Upper Limb Anatomy PDF

Upper limb[1 -50] BONES The upper limb is composed of the shoulder girdle and 3 segments : arm, forearm and hand.The bones of the shoulder girdle [connect the limb to the trunk] are the 2 scapulae and the 2 clavicles. The clavicles articulate in front with the upper border of the stern...

Upper limb[1 -50] BONES The upper limb is composed of the shoulder girdle and 3 segments : arm, forearm and hand.The bones of the shoulder girdle [connect the limb to the trunk] are the 2 scapulae and the 2 clavicles. The clavicles articulate in front with the upper border of the sternum, but the scapulae are connected behind to the trunk only by muscles. CLAVICLE FUNCTIONS : 1. Acts as a prop to allow the arm to swing away from the trunk. 2. Transmits part of the weight of the limb to the trunk. It has a shaft and 2 ends [medial and lateral]. SHAFT : Its lateral 1/3 is flattened, while its medial 2/3 is cylindrical [has 4 surfaces]. Superior surface :  subcutaneous and smooth.  Sternocleidomastoid [sternomastoid] takes origin from its medial 1/3. Inferior surface:  Rough medially for the articulation of the costoclavicular ligament.  Rough laterally for the attachment of the coraco-clavicular ligament [conoid part in the conoid tubercle and trapezoid part in the trapezoid ridge].  A groove is present in the middle part for the subclavius muscle[insertion]. Anterior surface:  Convex forwards in its medial 2/3 and concave forwards in its lateral 1/3.  Deltoid is attached to its lateral 1/3[origin].  Pectoralis major is attached to its medial 1/2[origin]. Posterior surface:  Has the reverse curves of the anterior surface.  Trapezius is attached to its lateral 1/3[insertion]. MEDIAL[STERNAL] END:  Quadrangular in shape  Articulates with the manubrium sterni to form the sternoclavicular joint.  The articular disc and interclavicular ligament are attached to it.  Sternohyoid muscle is attached to its posterior surface. LATERAL {ACROMIAL] END:  Flattened.  Articulates with the acromion to form the acromio-clavicular joint. SUBCUTANEOUS PART OF THE CLAVICLE:  The upper surface.  The medial end.  The lateral end. OSSIFICATION :  Although it is a long bone its shaft ossifies in membrane. Its ends ossify in cartilage.  It is the earliest bone to begin ossification [5th week of intrauterine].  It has one secondary centre at the medial end. It fuses with the shaft at the age of 25 years. 1  Upper limb[1 -50] APPLIED ANATOMY:  The weakest point of the clavicle is at the junction of its 2 curves[between medial 2/3 and lateral1/3], and this is a common site for fracture.  In case of a fracture medial to the coraco-clavicular ligament, the lateral segment [to which the scapular is attached] falls down by the weight of the limb, while the medial segment of the clavicle is little deformed due to balanced action of pectoralis major and sternomastoid muscles. SCAPULA It is triangular in shape having 3 borders, 3 angles and 2 surfaces. BORDERS : Upper border:  Extends from the superior angle to the lateral angle [glenoid cavity].  It has the suprascapular notch which is transformed into a foramen by the suprascapular ligament. The suprascapular nerve passes through the foramen while the suprascapular vessels pass over the ligament.  The inferior belly of omohyoid muscle arises from this border close to the notch. Medial [ vertebral] border:  Extends from the superior angle to the inferior angle [opposite2-7 ribs].  The muscles inserted into the medial border are : 1. Levator scapulae: in its dorsal surface from the superior angle to the spine. 2. Rhomboidus minor: in its dorsal surface opposite the root of the spine of the scapula. 3. Rhomboidus major: in its dorsal surface from the spine to the inferior angle. 4. Serratus anterior: in its anterior surface from the superior angle to the inferior angle. Lateral [vertebral] border:  Extends from the glenoid cavity to the inferior angle.  It has a prominent ridge in it anterior surface which act as a lever for serratus anterior muscle in rotating the scapula.  The muscles that take origin from it are: 1. Teres minor: from the upper 2/3 of its dorsal surface. Here the border is grooved by circumflex scapula artery which is a branch of the subscapular artery. 2. Teres major: from the dorsal surface of the inferior angle. 3. Long head of triceps: from the infraglenoid tubercle. 4. Some slips of lattissmus dorsi: from the back of the inferior angle. SURFACES: Anterior [ ventral] surface: 1. Concave and faint ridges called the subscapular fossa. 2. The subscapularis muscle arises from its medial 4/5. 3. The subscapular bursa is related to its lateral 1/5. Posterior [dorsal] surface: 1. It has the spine of the scapula which divides the surface into a supraspinous fossa and an infraspinous fossa. 2. The spine has an end which shows an upper and lower lips and ends laterally by the acromial process,[acromion]. 2  Upper limb[1 -50] 3. The spine is separated from the glenoid notch by the spino-glenoid notch,in the notch pass the suprascapular nerve and vessels from the supraspinous fossa to the infraspinous fossa. The muscles attached to the dorsal surface are: 1. Supraspinatous: fron the medial 2/3 of the supraspinous fossa[,origin]. 2. Infraspinatous: from the medial 2/3 of the infraspinous fossa,[origin]. Muscles attached to the spine of the scapula are: 1. Deltoid: from the lower lip of the crest of the spine and the lateral border of the acromion,[origin]. 2. Trapezius: inserted into the upper lip of the crest of the spine and from the medial border of the acromion;[corresponds to the origin of deltoid]. The glenoid cavity: 1. A pear-shaped shallow smooth cavity. 2. It is deepened by a lip of cartilage attached to its margin called labrum glenoidale. 3. Above the cavity there is the supraglenoid tuberele [origin of long head of biceps and below it there is the infraglenoid tubercle[ origin of long head of triceps]. 4. The cavity is directed upwards, forwards and laterally to articulate with the head of the humerus forming the shoulder joint. 5. The capsule of the shoulder joint and the gleno-humeral ligaments are attached to the border of the glenoid cavity. The coracoid process; Is present above the glenoid cavity and directed forwards and slightly laterally. When the arm is in contact to the side of the body, the the coracoid process is directed straight forwards below the clavicle at the junction of the lateral 1/4 of the shaft with its medial 3/4. Muscles attached to the coracoid process 1. The common origin of the coracobrachialis and short head of biceps : from the tip of the process. 2. Pectoralis minor; inserted into the upper surface and medial border of the process near its tip. Ligaments attached to the coracoid process: 1. coraco-acromial ligament: triangular and attached by its base to the lateral border of the process and by its apex to the tip of the acromion. This ligament together with the acromion and the coracoid process form the coraco-acromial arch which may act as a secondary socket for the shoulder joint. 2. Coraco-clavicular ligament; attached near the root of the process. The trapezoid part attaches to the upper surface and its conoid part to the bend of the process. 3. The suprascapular ligament: attached near the root of the process. 4. The coraco humeral ligament: to the the coraco-acromial ligament. MOVEMENTS OF THE SCAPULA [as part of the shoulder girdle] Elevation by 1. Upper fibres of trapezius. 2. Levator scapulae. Depression by 1. serratus anterior [lower fibres]. 2. Pectoralis minor. 3  Upper limb[1 -50] 3. Lower fibres of trapezius. Forward movement [protraction] by 1. serratus anterior [whole muscle]. 2. Pectoralis minor. Backward movement [retraction] by 1. Trapezius [middle fibres]. 2. Rhomboidus minor and major. Rotation downwards of the glenoid cavity by 1. Levator scapulae. 2. Rhomboidus major and minor. 3. Pectoralis minor. Rotation upwards of the glenoid cavity by 1. Trapezius [upper and lowers fibres]. 2. Serratus anterior [lower digitations]. N.B. In all movements of the scapula, the subclavius muscle steadies the clavicle. THE ARTICULATIONS OF SCAPULA: 1. The glenoid cavity articulates with the head of the humerus to form the shoulder joint. 2. The acromial process articulates with the lateral end of the clavicle to form acromioclavicular joint. SUBCUTANEOUS PARTS OF THE SCAPULAR: 1. The acromial process. 2. The crest of the spine of the scapula. 3. The medial border. 4. The inferior angle. 5. The coracoid process just below the clavicle in the infraclavicular fossa. OSSIFICATION; 1. It ossifies in cartilage. 2. It has one primary centre in the body [8th week]. 3. It has 8 secondary centres that fuse with the body of the scapula at 25 years. HUMERUS UPPER END : It shows the following features: 1. Head: is the articular smooth surface that enters in the formation of the shoulder joint. It is directed backwards,medially and upwards. 2. Lesser tuberosity [tubercle] : directed medially. 3. Greater tuberosity [tubercle] directed laterally [it is the most lateral bony point in the shoulder region]. 4. Bicipital [intertubercular]groove: directed anteriorly and has a lateral lip and medial lip. 5. Anatomical neck: is the slight constriction which immediately adjoins the articular surface. 6. Surgical neck: the constriction in the upper part of the shaft just below the two tubercles. Muscles attached to the upper end: 1. Subscapularis: inserted in the lesser tubercle. 2. From above downwards in the greater tubercle are insertions of:  Supraspinatous  Infraspinatous 4  Upper limb[1 -50]  Teres minor Ligaments attached to the upper end : 1. Gleno-humeral ligaments: attached close to the lesser tubercle. 2. Coraco-humeral ligament: attached to the greater tubercle. 3. Transverse humeral ligament: attached between 2 tubercles. SHAFT It is cynlindrical in its upper 1/2 but triangular in its lower 1/2. It has 3 borders [anterior, medial and lateral] and 3 surfaces [antero-medial,antero-lateral and posterior]. Medial border:  Extends downwards as medial supracondylar ridge.  Attachments are: 1. Coracobrachialis muscle is inserted in the middle of the border opposite the deltoid tuberosity. 2. Medial intermuscular septum to the medial supracondylar ridge. 3. A part of origin of pronator teres: just above the medial epicondyle. Lateral border:  Extends downwards as the lateral supracondylar ridge.  Attachments are: 1. Lateral intermuscular septum to the lateral supracondylar ridge. 2. Brachio-radialis: from the upper 2/3 of the lateral supracondylar ridge [origin]. 3. Extensor carpi radialis longus: from the lower 1/3 of the lateral supracondylar ridge [origin]. Front of shaft: Origin of brachialis from the lower 1/2 of the front of the humerus. Antero-medial surface:  Nutrient foramen: is found a little below its middle and is directed downwards [for the nutrient artery].  Intertubercular groove: in the upper 1/3 of the surface and has the following relations: 1. Pectoralis major: inserted in its lateral lip. 2. Teres major: inserted in its medial lip. 3. Latissimus dorsi: inserted in its floor. 4. Long head of biceps: passes in the groove and is fixed there by the transverse humeral ligament attached to the tubercles. 5. A branch from the anterior circumflex humeral artery ascends upwards in the groove. Antero-lateral surface: The deltoid tuberosity : is present just above its middle Posterior surface:  The spiral [radial] groove begins above its middle and transmits: 1. The radial nerve. 2. The profunda brachii vessels.  The medial head of triceps extends from the lower lip of the spiral groove to the lower end of the shaft [origin]. LOWER END: Has an articular part and non-articular part. Articular part: Forms the elbow joint, it is composed of: 1. Trochlea: is medial and articulates with the trochlear notch of the ulna. 2. Capitulum: is lateral and articulates with the head of the radius. 5  Upper limb[1 -50] Non-articular part: 1. Medial epicondyle: more prominent than the lateral epicondyle. It has the following relations:  Its anterior surface: gives attachment to the common flexor origin of muscles of forearm.  Its posterior surface: related to the ulna nerve and ulna collateral arteries.  Its tip: attachment of the ulna collateral [medial] ligament of the elbow joint. 2. Lateral epicondyle:  Its anterior surface: attachment of the common extensor origin of muscles of forearm.  Its posterior surface: origin of the anconeus muscle.  Its tip: attachment of the radial collateral [lateral] ligament of the elbow joint. Fossae: There are 3 fossae filled with pads of fats. They are found inside the capsule of the elbow joint but are extrasynovial. These fossae are: 1. Coronoid fossa: on the anterior surface above the trochlear. The coronoid process of the ulna lies in it in flexion of the elbow. 2. Radial fossa: on the anterior surface above the capitulum. The head of the radius lies in it in flexion of the elbow. 3. Olecranon fossa: on the posterior surface, for the olecranon process. NERVES CLOSELY RELATED TO THE HUMERUS:[in direct contact with it]: 1. Radial nerve: in the spiral groove. 2. Axillary nerve: along the medial surface of the surgical neck. 3. Ulna nerve: behind the medial epicondyle. SUBCUTANEOUS PARTS OF THE HUMERUS: 1. Medial epicondyle. 2. Lateral epicondyle. OSSIFICATION:  It ossifies from cartilage.  It has a primary centre at 8th week.  It has 3 secondary centres at the upper end that fuse with the shaft at 21 years.  It has 4 secondary centres at the lower end that fuse with the shaft earlier than the upper end[at 18 years]. APPLIED ANATOMY: 1. The upper end joins the shaft later than the lower end [21 years] and therefore its epiphyseal plate cartilage is responsible for most growth in length of the bone. 2. Most common sites of fracture are below the insertion of deltoid. 3. The radial nerve, axillary nerve and ulna nerve are most commonly injured in fractures of the humerus. 4. It is difficult to fix the humerus in treating its fractures and thus leading to non-union. Non-union is common in the humerus than in any other bone of the body except the tibia. 5. Fractures of the lower end may involve the articular surface and may impair the movement of the elbow joint. 6. Separation of the upper epiphypis [end] may occur in the young. 6  Upper limb[1 -50] BONES OF THE FOREARM These are the radius [laterally] and the ulna [medially]. RADIUS UPPER END: 1. Head: Circular and articulates by its upper surface with the capitulum of the humerus and by its medial surface with the radial notch of the ulna. Therfore it is related to the elbow and superior radio-ulnar joints. 2. Neck:  Is the constriction below the head.  The annular ligament surrounds the head.  The quadrate ligament is attached to the medial side of the neck. 3. Radial tuberosity:  Is directed medially.  It is rough posteriorly for the insertion of the tendon of biceps and smooth anteriorly for a bursa between the bone and the tendon of biceps. SHAFT: It has 3 borders [anterior, interosseous and posterior] and 3 surfaces [anterior, lateral and posterior]. Anterior border: It has an oblique upper part[1/3]: to which the radial head of flexor digitorum superficialis takes origin. This oblique line separates between the supinator above and the flexor pollicis longus below. Interosseous border:  Gives attachment to the interosseous membrane.  The oblique cord is attached a little below the radial tuberosity. Anterior surface:  Flexor pollicis longus: origin from its upper 2/3.  Pronator quadratus: inserted in its lower 1/4. Lateral surface:  Supinator: inserted in its upper 1/3.  Pronator teres: inserted in its middle 1/3 [in a rough impression at the maximum convexity]. Posterior surface:  Abductor pollicis longus: origin from its upper part below the level of the supinator.  Extensor pollicis brevis: origin from the area below the abductor pollicis longus. LOWER END: Broader than the upper end and has styloid process and 5 surfaces [anterior,posterior,lateral,medial and inferior]. 1. The styloid process projects from the lateral surface and the lateral ligament of the wrist is attached to its lip. 2. The ulnar notch is on the medial surface, it articulates with the head of the ulna to form the inferior radio-ulnar joint. The intra-articular disc is attached to the lower part of the medial surface below the ulnar notch. 3. The posterior surface is very irregular, and contains the radial tubercle. It lodges some extensor tendons. 4. The anterior surface is very smooth. The pronator quadratus is inserted in it. 7  Upper limb[1 -50] 5. The lateral surface: the brachioradialis is inserted in it just above the styloid process. 6. The inferior surface has 2 facets: lateral triangular facet for the articulation with the scaphoid bone and a quadrangular facet medially for articulation with the lunate bone. It therefore enters the formation of the wrist joint. STRUCTURES CONNECTING RADIUS TO ULNA: 1. Annular ligament. 2. Quadrate ligament. 3. Oblque cord. 4. Interosseous membrane. 5. Pronator quadratus and pronator teres muscles. 6. Supinator muscle. 7. Capsules of both radio-ulnar joints. 8. The intr-articular disc. SUBCUTANEOUS PARTS OF THE RADIUS: 1. Head: can be felt on the back of the elbow in a pit below the lateral epicondyle. 2. Styloid process. 3. Dorsal tubercle: on the back of the lower end opposite the cleft between the index and the middle fingers. ULNA UPPER END 1. Trochlear notch: directed forwards between the coronoid process and the olecranon process. It articulates with the trochlea of the humerus. 2. Coronoid process: directed forwards below the trochlear notch. Its anterior surface has a rough area called the tuberosity of ulna. 3. Olecranon process: above the trochlear notch. 4. Radial notch: directed laterally and articulates with the head of the radius to form the superior radio-ulnar joint. Muscles and ligaments attached to the coronoid process: 1. Brachialis: inserted in its anterior surface. 2. Its medial margin gives accessory heads of origin to the following muscles from above downward[F.P.F.]  Flexor digitorum superficialis.  Pronator teres.  Flexor pollicis longus. 3. Ulnar collateral [medial] ligament of elbow: it has 3 bands :  Anterior band: from the medial epicondyle to the medial margin of the coronoid process.  Posterior band: from the medial epicondyle to the medial border of olecranon process.  Oblique band: [differs from the oblique cord] from the medial border of the coronoid process to the medial border of olecranon process. Muscles attached to the olecranon process: 1. Triceps: inserted in its upper surface. 2. Anconeus: inserted in its lateral surface. 3. Flexor digitorum profundus: upper part of origin from its medial surface. 4. Ulnar head of flexor carpi-ulnaris: origin from its medial surface. Other attachments to the upper end: 8  Upper limb[1 -50] 1. Annular ligament: attached to the anterior and posterior borders of the radial notch surrounding the head of the radius. 2. Quadrate ligament: attached to the lower border of the radial notch. 3. Supinator muscles: origin from the supinator crest and the supinator fossa below the radial notch. 4. Oblique cord: attached below the supinator crest. SHAFT: It has 3 borders [anterior,posterior and interosseous] and 3 surfaces [anterior, posterior and medial]. Muscles attached to the shaft: 1. Flexor digitorum profundus: origin from the upper 2/3 of the anterior and medial surfaces. 2. Pronator quadratus: origin from the lower 1/3 of the anterior surface. 3. Muscles attached to the back of the ulna from above downwards are :  Abductor pollicis longus: origin from upper 1/4.  Extensor pollicis longus: origin from following 1/4.  Extensor indicis: origin from following 1/4. N. B. : the lower 1/4 is devoid of muscle attachments. 4. Muscles attached to the posterior border through a strong aponeurosis are:  Flexor carpi ulnaris.  Extensor carpi ulnaris.  Flexor digitorum profundus. LOWER END: It is smaller than the upper end and is composed of the head [laterally] and the styloid process [medially]. 1. Head:  It has a groove in its posterior surface for the tendon of the extensor carpi ulnaris.  It articulates with the ulnar notch of the radius to form the inferior radio-ulnar joint.  It does not articulate directly with the bones of the wrist but is separated from them by the intra-articular disc. This disc is triangular and is attached by its apex to the base of the styloid process. 2. Styloid process: 1. Its tip gives attachment to the medial ligament of the wrist. 2. Its base gives attachment to the apex of the intra-articular disc. SUBCUTANEOUS PARTS OF THE ULNA: 1. The posterior surface of the olecranon process. 2. Posterior border. 3. Styloid process [felt at the back in supination]. 4. Head [felt at the back in pronation]. OSSIFICATION OF RADIUS AND ULNA:  A primary centre in the shaft appears at 8th week.  A secondary centre in the upper end that fuses with the shaft at 18 years.  A secondary centre in the lower end that fuses with the shaft at 21 years [similar to the upper end of the humerus]. APPLIED ANATOMY:  The radius is more liable to fracture than the ulna if an indirect force is applied to the forearm. 9  Upper limb[1 -50]  In fixing the forearm in fractures of its bones. It should be in a position midway between supination and pronation as in this position the radius and ulna are widely separated from each other so it is not easy for them to fuse together. SKELETON OF THE HAND CARPAL BONES [Carpus] There are 8 carpal bones arranged in 2 rows [proximal and distal]. 1. Proximal row: formed of 4 bones : scaphoid, lunate, triquetral and pisiform [from lateral to medial]. All these bones except the pisiform articulates with the lower end of the radius and the articular disc to form the radio-carpal [wrist] joint. 2. Distal row: formed of 4 bones : trapezium, trapezoid, capitate and hamate [from lateral to media].  The carpus has a concavity on its anterior aspect called carpal groove which is coverted into a carpal tunnel by the flexor retinaculum.  The flexor retinaculum is attached laterally to the tubercle of scaphoid and crest of trapezium and attached medially to the pisiform and hook of hamate.  The trapezium has a groove on its anterior surface through which the tendon of flexor carpi radialis passes.  The flexor carpi ulnaris is inserted in the pisiform bone. OSSIFICATION: The carpal bones ossify [primary centres] after birth. N.B. 1. All primary centres of ossification appear before birth except the carpal bones, patella and most of the tarsal bones[calcaneum and talus before birth while the cuboid at 9th month]. 2. All secondary centres appear after birth except at the lower end of the femur and the upper end of the tibia which appear just before birth. METACARPAL BONES:s  They are 5 bones each of which has a head, shaft and base.  They lie side by side except that of the thumb that lies on a more anterior plane and is rotated medially around its long axis for 90 degrees so that its dorsal surface looks laterally and its lateral border looks anteriorly. This change of direction of the first metacarpal bone is essential to help the thumb to oppose the other 4 fingers.  Each bone has one primary centre for the shaft [8th week] and one secondary centre for the head except the first metacarpal bone [of the thumb] which has its secondary centre at its base resembling the phalanges. PHALANGES: Each finger has 3 phalanges: proximal, middle and distal except the thumb which has 2 phalanges only. APPLIED ANATOMY: Fracture of the carpal bones is common in the scaphoid in which the fracture runs at right angle to its long axis. As the proximal part of the scaphoid is devoid of nutrient foramina [in 13%] non-union of its fracture is common. THE AXILLA It is a pyramidal that has an apex, base and 4 walls [anterior, posterior, medial and lateral]. 10  Upper limb[1 -50] BOUNDARIES OF THE AXILLA: Anterior wall:  Pectoralis major muscle.  Pectoralis minor muscle.  Subclavius muscle.  Clavi-pectoral fascia. The lower margin of the anterior wall is called the anterior fold and is formed by the pectoralis major only. Posterior wall:  Subscapularis muscle.  Teres major muscle.  Latissimus dorsi muscle. The lower margin of the posterior wall is called the posterior fold and is formed by the teres major and latissimus dorsi. This fold extends lower down than the anterior fold. Medial wall:  Upper 5 ribs and intercostals spaces.  Upper digitations of the serratus anterior. Lateral wall:  Upper part of the shaft of the humerus.  Coraco-brachialis muscle.  Short head of biceps muscle. The medial wall is more extensive than the lateral wall so both the anterior and posterior walls converge as they pass towards the lateral wall. Base: Formed by skin and deep [axillary] fascia. Apex: It is directed towards the neck with which it is continuous through a triangular gap called the cervico-axillary canal that transmits the axillary vessels and the brachial plexus. This canal has the following walls: 1. Anteriorly: the clavicle. 2. Posteriorly:upper border of the scapula. 3. Medially: outer border of the 1st rib. CONTENTS OF THE AXILLA: 1. Axillary vessels [artery and vein]. 2. Cords of the brachial plexus [its trunks are in the neck]. 3. Axillary lymph nodes. 4. Fat. MUSCLES OF THE AXILLA PECTORALIS MAJOR: Origin: 1. Clavicular head: from the medial 1/2 the anterior surface of the clavicle. 2. Sterno-costal head: from the anterior surface of the sternum and the upper 6 costal cartilages and the aponeurosis of the external oblique muscle. Insertion: It has a bilaminar tendon which is folded upon itself. Its anterior lamina is formed from the clavicular part and the upper fibres of the sternocostal head while the posterior lamina is formed from the lower fibres of the sternocostal head. The anterior lamina is 11  Upper limb[1 -50] inserted lower down in the lateral lip of the bicipital groove while the posterior lamina is inserted in its upper part. Nerve supply: Lateral and medial pectoral nerves from the lateral and medial cords of brachial plexus. The lateral pectoral nerve pierces the clavipectoral fascia to enter the clavicular part while the medial pectoral pierces the pectoralis minor to enter the lower part of the muscle. Action: 1. Adducts the arm and rotates it medially. 2. Assists in flexion of the arm [flexion draws the arm in front of the chest]. PECTORALIS MINOR: Origin: From 3,4 and 5 ribs at their junctions with their costal cartilages. Insertion: In the upper surface and medial border of the coracoid process near its tip. Nerve supply: Medial pectoral nerve. Action: Draws the scapula downwards and forwards[helps in its protraction]. SUBCLAVIUS: Origin: From the upper surface of the 1st rib at the junction with its cartilage. Insertion: In the groove on the inferior surface of the clavicle. Nerve supply: Nerve to subclavius [from upper trunk]. Action: Steadies the clavicle during movements of the shoulder girdle. SERRATUS ANTERIOR: Origin: By 8 digitations from the outer surface and lower border of the upper 8 ribs midway between their angles and their cartilages. Insertion: Into the ventral surface of the medial border of the scapula in the following manner:  The 1st digitations [from 1st and 2nd ribs and the fibro-tendinous arch in between] in the superior angle of the scapula.  The 2nd and 3rd digitations spread along the whole length of the medial border.  The lower 5 digitations in the inferior angle. Nerve supply: Long thoracic nerve[C. 5, 6, 7] from the roots of the brachial plexus in the neck. Action: 1. Protraction [pulls forwards] of the scapula. If paralysed gives winged scapula. 2. The lower 5 digitations rotate the scapula upwards in raising of the arm above the head[abduction > 90 degrees] together with the trapezius. 12  Upper limb[1 -50] SUBSCAPULARIS: Origin: Medial 2/3 of the subscapular fossa. Insertion: Lesser tuberosity of the humerus. Nerve supply: Upper and lower subscapular nerves from the posterior cord of brachial plexus. Action: Adducts the arm and rotates it medially. TERES MAJOR: Origin: The back of the inferior angle of the scapula [from an oval impression]. Insertion: The medial lip of the bicipital groove. Nerve supply: Lower subscapular nerve [teres minor muscle from the axillary nerve]. Action: Adducts the arm and rotates it medially. LATISSIMUS DORSI: Origin:  Lower 6 thoracic spines.  Iliac crest [posterior part of its outer lip ].  Lumbar fascia [posterior layer].  Lower 4 ribs.  Back of inferior angle of the scapula. Insertion:  This wide muscle ends in a narrow tendon that has a triple relation to the teres major muscle: [at 1st behind then below then in front of it]. It is inserted into the floor of the bicipital groove. Nerve supply:  Thoraco-dorsal nerve [nerve to latissimus dorsi] from the posterior cord[C. 6, 7, 8]. Action: Adduction,extension and rotation of the arm medially. MAMMARY GLAND POSITION AND STRUCTURE  lies inside the superficial fascia of the front and side of the chest.  Extends from 2-6 ribs and from the sternum to the midaxillary line.  It extends also upwards to the axilla along the lower border of pectoralis major forming the axillary tail.  Its nipple lies opposite the 4th intercostals space and is perforated by 15-20 orifices of the lactiferous ducts.  The coloured area of skin around the base of the nipple is called the areola.  The gland consists of numerous lobes which are composed of lobules and these open in the lactiferous ducts. These ducts have radial course towards the nipple. 13  Upper limb[1 -50]  Fibrous tissue surrounds the gland and sends septa between its lobes,it gives other septa [processes] to the skin and the nipple called suspensory ligaments. LYMPH DRAINAGE 1. Lymph vessels:  From plexuses inside the gland between the lobules [interlobular plexus] and beneath the areola [subareolar plexuses].  These vessels communicate with:  A plexus in the fascia of pectoralis major muscle.  Lymph vessels of the opposite mammary gland.  A plexus on the upper part of the rectus sheath of the abdomen.  Vessels that perforate the intercostal spaces to reach the parasternal nodes. 2. Lymph nodes: The efferent vessels drain into the following nodes:  Axillary nodes: [receive 70% of the vessels]. The 1st groups to receive the lymphatics are the pectoral and apical nodes.  Parasternal nodes: [receive 25% of the vessels] along the internal thoracic artery.  Lymph nodes of the opposite axilla. APPLIED ANATOMY: As the lactiferous ducts radiate from the nipple, incision of the gland should be made in a radial direction to avoid cutting across the ducts and lobules. Malignancy in the gland is common. Contraction of the suspensory ligaments by cancer will pull on the skin over the gland [peau d’orange] and retract the nipple. Infiltration of the pectoralis major leads to fixation of the tumour. CLAVI-PECTORAL FASCIA It is a strong part of the deep fascia of the pectoral region that occupies the interval between the pectoralis minor and the clavicle undercover the clavicular part of the pectoralis major. It encloses the subclavius above and the pectoralis minor below. Its part which is attached medially to the 1st rib and laterally to the coracoid process is thickened and called the costo-coracoid ligament. It is pierced by: 1. Cephalic vein. 2. Thoraco-acromial artery. 3. Lateral pectoral nerve. 4. Lymphatics. AXILLARY VESSELS AXILLARY ARTERY: COURSE AND RELATIONS: Begins at the outer border of the 1st rib as a continuation of the subclavian artery, and ends at the lower border of the teres major [lowest limit of the axilla]. The pectoralis minor as it crosses superficial to the artery divides it [for descriptive purpose] into 3 parts; 1st part above the level of the muscle, 2nd part under cover of the muscle and 3rd part below the muscle. RELATION OF THE FIRST PART: Anteriorly:  Skin and superficial fascia. 14  Upper limb[1 -50]  clavicular part of pectoralis major.  Clavi-pectoral fascia Posteriorly: The medial cord and the nerve to the serratus anterior separate the artery from the 1st intercostal space and 1st digitations of the serratus anterior. Medially: Axillary vein Above and lateral: Lateral and posterior cords of brachial plexus. RELATIONS OF THE SECOND PART: Anteriorly:  Skin and fascia.  Pectoralis major and minor. Posteriorly: Posterior cord separating it from the axillary vein. Laterally: Lateral cord. N.B. : The cords of the brachial plexus are arranged around the 2nd part of the artery according to their names, i.e. lateral cord on the lateral side, medial cord on medial side and the posterior cord posteriorly. while for the 1st part of the artery the cords are arranged differently as if they were rotated around the artery in a clockwise manner so the medial cord becomes posterior and the posterior cord becomes lateral and the lateral cord becomes above and lateral. RELATIONS OF THE THIRD PART: Anteriorly:  Upper 1/2: skin, fascia and pectoralis major.  Lower 1/2: [subcutaneous] skin and fascia only and crossed by medial root of median nerve. Posteriorly:  Radial and axillary nerves separating the artery from the subscapularis.  Tendons of latissimus dorsi and teres major. Medially:  Axillary vein.  Ulnar nerve between the vein and the artery.  Medial cutaneous nerve of forearm between the vein and the artery superficial to the ulnar nerve.  Medial cutaneous nerve of arm on the medial side of the vein. Laterally: 1. Musculo-cutaneous nerve. 2. Median nerve. BRANCHES : Branches of the first part:[ 1 branch]. 1. Superior thoracic artery : ramifies in the upper part of the lateral wall of the chest. Branches of the second part: [2 branches]. 1. Thoraco-acromial artery: pierces the clavipectoral fascia and divides into 4 branches[A, P, C, D]: Acromial, pectoral, clavicular and deltoid. 2. Lateral thoracic artery: descends along the lower border of the pectoralis minor to supply the mammary gland. Branches of the third part: [3 branches] 15  Upper limb[1 -50] 1. Anterior circumflex humeral artery : passes laterally deep to the coracobrachialis and the short head of biceps in front of the surgical neck of the humerus to anastomose with the posterior circumflex humeral. It gives an ascending branch to the bicipital groove. 2. Posterior circumflex humeral artery: passes backwards with the axillary [circumflex] nerve through the quadrangular space and winds laterally behind the surgical neck of humerus to anastomose with the anterior circumflex humeral and the ascending branch of the profunda brachii artery forming an anastomosis around the surgical neck of humerus. 3. Subscapular artery: descends along the lateral border of the scapula to its inferior angle accompanied by the thoraco-dorsal nerve [n. to latissimus dorsi]. It gives the circumflex scapular branch which winds around the lateral border of the scapula deep to the teres minor to reach the infraspinous fossa and enters into the anastomosis around the scapula. ANASTOMOSIS AROUND THE SCAPULA: 1. Subscapular artery: from the 3rd part of axillary artery. 2. Suprascapular artery: a branch of the thyro-cervical trunk from the 1st part of subclavian artery. It passes above the suprascapular ligament to reach the supraspinous fossa then through the spino-glenoid notch to the infraspinous fossa. 3. Deep branch of the transverse cervical artery : the transverse cervical artery is a branch of the thyrocervical artery. Its deep branch descends along the medial border of the scapula deep to the levator scapulae and rhomboids muscle. N.B. : The anastomosis is important for any obstruction of the blood supply between the 1st part of subclavian and 3rd part axillary artery[a long distance]. AXLLARY VEIN Begins at the lower border of the teres major as a continuation of the basilic vein and ascends on the medial side of the artery and ends at the outer border of the 1st rib to become the subclavian vein. It has the following tributaries:  Cephalic vein.  Venae comitantes of the brachial artery.  Veins corresponding to the branches of the axillary artery. BRACHIAL PLEXUS 1. It is formed from the anterior primary rami of C. 5, 6, 7, and T. 1 with contributions from C. 4 and T. 2 [these are its roots]. 2. It is formed of roots, trunks and cords. The roots and trunks are found in the neck while the cords are found in the axilla. 3. The trunks are 3: upper [C. 5. 6]. middle [C. 7] and lower [C. 8, T. 1]. They are in the posterior triangle of the neck between the scalenus anterior and scalenus medius. Each trunk gives a ventral and a dorsal division. 4. The cords are 3: lateral [ union of ventral divisions of the upper and middle trunks], medial [ventral division of the lower trunk] and posterior [union of the dorsal divisions of the 3 trunks]. The cords end at the lower border of pectoralis minor by giving its branches around the 3rd part of the axillary artery. BRANCHES OF THE PLEXUS : 16  Upper limb[1 -50] Branches from the roots: 1. Long thoracic nerve[n. to serratus anterior][C. 5, 6, 7]. 2. Nerve to rhomboids[dorsal scapula n.][C. 5]. 3. A root to the phrenic nerve. Branches from the trunks:[only from the upper]. 1. Suprascapular nerve[C. 5, 6]. 2. Nerve to subclavius[C. 5, 6]. Branches from the cords:  Lateral cord:[C. 5, 6, 7] 1. Lateral pectoral. 2. Musculocutaneous. 3. Lateral root of the median nerve.  Medial cord:[C. 8, T. 1]. 1. Medial pectoral. 2. Medial root of the median nerve. 3. Medial cutaneous nerve of the forearm. 4. Medial cutaneous nerve of arm. 5. Ulnar nerve [C. 7, 8, T. 1]. The fibres of C. 7 join the ulnar through connections with the lateral root of median nerve in the axilla or elsewhere.  Posterior cord:[C. 5, 6, 7, 8, T. 1]. 1. Upper and lower subscapular[C. 5, 6]. 2. Thoraco-dorsal [n. to latissimus dorsi][C. 6, 7, 8]. 3. Axillary[circumflex][C. 5, 6]. 4. Radial [C. 5, 6, 7, 8 T. 1]. APPLIED ANATOMY: 1. Erb’s paralysis:  A lesion of the upper trunk [C 5, 6] due to birth injury may lead to paralysis of the muscles supplied by the 5th nerve [deltoid, biceps, brachialis, bracho-radialis,supraspinatous, infraspinatous, and supinator].  The arm hangs by the side [deltoid], and medially rotated[infraspinatous]. The forearm is extended[brachialis and biceps] and pronated [supinator and biceps]. So the arm cannot be raised from the side, and the elbow cannot be fixed and no supination is possible. 2. Klumpke’s paralysis: Injury of the lower trunk [C. 8, T. 1] affects mainly the intrinsic muscles of the hand and the flexors of the wrist and fingers. AXILLARY LYMPH NODES There are 5 main group: 1. Brachial group: It is present along the upper part of the brachial vessels and lower part of axillary vessels in the lateral wall of the axilla. They receive most of the lymph of the upper limb and send efferents to the central and apical groups. 2. Pectoral group: Along the lateral thoracic vessels at the lower border of the pectoralis minor. They receive lymphatics from the mammary gland and the anterior and lateral walls of the trunk above umbilicus. They send efferents to the central and apical groups. 3. Subscapular group: 17  Upper limb[1 -50] Along the subscapular vessels at the lower border of the subscapularis. They receive lymphatics from the back of the trunk and efferents to the apical and central groups. 4. Central group: It lies in the fat filling the axilla. They receive afferents from the previous groups and efferents to the apical group. 5. Apical group: Lies in the apex of the axilla. They receive lymphatics from the other axillary groups and direct vessels from the mammary gland. They give efferents which form the subclavian lymph trunk which opens in the thoracic duct on the left side or at the junction of the subclavian vein and internal jugular vein on the right side. SCAPULAR REGION MUSCLES TRAPEZIUS: Origin: 1. External occipital protuberance and medial 1/3 of the superior nuchal line. 2. Ligamentum nuchae and the 7th cervical spine. 3. All thoracic spine and the corresponding supraspinous ligaments. Insertion: 1. Upper fibres into the posterior border of the lateral 1/3 of the clavicle. 2. Middle fibres into the medial border of the acromion and upper lip of the crest of the spine of the scapular. 3. Lower fibres into the medial part of the crest of the spine of the scapula. Nerve supply: 1. Spinal root of the accessory nerve. 2. Cervical nerves 3 and 4. Action: 1. Braces the shoulder backwards [by the middle fibres]. 2. Rotates the scapula upwards [by the lower and upper fibres]. LEVATOR SCAPULAE: Origin: The posterior tubercles of the transeverse processes of the upper 4 cervical vertebrae. Insertion: The back of the medial border of the scapula from the superior angle to the spine. Nerve supply: Nerve to rhomboids [dorsal scapula n.]. Action: 1. Rotates the scapula downwards. 2. Together with the trapezius elevate the scapula. RHOMBOIDUS MINOR: Origin: 1. Lower part of ligamentum nuchae. 2. Spines of the 7th cervical vertebrae and 1st thoracic vertebrae. Insertion: Media border of the scapula opposite its spine. RHOMBOIDUS MAJOR: 18  Upper limb[1 -50] Origin: Spines of 2, 3, 4, 5 thoracic vertebrae and the corresponding supraspinous ligaments. Insertions: Medial border of the scapula from the spine to inferior angle. Nerve supply: Dorsal scapula nerve [ n. to rhomboid]. Action: Both rhomboids brace the shoulder backwards and helps in elevation and rotation downward of the scapula. INFERIOR BELLY OF OMO-HYOID: Origin: Upper border of scapula very close to the supra-scapula notch. Insertion: In intermediate tendon of the omo-hyoid [in the neck]. Nerve supply: Ansa cervicalis [ C. 1, 2, 3]. N.B. : These mentioned muscles are present in 2 layers in the back of the neck and trunk: 1. Superficial layer: Trapezius and latissimus dorsi. 2. Deep layer: Levator scapula and both rhomboids. SUPRASPINATOUS: Origin: Medial 2/3 of the supraspinous fossa. Insertion: Top of the greater tubercle of the humerus. Action: 1. Assists in maintaining the head of the humerus in the glenoid cavity during abduction of the shoulder joint. 2. Starts abduction at the shoulder joint [till 15 degrees]. INFRASPINATOUS: Origin: Medial 2/3 of the infraspinous fossa. Insertion: In the greater tubercle below the supraspinatous. Nerve supply: Suprascapular nerve. Action: 1. Steadies the head of the humerus in the glenoid cavity. 2. Adducts and rotates the arm laterally. SUBSCAPULARIS:discussed before now. TERES MAJOR: ,, TERES MINOR: Origin: Upper 2/3 of the back of the lateral border scapula. Insertion: Into the greater tubercle below the infraspinatous. Nerve supply: By a branch from the posterior division of the axillary nerve. Action: 1. Helps in steadying the head of the humerus. 2. Adducts the arm and rotates it laterally. N.B. : Muscles connecting the upper limb with the vertebral column [4 muscles]: 19  Upper limb[1 -50] Trapezius – Latissimus dorsi – Levator scapulae – Rhomboides. *Muscles connecting the upper limb with the ribs [4 muscles]: Pectoralis major – Pectoralis minor – serratus anterior – subclavius. DELTOID: Origin: 1. Anterior border of lateral 1/3 of clavicle. 2. Lateral border of acromion. 3. Lower lip of crest of spine of scapula.[This origin corresponds to the insertion of trapezius]. Insertion: Into the deltoid tuberosity. Nerve supply: Axillary nerve [C. 5, 6]. Action: It is powerful [fibres are multipennaie] 1. Anterior part: flexes arm and rotates it medially. 2. Posterior part: extends arm and rotates it laterally. 3. Middle [acromial] part: abducts arm till right angle to the body [90 degrees only]. Relations of the deltoid:  The anterior border is separated from the pectoralis major by the delto-pectoral groove in which lie: 1. Cephalic vein. 2. Delto-pectoral lymph nodes. 3. Deltoid branch of the thoraco-acromial artery. Deep relations: 1. Lesser tubercle and the muscles inserted into it: subscapularis and teres major. 2. Greater tubercle and the muscles inserted into it: supraspinatous, infraspinatous and teres minor. 3. Coracoid process and structures attached to it: short head of biceps and coracobrachialis, pectoralis minor, and coracoacromial arch. 4. Capsule of shoulder joint and the 2 long heads related to it: long head of biceps and long head of triceps. 5. Subacromial bursa. 6. Axillary nerve around the surgical neck of humerus. 7. The anastomosis around the surgical neck of humerus: anterior and posterior circumflex humeral and ascending branch of the profunda brachii arteries. [Therefore, the deltoid is related to: bones – muscles – ligament – bursa – nerves and vessels]. THE QUADRANGULAR SPACE: It is an artificial space between muscles through which pass: 1. Axillary nerve. 2. Posterior circumflex humeral vessels. It has the following boundaries: Superiorly: Lateral border of scapula with subscpularis in front and teres minor behind. Inferiorly: Teres major. Laterally: Surgical neck of humerus. 20  Upper limb[1 -50] Medially: Long head of triceps. THE TRIAGULAR SPACE: It is also an artificial space through which passes only the circumflex scapular branch of the subscapular artery. Boundaries: Superiorly: Lateral border of scapula with subscapularis in front and teres minor behind. Inferiorly: Teres major. Laterally: Long head of triceps. AXILLARY NERVE:[C. 5, 6] Course: Arises from the posterior cord and passes behind the axillary artery between it and the subscapularis. It then passes together with the posterior circumflex humeral artery through the quadrangular space and curves laterally round the surgical neck of humerus undercover of the deltoid where it divides into an anterior and posterior divisions. Branches: 1. Articular branch: ascends to supply the shoulder joint. 2. Anterior division: supplies the deltoid then pierces it to supply the skin over it. 3. Posterior division gives:  branches to deltoid.  nerve to teres minor.  ends as the upper lateral cutaneous nerve of the arm which supplies the skin of the upper part of the lateral side of the arm. APPLIED ANATOMY: An injury to the nerve as in fracture of the surgical neck of the humerus leads to: 1. Paralysis of deltoid and teres minor: This results in flattening of the roundness of the shoulder due to atrophy of the deltoid. Also there is inability to abduct the arm. 2. Cutaneous sensation is lost from the skin over the lower 1/2 of deltoid [N. B. Skin over its upper 1/2 is supplied by lateral supraclavicular nerve, C. 4]. SUPRASCAPULAR ARTERY: It is a branch of trhyrocervical trunk that arises from the 1st part of subclavian artery in the neck. It runs deep to the sternomastoid and enters the posterior triangle of the neck just above the clavicle. It passes superficial to the suprascapular ligament to enter the supraspinous fossa then through the spinoglenoid notch to the infraspinous fossa. It shares into the anastomosis around the scapula [mentioned above]. SUPRASCAPULAR NERVE: [C. 5, 6] It arises from the upper trunk of brachial plexus in the posterior triangle of the neck. It accompanies the suprascapular vessels but differs in that it passes deep to the suprascapular ligament. It supplies: 1.Supraspinatous muscle. 2.Infraspinatous muscle. 3. Shoulder joint. 21  Upper limb[1 -50] SHOULDER JOINT TYPE: Synovial, ‘‘ball and socket”. ARTICULAR SURFACES: 1. Head of the humerus [less than 1/2 a sphere]. 2. Glenoid cavity: shallow and deepened by the labrum glenoidale. CAPSULE: Attachments to: 1. Margins of the glenoid cavity outside the labrum glenoidale. 2. Anatomical neck of humerus except on the medial side where it descends about 1/2 inch on the surgical neck to become intracapsular [but extra synovial]. Perforations in the capsule 1. An opening for the subscaplar bursa in the anterior part. 2. An opening for the long head of biceps in the lateral part between the 2 tubercles. SYNOVIAL MEMBRANE: The capsule is lined by a synovial membrane which is reflected on the surgical neck of the humerus and on the labrum glenoidale. It forms a sheath for the long head of biceps which is extrasynovial. It bulges through the subscapular opening in the capsule to form the subscapular bursa. LIGAMENTS: The capsule is supported by: 1. Caraco – humeral ligament:strengthens the upper part capsule. From the root of the process to the greater tubercle of humerus. 2. Gleno-humeral ligaments [superior, middle and inferior] from the upper part of the medial margin of the glenoid cavity to the region of the lesser tubercle. 3. Transverse humeral ligament:extends from the lesser to the greater tubercle. BURSAE RELATED TO THE JOINT: 1. Subscapularis bursa: deep to the tendon of subscapularis. It comunicates with the joint. 2. Subacromial bursa: deep to the deltoid and is prolonged under the acromion and the coraco-acromial ligament. RELATIONS: Above: Supraspinatous. Below: Long head of triceps. Anteriorly: Subscapularis. Posteriorly: Infraspinatous and teres minor. N.B. : The deltoid covers the joint in front, behind and laterally. Inside: Tendon of long head of biceps. STABILITY: Unlike the hip joint, the shoulder joint is weak and not so steady due to the shape of the articular surfaces which are shallow and the absence of strong supporting ligaments. It is mainly supported by the surrounding muscles and protected above by the coraco-acromial arch. MOVEMENTS: The movements of the humerus at the shoulder joint [polyaxial] should be analysed in relation to the plane of the scapula and not to the plane of the trunk, therefore: 22  Upper limb[1 -50] 1. Flexion: the movement occurs at right angle to the plane of the scapula and the arm moves forwards and medially across the front of the chest. Produced mainly by:  Clavicular head of deltoid.  Anterior fibres of deltoid.  Coracobrachialis. 2. Extension [reverse of flexion ] carried by:  posterior fibres of deltoid.  Teres major.  Latissimus dorsi. 3. Abduction: [The movement is in the plane of the scapula]. This movement takes place from the start at the shoulder joint with some upward rotation of the scapula until the arm is 90 degrees with the trunk after which abduction occurs only by upward rotation of the scapula which raise the arm above the head. To affect abduction the head of the humerus must be in opposition with the glenoid cavity to prevent upward displacement of the head; this is produced by the small muscles inserted around the joint viz, supraspinatous, infraspinatous, subscapularis and teres minor [muscle cuff].  Abduction up to the 1st 15 degrees is by supraspinatous.  Abduction from 15 – 90 degrees is by the deltoid.  Upward rotation of the scapula is produced by the trapezius and the lower 5 digitations of serratus anterior. 4. Adduction: by:  pectoralis major.  Teres major.  Latissimus dorsi. 5. Medial rotation: by:  pectoralis major.  Latissimus dorsi.  Teres major.  Anterior fibres of deltoid.  Subscapularis. 6. Lateral rotation: by:  Infrsapinatous.  Teres minor.  Posterior fibres of deltoid. 7. Circumduction: is a combination of flexion, abduction, extension and adduction, occurring one after the other. APPLIED ANATOMY:  Due to its relative instability it is frequently dislocated than any other joint. Dislocation occurs when the arm is abducted. The head of humerus presses against the thin lower part of the capsule and may destroy it.  In ankylosis [fixation] of the joint, the loss of movement is compensated partly by increased mobility of the scapula. SHOULDER GIRDLE Movements of the shoulder girdle occur at the sternoclavicular and acromio-clavicular joints and include movements of both the scapula and the clavicle. The range of movement of the scapula at the acromio-clavicular joint is increased by the movement at the sternoclavicular joint. 23  Upper limb[1 -50] The movements of the scapula are mentioned in the chapter of bones.  In elevation of the scapula: the sternal end of the clavicle rotates downwards around an anteroposterior axis and vice versa in depression of the scapula.  In forward movement of the scapula: the sternal end of the clavicle moves backwards.  Excessive movements at the sternal end of the clavicle are checked by:  Surrounding muscles.  Costoclavicular ligament.  The articular disc of the sternoclavicular joint.  Capsule of the sternoclavicular joint.  Interclavicular ligament. ARM The arm is divided by the lateral and medial intermuscular septa into 2 compartments: 1. Anterior compartment: has the flexor group of muscles supplied by the musculo-cutaneous nerve. 2. Posterior compartment: has the extensor muscle [triceps] supplied by the radial nerve. The vessels and nerves of the axilla are continued on the medial side of the arm in the anterior compartment where the axillary vessels and the 3 main nerves of the forearm separate to reach the forearm:  Median nerve: passes straight to the cubital fossa by the side of the brachial artery.  Ulnar nerve: enters the posterior compartment by piercing the medial intermuscular septum to reach medial epicondyle of humerus.  Radial nerve: winds round the back of the humerus in the spiral groove to reach the lateral side of arm. MUSCLES OF THE ARM CORACO-BRACHIALIS: Origin: Arises by a common tendon with the short head of biceps from the tip of the coracoid process. Insertion: Into the middle of the medial border of the humerus. Nerve supply: Musculocutaneous[supplies it before it pierces the muscle]. Action: Helps in flexion of the arm. STRUCTURES AT THE INSERTION OF CORACO-BRACHIALIS 1. Median nerve: crosses brachial artery from lateral to medial. 2. Radial nerve: pierces the lateral intermuscular septum. 3. Ulnar nerve: pierces the medial intermuscular septum. 4. Nutrient artery: enters the nutrient foramen. 5. Medial cutaneous nerve of forearm: pierces the deep fascia. 6. Basilic vein: pierces the deep fascia. BICEPS BRACHII: Origin: It arises by 2 heads: 1..Short head: Arises in conjunction with the coracobrachialis from the tip of the coracoid process. 24  Upper limb[1 -50] 2. Long head: From the supraglenoid tubercle. This tendon traverses the cavity of the shoulder joint [intracapsular, extrasynovial] to pass in the intertubercular groove under cover of the transverse humeral ligament. Insertion: Has 2 insertions:[tendon and aponeurosis]. 1. A rounded tendon into the rough posterior part of the radial tuberosity at upper end of radius. 2. An aponeurosis [expanded tendon] from the medial border of the tendon [bicipital aponeurosis] and inserted into the deep fascia of the upper part of the medial side of the forearm. The aponeurosis separates the median cubital vein from the brachial artery. Nerve supply: Musculo-cutaneous nerve [a branch to each head]. Action:  Flexes elbow joint.  Powerful supinator to forearm.  Long head helps in fixation of shoulder joint.  Short head helps in fixation of shoulder joint. BRACHIALIS: Origin: From the lower 1/2 of the anterior surface of the humerus, extending up to the deltoid tuberosity. Insertion: Into the coronoid process of the ulna. Nerve supply: 1. Mainly by the musculocutaneous nerve. 2. Its lateral part by the radial nerve. Action: Main flexor of the elbow joint. TRICEPS: Origin: It arises by 3 heads: 1. Long head: from the infraglenoid tubercle. 2. Medial head: from the back of the humerus from the lower lip of the spiral groove. 3. Lateral head: from the upper lip of the spiral groove on the back of the humerus. N B.: The medial head is the deepest one while the other 2 heads are superficial [ long head is medial to lateral head]. Insertion: The heads fuse together forming one tendon which is inserted into the summit of the olecranon process of the ulna. Nerve supply: Radial nerve. The long head is supplied in the axilla while the other 2 heads in the spiral groove. Action: Main extensor of the elbow joint. BRACHIAL ARTERY COURSE: Begins at the lower border of the teres major and ends opposite the neck of the radius by dividing into 2 branches: radial and ulna. It is at first 25  Upper limb[1 -50] medial to the humerus but in the lower 1/2 of the arm it is in front , and is accompanied by 2 venae comitantes. RELATIONS: Anteriorly:  Skin and fascia.  Coraco-brachialis and biceps overlap the upper 1/2 of the artery only.  Median nerve: crosses in front of the artery at the insertion of coracobrachialis. Posteriorly: [from above downwards].  Long head of triceps separated from it by the radial nerve.  Medial head of triceps.  Brachialis. Laterally:  Median nerve [lateral to its upper 1/2]  Tendon of biceps [lateral to the lower 1/2]. Medially:  Ulna nerve[medial to its upper 1/2].  Median nerve [medial to its lower 1/2]. BRANCHES: 1. Profunda brachii artery: it enters the spiral groove accompanied by the radial nerve with the lateral head of triceps forming the roof of the groove. In the groove it gives:  Ascending branch: anastomose with the posterior circumflex humeral artery [a branch of the subscapular artery].  Anterior and posterior descending branches: Descends with the radial nerve towards the lateral epicondyle: one anterior and one posterior to the epicondyle to anastomose with the radial and interosseuos recurrent arteries respectively. 2. Superior ulnar collateral artery: Arises below the level of profunda brachii and passes downwards and medially accompanying the ulna nerve till the insertion of coracobrachialis where it pierces the medial intermuscular septum and descends in the posterior compartment to anastomose with the posterior ulnar recurrent artery behind the medial epicondyle of the humerus. 3. Inferior ulnar collateral artery: Arises from the lower part of the brachial artery [2 inches] above the elbow joint and divides into an anterior and posterior divisions which descends to the medial epicondyle where they anastomose with the ulnar recurrent arteries. 4. Nutrient artery: It enters the nutrient foramen at the insertion of the coracobrachialis. 5. Muscular branches:[unnamed]: Arises from the lateral side of the artery. 26  Upper limb[1 -50] FOREARM THE CUBITAL FOSSA It is triangular shape. BOUNDERIES: Base: Represented by a line between the 2 epicondyles. Apex: Meeting of the lateral with the medial borders. Medially: Pronator teres. Laterally: Brachio-radialis. Roof: Skin and fascia including bicipital aponeurosis and median cubital vein. Floor: Insertion of brachialis and supinator. CONTENTS: 1. Lower part of brachial artery: just medial to the biceps tendon. 2. Radial artery: descends laterally on the tendon of the biceps and the supinator and leaves the fossa at its apex. It gives the radial recurrent artery which ascends toward the lateral epicondyle. 3. Ulnar artery: passes medial to the biceps tendon and gives 2 ulnar recurrent branches which ascend toward the medial epicondyle and also gives here the common interosseous artery. 4. Median nerve: descends medial to the brachial artery and leaves the fossa between the 2 heads of pronator teres. 5. Tendon of biceps muscles. MUSCLES OF THE FRONT OF FOREARM[Flexor group] The muscles are arranged in 2 layers: superficial and deep. A - MUSCLES OF THE SUPERFICIAL LAYER: They are arranged from lateral to medial: Pronator teres - flexor carpi radialis - palmaris longus - flexor digitorum superficialis - flexor carpi ulnaris. [They are better identified from their insertions]. PRONATOR TERES: Origin: Arises by 2 heads: 1. Superficial humeral head: [main part] from the medial epicondyle and the adjoining part of the medial supracondylar ridge. 2. Deep ulnar head: [small part] from the middle of the medial border of the coronoid process of the ulna. Insertion: Into a rough area in the middle of the lateral surface of the radius on its maximum convexity. Nerve supply: Median nerve before it passes between the 2 heads of the muscle. The deep head separates the median nerve from the ulnar artery. Action: Pronates the forearm [palm of the hand looks downward]. 27  Upper limb[1 -50] FLEXOR CARPI RADIALIS: Origin: From the common flexor origin, i.e. from the front of the medial epicondyle. Insertion: Its tendon passes in a groove on the anterior surface of the trapezium [which is transformed into a tunnel by the splitted lateral end of the flexor reticulum], to be inserted into the palmar surface of the bases of the 2nd and 3rd metacarpal bones [This corresponds to the insertion of the extensor carpi radialis longus and brevis in the back of the 2nd and 3rd metacarpals]. Nerve supply: Median nerve. Action: Flexion and abduction of the wrist joint. PALMARIS LONGUS:[may be absent]. Origin: From the common flexor origin. Insertion: Into the apex of the palmer aponeurosis [deep fascia of the palm]. Nerve supply: Median nerve. FLEXOR DIGITORUM SUPERFICIALIS: Origin: By 2 heads. 1. Humero- ulnar head: from the medial epicondyle[common origin] and from the medial border of the coronoid process of the ulna. 2. Radial head: from the oblique upper part of the anterior border of the radius between the supinator above and the flexor pollicis longus below. The muscle has an upper border in contact to the lower border of the pronator teres, so as the median nerve passes between the 2 heads of the pronator teres it passes directly deep to the flexor digitorum superficialis [between the muscle and it fascia]. The muscle lies in a more deeper plane than the flexor carpi radialis, palmaris longus and flexor carpi ulnaris. Insertion: The muscle gives off 4 tendons for the medial 4 fingers arranged as follows: Tendons of the middle and ring fingers are superficial while tendon of the index and little fingers are deeper. The 4 tendons pass deep to the flexor retinaculum and then deep to the palmar aponeurosis to reach the phalanges where each tendon passes deep to the fibrous flexor sheath. Each tendon, while in the fibrous flexor sheath is pierced by a tendon of the flexor digitorum profundus then is inserted into the margins of the middle phalanx. Nerve supply: Median nerve. Action: 1. Flexion of the 1st interphalangeal and metacarpo-phalangeal joints of the medial 4 fringers. 2. Assists in flexion of the wrist joint. FLEXOR CARPI ULNARIS: Origin: By 2 heads: 28  Upper limb[1 -50] 1. Humeral head: from the medial epicondyle. 2. Ulnar head: from the olecranon process and from the aponeurosis attached to the posterior border of the ulna. Insertion: The muscle passes on the medial side of the forearm superficial to the ulnar nerve and artery. It is inserted into: 1. Pisiform bone: 2. Base of the 5th metacarpal bone through the pisio-metacarpal ligament. Nerve supply: Ulnar nerve. Action: Flexion and adduction of the wrist joint. Acting with the flexor carpi radialis they produce pure flexion of the wrist, while with the extensor carpi ulnaris they produce pure adduction of the wrist. B - MUSCLES OF THE DEEP LAYER: These are 3 muscles: 1st related to the ulna [flexor digitorum profundus],2nd related to the radius[flexor pollicis longus] and 3rd related to both bones [pronator quadratus]. FLEXOR POLLICIS LONGUS: Origin: From the upper 2/3 of the anterior surface of the radius and from the interosseous membrane. Insertion: The tendon passes deep to the flexor retinaculum and curves laterally to be inserted into the palmer surface of the base of the distal phalanx of the thumb. Nerve supply: Anterior interosseous branch of the median nerve. Action: Flexion of all joint of the thumb. FLEXOR DIGITORUM PROFUNDUS: Origin: 1. From the upper 2/3 of the anterior and medial surfaces of the ulna. 2. From the aponeurosis attached to the posterior border of the ulna. 3. Also from the interosseous membrane. Insertion: The muscle divides into 4 tendons which pass deep to the tendons of the flexor digitorum superficial to enter the palm through the carpal tunnel. Each tendon pierces tendon of the flexor digitorum superficialis while within the fibrous flexor sheath and passes to be inserted into the base of the distal phalanx for the medial 4 fingers [ventral surfaces]. Nerve supply: 1. The anterior interosseous nerve [of median] supplies the lateral. 2. The ulnar nerve supplies the medial. Action: 1. Flexion of all the interphalangeal [I/P] and metacarpophalangeal [M/P] Joints 2. Helps in flexion of the wrist joint. PRONATOR QUADRATUS: Origin: From the anterior surface of the lower 1/3 of the ulna. Insertion: Into the anterior surface of the lower 1/3 of the radius. 29  Upper limb[1 -50] Nerve supply: Anterior interosseous nerve [of median]. Action: Binds the radius to the ulna and helps pronator of the forearm. MUSCLES OF THE BACK OF FOREARM [Extensor group]. Are arranged in a superficial layer and a deep layer. They are all supplied from the radial nerve or its posterior interosseous branch. As those of the front of forearm, these muscles are either acting on the digits [digitorum], on the wrist [carpi] or on the bones of the forearm [supinator][They are easily identified from their insertions]. A - MUSCLES OF THE SUPERFICIAL LAYER: BRACHIO-RADIALIS: [most lateral]. Origin: From the upper 2/3 of the lateral supracondylar ridge. Insertion: Into the lateral surface of the lower end of the radius above the styloid process. Nerve supply: From the radial nerve [above the elbow]. Action: 1. Initiates both pronation and supination. 2. Brings the forearm midway between pronation and supination. 3. Helps in flexion of the elbow joint. EXTENSOR CARPI RADIALIS LONGUS: Origin: From the lower 1/3 of the lateral supra-condylar ridge. It is deep to the brachio-radialis. Insertion: Into the back of the base of the 2nd metacarpal bone. Nerve supply: From the radial nerve above the elbow joint and after it leaves the spiral groove [as brachio-radialis]. Action: Extension and abduction of the wrist joint. EXTENSOR CARPI RADIALIS BREVIS: Origin: From the common extensor origin from the anterior surface of the lateral epicondyle. N.B. : [common flexor origin is also from the anterior surface but of the medial epicondyle]. Insertion: Into the back of the base of the 3rd metacarpal bone. Nerve supply: From the posterior interosseous nerve [of Radial] before piercing the supinator. Action: As extensor carpi radialis longus [extension and abduction of the wrist]. EXTENSOR DIGITORUM: Origin: From the common extensor origin. Insertion: It divides into 4 tendons for the medial 4 fingers. Their mode of insertion differs from the mode of flexor digitorum superficialis. Each tendon is 30  Upper limb[1 -50] transformed into an expansion on the dorsum of the proximal phalanx. Each extensor expansion divides into a median part and 2 collaterals. The median part is inserted into the base of the middle phalanx, while the 2 collaterals pass on the sides of the middle phalanx to gain insertion into the base of the terminal phalanx. Nerve supply: Posterior interosseous nerve [after piercing the supinator and reaching the back of forearm]. Action: 1. Extension of I/p and M/p joints of the medial 4 fingers. 2. Extension of the wrist joint. EXTENSOR DIGITI MINIMI: Origin: From the common extensor origin. Insertion: Though it is a slip from the extensor digitorum, it tendon passes in a special compartment deep to the extensor retinaculum to be inserted into the extensor expansion of the little finger. Nerve supply: Posterior interosseuos nerve. Action: Extension of the joints of the little finger. EXTENSOR CARPI ULNARIS: Origin: 1. From the common extensor origin. 2. From the posterior border of the ulna through the ulna aponeurosis. Insertion: Into the back of the base of the 5th metacarpal bone. Nerve supply: Posterior interosseous nerve. Action: Extension and adduction of wrist joint. ANCONEUS: Origin: From the back of the lateral epicondyle by a rounded tendon. Insertion: Into the lateral surface of the olecranon and the upper 1/2 of the back of shaft of ulna. Nerve supply: A branch from the radial nerve while in the spiral groove. This branch passes through the medial head of triceps to reach the anconeus. Action: Helps in extension of the elbow joint. B - MUSCLES OF THE DEEP LAYER: From above downwards they are arranged as follows: 1. Supinator: related to both bones[arises from the ulna and inserted into the radius]. 2. Abductor pollicis longus: arises from both bones below the supinator with the posterior interosseous artery between the 2 muscles but the posterior interosseous nerve pierces the lower part of the supinator. 3. Extensor pollicis longus and brevis: They appear as one mass lying below the abductor pollicis longus. The long extensor of the thumb is attached to the ulna while the short one to the radius. 31  Upper limb[1 -50] 4. Extensor indicis: is attached to lower 1/4 of ulna [the more fixed bone of the forearm]. SUPINATOR: Origin: 1. From the supinator crest and the depression in front of it [deep part]. 2. From the lateral epicondyle of humerus and lateral ligament of elbow [superficial part]. Insertion: Into the lateral surface of the upper 1/3 of the radius [this surface extends on the back and on the front of the bone]. Nerve supply: From the posterior interosseous nerve before it pierces the muscle. Action: Supination of the forearm [movement of the radius so that the palmar surface of the hand looks upwards]. ABDUCTOR POLLICIS LONGUS: Origin: From the back of the upper 1/3 of the radius and ulna and the interosseous membrane. Insertion: Into the lateral side of the base of the 1st metacarpal bone [of the thumb]. Nerve supply: Posterior interosseous n. Action: Abduction of the carpo - metacarpal [C/M] joint of the thumb and helps in abduction of the wrist. EXTENSOR POLLICIS LONGUS: Origin: From the back of the middle 1/3 of ulna and interosseous: membrane. Insertion: Into the back of the base of the distal phalanx of thumb [it has no expansion]. Nerve supply: Post. Inteross. n. Action: Extension of all the joints of the thumb. EXTENSOR POLLICIS BREVIS: Origin: Back of the middle 1/3 of the radius and interosseous membrane. Insertion: Into the back of the base of the proximal phalanx of the thumb. EXTENSOR INDICIS: Origin: Back of the lower 1/3 of the ulna and interosseous membrane. Insertion: Into the extensor expansion of the index. Nerve supply: Post. Inteross. n. Action: Extension of the index finger. N. B.: Each of the thumb , index and little finger has 2 extensor tendons:  Thumb: extensor pollicis longus and brevis. 32  Upper limb[1 -50]  Index: extensor digitorum tendon and extensor indicis.  Little finger: extensor digitorum tendon and extensor digiti minimi. ANATOMICAL SNUFF-BOX: Bounderies: Laterally: Tendon of abductor pollicis longus and extensor pollicis brevis. Medially: Tendon of extensor pollicis longus. Floor: scaphoid and trapezium. Structures crossing:  Radial artery: on the floor.  Radial nerve: in the roof.  Cephalic vein: in the roof. RETINACULA OF THE WRIST There are 2 fibrous band that are stretched across the wrist joint, one front [flexor retinaculum] and one behind [extensor retinaculum]. FLEXOR RETINACULUM: Attachments: [to carpal bones] Medially: To the pisiform bone and hook of hamate. Laterally: To the tubercle of scaphoid and crest of trapezium. Relations: Structures passing superficial [from medial to lateral]: 1. Ulna nerve. 2. Ulna artery. 3. Palmar cutaneous nerve of ulna nerve. 4. Tendon of the palmaris longus. 5. Palmar cutaneuos nerve of median nerve. Structures passing deep [in carpal tunnel]: 1. Tendons of flexor digitorum superficialis. 2. Tendons of flexor digitorum profundus. 3. Tendon of flexor pollicis longus. 4. Median nerve. 5. Synovial sheath around the previous tendons. N. B.: The tendon of flexor carpi radialis passes through the lateral end of the retinaculum and not deep to it. EXTENSOR RETINACULUM: Attachments: [mainly to radius and ulna]. Medially: the styloid process of the ulna. the triquetral and pisiform bones. Laterally: Anterior border of the lower end of radius. Relations : Superficial relations: 1. The beginning of the cephalic vein: laterally. 2. The beginning of basilic vein: medially. 3. The terminal part of the radial nerve: laterally. Deep relation: 33  Upper limb[1 -50] Five septa extend from the deep surface of the retinaculum to be attached to the back of the lower end of the radius and ulna thus dividing the space deep to the retinaculum into 6 compartments 1. First compartment [most lateral] is related to the lateral surface of the lower end of the radius. It transmits the tendons of:  Abductor pollicis longus.  Extensor pollicis longus. 2. Second compartment: transmit:  Extensor carpi radialis longus.  Extensor carpi radialis brevis. 3. Third compartment: medial to the dorsal tubercle of the radius. It transmits:  Extensor pollicis longus. 4. Fourth compartment:  Extensor digitorum.  Extensor indices.  Post. Inteross. Nerve.  Ant. Inteross. Artery. 5. Fifth compartment: in the interval between the radius and ulna for:  Extensor digiti minimi. 6. Sixth compartment: on the back of the head of ulna, for:  Extensor carpi ulnaris. RADIAL NERVE COURSE AND RELATIONS: In the axilla: It arises fron the posterior cord of the brachial plexus[ C. 5, 6, 7, 8 T. 1] behind the third part of the axillary artery and lies on the subscapularis and the tendons of latissimus dorsi and teres major. After leaving the axilla[ in the arm]: In the arm: It arises behind the brachial artery and on the long head fo triceps. It enters the spiral groove accompanied with the profunda brachial artery where it is covered by the lateral head of triceps [roof of the groove]. It pierces the lateral intermuscular septum from behind and descends in the groove between the brachialis and brachioradialis in front of the septum [brachialis separates the radial nerve from the musculocutaneuos nerve]. In the cubital fossa and forearm: It lies on the supinator where it gives the posterior interosseuos nerve then descends [as superficial radial nerve] in the forearm lateral to the radial artery under cover of the brachioradialis muscle and superficial to the radius and the muscles attached to it: 1. Supinator. 2. Insertion of pronator teres. 3. Radial head of flexor digitorum superficialis 4. Flexor pollicis longus. In the lower part of the forearm it wind laterally deep to the tendon of brachioradialis to reach back of the forearm superficial to the tendons 34  Upper limb[1 -50] of the abductor pollicis longus and extensor pollicis brevis then to the extensor retinaculum to reach the back of the hand. In the hand: It divides into digital branches to supply the back of the lateral 2/3 of the hand and the back of the lateral three and half fingers till only the middle phalanx[remaining parts of these fingers are supplied by the median nerve]. BRANCHES: In the axilla: 1. N. to long head of triceps. 2. Posterior cutaneuos nerve of the arm to the skin of the back of the arm. In the spiral groove: 1. N. to lateral head of triceps. 2. N. to medial head of triceps. 3. N. to anconeuos: descends through the medial head of triceps to reach anconeus. 4. The lower lateral cutaneous N. of arm: to the skin of the lower part of the lateral side of the arm[upper lateral cut. N. of arm is from the axillary N.]. 5. The posterior cutaneuos nerve of forearm: to supply the skin of the back of forearm. In the interval between the brachialis and brachioradialis: 1. N. to brachoradialis. 2. N. to extensor carpi radialis longus. 3. Twigs to the lateral part of brachialis. In the cibital fossa: Gives its important branch: the posterior interosseuos nerve[motor]. The terminal part of the radial nerve after giving the post. Interosseuos nerve is purely sensory and supplies only the skin of the lateral 2/3 of the dorsum of the hand and the lateral three and half fingers till the middle phalanx only. THE POSTERIOR INTEROSSEUOS NERVE: while in the cubital fossa and before it pierces the supinator supplies 2 muscles: 1. The supinator. 2. The extensor carpi radialis brevis. It pierces the supinator and passes through its substance lateral to the radius to reach the back of the forearm [the posterior interosseuos artery on the other hand reaches the back between the radius and ulna]. It supplies the remainig muscles of the back of forearm. N. B.: The muscles of back of forearm are supplied as follows: 1. Extensor carpi radialis longus from radial nerve. 2. Extensor carpi radialis brevis and supinator from posterior interosseuos nerve in the cubital fossa. 3. Remaining muscles from posterior interosseuos nerve after reaching the back of forearm. The posterior interosseuos nerve is accompanied by the posterior interosseuos artery in the upper part of the back of the forearm, but in the lower part it is accompanied by the anterior interosseuos artery. APPLIED ANATOMY: I. Lesion in the axilla [above its branches to triceps]: 1. Paralysis of triceps - Loss of extension of elbow. 2. Paralysis of supinator - Loss of supination. 35  Upper limb[1 -50] 3. Paralysis of all the extensor muscles of the wrist and fingers - “wrist drop” and inability to extend the fingers. 4. Cutaneous loss of sensation is limited to a small a area on the lateral side of the back of the hand due to overlap from the median and ulnar nerves on the back of the hand. II. Lesion in the forearm [below the origin of the posterior interosseuos nerve]: No muscular paralysis at all and the lesion leads only to a limited area of skin loss of sensation as mentioned above. MEDIAN NERVE COURSE AND RELATIONS: In the axilla and arm: It arises in the axilla by 2 roots: a medial root from the medial cord and a lateral root from the lateral cord of the brachial plexus. The medial root descends in front of 3rd part of the axillary artery to fuse with the lateral root and the median nerve descends lateral to the upper 1/2 of the brachial artery. At the insertion of coracobrachialis the nerve crosses in front of the brachial artery [ sometimes deep to it] to reach its medial side. In the cubital fossa and forearm: The median nerve is medial to the brachial artery. It leaves the fossa between the 2 heads of pronator teres to gain the deep surface of the flexor digitorum superficialis and descends between this muscle and the flexor digitorum profundus till shortly above the wrist joint. It comes out from undercover of the lateral border of the flex. digit. superf. to become subcutaneous in the interval between the tendon of palmaris longus medially and that of the flexor carpi radialis laterally. The nerve passes deep to the flexor retinaculum to enter the hand deep to the palmar aponeurosis. In the hand: It divides into lateral and medial divisions each of which gives digital branches. BRANCHES: 1. In the axilla and arm: No branches. 2. In the forearm: No branches. 3. In the cutibal fossa: it supplies 4 muscles: 1. Pronator teres. 2. Flexor Carpi radialis. 3. Flexor digitorum superficialis 4. Palmaris longus 4. After it leaves the cubital fossa : it gives: 1. The anterior interosseous nerve: arises just after the median n. comes out between the 2 heads of the pronator teres. It descends in front of the interosseous membrane between the flexor pollicis longus and the flex. Digt. Profundus muscles till the pronator quadratus where it passes deep to it and ends there. It supplies the 3 muscles in addition to the supply of the carpal joints. 2. The palmar cutaneuos branch arises 5cm above the wrist and descends in front of the flexor retinaculum to supply the skin of the lateral 2/3 of the palm. 5. In the hand : 36  Upper limb[1 -50] It gives medial and lateral divisions at the distal end of the carpal tunnel, which supply the thenar muscles, and 1st and 2nd lumbricals as well as the skin of the lateral 31/2 fingers. a. Lateral division: gives: 1. nerves to the muscles of the thenar eminence, [flexor pollicis brevis, abductor pollicis brevis and opponens pollicis]. 2. nerve to the 1st lumbrical muscle. 3. Cutaneous supply to the palmar surfaces of the adjacent sides of the index and middle fingers, and of the middle and ring fingers. b. Medial division: gives: 1. nerve to the 2nd lumbrical muscle. 2. Cutaneous supply to the palmar surfaces of the adjacent sides of the index and middle fingers, and of the middle and ring fingers. APPLIED ANATOMY: 1 - Lesion above the elbow: [above its muscular and anterior inteross branches]. a. Paralysis of the following muscles: 1. Both pronators - loss of pronation. 2. Flexor digitorum superf. and lateral of the flex. digit. Profundus and related lumbricals, loss of flexion of the `middle phalanges of the medial 4 fingers, and loss of flexion of the distal phalanges of the index and middle fingers only medial 1/2 of flex. digit profundus is supplied by ulnar n]. 3. Palmaris longus and flex. carpl radialis - weak flexion of the wrist. 4. The following muscles of the thumb:  Flexor pollicis longus  Flexor pollicis brevis.  Opponens pollicis Accordingly, the thumb is hyperextended and the thenar eminence is flattened (atrophied). This deformity is called “Ape-hand”. b. Loss of cutaneous sensation: 1. Skin of the lateral 2/3 of the palm. 2. Skin of the palmar surfaces of the lateral 31/2 fingers 2 - Lesion just above the wrist: 1. No affection of the pronators or the flexors of the digits. 2. The thenar muscles are paralysed [Ape-hand]. 3. Cutaneous sensory loss only in the lateral 31/2 fingers [not the skin of palm as its nerve arises higher]. ULNA NERVE COURSE AND RELATIONS: In the axilla: It arises from the medial cord of brachial plexus and descends medial to the 3rd part of axilliary artery with the med. Cut. N. of forearm in front of it and the axilliary vein medial to it. In the arm: It descends medial to the brachial artery till the insertion of the coraco- brachialis where it leaves the artery and pierces the medial intermuscular septum in company with the superior ulnar collateral 37