior ulnar collateral arteries, respectively, thereby
participating in the periarticular arterial anastomoses of the elbow.
} The
common interosseous artery,
} The
anterior interosseous artery
} Unnamed
muscular branches of the ulnar artery
} RADIAL
ARTERY
} The
pulsations of the radial artery can be felt throughout the forearm,
making it useful as an anterolateral demarcation of the flexor and extensor
compartments of the forearm.
Ø The
radial recurrent artery participates in the periarticular arterial
anastomoses around the elbow by anastomosing with the radial collateral
artery, a branch of the deep artery of the arm.
Ø The
palmar and dorsal carpal branches of the radial artery participate
in the periarticular arterial anastomosis around the wrist by
anastomosing with the corresponding branches of the ulnar artery and terminal
branches of the anterior and posterior interosseous arteries, forming
the palmar and dorsal carpal arches.
Ø The
unnamed muscular branches of the radial artery supply muscles
in the adjacent (anterolateral) aspects of both the flexor and the extensor
compartments.
} Veins
of Forearm
Ø In
the forearm, as in the arm, there are superficial and deep veins. The
superficial veins ascend in the subcutaneous tissue.
Ø The
deep veins accompany the deep arteries of the forearm.
} Nerves
of Forearm
Ø The
nerves of the forearm are the median, ulnar, and radial.
Ø The
median nerve is the principal nerve of the anterior (flexor–pronator)
compartment of the forearm (Figs. 6.57B and 6.69A).
Ø there are only two nerves of the anterior
aspect of the forearm: the median and ulnar nerves.
} MEDIAN
NERVE IN FOREARM
Ø The
median nerve is the principal nerve of the anterior compartment of the
forearm.
Ø It supplies muscular branches directly
to the muscles of the superficial and intermediate layers of forearm
flexors (except the FCU), and deep muscles (except for the medial
[ulnar] half of the FDP) via its branch, the anterior interosseous nerve.
Ø The
median nerve has no branches in the arm other than small twigs to the
brachial artery. Its major branch in the forearm is the anterior interosseous
nerve
q branches of the medial nerve arise in the
forearm:
Ø Articular branches.
Ø Muscular branches
Ø Anterior
interosseous nerve
Ø Palmar
cutaneous branch
} Articular branches. These branches pass
to the elbow jointas the median nerve passes it
Ø Muscular
branches. The nerve to the pronator teres usually arises at the
elbow and enters the lateral border of the muscle. innervates the FCR, the palmaris
longus, and the FDS.
Ø Anterior
interosseous nerve.
After supplying
the deep forearm flexors (except the ulnar part of the FDP, which sends tendons
to 4th and 5th fingers), it passes deep
and supplies the pronator quadratus, then ends by sending
articular branches to the wrist joint.
Ø Palmar
cutaneous branch of the median nerve. This branch arises in the
forearm, just proximal to the flexor retinaculum, but is distributed to skin of
the central part of the palm.
} ULNAR
NERVE IN FOREARM
Ø the
ulnar nerve does not give rise to branches during its passage
through the arm. In the forearm it supplies only one and a half muscles,
the FCU (as it enters the forearm by passing between its two heads of proximal
attachment) and the ulnar part of the FDP,
Ø The
branches of the ulnar nerve arising in the forearm include: unnamed muscular
and articular branches, and cutaneous branches that
pass to the hand:
Ø Articular branches pass to the elbow joint.
Ø Muscular
branches supply the FCU and the medial half of the FDP.
Ø •
The palmar and dorsal cutaneous branches arise from the ulnar
nerve in the forearm, but their sensory fibers are distributed to the skin of
the hand.
} RADIAL
NERVE IN FOREARM
Ø Unlike
the medial and ulnar nerves, the radial nerve serves motor and sensory
functions in both the arm and the forearm (but only sensory functions in
the hand).
Ø its
sensory and motor fibers are distributed in the forearm by two separate
branches, the superficial (sensory or cutaneous) and deep radial/posterior
interosseous nerve (motor)
Ø It
divides into these terminal branches as it appears in the cubital fossa,
anterior to the lateral epicondyle of the humerus, between the brachialis and
the brachioradialis (Fig. 6.64).
Ø The
posterior cutaneous nerve of the forearm arises from the radial nerve in
the posterior compartment of the arm.
Ø descending
in the subcutaneous tissue of the posterior aspect of the forearm to the wrist,
supplying the skin
Ø The
superficial branch of the radial nerve is also a
cutaneous nerve, but it gives rise to articular branches as well.
Ø The deep branch of the radial
nerve It supplies motor innervation to all the muscles with fleshy
bellies located entirely in the posterior compartment of the forearm (distal to
the lateral epicondyle of the humerus).
} LATERAL
AND MEDIAL CUTANEOUS NERVES OF FOREARM
Ø The
lateral cutaneous nerve of the forearm (lateral antebrachial cutaneous
nerve) is the continuation of the musculocutaneous nerve after
its motor branches have all been given off to the muscles of the anterior
compartment of the arm.
Ø The
medial cutaneous nerve of the forearm (medial antebrachial cutaneous
nerve) is a branch of the medial cord of the brachial plexus.
Ø With
the posterior cutaneous nerve of the forearm from the radial
nerve, each supplying the area of skin indicated by its name, these
three nerves provide all the cutaneous innervation of the forearm
HAND
Ø The
hand is the manual part of the upper limb distal to the forearm.
Ø The
skeleton of the hand consists of carpals in the wrist,metacarpals
in the hand proper, and phalanges in the digits (fingers, including
thumb).
Fascia and Compartments of Palm
Ø The
fascia of the palm is continuous with the antebrachial fascia and the
fascia of the dorsum of the hand.
Ø The
palmar fascia is thin over the thenar and hypothenar eminences, as thenar
and hypothenar fascia, respectively
Ø A
medial fibrous septum extends deeply from the medial border of the
palmar aponeurosis to the 5th metacarpal
Ø Medial
to this septum is the medial or hypothenar compartment, containing the
hypothenar muscles and bounded anteriorly by the hypothenar fascia.
Ø lateral
fibrous septum extends deeply from the lateral border of the palmar
aponeurosis to the 3rd metacarpal.
Ø Lateral to this septum is the lateral or thenar
compartment, containing the thenar muscles and bounded anteriorly by the
thenar fascia.
Ø Between
the hypothenar and the thenar compartments is the central compartment,
bounded anteriorly by the palmar aponeurosis and containing the flexor
tendons and their sheaths, the lumbricals, the superficial palmar arterial
arch, and the digital vessels and nerves.
Ø The
deepest muscular plane of the palm is the adductor compartment containing
the adductor pollicis.
Muscles of Hand
Ø The
intrinsic muscles of the hand are located in five compartments:
1. Thenar muscles in
the thenar compartment: abductor pollicis brevis,
flexor pollicis brevis, and opponens pollicis.
2. Adductor pollicis in the adductor compartment.
3. Hypothenar muscles in the hypothenar compartment: abductor
digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi.
4. Short muscles of the hand, the lumbricals, in the
central compartment with the long flexor tendons.
5. The interossei in separate interosseous compartments
between the metacarpals.
THENAR MUSCLES
The thenar muscles form the thenar eminence on the
lateral surface of the palm and are chiefly responsible for opposition
of the thumb.
Ø Thus
several muscles are required to control its freedom of movement:
Ø • Extension: extensor pollicis longus, extensor
pollicis brevis, and abductor pollicis longus.
Ø Flexion: flexor pollicis longus
and flexor pollicis brevis.
Ø •
Abduction: abductor pollicis longus and abductor pollicis brevis.
Ø •
Adduction: adductor pollicis and 1st dorsal interosseous.
Opposition: opponens pollicis.
This movement occurs at the carpometacarpal joint and
results in a “cupping” of the palm. Bringing the tip of the thumb into contact
with the 5th finger or any of the other fingers involves considerably more
movement than can be produced by the opponens pollicis alone.
Abductor Pollicis Brevis.
Ø The
abductor pollicis brevis (APB), the short abductor of the thumb, forms the
anterolateral part of the thenar eminence.
Ø In addition to abducting the thumb, the APB
assists the opponens pollicis during the early stages of opposition by rotating
its proximal phalanx slightly medially.
Flexor Pollicis Brevis.
Ø The
flexor pollicis brevis (FPB), the short flexor of the thumb, is located
medial to the APB , share (with each other with the APB) a common,
sesamoid-containing tendon at their distal attachment.
Ø The
FPB flexes the thumb at the carpometacarpal and metacarpophalangeal
joints and aids in opposition of the thumb.
innervation:
The larger superficial head of the FPB is innervated by the recurrent
branch of the median nerve, whereas the smaller deep head is usually
innervated by the deep palmar branch of the ulnar nerve.
Opponens Pollicis.
Ø The
opponens pollicis is a quadrangular muscle that lies deep to the APB and
lateral to the FPB.
Ø The
opponens pollicis opposes the thumb, the most important thumb movement.
Ø It
flexes and rotates the 1st metacarpal medially at the
carpometacarpal joint during opposition; this movement occurs when picking up
an object.
ADDUCTOR POLLICIS
Ø The
adductor pollicis is located in the adductor compartment of the hand.
Ø The
fan-shaped muscle has two heads of origin, which are separated by the radial
artery as it enters the palm to form the deep palmar arch.
Ø The
adductor pollicis adducts the thumb, moving the thumb to the palm
of the hand thereby giving power to the grip.
HYPOTHENAR MUSCLES
The hypothenar muscles (abductor digiti minimi, flexor
digiti minimi brevis, and opponens digiti minimi) produce the hypothenar
eminence on the medial side of the palm and move the little finger (Fig.
6.87).
Abductor Digiti Minimi
Ø The
abductor digiti minimi is the most superficial of the three muscles
forming the hypothenar eminence. The abductor digiti minimi abducts the 5th
finger and helps flex its proximal phalanx.
Flexor Digiti Minimi Brevis.
Ø The
flexor digiti minimi brevis is variable in size; it lies lateral to the
abductor digiti minimi.
Ø The flexor digiti minimi brevis flexes
the proximal phalanx of the 5th finger at the metacarpophalangeal joint.
Opponens Digiti Minimi.
Ø The
opponens digiti minimi is a quadrangular muscle that lies deep to the
abductor and flexor muscles of the 5th finger.
Ø rotates it laterally and bringing the 5th
finger into opposition with the thumb.
Palmaris Brevis.
The palmaris brevis is a small, thin muscle in the
subcutaneous tissue of the hypothenar eminence it is not in the hypothenar
compartment.
The palmaris brevis wrinkles the skin of the hypothenar
eminence, aiding the palmar grip.
SHORT MUSCLES OF HAND
The short muscles of the hand are the lumbricals and
interossei
Lumbricals.
Ø The
four slender lumbrical muscles were named because of their worm-like form.
Ø The lumbricals flex the fingers at the
metacarpophalangeal joints and extend the interphalangeal joints.
Interossei.
The four dorsal interosseous muscles (dorsal
interossei) are located between the metacarpals; the three palmar
interosseous muscles (palmar interossei) are on the palmar surfaces of the
metacarpals in the interosseous compartment of the hand.
Ø Acting
together, the dorsal and palmar interossei and the lumbricals produce flexion
at the metacarpophalangeal joints and extension of the interphalangeal
joints (the so-called Z-movement).
Long Flexor Tendons and Tendon
Sheaths in Hand
Sheaths in Hand
Ø The
tendons of the FDS and FDP enter the common flexor sheath (ulnar bursa) deep
to the flexor retinaculum.
Ø The
tendons enter the central compartment of the hand
Ø The
fibrous digital sheaths are the strong ligamentous tunnels containing
the flexor tendons and their synovial sheaths
Arteries of Hand
Arteries of Hand
Ø The
ulnar and radial arteries and their branches provide all the
blood to the hand.
ULNAR ARTERY IN HAND
Ø The
ulnar artery enters the hand anterior to the flexor retinaculum between
the pisiform and the hook of the hamate via the ulnar canal.
Ø The
ulnar artery lies lateral to the ulnar nerve.
q The artery divides into two terminal branches:
v superficial
palmar arch.
v deep palmar branch .
Ø The
superficial palmar arch, the main termination of the ulnar artery, gives rise
to three common palmar digital arteries that anastomose with the palmar
metacarpal arteries from the deep palmar arch.
Ø Each
common palmar digital artery divides into a pair of proper palmar digital
arteries, which run along the adjacent sides of the 2nd–4th digits
RADIAL ARTERY IN HAND
Ø The
radial artery curves dorsally around the scaphoid and trapezium and
crosses the floor of the anatomical snuff box Fig. 6.65).
Ø It
enters the palm by passing between the heads of the 1st dorsal interosseous
muscle and then turns medially, passing between the heads of the adductor
pollicis.
Ø The
radial artery ends by anastomosing with the deep branch of the ulnar artery to
form the deep palmar arch, which is formed mainly by the radial artery.
Veins of Hand
Superficial and deep venous palmar arches, associated
with the superficial and deep palmar (arterial) arches, drain into the deep
veins of the forearm (Fig. 6.68).
Ø The
dorsal digital veins drain into three dorsal metacarpal veins, which unite to
form a dorsal venous network .
Ø Superficial
to the metacarpus, this network is prolonged proximally on the lateral side
as the cephalic vein.
Ø The
basilic vein arises from the medial side of the dorsal venous network.
Nerves of Hand
Ø The
median, ulnar, and radial nerves supply the hand.
Ø In
addition, branches or communications from the lateral and posterior cutaneous
nerves may contribute some fibers that supply the skin of the dorsum of the
hand.
Ø In
the hand, these nerves convey sensory fibers from spinal nerves C6–C8 to the
skin, so that the C6–C8 dermatomes include the hand (Fig. 6.86C & D).
Ø The
median and ulnar nerves convey motor fibers from spinal nerve T1 to the
hand; the intrinsic muscles of the hand make up myotome T1
MEDIAN NERVE IN HAND
Ø The
median nerve enters the hand through the carpal tunnel, deep to
the flexor retinaculum, along with the nine tendons of the FDS, FDP, and FPL.
Ø The
carpal tunnel is the passageway deep to the flexor retinaculum between
the tubercles of the scaphoid and trapezoid bones on the lateral side
and the pisiform and the hook of the hamate on the medial side.
Ø Distal
to the carpal tunnel, the median nerve supplies two and a half thenar
muscles and the 1st and 2nd lumbricals.
Ø It
also sends sensory fibers to the skin on the entire palmar surface,
the sides of the first three digits, the lateral half of
the 4th digit, and the dorsum of the distal halves of
these digits.
THE ULNAR NERVE IN HAND
Ø The
ulnar nerve leaves the forearm by emerging from deep to the tendon of
the FCU.
Ø It
continues distally to the wrist via the ulnar canal Just proximal to the
wrist, the ulnar nerve gives off a palmar cutaneous branch,
which passes superficial to the flexor retinaculum and palmar
aponeurosis and supplies skin on the medial side of the palm.
Ø The
dorsal cutaneous branch of the ulnar nerve supplies the medial half of
the dorsum of the hand, the 5th finger, and the medial
half of the 4th finger .
Ø The
superficial branch of the ulnar nerve supplies cutaneous branches to the
anterior surfaces of the medial one and a half digits.
Ø The
deep branch of the ulnar nerve supplies the hypothenar muscles,
the medial two lumbricals, the adductor pollicis, the deep
head of the FPB, and all the interossei.
Ø The
deep branch also supplies several joints (wrist, intercarpal,carpometacarpal,
and intermetacarpal).
RADIAL NERVE IN HAND
Ø The
radial nerve supplies no hand muscles.
Ø The
superficial branch of the radial nerve is entirely sensory (Fig. 6.85B).
Ø It supply the skin and fascia over the lateral
two thirds of the dorsum of the hand, the dorsum of the thumb, and proximal
parts of the lateral one and a half digits.
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