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Ministry of Health of Ukraine

Bukovinian State Medical University


APPROVED”


on methodical meeting of the Department of Anatomy, Topographical anatomy and Operative Surgery

…………………………….2007 р. (Protocol №……….)

The chief of department


professor ……………………….……Yu.T.Achtemiichuk

…………………………….2007 р.


METHODICAL GUIDELINES



for the 3d-year foreign students of English-spoken groups of the Medical Faculty

(speciality “General medicine”)

for independent work during the preparation to practical studies



the Theme of studies

TOPOGRAPHICAL ANATOMY AND OPERATIVE SURGERY OF THE SHOULDER AND ARM”


Module 2

“Topographical anatomy and operative surgery of the regions and organs of the lumbar region, pelvis and extremities”


Semantic module

“Topographical anatomy and operative surgery of the vertebral column and extremities”


Chernivtsi – 2007

^ 1. Actuality of theme:

The topographical anatomy and operative surgery of the shoulder and arm are very importance, because without the knowledge about peculiarities and variants of structure, form, location and mutual location of their anatomical structures, their age-specific it is impossible to diagnose in a proper time and correctly and to prescribe a necessary treatment to the patient. Surgeons and traumatologists usually pay much attention to the topographic anatomy of the upper extremities. Topography of the shoulder and arm is important for surgeons, traumatologists and neuropathologists. The availability a number of the nerves and vessels causes the certain difficulties for surgical interventions for clinical and topical diagnosis.


^ 2. Duration of studies: 2 working hours.


3. Objectives (concrete purposes):

To know peculiarities and variants of structure, form, location of upper extremities.

To be able to define the skeletotopy and projectors of the shoulder and arm.

To master practical skills to make the manipulation on the shoulder and arm (puncture, blockade, amputations and so on).


^ 4. Basic knowledges, abilities, skills, that necessary for the study themes (interdisciplinary integration):


The names of previous disciplines

The got skills

1. Normal anatomy

2. Physiology


To describe the structure and function of the different organs of the human body, to determine projectors and landmarks of the anatomical structures.


5. Advices to the student.

5.1. Table of contents of the theme:

The upper limb


The upper limb can be divided into the shoulder (junction of the trunk with the arm), arm, elbow, forearm, wrist, and hand.

^ BONES OF THE SHOULDER GIRDLE AND ARM

The shoulder girdle consists of the clavicle and the scapula, which articulate with one another at the acromioclavicular joint.

THE AXILLA

The axilla, or armpit, is a pyramid-shaped space between the upper part of the arm and the side of the chest. It forms an important passage 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 the root of the neck and is bounded in front by the clavicle, behind by the upper border of the scapula, and medially by the outer border of the first rib.

The lower end, or base, is bounded in front by the lower border of the pectoralis major muscle, behind by the tendon of latissimus dorsi and the teres major muscle, and medially by the chest wall.

^ Walls of the Axilla

The walls of the axilla are made up as follows:

Anterior wall, by the pectoralis major, subclavius, and pectoralis minor muscles.

Posterior wall, by the subscapularis, latissimus dorsi, and teres major muscles from above down.

^ Medial wall, by the upper four or five ribs and the intercostals spaces covered by the serratus anterior muscle.

Lateral wall, by the coracobrachialis and biceps muscles in the bicipital groove of the humerus.

The base is formed by the skin stretching between the anterior and posterior walls.

^ The axilla contains the principal vessels and nerves to the upper limb and many lymph nodes.

Clavipectoral Fascia

The clavipectoral fascia is a strong sheet of connective tissue that is split above to enclose the subclavius muscle and is attached to the clavicle. Below it splits to enclose the pectoralis minor muscle and then continues downward as the suspensory ligament of the axilla and joins the fascial floor of the armpit.

Contents of the Axilla

The axilla contains the axillary artery and its branches, and lymph vessels and lymph nodes and the brachial plexus, which innervates the upper limb. The above structures are embedded in fat.

^ Brachial Plexus

The brachial plexus is formed in the posterior triangle of the neck by the union of the anterior rami of the fifth, sixth, seventh, and eighth cervical and the first thoracic spinal nerves.

The plexus can be divided into roots, trunks, divisions, and cords. The roots of C5 and 6 unite to form the upper trunk, the root of C7 continues as the middle trunk, and the roots of C8 and T1 unite to form the lower trunk.

Each trunk then divides into anterior and posterior divisions.

The anterior divisions of the upper and middle trunks unite to form the lateral cord, the anterior division of the lower trunk continues as the medial cord, and the posterior divisions of all three trunks join to form the posterior cord.

The roots, trunks, and divisions of the brachial plexus reside in the lower part of the posterior triangle of the neck and are fully described on page 643. The cords become arranged around the axillary artery in the axilla. Here, the brachial plexus and the axillary artery and vein are enclosed by a sheath of fascia called the axillary sheath.

Cords of the Brachial Plexus All three cords of the brachial plexus lie above and lateral to the first part of the axillary artery. The medial cord crosses behind the artery to reach the medial side of the second part of the artery. The posterior cord lies behind the second part of the artery, and the lateral cord lies on the lateral side of the second part of the artery. Thus, the cords of the plexus have the relationship to the second part of the axillary artery that is indicated by their names.

Most branches of the cords that form the main nerve trunks of the upper limb continue this relationship to the artery in its third part.

The branches of the different parts of the brachial plexus are as follows:

^ Roots

Dorsal scapular nerve (C5)

Long thoracic nerve (C5, 6, and 7)

Upper trunk

Nerve to subclavius (C5 and 6)

Suprascapular nerve (supplies the supraspinatus and infraspinatus muscles)

Lateral cord

Lateral pectoral nerve

Musculocutaneous nerve

Lateral root of median nerve

^ Medial cord

Medial pectoral nerve

Medial cutaneous nerve of arm and medial cutaneous nerve of forearm

Ulnar nerve

Medial root of median nerve

Posterior cord

Upper and lower subscapular nerves

Thoracodorsal nerve

Axillary nerve

Radial nerve

^ Branches of the Brachial Plexus Found in the Axilla

The nerve to the subclavius (C5 and 6) supplies the subclavius muscle. It is important clinically because it may give a contribution (C5) to the phrenic nerve; this branch, when present, is referred to as the accessory phrenic nerve.

The long thoracic nerve (C5, 6, and 7) arises from the roots of the brachial plexus in the neck and enters the axilla by passing down over the lateral border of the first rib behind the axillary vessels and brachial plexus. It descends over the lateral surface of the serratus anterior muscle, which it supplies.

The lateral pectoral nerve arises from the lateral cord of the brachial plexus and supplies the pectoralis major muscle.

The musculocutaneous nerve arises from the lateral cord of the brachial plexus, supplies the coracobrachialis muscle, and leaves the axilla by piercing that muscle.

The lateral root of the median nerve is the direct continuation of the lateral cord of the brachial plexus. It is joined by the medial root to form the median nerve trunk, and this passes downward on the lateral side of the axillary artery. The median nerve gives off no branches in the axilla.

^ The medial pectoral nerve arises from the medial cord of the brachial plexus, supplies and pierces the pectoralis minor muscle, and supplies the pectoralis major muscle.

The medial cutaneous nerve of the arm (T1) arises from the medial cord of the brachial plexus and is joined by the intercostobrachial nerve (lateral cutaneous branch of the second intercostal nerve). It supplies the skin on the medial side of the arm.

^ The medial cutaneous nerve of the forearm arises from the medial cord of the brachial plexus and descends in front of the axillary artery.

The ulnar nerve (C8 and T1) arises from the medial cord of the brachial plexus and descends in the interval between the axillary artery and vein. The ulnar nerve gives off no branches in the axilla.

^ The medial root of the median nerve arises from the medial cord of the brachial plexus and crosses in front of the third part of the axillary artery to join the lateral root of the median nerve.

The upper and lower subscapular nerves arise from the posterior cord of the brachial plexus and supply the upper and lower parts of the subscapularis muscle. In addition, the lower subscapular nerve supplies the teres muscle.

^ The thoracodorsal nerve arises from the posterior cord of the brachial plexus and runs downward to supply the latissimus dorsi muscle.

The axillary nerve is one of the terminal branches of the posterior cord of the brachial plexus. It turns backward and passes through the quadrangular space. Having given off a branch to the shoulder joint, it divides into anterior and posterior branches.

The radial nerve is the largest branch of the brachial plexus and lies behind the axillary artery. It gives off branches to the long and medial heads of the triceps muscle and the posterior cutaneous nerve of the arm. The latter branch is distributed to the skin on the middle of the back of the arm.

^ Lymph Nodes of the Axilla

The axillary lymph nodes (20 to 30 in number) drain lymph vessels from the lateral quadrants of the breast, the superficial lymph vessels from the thoracoabdominal walls above the level of the umbilicus, and the vessels from the upper limb.

The lymph nodes are arranged in six groups.

^ 1. Anterior (pectoral) group: Lying along the lower border of the pectoralis minor behind the pectoralis major, these nodes receive lymph vessels from the lateral quadrants of the breast and superficial vessels from the anterolateral abdominal wall above the level of the umbilicus.

^ 2. Posterior (subscapular) group: Lying in front of the Subscapularis muscle, these nodes receive superficial lymph vessels from the back, down as far as the level of the iliac crests.

3. Lateral group: Lying along the medial side of the axillary vein, these nodes receive most of the lymph vessels of the upper limb (except those superficial vessels draining the lateral side - see infraclavicular nodes below).

^ 4. Central group: Lying in the center of the axilla in the axillary fat, these nodes receive lymph from the above three groups.

5. Infraclavicular (deltopectoral) group: These nodes are not strictly axillary nodes because they are located outside the axilla. They lie in the groove between the deltoid and pectoralis major muscles and receive superficial lymph vessels from the lateral side of the hand, forearm, and arm.

^ 6. Apical group: Lying at the apex of the axilla at the lateral border of the first rib, these nodes receive the efferent lymph vessels from all the other axillary nodes.

The apical nodes drain into the subclavian lymph trunk. On the left side this trunk drains into the thoracic duct and on the right side it drains into the right lymph trunk. Alternatively, the lymph trunks may drain directly into one of the large veins at the root of the neck.


^ The Superficial Part of the Back and the Scapular Region

SKIN

The sensory nerve supply to the skin of the back is from the posterior rami of the spinal nerves. The first and eighth cervical nerves do not supply the skin, and the posterior rami of the upper three lumbar nerves run downward to supply the skin over the buttock.

The blood supply to the skin is from the posterior branches of the posterior intercostal arteries and the lumbar arteries. The veins correspond to the arteries and drain into the azygos veins and the inferior vena cava.

The lymph drainage of the skin of the back above the level of the iliac crests is upward into the posterior group of axillary lymph nodes.

^ MUSCLES

Trapezius

Latissimus Dorsi

Levator Scapulae

Rhomboid Minor

Rhomboid Major

Deltoid

Supraspinatus


Quadrangular Space

The quadrangular space is an intermuscular space bounded above by the subscapularis and capsule of the shoulder joint and below by the teres major muscle. It is bounded medially by the long head of the triceps and laterally by the surgical neck of the humerus.

The axillary nerve and the posterior circumflex humeral vessels pass backward through this space.

^ NERVES

Spinal Part of the Accessory Nerve (Cranial Nerve XI)

The spinal part of the accessory nerve runs downward in the posterior triangle of the neck on the levator scapulae muscle. It is accompanied by branches from the anterior rami of the third and fourth cervical nerves. The accessory nerve runs beneath the anterior border of the trapezius muscle at the junction of its middle and lower thirds and, together with the cervical nerves, supplies the trapezius muscle.

^ ARTERIAL ANASTOMOSIS AROUND THE SHOULDER JOINT

The extreme mobility of the shoulder joint may result in kinking of the axillary artery and a temporary occlusion of its lumen. To compensate for this, an important arterial anastomosis exists between the branches of the subclavian artery and the axillary artery, thus ensuring that an adequate blood flow takes place into the upper limb irrespective of the position of the arm.

Branches From the Subclavian Artery

^ 1. The Suprascapular artery, which is distributed to the supraspinous and infraspinous fossae of the scapula.

2. The superficial cervical artery, which gives off a deep branch that runs down the medial border of the scapula.

Branches From the Axillary Artery

^ 1. The subscapular artery and its circumflex scapular branch supply the subscapular and infraspinous fossae of the scapula, respectively.

2. The anterior circumflex humeral artery.

3. The posterior circumflex humeral artery.

Both the circumflex arteries form an anastomosing circle around the surgical neck of the humerus.

Sternoclavicular Joint

Articulation: This occurs between the sternal end of the clavicle, the manubrium sterni, and the first costal cartilage.

• Type: Synovial double-plane joint.

• Capsule: This surrounds the joint and is attached to the margins of the articular surfaces.

• Ligaments: The capsule is reinforced in front of and behind the joint by the strong sternoclavicular ligaments.

Articular disc: This flat fibrocartilaginous disc lies within the joint and divides the joint's interior into two compartments. Its circumference is attached to the interior interior of the capsule, but it is also strongly attached to the superior margin of the articular surface of the clavicle above and to the first costal cartilage below.

^ Accessory ligament: The costoclavicular ligament is a strong ligament that runs from the junction of the first rib with the first costal cartilage to the inferior surface of the sternal end of the clavicle.

Synovial membrane: This lines the capsule and is attached to the margins of the cartilage covering the articular surfaces.

^ Nerve supply: The supraclavicular nerve and the nerve to the subclavius muscle.


MOVEMENTS

Forward and backward movement of the clavicle takes place in the medial compartment. Elevation and depression of the clavicle take place in the lateral compartment.


^ The Upper Arm

SKIN

The sensory nerve supply to the skin over the point of the shoulder to halfway down the deltoid muscle is from the supraclavicular nerves (C3 and 4). The skin over the lower half of the deltoid is supplied by the upper lateral cutaneous nerve of the arm, a branch of the axillary nerve (C5 and 6). The skin over the lateral surface of the arm below the deltoid is supplied by the lower lateral cutaneous nerve of the arm, a branch of the radial nerve (C5 and 6). The skin of the armpit and the medial side of the arm is supplied by the medial cutaneous nerve of the arm (Tl) and the intercostobrachial nerves (T2). The skin of the back of the arm is supplied by the posterior cutaneous nerve of the arm, a branch of the radial nerve (C8).

The superficial veins of the arm lie in the superficial fascia.

The cephalic vein ascends in the superficial fascia on the lateral side of the biceps and, on reaching the infraclavicular fossa, drains into the axillary vein.

The basilic vein ascends in the superficial fascia on the medial side of the biceps. Halfway up the arm, it pierces the deep fascia and at the lower border of the teres major joins the venae comitantes of the brachial artery to form the axillary vein.

The superficial lymph vessels draining the superficial tissues of the upper arm pass upward to the axilla. Those from the lateral side of the arm follow the cephalic vein to the infraclavicular group of nodes; those from the medial side follow the basilic vein to the lateral group of axillary nodes.

The deep lymphatic vessels draining the muscles and deep structures of the arm drain into the lateral group of axillary nodes.


^ FASCIAL COMPARTMENTS OF THE UPPER ARM

The upper arm is enclosed in a sheath of deep fascia. Two fascial septa, one on the medial side and one on the lateral side, extend from this sheath and are attached to the medial and lateral supracondylar ridges of the humerus, respectively. By this means the upper arm is divided into an anterior and a posterior fascial compartment, each having its muscles, nerves, and arteries.

^ Contents of the Anterior Fascial Compartment of the Upper Arm

Muscles: Biceps brachii, coracobrachialis, and brachialis.

Blood supply: Brachial artery.

Nerve supply to the muscles: Musculocutaneous nerve.

^ Structures passing through the compartment:

Median Nerve

Origin - from the medial and lateral cords of the brachial plexus in the axilla. It runs downward on the lateral side of the brachial artery. Halfway down the upper arm, it crosses the brachial artery and continues downward on its medial side. The nerve, like the artery, is therefore superficial, but at the elbow it is crossed by the bicipital aponeurosis. The median nerve has no branches in the upper arm, except for a small vasomotor nerve to the brachial artery.

^ Ulnar Nerve

Origin - from the medial cord of the brachial plexus in the axilla. It runs downward on the medial side of the brachial artery as far as the middle of the arm. Here, at the insertion of the coracobrachialis, the nerve pierces the medial fascial septum, accompanied by the superior ulnar collateral artery, and enters the posterior compartment of the arm; the nerve passes behind the medial epicondyle of the humerus. The ulnar nerve has no branches in the anterior compartment of the upper arm.

^ Radial Nerve

On leaving the axilla, the radial nerve immediately enters the posterior compartment of the arm and only enters the anterior compartment just above the lateral epicondyle.


Contents of the Posterior Fascial Compartment of the Upper Arm

Muscle: The three heads of the triceps muscle.

^ Nerve supply to the muscle: Radial nerve.

Blood supply: Profunda brachii and ulnar collateral arteries.

Structures passing through the compartment: Radial nerve and ulnar nerve.


Muscle of the Posterior Fascial Compartment

^ Triceps The triceps is a large muscle that forms the greater part of the substance of the back of the arm.

Origin: Long head from the infraglenoid tubercle of the scapula; lateral head from the upper half of the posterior surface of the shaft of the humerus above the spiral groove; medial head from the posterior surface of the lower half of the shaft of the humerus below the spiral groove.

Insertion: The common tendon is inserted into the upper surface of the olecranon process of the ulna.

^ Nerve supply: Radial nerve.

Action: This muscle is a strong extensor of the elbow joint.

Structures Passing Through the Posterior Fascial Compartment

Radial Nerve

Origin - from the posterior cord of the brachial plexus in the axilla. The nerve winds around the back of the arm in the spiral groove on the back of the humerus between the heads of the triceps. It pierces the lateral fascial septum above the elbow and continues downward into the cubital fossa in front of the elbow, between the brachialis and the brachioradialis muscles. In the spiral groove the nerve is accompanied by the profunda vessels, and it lies directly in contact with the shaft of the humerus.

Branches

^ 1. In the axilla: Branches are given to the long and medial heads of the triceps, and the posterior cutaneous nerve of the arm is given off.

2. In the spiral groove: Branches are given to the lateral and medial heads of the triceps and to the anconeus. The lower lateral cutaneous nerve of the arm supplies the skin over the lateral and anterior aspects of the lower part of the arm. The posterior cutaneous nerve of the forearm runs down the middle of the back of the forearm as far as the wrist.

^ 3. In the anterior compartment of the arm: After the nerve has pierced the lateral fascial septum, it gives branches to the brachialis, the brachioradialis, and the extensor carpi radialis longus muscles. It also gives articular branches to the elbow joint.

Ulnar Nerve Having pierced the medial fascial septum halfway down the upper arm (see previous column), the ulnar nerve descends behind the septum, covered posteriorly by the medial head of the triceps. The nerve is accompanied by the superior ulnar collateral vessels. At the elbow, it lies behind the medial epicondyle of the humerus on the medial ligament of the elbow joint. It continues downward to enter the forearm between the two heads of origin of the flexor carpi ulnaris.

Branches The ulnar nerve has an articular branch to the elbow joint.

^ Profunda Brachii Artery The profunda brachii artery arises from the brachial artery near its origin. It accompanies the radial nerve through the spiral groove, supplies the triceps muscle, and takes part in the anastomosis around the elbow joint.

Superior and Inferior Ulnar Collateral Arteries The superior and inferior ulnar collateral arteries arise from the brachial artery and take part in the anastomosis around the elbow joint.


^ The Cubital Fossa

The cubital fossa is a depression that lies in front of the elbow and is triangular.

BOUNDARIES

Laterally: The brachioradialis muscle.

Medially: The pronator teres muscle.

The base of the triangle is formed by an imaginary line drawn between the two epicondyles of the humerus.

The floor of the fossa is formed by the supinator muscle laterally and the brachialis muscle medially.

The roof is formed by skin and fascia and is reinforced by the bicipital aponeurosis.

CONTENTS

The cubital fossa contains the following structures, enumerated from the medial to the lateral side: the median nerve, the bifurcation of the brachial artery into the ulnar and radial arteries, the tendon of the biceps muscle, and the radial nerve and its deep branch.

The supratrochlear lymph node lies in the superficial fascia over the upper part of the fossa, above the trochlea. It receives afferent lymph vessels from the third, fourth, and fifth fingers; the medial part of the hand; and the medial side of the forearm. The efferent lymph vessels pass up to the axilla and enter the lateral axillary group of nodes.


^ FOREARM


Bones of the Forearm

The forearm contains two bones: the radius and the ulna.

RADIUS

The radius is the lateral bone of the forearm. Its proximal end articulates with the humerus at the elbow joint and with the ulna at the proximal radioulnar joint. Its distal end articulates with the scaphoid and lunate bones of the hand at the wrist joint and with the ulna at the distal radioulnar joint.

At the proximal end of the radius is the small circular head. The upper surface of the head is concave and articulates with the convex capitulum of the humerus. The circumference of the head articulates with the radial notch of the ulna. Below the head the bone is constricted to form the neck. Below the neck is the bicipital tuberosity for the insertion of the biceps muscle.

The shaft of the radius, in contradistinction to that of the ulna, is wider below than above. It has a sharp interosseous border medially for the attachment of the interosseous membrane that binds the radius and ulna together.

The pronator tubercle, for the insertion of the pronator teres muscle, lies halfway down on its lateral side. At the distal end of the radius is the styloid process; this projects distally from its lateral margin. On the medial surface is the ulnar notch, which articulates with the round head of the ulna. The inferior articular surface articulates with the scaphoid and lunate bones. On the posterior aspect of the distal end is a small tubercle, the dorsal tubercle, which is grooved on its medial side by the tendon of the extensor pollicis longus.


ULNA

The ulna is the medial bone of the forearm. Its proximal end articulates with the humerus at the elbow joint and with the head of the radius at the proximal radioulnar joint. Its distal end articulates with the radius at the distal radioulnar joint, but it is excluded from the wrist joint by the articular disc.

The proximal end of the ulna is large and is known as the olecranon process; this forms the prominence of the elbow. It has a notch on its anterior surface, the trochlear notch, which articulates with the trochlea of the humerus. Below the trochlear notch is the triangular coronoid process, which has on its lateral surface the radial notch for articulation with the head of the radius.

^ The shaft of the ulna tapers from above down.

It has a sharp interosseous border laterally for the attachment of the interosseous membrane. The posterior border is rounded and subcutaneous and can be easily palpated throughout its length. Below the radial notch is a depression, the supinator fossa, which gives clearance for the movement of the bicipital tuberosity of the radius. The posterior border of the fossa is sharp and is known as the supinator crest; it gives origin to the supinator muscle.

At the distal end of the ulna is the small rounded head, which has projecting from its medial aspect the styloid process.


^ Bones of the Hand

There are eight carpal bones, made up of two rows of four. The proximal row consists of (from lateral to medial) the scaphoid, lunate, triquetral, and pisiform bones. The distal row consists of (from lateral to medial) the trapezium, trapezoid, capitate, and hamate bones. Together, the bones of the carpus present on their anterior surface a concavity, to the lateral and medial edges of which is attached a strong membranous band called the flexor retinaculum. In this manner, an osteofascial tunnel, the carpal tunnel, is formed for the passage of the median nerve and the flexor tendons of the fingers.

The bones of the hand are cartilaginous at birth. The capitate begins to ossify during the first year, and the others begin to ossify at intervals thereafter until the twelfth year, when all the bones are ossified.

Although detailed knowledge of the bones of the hand is unnecessary for a medical student, the position, shape, and size of the scaphoid bone should be studied because it is commonly fractured. The ridge of the trapezium and the hook of the hamate should be examined.


^ THE METACARPALS AND PHALANGES

There are five metacarpal bones, each of which has a base, a shaft, and a head.

The first metacarpal bone of the thumb is the shortest and most mobile. It does not lie in the same plane as the others but occupies a more anterior position. It is also rotated medially through a right angle so that its extensor surface is directed laterally and not backward.

The bases of the metacarpal bones articulate with the distal row of the carpal bones; the heads, which form the knuckles, articulate with the proximal phalanges. The shaft of each metacarpal bone is slightly concave forward and is triangular in transverse section. Its surfaces are posterior, lateral, and medial.

There are three phalanges for each of the fingers but only two for the thumb.


^ The Forearm

SKIN

The sensory nerve supply to the skin of the forearm is from the anterior and posterior branches of the lateral cutaneous nerve of the forearm, a continuation of the musculocutaneous nerve, and from the anterior and posterior branches of the medial cutaneous nerve of the forearm. A narrow strip of skin down the middle of the posterior surface of the forearm is supplied by the posterior cutaneous nerve of the forearm.

The superficial veins of the forearm lie in the superficial fascia. The cephalic vein arises from the lateral side of the dorsal venous arch on the back of the hand and winds around the lateral border of the forearm; it then ascends into the cubital fossa and up the front of the arm on the lateral side of the biceps. It terminates in the axillary vein in the deltapectoral triangle. As the cephalic vein passes up the upper limb, it receives a variable number of tributaries from the lateral and posterior surfaces of the limb. The median cubital vein, a branch of the cephalic vein in the cubital fossa, runs upward and medially and joins the basilic vein. In the cubital fossa the median cubital vein crosses in front of the brachial artery and the median nerve, but it is separated from them by the bicipital aponeurosis.

The basilic vein arises from the medial side of the dorsal venous arch on the back of the hand and winds around the medial border of the forearm; it then ascends into the cubital fossa and up the front of the arm on the medial side of the biceps. Its termination by joining the venae comitantes of the brachial artery to form the axillary vein is described on page 403. It receives the median cubital vein and a variable number of tributaries from the medial and posterior surfaces of the upper limb.

The superficial lymph vessels from the thumb and lateral fingers and the lateral areas of the hand and forearm follow the cephalic vein to the infraclavicular group of nodes.

Those from the medial fingers and the medial areas of the hand and forearm follow the basilic vein to the cubital fossa. Here, some of the vessels drain into the supratrochlear lymph node, whereas others bypass the node and accompany the basilic vein to the axilla, where they drain into the lateral group of axillary nodes. The efferent vessels from the supratrochlear node also drain into the lateral axillary nodes.

^ FASCIAL COMPARTMENTS OF THE FOREARM

The forearm is enclosed in a sheath of deep fascia, which is attached to the periosteum of the posterior subcutaneous border of the ulna. This fascial sheath, together with the interosseous membrane and fibrous intermuscular septa, divides the forearm into several compartments, each having its own muscles, nerves, and blood supply.

^ Carpal Tunnel

The bones of the hand and the flexor retinaculum form the carpal tunnel. The median nerve lies in a restricted space between the tendons of the flexor digitorum superficialis and the flexor carpi radialis muscles.

Contents of the Anterior Fascial Compartment of the Forearm

Muscles: A superficial group, consisting of the pronator teres, the flexor carpi radialis, the palmaris longus, and the flexor carpi ulnaris; an intermediate group consisting of the flexor digitorum superficialis; and a deep group consisting of the flexor pollicis longus, the flexor digitorum profundus, and the pronator quadratus.

^ Blood supply to the muscles: Ulnar and radial arteries.

Nerve supply to the muscles: All the muscles are supplied by the median nerve and its branches, except the flexor carpi ulnaris and the medial part of the flexor digitorum profundus, which are supplied by the ulnar nerve.

^ Arteries of the Anterior Fascial Compartment of the Forearm

Ulnar Artery

The ulnar artery is the larger of the two terminal branches of the brachial artery. It begins in the cubital fossa at the level of the neck of the radius. It descends through the anterior compartment of the forearm and enters the palm in front of the flexor retinaculum in company with the ulnar nerve. It ends by forming the superficial palmar arch, often anastomosing with the superficial palmar branch of the radial artery.

In the upper part of its course, the ulnar artery lies deep to most of the flexor muscles. Below it becomes superficial and lies between the tendons of the flexor carpi ulnaris and the tendons of the flexor digitorum superficialis. In front of the flexor retinaculum it lies just lateral to the pisiform bone and is covered only by skin and fascia (site for taking ulnar pulse).

Branches

^ 1. Muscular branches to neighboring muscles.

2. Recurrent branches that take part in the arterial anastomosis around the elbow joint.

3. Branches that take part in the arterial anastomosis around the wrist joint.

4. The common interosseous artery, which arises from the upper part of the ulnar artery and after a brief course divides into the anterior and posterior interosseous arteries. The interosseus arteries are distributed to the muscles lying in front and behind the interosseous membrane; they provide nutrient arteries to the radius and ulna bone.
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