Musculoskeletal Upper Limb

Bones of the upper limb:

 Clavicle: the shaft of the clavicle has a double curve with the medial half curving anteriorly and the lateral half posteriorly. The bone has no medullary cavity and consist of trabecular with shell of compact bone.
- sternal end: medial end of the clavicle that articulates with the sternum at the sternoclavicular joint
- acromial end: lateral end of the clavicle that articulates with the acromion of scapula at the acromioclavicular joint.
- conoid tubercle: tubercle of the inferior posterior surface near the acromial end that gives attachment to conoid ligament (medial part of coracoclavicular ligament)
- trapezoid line: bulge on the inferior side near the acromial end that allows for the trapezoid ligament (lateral part of coracoclavicular) to attach.
 Function of clavicle:
- serves as moveable, crane-like strut from which the scapula and free limb are suspended and keeping them away from the trunk
- forms one of the bony boundaries of the cervicoaxillary canal and affording protection to neurovascular bundle to upper limb
- transmit shocks from upper limb to axial skeleton
 Scapula: triangular flat bone that lies on the posterolateral aspect of the thorax, overlying the 2nd to 7th ribs. The spine of the scapula divides the posterior surface into a small supraspinous fossa and larger infraspinous fossa
- acromion: bony hook that extends from the spine of scapula forms the subcutaneous point of the shoulder and articulates with acromial end giving the anatomical horseshoe.
- Deltoid tubercle of the scapular spine: prominence indicating the medial attachment of the deltoid
- Glenoid cavity: shallow concave oval fossa at the lateral surface of the scapula that receives articulation from the head of the humerus.
- Coracoid process: structure resembling that of a bent finger projecting anterolaterally just above the glenoid cavity, which provide inferior attachment for coracoclavicular ligament.

Muscles of Pectoral Girdle

 Pectoralis major: large fan-shaped muscle that covers the superior part of the thorax. Sternocostal head forms the muscular mass that makes up most of the anterior wall of the axilla while inferior border forms the anterior axillary fold.
- origin: anterior surface of medial half of clavicle (clavicular head), anterior surface of sternum and superior six costal cartilages and external oblique aponeurosis
- insertion: lateral lip of intertubercular groove of humerus
- action: adducts and medially rotate humerus and clavicular head flexes and sternocostal head extends humerus
- nerve innervation: lateral and medial pectoral nerves, clavicular head (C5-C6) and sternocostal head (C7-T1)
 Pectoralis minor: triangular muscles that lies in the anterior wall of the axilla. It forms a bridge with the coracoid process under which vessels and nerves must pass to reach the arm.
- origin: 3rd to 5th ribs near their costal cartilages
- insertions: medial border and superior surface of coracoid processes of scapula
- action: stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall
- nerve innervation: medial pectoral nerve C8, T1
 Serratus anterior: this saw-toothed shaped sheet of muscles overlies the lateral part of the thorax and forms the medial wall of the axilla. It helps to anchor the scapula and inferior fibers used to elevate glenoid cavity.
- origin: external surfaces of lateral parts of 1st to 8th ribs
- insertion: anterior surface of medial border of scapula
- action: protraction and rotation of scapula
- nerve innervation: long thoracic nerve C5, C6, C7
 Trapezius: direct attachment of pectoral girdle to trunk and cranium and assists in suspending the upper limb.
- origin: medial third of superior nuchal line, external occipital protuberance and spinous process of T7-T12 vertebra
- insertion: lateral third of clavicle, acromion and spine of scapula
- action: descending, ascending part and middle part respectively elevates, depress and retract scapula. Rotation of glenoid cavity superiorly (action of superior and inferior fibers)
- nerve innervation: accessory nerve (CN XI) and C3 and C4 spinal nerves
 Latissimus dorsi: large fan-shaped muscles passes from trunk to humerus and acts directly on glenohumeral joint. Plays a major role in the downward rotation of scapula
- origin: spinous process of T7-T12, thoracolumbar fascia, iliac crest and inferior 3 ribs
- insertion: floor of intertubercular groove of humerus
- action: extends, adducts and medially rotates humerus
- nerve innervation: thoracodorsal nerve C6-C8
 Rhomboid minor: lies deep to the trapezius and form broad parallel bands that pass inferolaterally from the vertebrae to the medial border of scapula.
- origin: nuchal ligament and spinous processes of C7 and T1
- insertion: smooth triangular area at the medial end of scapular spine
- action: retract scapula and rotate it to depress glenoid cavity
- nerve innervation: dorsal scapular nerve C4, C5
 Rhomboid major: thin flat muscles that is approximately two times wider than the superior thicker rhomboid minor
- origin: spinous processes of T2 to T5 vertebra
- insertion: medial border of scapula from level of spine to inferior angle (tip)
- action: same as rhomboid minor
- nerve innervation: same as rhomboid minor
 Deltoid: thick powerful courses textured muscles covering the shoulder with unipennate anterior and posterior part but multipennate middle part. Strong abductor (effective at 15o) but also acts as shunt muscle to resist inferior displacement of the head of the humerus. Anterior and posterior part used for arm swinging
- origin: lateral third of clavicle, acromion and spine of scapula
- insertion: deltoid tuberosity of humerus
- action: anterior part flexes and medially rotate the arm, middle part abducts, posterior part extends and laterally rotate the arm
- nerve innervation: axillary nerve C5, C6
 Supraspinatus: one of the rotator cuff muscles
- origin: supraspinous fossa of scapula
- insertion: superior facet of greater tubercle of humerus
- action: initiates and assists deltoid in abduction of arm and acts with rotator cuff muscles
- nerve innervation: suprascapular nerve C4-C6
 Infraspinatus: one of the rotator cuff muscles and occupies the medial three quarters of infraspinous fossa and is partly covered by deltoid and trapezius.
- origin: infraspinous fossa of scapula
- insertion: middle facet of greater tubercle of humerus
- action: laterally rotate arm and help hold humeral head in glenoid cavity
- nerve innervation: suprascapular nerve C4-C6
 Teres minor: one of the rotator cuff muscles hidden by the deltoid. It’s a narrow elongate muscle that works with infraspinatus to rotate arm laterally and assists adduction.
- origin: middle part of lateral border of scapula
- insertion: inferior facet of greater tubercle of humerus
- action: same as infraspinatus
- nerve innervation: axillary nerve C5, C6
 Teres major: thick rounded muscles that forms the inferior border of the lateral part of the posterior wall of the axilla. Also help extend arm from flexed position and is an important stabilized of the humeral head.
- origin: posterior surface of inferior angle of scapula
- insertion: medial lip of intertubercular groove of humerus
- action: adducts and medially rotate arm
- nerve innervation: lower subscapular nerve C5, C6
 Subscapularis: thick triangular rotator cuff muscle that lies on costal surface of the scapula and forms part of the posterior wall of the axilla. It’s the primary medial rotator of the arm
- origin: subscapular fossa
- insertion: lesser tubercle of humerus
- action: medially rotate and adduct arm, and help hold humeral head in glenoid cavity
- nerve innervation: upper and lower subscapular nerve C5-C7

Anatomy of the pectoral girdle:

 Deltopectoral groove: a groove between the pectoralis major and its adjacent deltoid in which the cephalic vein runs
 Clavipectoral triangle: divergence of the pectoralis major and deltoid superiorly near the clavicle forms a triangular space.
 Clinical significance of pectoral girdle:
- Fracture of clavicle: occurs most commonly in children with an indirect force transmitting from an outstretched hand through the bones of the whole arm or a direct force to the shoulder during a fall. The weakest point is the junction of the middle and lateral third. The result is a shoulder drop and elevation of the medial clavicle.
- Fracture of scapula: fracture of scapula occurs with severe trauma such as vehicle accidents along with fractures ribs. Most fracture requires little treatment because scapula is covered n both sides by muscle.
- Winged scapula: paralysis of serratus anterior due to injury to the long thoracic nerve causes the medial border of the scapula to move laterally and posteriorly way from the thoracic wall giving an appearance of a “wing”, especially when the person leans on a hand or presses against a wall. Common causes are knife fights and the person can not abduct past horizontal.
- Rotator cuff injury: injury or disease can damage the musculotendinous rotator cuff, causing instability of the glenohumeral joint. Trauma can rupture the tendons of the STIS muscle with supraspinatus being the most common one.

Sternoclavicular joint:

 Sternoclavicular joint: saddle type of synovial joint between sternal end of the clavicle and the manubrium and 1st costal cartilage of sternum but functions as a ball and socket joint. Articular disc separate the SC joint into two compartments and is attached firmly to anterior and posterior SC ligaments. This is the only articulation between upper limb and axial skeleton.
 Ligament of SC joint:
- anterior posterior sternoclavicular ligament: reinforces the joint capsule anteriorly and posteriorly
- interclavicular ligament: extends from the sternal end of the one clavicle to super border of the manubrium and to the sternal end of other clavicle. Helps strengthens the capsules superiorly
- costoclavicular ligament: anchors the inferior surface of the sternal end to the 1st rib and its costal cartilage.
 Movement of the SC joint: elevation, depression, protraction and retraction thus circumduction
 Blood supply of SC joint: internal thoracic and suprascapular arteries
 Nerve supply of SC joint: branches of the medial supraclavicular nerve and nerve to subclavius
 Clinical significance of SC joint:
- dislocation: the strength of the SC ligaments means dislocation of SC joints is rare. Dislocation of the SC joint occurs mainly in people younger than 25 years of age resulting in fractures through the epiphyseal plate.

Acromioclavicular joint:

 Acromioclavicular joint: plane synovial joint where the acromial end of the clavicle articulates with the acromion of the scapula. The articular surfaces covered with fibrocartilage are separated by articular disc. The joint capsule itself is relatively loose fibrous layer of the joint capsule and is attached to the margin of the articular surfaces
 Acromioclavicular ligament:
- acromioclavicular ligament: fibrous band extending from the acromion to the clavicle that strengthens the AC superiorly
- coracoclavicular ligament: pair of extrinsic bands that unite the coracoid process to clavicle. Coracoid ligament is an inverted triangle with its apex inferiorly attaches to the root of the coracoid process and its wide attachment to the coracoid tubercle. Trapezoid ligament is attached to the superficial surface of the coracoid process and extends laterally to the trapezoid line.
 Movement of the acromioclavicular joint: the acromion of the scapula rotates on the acromial end of the clavicle. Movement produced by muscles attached to the scapula instead of the articulating bones
 Blood supply: the suprascapular and thoracoacromial arteries
 Nerve supply: lateral pectoral and axillary nerve supply the AC joint
 Clinical significance of the acromioclavicular joint:
- Dislocation of the AC joint: easily injured by a direct blow such as a hard fall on the shoulder or outstretched upper limb. When both the AC and coracoclavicular ligament are torn, the shoulder separates from the clavicle and falls due to the weight

Axilla

 Axilla: the pyramidal fat-filled space inferior to the glenohumeral joint and superior to the axillary fascia at the junction of the arm and thorax. It provides a passageway, and protection by the adducted limb, for the neurovascular structures that serve the upper limb.
 Course of neurovascular structures from axilla:
- superiorly via the cervicoaxillary canal to the root of neck
- anterior via the clavipectoral triangle to pectoral region
- inferiorly and laterally into the limb
- posteriorly via the quadrangular space to the scapular region
- inferiorly and medially along the thoracic wall to serratus anterior and latissimus dorsi
 Boundary of axilla:
- apex: cervicoaxillary canal bounded by 1st rib, clavicle and superior edge of scapula.
- base: concave skin, subcutaneous tissue and deep fascia extending from the arm to the thoracic wall (the armpit or axillary fossa). This is bounded by the medial side of arm, anterior and posterior axillary fold and lateral thoracic wall
- anterior wall: formed by pectoralis major and minor and pectoral and clavicopectoral fascia. The anterior fold is formed by inferiormost part of the pectoralis major as it bridge the thoracic wall to humerus
- posterior wall: formed by the scapula and subscapularis and inferiorly the teres major and latissimus dorsi. The posterior fold is formed by latissimus dorsi, teres major and overlying integument
- medial wall: formed by the thoracic wall 1st to 4th rib and the overlying serratus anterior
- lateral wall: narrow bony wall formed by the intertubercular groove
 Clinical significance of axilla:
- injury of axillary vein: exposed position and large size of axillary vein makes its prone to injury, especially when the arm is fully abducted. Wound in the proximal part of axillary vein cause profuse bleeding and also air can enter it producing air emboli in the blood
- dissection of axillary lymph nodes: used for staging and determining the appropriate treatment of cancer such as breast cancer. The axillary lymph nodes receive lymph in a specific order, removal in that order is also important to determine degree of metastasis of cancer. During dissection two nerves that are at risk of injury are long thoracic nerve and thoracodorsal nerve.

Vessel supply to axilla

 Axilla arteries:

 Axillary artery: begins at the lateral border of the 1st rib and ends at the inferior border of the teres major
- first part: located between lateral border of 1st rib and medial border of the pectoralis minor
- second part: lies posterior to pectoralis minor
- third part: extends form lateral border of pectoralis minor to the inferior border of the teres major
 Superior thoracic: the only branch coming off the first part of axillary artery an supplies the subclavius, 1st and 2nd intercostal muscles and superior serratus anterior and overlying pectoral muscles.
- course: runs anteromedially along superior border of pectoralis minor then passes between it and pectoralis major to thoracic wall
 Thoracoacromial: the first branch coming off the second part of axillary artery
- course: curls around superomedial border of pectoralis minor and pierces the clavipectoral fascia and split into four branches deep to the clavicular head: pectoral, deltoid, clavicular, acromial
 Lateral thoracic: the second branch of the second part of the axillary artery and supplies the pectoral, serratus anterior, and intercostal muscles and lateral aspect of breast
- course: descends along lateral border of pectoralis minor and follows it onto thoracic wall
 Subscapular: largest branch of the third part of axillary artery
- course: descend along lateral border of subscapularis and divide into two terminal branches, the circumflex scapular and thoracodorsal arteries
 Circumflex humeral: arising opposite side of the subscapular artery
- course: encircle the surgical neck of humerus and anastomising with each other laterally . Anterior branch passes laterally supplying the shoulder and biceps brachii while posterior branch passes medially through the posterior wall to supply he glenohumeral joint and surrounding muscles
 Circumflex scapular: larger terminal branch of the subscapular artery and supply muscles on the dorsum of the scapula
- course: curves around lateral border of scapula to enter infraspinous fossa and anastomising with suprascapular artery
 Thoracodorsal: supplies principally the latissimus dorsi and participates in anastomoses around scapula
- course: continues course of subscapular artery, descending and entering apex of latissimus dorsi
 Axillary veins: the vein lies initially on the anteromedial side of the axillary artery but later courses on the anteroinferior side to the artery. Features include
- formed by the union of brachial vein and basilic vein
- also divided into three parts corresponding to that of the axillary artery
- cephalic pierces the costalcoracoid membrane and empties into axillary vein
 Differences of branching to axillary artery:
- veins corresponding to branches thoracoacromial artery do not merge and enter as one vein but enter independently into the axillary vein
- axillary vein receives directly or indirectly the thoracoepigastric vein. This is to allow collateral route of venous return in the presence of obstruction of the inferior vena cava.

Axillary lymph nodes

 Pectoral nodes: three to five nodes lie along the medial wall of the axilla and around the lateral thoracic vein. It receives lymph from mainly the anterior thoracic wall including most of the breast
 Subscapular node: six or seven nodes that lie along the posterior axillary fold and subscapular blood vessels. These receive lymph from the posterior aspect of the thoracic wall and scapular region
 Humeral nodes: four to six nodes lie along the lateral wall of the axilla, medial and posterior to the vein. These receive all the lymph from the upper limb except that carried by lymphatic accompanying the cephalic vein.
 Central nodes: three or four large nodes situated deep to the pectoralis minor near the base of the axilla and received efferent vessels from the above three groups
 Apical nodes: located at the apex of the axilla along the medial side of the axillary vein and received vessels from all other axillary lymph nodes

Brachial Plexus

 Brachial plexus: the network of the anterior rami of the last four cervical and first thoracic nerves that supplies the upper limb. It beings in the neck and extends into the axilla.
- trunks: anterior root of C5 and C6 forms the superior trunk; anterior root of C7 continues as the middle trunk and anterior root of C8 and T1 unite forming the inferior trunk. These emerge between scalenus anterior and scalenus medius
- divisions: each trunk divides into anterior and posterior divisions, hence 3 anterior and 3 posterior divisions in total. These occur behind the clavicle.
- cords: anterior division of superior and middle trunk give rise to the lateral cord; anterior division of inferior trunk continues as the medial cord; and the 3 posterior divisions all the trunk unite to give the posterior cord. These are formed at the outer border of the first rib and enter the apex of the axilla together with axillary vessels.
 Relationship with axillary artery: as the name suggests the lateral cord lies lateral to the second part of the axillary artery while medial cord would lie medially.

Nerve organization of brachial plexus

 Median: lateral and medial cord C6 – T1
 Ulnar: larger terminal branch of medial cord C7, C8, T1
 Radial: larger terminal branch of posterior cord C5- T1
 Axillary: terminal branch of posterior cord C5, C6
 Clinical significance of brachial plexus:
- injury of the thoracodorsal nerve: surgery of he inferior part of the axilla puts the thoracodorsal nerve (C6-C8) supplying he latissimus dorsi at risk of injury
- injury to the axillary nerve: the axillary passes inferior to the humeral head and winds around surgical neck, so is usually injured during fracture of the humerus or dislocation of the glenohumeral joint. The consequences is deltoid atrophy, loss of teres minor action and loss of sensation of the area supplied by superior lateral cutaneous nerve of arm (area over the deltoid)
- injury to superior parts of brachial plexus: result in from an excessive increase in the angle between neck and shoulder, e.g. thrown off a horse and lands on shoulder. This can stretch or rupture the brachial plexuses, paralyze muscle innervated by C5 and C6 and produce a waiter’s tip position where the limb hangs by the sides medially rotated.
- Injury to inferior parts of brachial plexus: occurs when the upper limb is suddenly pulled superiorly, e.g. when person grasp something to break a fall. This causes injury to the inferior trunk which cause claw hand

Bones of the upper limb:

 Clinical significance of humerus: most of the injuries occurs at the surgical neck and are especially common in elderly people with osteoporosis. Avulsion of the greater tubercle results from a fall on the acromion or on the hand when the arm is abducted. These structures can be damages due to humerus fracture:
- Surgical neck: axillary nerve
- Radial groove: radial nerve
- Distal humerus: median nerve
- Medial epicondyle: ulnar nerve

Muscle of the arm:

 Biceps brachii: fusiform muscles with two heads. Located in the anterior compartment it has no attachment to the humerus and extends over three joints, i.e. affecting movement of glenohumeral, elbow and radioulnar. 90o flexion of a supinated forearm is where biceps can generate most power. Long head of the biceps crosses the head of humerus within the shoulder joint and is later surrounded by synovial membrane as it descends in the intertubercular groove of the humerus.
- origin: the tip of coracoids process (short head), supraglenoid tubercle of scapula (long head)
- insertion: tuberosity of radius and fascia of forearm via bicepital aponeurosis
- action: supinate forearm and flex supine forearm
- nerve innervations: musculocutaneous C5, C6
- Testing: supine forearm flexed and prominent bulge on anterior aspect is palpable.
 Brachialis: flattened fusiform muscle lies posterior to the biceps. Its distal attachment covers the anterior part of the elbow joint and is the main and pure flexor of the forearm. Also maintains flexed tone.
- origin: distal half of anterior humerus
- insertion: coronoid process and tuberosity of ulna
- action: flexes forearm
- nerve innervations: same as biceps brachii
 Coracobrachialis: elongated muscle in the superomedial part of the arm and is useful to locate musculocutaneous nerve. Along with deltoid and long head of triceps it serves as shunt muscle resisting downward dislocation of humerus. Median nerve and brachial artery run deep to it and can be compressed.
- origin: tip of coracoids process
- insertion: middle medial humerus
- action: aid flexion and adduction of arm; resists dislocation of shoulder
- nerve innervations: musculocutaneous nerve C5, C6
 Triceps brachii: large fusiform muscle. The long head crosses the shoulder joint so stabilize the adducted glenohumeral joint as a shunt muscle in addition aid extension and adduction of arm. Medial head works as main extensor of forearm in any situation while lateral head is recruited only against resistance.
- origin: infraglenoid tubercle of scapula (long head), posterior surface of humerus (lateral head) superior to radial groove, posterior surface of humerus inferior to radial groove (medial head)
- insertion: proximal end of olecranon and fascia of forearm
- action: extensor of forearm and long head resist dislocation of humerus especially during abduction
- nerve innervation: radial nerve C6, C7, C8
- testing: abduction of arm 90o and extension of arm against resistance. Tendon are palpable.
 Anconeus:
- origin: lateral epicondyle of humerus
- insertion: lateral surface of olecranon and superior part of posterior ulna
- action: extending forearm, stabilizing elbow joint and pronate ulna
- nerve innervation: radial nerve C7, C8, T1

Muscle of the forearm (Flexor):

Superficial layer
 Pronator teres: most lateral of the superficial flexors. Its lateral border forms the medial cubital fossa boundary.
- origin: medial epicondyle of humerus (humeral head), coronoid process (ulnar head)
- insertion: middle convexity of lateral radius
- action: pronates and flexes forearm
- nerve innervation: median nerve C6, C7
 Flexor carpi radius: long fusiform muscle located medial to pronator teres. FCR forms a tendon middle of forearm and the tendon passes through a canal in the lateral flexor retinaculum within its own synovial tendinous sheath of the FCR.
- origin: same as palmaris longus
- insertion: base of 2nd metacarpal
- action: flexes and abducts hand
- nerve innervation: median nerve C6, C7
 Palmaris longus: small fusiform with a long tendon that passes superficial to the flexor retinaculum. The tendon lies deep and slightly medial to this nerve before it passes deep into the retinaculum.
- origin: medial epicondyle of humerus
- insertion: distal half of flexor retinaculum and apex of palmar aponeurosis
- action: flexes hand and tenses palmar aponeurosis
- nerve innervation: median nerve C7, C8
 Flexor carpi ulnaris: most medial superficial flexor. The ulnar nerve enters the forearm by passing between the humeral and ulnar heads of its proximal attachment and FCU also provide guide to the artery which is on its lateral side.
- origin: same as palmaris longus (humeral head), olecranon (ulnar head)
- insertion: pisiform, hook of hamate and 5th metacarpal
- action: flexes and adducts hand
- nerve innervation: ulnar nerve C7, C8
Intermediate layer:
 Flexor digitorum superficialis: median nerve and ulnar artery enter the forearm by passing between the humeroulnar and radial head of the FDS. Near the wrist, FDS gives rise to four tendons passing deep to the flexor retinaculum each enclosed in a synovial common flexor sheath along with FDP.
- origin: medial epicondyle (humeroulnar head), superior half of anterior radius (radial head)
- insertion: shafts of middle phalanges of medial four fingers
- action: flexes middle phalanges and proximal phalanges at proximal interphalangeal and metacarpophalangeal joints respectively
- nerve innervation: median nerve C7, C8, T1
Deep layer:
 Flexor digitorum profundus: the only muscle that flex the distal interphalangeal joints of the fingers anterior to the ulna. FDP tendons are capable of flexing both metacarpophalangeal and wrist joint and enter the fibrous sheath posterior to FDS tendon. FDP can flex only the index finer independently hence fingers can only be flexed independently at proximal and not distal
- origin: proximal medial and anterior surface of ulna and interosseous membrane
- insertion: bases of distal phalanges of fingers
- action: flexes distal phalanges at distal interphalangeal joints
- nerve innervation: ulnar nerve C8, T1 (medial part), anterior interosseous nerve from median C8, T1 (lateral part)
 Flexor pollicis longus: long flexor of the thumb lies lateral to the FDP anterior to the radius. FPL tendon passes deep to flexor retinaculum within its own synovial tendinous sheath.
- origin: anterior surface of radius and interosseous membrane
- insertion: base of distal phalanx of thumb
- action: flexes thumb at all three joints
- nerve innervation: same as lateral part of FDP
 Pronator quadratus: quadrangular pronator of the forearm and is the deepest muscle in the anterior forearm. The muscle initiate pronation and hold ulna and radius together especially when an upwards thrusts are transmitted.
- origin: distal anterior surface of ulna
- insertion: distal anterior surface of radius
- action: pronates forearm; deep fibers bind radius and ulnar together
- nerve innervation: possible median nerve

Muscle of the forearm (extensor):

Superfical layer:
 Brachioradialis: fusiform muscles that lie superficially on the anterolateral surface of the foream. It forms the lateral border of the cubital fossa and does not act on the wrist. Brachioradialis overlies the radial nerve and artery and covered distally by the tendon of abductor pollicis longus and brevis.
- origin: supraepicondular ridge of humerus
- insertion: lateral surface of distal end of radius
- action: weak flexion of forearm but maximal when forearm is midpronated
- nerve innervation: radial nerve C5 - C7
 Extensor carpi radialis longus: partly overlapped by the brachioradialis with which it often blends. It is indispensable during fist clenching
- origin: lateral supraepicondylar ridge of the humerus
- insertion: dorsal aspect of base of 2nd metacarpal
- action: extends and abduct hand at wrist joint
- nerve innervation: radial nerve C6, C7
 Extensor carpi radialis brevis: as it passes distally, it is covered by the ECRL and proceeds under the extensor retinaculum together with ECRL within the tendinous sheath of the extensor carpi radialis. They act synergistically to produce various actions, e.g. with ECU to produce pure flexion or FCR to produce pure abduction.
- origin: lateral epicondyle
- insertion: dorsal aspect of the base of 3rd metacarpal
- action: extends and abduct hand at wrist joint
- nerve innervation: deep branch of radial nerve C7, C8
 Extensor digitorum: principle extensor of the four fingers and the distal tendons pass deep to the extensor retinaculum through tendinous sheath of extensor digitorum and extensor indicis. On the dorsum of hand, the tendons spreads out to the fingers are adjacent ones are linked by inter-tendinous connection.
- origin: lateral epicondyle
- insertion: extensor expansion of medial four fingers
- action: extends medial four fingers across all joints
- nerve innervation: posterior interossesous nerve (radial) C7, C8
 Extensor digiti minimi: tendon of this extensor of little finger runs through a separate compartment of the extensor retinaculum within the tendinous sheath of EDM.
- origin: lateral epicondyle
- insertion: extensor expansion of the 5th finger
- action: extends the 5th finger across all joints
- nerve innervation: posterior interosseous nerve (radial) C7, C8
 Extensor carpi ulnaris: long fusiform muscle located on the medial border of the forearm and has two heads. Distally its tendon runs in a groove between the ulnar head and its styloid process through the tendinous sheath of the ECU. Also indispensable during fist clenching.
- origin: lateral epicondyle of humerus
- insertion: dorsal aspect of base of 5th metacarpal
- action: extends and adducts hand at wrist joint
- nerve innervation: posterior interosseous nerve (radial) C7, C8
Deep layer
 Supinator: lies deep and forms the floor of the cubital fossa. It spirales medially and distance from it origin and envelops the neck of the radius. Radial nerve pierces this muscle and dividing it into deep and superficial parts. It the prime mover for slow and unopposed supination.
- origin: lateral epicondyle of humerus, ulnar crest and supinator fossa
- insertion: lateral posterior and anterior surface of radius
- action: supinates forearm
- nerve innervation: deep branch of radial C7, C8
 Extensor indicis: narrow elongated muscles that lies medial to the EPL. This muscle extends the index finger independently but can also act together with extensor digitorum.
- origin: posterior surface of distal ulna and interosseous membrane
- insertion: extensor expansion of 2nd finger
- action: extends 2nd finger and help extend hand at wrist
- nerve innervation: posterior interosseous nerve (radial) C7, C8
Outcropping muscles
 Abductor pollicis longus: lies just distal to the supinator and closely related to the extensor pollicis brevis. Its tendon may splits into two parts with one attached to the trapezium instead of the usual base of 1st metacarpal. APL acts with APB during abduction of the thumb and with extensor pollicis muscles to extend.
- origin: posterior surface of proximal ulna and radius and interosseous membrane
- insertion: base of 1st metacarpal
- action: abducts thumb and extends at carpometacarpal joint
- nerve innervation: posterior interosseous nerve (radial) C7, C8
 Extensor pollicis longus: short extensor of the thumb lies distal to the APL and its tendon lies parallel to that of the APL. It helps extend the 1st metacarpal and abducts the hand.
- origin: posterior surface of middle ulna and interosseous membrane
- insertion: dorsal aspect of base of distal phalanx of thumb
- action: extends the thumb across all joints
- nerve innervation: posterior interosseous nerve (radial) C7, C8
 Extensor pollicis brevis: larger and longer tendon that that of the EPB. The tendon passes under the extensors retinaculum in its own tendinous sheath of extensor pollicis longus medial to the dorsal tubercle of the radius.
- origin: posterior surface of distal radius and interosseous membrane
- insertion: dorsal aspect of base of proximal phalanx of thumb
- action: extends proximal phalanx of thumb across all joint
- nerve innervation: posterior interosseous nerve (radial) C7, C8

Muscle of the hand:

Thenar muscles:
 Opponens pollicis: lies deep to ADP and lateral to FPB.
- origin: flexor retinaculum and tubercles of scaphoid and trapezium
- insertion: lateral side of 1st metacarpal
- action: opposition of the thumb (rotate metacarpal medially)
- nerve innervation: recurrent branch of medial nerve C8, T1
 Abductor pollicis brevis: short abductor of the thumbs that forms the anterolateral part of the thenar eminence. Assist opposition by slight rotation of the proximal phalanx.
- origin: same as opponens pollicis
- insertion: lateral base of proximal thumb
- action: abducts thumb and helps opposition
- nerve innervation: same as opponens pollicis
 Flexor pollicis brevis: short flexor of the thumb located medial to the APB. Share a common tendon with FPL at the distal attachment.
- origin: same as opponens pollicis (both superficial and deep head)
- insertion: same as abductor pollicis brevis
- action: flexes thumb and aids opposition
- nerve innervation: recurrent branch of medial nerve (superficial head), deep branch of ulnar nerve (deep head)
 Adductor pollicis: deeply placed fan-shaped adductor of the thumb. Two head of the muscle is separated by the radial artery as it enters the palm to form the deep palmar arch.
- origin: base of 2nd metacarpals, capitate and adjacent carpals (oblique head), anterior surface of 3rd metacarpal (transverse head)
- insertion: medial base of proximal thumb
- action: adducts thumb toward lateral border
- innervation: deep branch of ulnar nerve C8, T1
Hypothenar muscles
 Abductor digiti minimi: most superficial hypothenar muscles forming the hypothenar eminence.
- origin: pisiform
- insertion: medial base of proximal 5th finger
- action: abducts 5th finger
- nerve innervation: deep branch of ulnar nerve C8, T1
 Flexor digiti minimi brevis: lies lateral to abductor digiti minimi
- origin: hook of hamate and flexor retinaculum
- insertion: same as abductor digiti minimi
- action: flexes proximal 5th phalanx
- nerve innervation: deep branch of ulnar nerve C8, T1
 Opponens digiti minimi: quadrangular muscle lies deep to the abductor and flexor muscles. Draws 5th metacarpal anteriorly and rotate laterally during opposition. An exclusive muscle in its action.
- origin: hook of hamate and flexor retinaculum
- insertion: medial border of 5th metacarpal
- action: draws 5th metacarpal anteriorly and rotate it
- nerve innervation: deep branch of ulnar nerve C8, T1
Short muscles
 Lumbricals: worm-like muscles
- origin: lateral two tendons of FDP (1st and 2nd), medial three tendons of FDP (3rd, 4th, and 5th)
- insertion: respective extensor expansion of the fingers
- action: flex metacarpophalangeal joint and extend interphalangeal joints (Z-movement)
- nerve innervation: median nerve C8, T1 (1st and 2nd), deep ulnar nerve C8, T1 (3rd and 4th)
 Dorsal interossei: component of the muscles producing the Z-movement
- origin: adjacent sides of two metacarpals
- insertion: proximal phalanges and extensor expansion
- action: abduct 2nd to 4th fingers and perform same action as lumbricals
- nerve innervation: deep branch of ulnar nerve C8, T1
 Palmar interossei: component of the muscles producing the Z-movement
- origin: palmar surfaces of 2nd, 4th and 5th metacarpals
- insertion: base of proximal phalanges and extensor expansion of 2nd, 4th and 5th fingers
- action: adduct 2nd, 4th and 5th finger toward axial line and perform same action of lumbricals
- nerve innervation: deep branch of ulnar nerve C8, T1

Fascia of the upper limb:

 Brachial fascia: deep fascia that encloses the arm and is continuous superiorly with the deltoid, pectoral; axillary and infraspinous fascia.
- Attachment: inferiorly to epicondyle of humerus and olecranon of ulna and continuous with interbrachial fascia and deep fascia of the forearm.
 Arm intermuscular septum: two intermuscular septa, medial and lateral, extend from brachial fascia to central shaft and medial and lateral supraepicondylar ridges of humerus. They divide the arm into anterior and posterior fascial compartment with muscles serving similar function and share common innervation.
 Antebrachial fascia: facia of the forearm and separated by interosseous membrane.
 Palmar fascia: deep fascia of the hand
- Palmer aponeurosis: thick tendinous central part of palmar fascia that overlies the central compartment of the pam. Its apex is continuous with tendon of Palmaris longus and forms four distinct thickenings that spans to and blends the fibrous tendon sheaths at the base of the digits. The superficial transverse metacarpal ligament forms the base of the palmer aponeurosis.
- Skin ligaments: ligaments extend from the palmar aponeurosis to the skin and close the two structures close together allowing little sliding movement.
- Palmar carpal ligament: anterior thickening of the antebrachial fasica that is continuous with the extensor retinaculum

Anatomical features of the upper limb:

 Retinaculum:
- Extensor retinaculum: thickening of the antebrachial fascia posteriorly over the distal end of the radius and ulna, forming a transverse band that retain the extensor tendons in position
- Flexor retinaculum: transverse carpal ligament that is immediately distal to the palmar carpal ligament. It extends between the anterior prominences of outer carp bones and forms the roof of the carpal tunnel.
 Quadrangular space: formed at the back of the shoulder by long head of triceps medially, teres major inferiorly, teres minor superiorly and laterally by the humerus. The axillary nerve and posterior humeral circumflex artery passes through this space
 Triangular space: formed medially to the long head of triceps with teres minor superiorly and major inferiorly. Circumflex scapular passes this space
 Triangular interval: below the teres major and between the long and lateral head of the triceps is another space in which the radial nerve and profunda brachii passes through before entering the radial groove
 Shunt muscles: the deltoid, short head of biceps, coracobrachialis, long head of triceps when contracted keeps the shoulder joints together
 Clinical significance of the arm:
- Bicepital myotatic reflex: limb is passively pronated and partially extended. Tapping of the biceps tendon with the hammer will produce an involuntary contraction of the biceps. Excessive or diminished response may indicated central or peripheral nervous disease.
- Biceps tendinitis: repeated wearing and tear of the synovial sheath in the intertubercular groove due to tendon movement from sports can inflame the tendon and cause shoulder pain.
- Rupture of tendon of long head: occurs in individuals over 35 years of age in which inflamed tendon is torn from its attachment to the supraglenoid tubercle of the scapula associated with a snap or pop sound. The detached muscle belly forms a ball near the centre of the distal part of the anterior aspect of the arm (popeye’ deformity).
- Interruption of blood flow of brachial artery: compressing medial to the humerus near the middle of the arm produces hemostasis but the collateral pathway of arterial anastomoses of the elbow joint Still deliver sustainable amount of blood. This confers protection during gradual or partial occlusion of the brachial artery. Sudden blockage can lead to ischemia and necrosis of forearm.
- Fractures of humeral:
- Injury to the musculocutaneous nerve: commonly inflicted by a weapon such as knife and results in the paralysis of all forearm flexors and the area skin supplied by lateral cutaneous nerve.
- Injury to radial nerve: injury superior to the origin of its branches causes paralysis of all muscles in the extensor compartment. Loss of sensation in the lateral dorsum of hand, back of forearm and arm also occurs. Damage in the radial groove means only the medial head of triceps is affected. Clinical sign is wrist drop.
 Clinical significance of forearm:
- Baseball finger: sudden severe tension on a long extensor tendon can avulse part of its attachment to the phalanx. This deformity results from the distal interphalangeal joint suddenly forced into extreme hyperflexion, e.g. jamming the finger into an object and consequent the person can no longer extend their distal joint.
- Fracture of olecranon: a fractures elbow that is common because the olecranon is subcutaneous and protrusive. Mechanism of injury involves a fall on the elbow combined with sudden contraction of triceps and avulsed segment is pulled away.
- Unusual arterial properties: the brachial artery may divides at a much more proximal position than normal and in 3% of the people, the ulnar nerve may course superficially to that of the flexor muscles. Care in identification is needed to ensure injections are not made in the wrong vessel.
- Median nerve injury: severing of the median nerve in the elbow region will cause flexion of 2nd -3rd fingers of the phalangeal and metacarpophalangeal joint to be lost as the lateral part of FDP, entire FDS and lateral lumbricals are lost. Clinical sign is an extended 2nd and 3rd finger when clenching a fist (hand of benediction)
- Radial nerve injury: a penetrating wound can injure the deep branch of the radial nerve in the forearm and this impairs the ability to extend the thumb and the metacarpophalangeal joints. Integrity of the deep radial nerve may be tested by asking the person to extend the MP joints against resistance; extensor tendon should be prominent.
 Clinical significance of hand:
- Hand infection: as the palmar fascia is thick and strong, swelling resulting from hand infection occurs on the dorsum of hands. Fascia spaces determine the extent of spread of pus, i.e. accumulation in either hypothenar, thenar or adductor compartments.
- Laceration of the palmar arches: bleeding is profuse when the palmar arches are lacerated. For a bloodless surgical operation of hand injuries, it is necessary to compress the brachial artery to prevent blood from reach the distal parts.
- Lesion of median nerve: occurs in two places, the forearm and the wrist where the nerve passes through the carpal tunnel.
- Carpal tunnel syndrome: any lesion that significantly decreases the size of the carpal tunnel or increases the size of the structures that passes through it (e.g. inflammation of synovial sheath) causes this. The median nerve is the most sensitive structure and the two sensory branches can cause paresthesia, hypoesthesia or anesthesia to the skin. Progressive loss of strength in the thenar muscles will occur if compression is not alleviated
- Ape hand: inability to oppose the thumb due to laceration damage to the thenar eminence that disrupts the recurrent branch of median nerve
- Ulnar canal syndrome: compression of the ulnar nerve may occur at the wrist where it passes through the guyon’s canal. It is manifested as hypoesthesia in the medial one and half fingers and weakness of the intrinsic hand muscles.
- Radial nerve injury of hand: even in severe injury of the radial nerve, the effect of radial nerve on hand is minimal as it only supplies a small area on the lateral part of the dorsum of hand.

Cubital fossa:

 Cubital fossa: depression on the anterior aspect of the elbow filled with variable amount of fat.
- Boundaries: superiorly by an imaginary line connecting the medial and lateral epicondyle; medially pronator teres (flexor muscles from medial epicondyle); laterally by the brachioradialis (extensor muscles from lateral epicondyle). Floor of cubital fossa formed by brachialis and supinator and roof is by brachial and antebrachial fascia.
 Content of cubital fossa:
- Terminal part of brachial artery and starting of radial and ulnar arteries
- Deep accompany veins of the arteries
- Biceps brachii tendon
- Median nerve and radial nerve dividing into its superficial and deep branches
- Superficial content of the fossa include median cubital nerve and medial and lateral antebrachial cutaneous nerves.

Arterial supply of arm and forearm

 Course of arteries of arm and forearm
- Brachial: continuation of the axillary artery beginning at the inferior border of teres major and passes anterior to triceps and brachialis. Its pulsation is palpable in the medial bicipital groove and then passes anterior to the medial supraepicondylar ridge in a lateral course. Brachial artery bifurcates under the bicipital aponeurosis into ulnar and radius
- Deep artery of arm: derived superiorly from the brachial artery, It accompanies the radial nerve in the radial groove as it passes posteriorly to the humerus and divids into middle and radial collateral arteries
- Humeral nutrient branch: arise from the artery at mid arm levels and enters the nutrient canal on the anteromedial side of humerus.
- Superior collateral: branches off medially from the brachial artery near mid-arm and accompanies ulnar nerve posterior to the medial epicondyle, where it anastomoses with posterior ulnar recurrent artery
- Inferior collateral: branches from the brachial artery just above the elbow joint and passes inferomedially anterior to the medial epicondyle and joins with ulnar recurrent artery in anastomoses.
- Ulna: descends inferomedially deep to superficial and intermediate layers of flexor muscles. At the medial side of the forearm, its passes superficial to flexor retinaculum at wrist in Guyon canal to enter hand
- Anterior ulnar recurrent: originates from ulnar just distal to elbow joint and passes superiorly between brachialis and pronator teres and anastomoses with inferior ulnar collateral
- Posterior ulnar recurrent: branch of ulnar distal to anterior recurrent. It passes superiorly posterior to medial epicondyle and anastomoses with superior ulnar collateral.
- Common interosseous: branching from the ulnar artery distal to brachial artery bifurcation, it passes lateral and deeply and divides into anterior and anterior interosseous arteries.
- Anterior interosseous: passes distally on anterior aspect of interosseous membrane and pierces membrane and continue distally to dorsal carpal arch
- Posterior interosseous: passes to posterior aspect of the interosseous membrane and gives recurrent interosseous and run distally between superficial and deep extensor muscles
- Radial: runs inferolaterally under brachioradialis and lies lateral to FCR. Later winds around lateral aspect of radius and crosses anatomical snuff box to pierce first dorsal interosseous muscle.
- Radial recurrent: lateral branch of radial artery distal to brachial artery bifurcation and ascends between brachioradialis and brachialis. Later anastomoses with radial collateral.
- Palmer carpal arch: ulnar branches in distal forearm and radial branches near distal border of pronator quadrates runs across anterior aspect of wrist deep to tendons of FDP and anastomoses
- Dorsal carpal arch: ulnar branch proximal to pisiform passes across dorsal surface of wrist deep to extensor tendon and anatomoses with radial branch that originated in proximal part of snuff box where it runs medially across wrist deep to pollicis and extensor radialis tendons.

Vessel supply of the hand

 Arteries of the palm

 Course of the palm
- superficial palmer arch: curves laterally at the level of extended thumb deep to palmar aponeurosis and superficial to long flexor tendons.
- deep palmer arc: curves medially deep to long flexor tendons and in contact with bases of metacarpals
- common palmar digital: pass distally on lumbricals to webbing of fingers
- proper palmar digital: runs along sides of 2nd to 5th fingers
- princeps pollicis: descends on palmar aspect of 1st metacarpal and divides at base of proximal phalanx and run along side of the thumb
- radialis indicis: passes along lateral side of index finger to its distal end
 Arteries of the dorsum

Venous drainage of arm and forearm

 Superficial vein of arm:
- Cephalic vein: lateral superficial vein that runs along the lateral border of the wrist and the anterolateral surface of proximal forearm and arm and into the deltopectoral groove, pierces the costocoracoid membrane and into the axillary vein.
- Basilic vein: medial superficial vein the ascending along the medial side of the forearm and inferior part of the arm, later piercing the brachial fascia and running superiorly parallel to the brachial artery and joints with accompanying veins into axillary vein.
- Median cubital vein: communicating vein between the cephalic and basilic vein in the cubital fossa
- Median antebrachial vein: begins at the base of the dorsum of the thumb and curves around the lateral side of the wrist and ascends the middle of the anterior aspect of the forearms between cephalic and basilica veins.
 Deep veins of arms:
- Brachial vein: paired vein accompanying the brachial artery. Pulsation of brachial artery help move the venous blood. Brachial vein beings at the elbow by union of accompanying veins of ulnar and radial arteries.
- Merging of brachial and basilica forms the axillary vein
 Deep veins of forearm: deep veins arise from the anastomosing deep venous palmar arch. They receive tributaries from veins leaving the muscles which they are related and communicate with e suyperficial veins.
- Radial veins: paired vein arise from the lateral side of the arch and accompany the radial artery
- Ulnar vein: paired vein arise from the medial side accompanying the ulnar artery
- In cubital fossa, deep veins connected to the median cubital vein and unite with accompanying veins of brachial artery.

Nerve supply of arm and forearm:

 Musculocutaneous nerve:
- origin: lateral cord
- course: begins opposite the inferior border of pectoralis minor and pierces the coracobrachialis and continues distally between brachialis and biceps. The nerve emerges lateral to biceps and forms the lateral cutaneous nerve of the forearm, piercing the deep fascia of the proximal cubital fossa.
 Lateral cutaneous nerve of forearm:
- origin: musculocutaneous nerve
- course: emerges lateral to biceps brachii running with cephalic vein and descends along lateral border of forearm to wrist
 Radial nerve:
- origin: posterior cord
- course: enters the arm posterior to the brachial artery and medial to humerus, then descends laterally with the deep artery of arm and passes around the humeral shaft in the radial groove. Radial nerve pierces the lateral intermuscular septum continues inferiorly between brachialis and the brachioradialis to anterior side of lateral epicondyle. In the cubital fossa it divides into deep and superficial branch.
 Posterior cutaneous nerve of the forearm:
- origin: radial nerve
- course: branch from the radial nerve in the radial groove and perforates lateral head of the triceps descends along lateral side of the arm and posterior aspect of forearm to wrist.
 Superficial branch of radial:
- origin: sensory terminal branch of radial nerve
- course: descends between pronator teres and brachioradialis, emerging and arborize over anatomical snuff box, distributing to the skin of the dorsum
 Deep branch of radial:
- origin: motor terminal branch of radial nerve
- course: winds around neck of radius and penetrate the supinator. Emerges in posterior compartment of forearm as posterior interosseous and descends on interosseous membrane
 Median nerve:
- origin: lateral and medial cord
- course: runs on the lateral side of the brachial artery and later crosses to the medial side around mid-arm region and contacts the brachialis. Median nerve then descends into cubital fossa lying deep to the bicipital aponeurosis and exists by passing between heads of pronator teres. Descending between FDS and FDP, it runs deep to Palmaris longus as it approach carpal tunnel.
 Anterior interossesous:
- origin: medial nerve
- distribution: branches distal to cubital fossa descends on anterior aspect of interosseous membrane between FDP and FPL
 Palmer cutaneous branch of median:
- origin: median nerve
- distribution: splits of proximal to flexor retinaculum at distal forearm passes superficial to flexor reticulum to reach skin of central palm
 Ulnar nerve:
- origin: medial cord
- course: passes from axilla anterior to insertion of teres major and long head of triceps on medial side of the brachial artery. Pierces the medial intermuscular septum with the superior ulnar collateral and descends between septum and medial head of the triceps. Ulnar nerve pass posterior to medial epicondyle into forearm between the heads of FCU and descends between FCU and FDP and later become superficial in distal forearm. Along with the artery, the ulnar nerve pass through the Guyon canal into the hand.
 Palmar cutaneous branch of ulnar:
- origin: ulnar nerve
- course: branches at middle of the forearm and descends anterior to ulnar artery and perforates deep fascia in distal forearm and runs in subcutaneous tissue to palmar skin medially
 Dorsal cutaneous branch of ulnar:
- origin: ulnar nerve
- course: branches distally at forearm and passes between ulna and FCU and enters subcutaneous tissue to dorsal skin medially
 Medial cutaneous:
- origin: medial cord C8, T1
- course: perforates deep fascia with basilic vein proximal to cubital fossa and descends medially of forearm in subcutaneous tissue.

Nerve supply of hand

Course of nerves in hand

 Recurrent branch of median: loops around distal border of flexor retinculum and enters thenar muscles
 Lateral branch of median nerve: branches from median immediately distal to flexor retinaculum and runs laterally to palmar thumb and radial side of 2nd finger
 Medial branch of median nerve: runs medially to adjacent sides of 2nd – 4th finger
 Palmer cutaneous branch of median nerve: refer to above (nerve of forearm)
 Palmar cutaneous branch of ulnar: refer to above (nerve of forearm)
 Dorsal branch of ulnar nerve: refer to above
 Deep branch of ulnar: arises from ulnar nerve as it passes between pisiform and hamate and courses between muscles of hypothenar eminence and deeply across palm with deep palmar arch
 Superficial branch of ulnar: passes palmaris brevis and divides into two common palmar digital nerves

Glenohumeral joint:
 Glenohumeral joint: a ball and socket type synovial joint that is the most mobile but unstable joint in the body. The large round humeral head articulates with a relatively shallow glenoid cavity. Both articular surfaces are covered with hyaline cartilage.
 Joint capsule of glenohumeral joint: joint surrounded by a loose fibrous joint capsule and is attached medially to the margin of the glenoid cavity and laterally to the anatomical neck of the humerus. It encloses the long head of the biceps attached to the supraglenoid tubercle of the scapula. The inferior of the joint, unsupported by the rotator cuff muscle is the weakest area and is lax when the arm is adducted and taught when abducted.
- apertures: opening between tubercles of the humerus for passage of the long head tendon and opening anteroinferiorly to the coracoids process that allows communication between the subscapular bursa and synovial cavity of the joint.
- Synovial membrane: lines the internal surface of the capsule and reflects onto the glenoid labrum and humerus. The membrane also forms a tubular sheath for the tendon of the long head of biceps and extends as far as the surgical neck of the humerus.
 Ligament of the Glenohumeral joint:
- Coracohumeral ligament: intrinsic ligament that strengthen the capsule superiorly (part of the fibrous layer) and passes from the base of the coracoids process to the anterior aspect of the greater tubercle of the humerus.
- Glenohumeral ligament: three fibrous bands located on the internal aspect of the capsule and reinforce the anterior part of the joint The ligament radiate laterally and inferiorly from the glenoid labrum at the supraglenoid tubercles of the scapula and attaches to the anatomical neck of the humerus
- Transverse humeral ligament: broad fibrous band that runs obliquely from the greater to the lesser tubercle of the humerus and bridging the intertubercular groove. The ligament converts the groove into a canal that holds the synovial sheath and the tendon f the biceps brachii in place during movements of shoulder joint.
- Coracoacromial arch: extrinsic structure formed with the coracoacromial ligament from the acromion to the coracoids process. This is a protective arch that prevents the superior displacement of the humeral head from the glenoid cavity. The arch is so strong that clavicle or humeral shaft will break first.
 Movement of the Glenohumeral joint: freedom of the movement of the shoulder joint is the result of the laxity of its joint capsule and large size of the humeral head compared with the small glenoid cavity. Movement around three axes are permitted.
 Blood supply of the Glenohumeral joint: supplied buy the anterior and posterior circumflex humeral arteries and branches of the suprascapular artery
 Innervation of the Glenohumeral joint: suprascapular, axillary and lateral pectoral nerve
 Bursa of the Glenohumeral joint: Shoulder joint of bursae are located where tendons rub against bone, ligament or other tendons. The bursae are of special clinical importance because some communicate with the articular cavity and consequently opening a bursa allows entrance into the cavity.
- Subscapular bursa: subscapular bursa is located between the tendon of subscapularis and the neck of the scapular and it protect the tendon where it passes inferior to the coracoids process. It is connected with the joint capsule.
- Subacromial bursa: located between the acromion, coracoacromial ligament and deltoid superiorly and supraspinatus tendon and joint capsule inferiorly, It facilitates movement of the supraspinatus tendon and the deltoid over the joint.
- Subdeltoid bursa: lateral continuation of the subacromial bursa and lies under the deltoid muscle
 Clinical significance of glenohumeral joint:
- Dislocation of the glenohumeral joint: due to support of the rotator cuff and the coracoacromiol arch, most dislocation occurs inferiorly and occurs after an avulsion fracture of the greater tubercle. Anterior dislocation occurs in young adults caused by excessive extension and lateral rotation of the humerus (e.g. baseball throw posture)
- Rotator cuff injury: musculotendinous rotator cuff is commonly injured during repetitive use of the upper limb above horizontal. Recurrent inflammation is common cause of the shoulder pain and results in tear of the muscles tendon
- Glenoid labrum tear: tearing of the glenoid labrum commonly occurs in athletes who throw a baseball or football or in those with unstable shoulders. Usually a tear occurs in the anterosuperiorly part of the labrum and typical symptoms are pain while throwing and a sense of snapping during abduction.

Elbow joint:

 Elbow joint: hinge type synovial joint made up of the spool shaped trochlea and spheroidal capitulum of the humerus with the trochlear notch of the ulna. The articular surfaces covered with hyaline cartilage and are most fully in contact when the forearm is flexed and midway between pronation and supination.
 Joint capsule of elbow joint: fibrous capsule surrounds the elbow joint and is attached to the humerus at the margins of the humeral articular surface and proximal to the coronoid and olecranon fossae. The joint is weak anteriorly and posteriorly by strengthened on the side by collateral ligaments.
- Synovial membrane: lines the internal surface of the fibrous layer of the capsule and the intracapsular non-articular parts of the humerus.
 Ligament of elbow joint: collateral ligament of the elbow are very strong triangular bands thickenings of the fibrous layer of the joint capsule
- Radial collateral ligament: extends from the lateral epicondyle of the humerus and blends distally with the anular ligament
- Anular ligament encircles and holds the hand of the radius in the radial notch of the ulna
- Ulnar collateral ligament: extends from the medial epicondyle of the humerus to the coronoid process and olecranon of the ulna consisting of three bands – strongest anterior cord-like, weakest posterior fan-like, and olique band
 Movement of elbow joint: allows flexion and extension at the elbow joint. Fully extended ulna makes an angle of 170o which is the carrying angle. In female the carrying angle is more acute to allow clearing of a greater pelvis when walking.
 Blood supply of elbow joint: anastomoses the arteries around the elbow joint
 Nerve innervation of the elbow joint: supplied by the musculocutaneous, radial and ulnar nerve
 Clinical significance of the elbow joint:
- Dislocation of the elbow joint: posterior dislocation of the elbow joint occurs when falling on theirs with elbows flexed, hyperextension or a blow that drives the ulna posteriorly. Ulnar nerve may be affected cause numbness of little finger and weakness of flexion and adduction of the wrist
- Avulsion of medial epicondyle: severe abduction and extension o the elbow in children can cause traction of the ulnar collateral ligament and pull the medial epicondyle distally.

Proximal Radioulnar joint:

 Proximal radioulnar joint: pivot type synovial joint that allows movement of head of the radius on ulna. The articulation involves the head of radius with radial notch of ulna.
 Joint capsule of the proximal radioulnar joint: fibrous layer of joint capsule encloses the joint and is continues with the capsule of the elbow joint. The synovial membrane is an inferior prolongation of the synovial membrane of the elbow joint.
 Ligament of proximal radioulnar joint: anular ligament attached to the ulna anterior and posterior to its radial notch and surrounds the radial head like a collar.
 Movement of the proximal radioulnar joint: the head of radius can rotate within the collar formed by the anular ligament producing supination and pronation. The axis passes through the centre of the radial head and the site.
 Blood supply of proximal radioulnar joint: periarticular arterial anastomoses of the elbow joints
 Nerve innervation of the proximal radioulnar joint: supplied by musculocutaneous, radial (supination) and median (pronation)

Distal Radioulnar joint:

 Distal radioulnar joint: a pivot type synovial joint and the radius moves around the relatively fixed distal end of the ulna. The joint is made up of the rounded head of the ulna articulated with the ulnar notch on the medial side of the radius. A fibrocartilagenous articular disc extending from the ulnar notch to the styloid process of the ulna binds the ulna and radius together.
 Joint capsule of distal radioulnar joint: fibrous capsule enclose the distal radioulnar joint by is deficient superiorly. The redundancy of the synovial capsule accommodates the twisting of capsule that occurs when the distal end of the radius travels around the fixed distal end of ulnar.
 Ligaments of the distal radioulnar joint: anterior and posterior ligament strengthen the fibrous layer of the joint capsule and these relative weak bands extends from radius to ulna across the anterior and posterior surface.
 Movement of the distal radioulnar joint: during pronation of the forearm, the distal end of the adjust rotates anteriorly and medially across the ulna. During supination the two bone uncrosses again.
 Blood supply of the distal radioulnar joint: anterior and posterior interosseous arteries
 Innervation of the distal radioulnar joint: anterior and posterior interosseous nerve

Wrist joint:

 Wrist joint: complex of eight carpal bones articulating proximally with the forearm and distally with the five metacarpals. Position of the joint is indicated by a line jointing the styloid processes of the radius and ulna. The ulna however does not participate in the wrist joint; the distal end of the radius and articular disc articulate with the proximal row of carpal bones except pisiform.
 Joint capsule of wrist joint: wrist joint is surrounded by fibrous capsule that;s attached to the distal ends of the radius and ulna and proximal row of carpals.
 Ligament of the wrist joint: both palmar and dorsal is directed so the hand follows the radius during the respective movement, supination and pronation
- Palmar radiocarpal ligament: strong ligament passing from the radius to the two rows of carpals
- Dorsal raduocarpal ligament: ligament on the dorsum of the hand
- Ulnar collateral: medial ligament attached to the ulnar styloid process and triquetrum
- Radial collateral: lateral ligament attached to the radial styloid process and scaphoid
 Movement of the wrist joint: permits movement in all three axis however more capable of flexion than extension, adduction than abduction.
 Blood supply of wrist joint: dorsal and palmar carpal arches
 Nerve innervation of wrist joint: anterior interosseous branch of median and posterior interosseous branch of radial and dorsal and deep branches of ulnar nerve.
 Clinical significance of wrist joint:
- Scaphoid is the most frequent fractured bone in a wrist fracture

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License