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31 Cards in this Set
- Front
- Back
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What is a dermatome and how are they developed.
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A dermatome is a segment of skin supplied by 1 spinal nerve. During development nerves grow into developing limb buds and as the limb bud increases in size the nerves are dragged along with the structures they innervate forming the dermatome pattern.
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Why does a lesion of single spinal nerve not usually result in anaesthesia of the entire dermatome area.
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Adjacent dermatomes overlap except at axial line, the line of junction of dermatomes supplied by discontinuous spinal levels.
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Where are the preaxial and post axial borders of the limbs
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Upper limb: preaxial border is outer border, postaxial is inner border.
Lower limb: preaxial border is inner border, postaxial is outer border. |
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State the segmental innervation of all movements at the shoulder, elbow, wrist and finger joints.
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Shoulder
- Abduction = C5 - Adduction = C6, C7, C8 Elbow - Flexion = C5, C6 - Extension = C7, C8 Wrist - Pronation =C6 – pronator quadrates and pronator teres – median nerve - Supination = C7,C8 – supinator –radial nerve - Flexion = C6,C7 - Extension =C6, C7 Hand - Intrinsic muscles – T1 – abduction and adduction of fingers – interossei Fingers - Flexion and extension = C7,C8 |
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Describe the segmental innervations of the various movements of the lower limb.
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HIP
- Lateral rotation = L5, S1 - Medial rotation = L1, L2,L3 - Adduction = L1,L2,L3,L4 - Abduction = L5,S1 - Extension = L4, L5 - Flexion = L2,L3 Knee - Flexion = L5,S1 - Extension = L3,L4 Foot - Inversion = L4, L5 - Eversion = L5, S1 - Dorsiflexion =L5, S1 - Plantarflexion = S1, S2 |
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Identify the segmental sensory innervations of all parts of the upper and lower limb
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C4-Skin Over The Shoulder Tip
•C5-Radial side of Upper Arm •C6 Radial Side of Forearm including thumb •C7 skin of the hand •C8-Ulnar side of the hand and Forearm •T1-Ulnar side of the Upper Arm •T2-Skin of the Axilla The Front of limb is supplied largely by lumbar segments •The Back of limb is supplied largely by Sacral Segments •The Saddle Area is supplied by Sacral Segments •The Perineal Area is supplied by Sacral Segments •To Note The Discontinuity of Dermatomes at the back of the limb (Axial Line) |
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Define a myotome and a motor unit
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A muscle mass supplied by a single spinal nerve. Most muscles are made up of more than one myotome.
A motor unit – the muscle fibres supplied by the single spinal nerve. The size of motor units varies considerably in different muscles eg in the eye, the ocular muscles may have motor units containing 5-6 muscle fibres whereas in the muscles of the buttocks there may be more than a 1000 muscle fibres in a motor unit. The smaller the motor unit the more precise the movement. |
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Describe the lumbar sacral plexus
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The Sacral Plexus:
Composed of: Lumbosacral trunk (half of L4 & all L5)Sacral spinal segmental outflow •Plexus forms within the pelvic cavity •Plexus lies in relation to piriformis •Sacral plexus supplies: - Pelvic region - Gluteal region - Perineal region - The lower limb (via the sciatic nerve) The Lumbar Plexus •It forms behind within the psoasmajor muscle •Nerves emerge either medial or lateral to the borders of the psoasmajor muscle •Nerves emerging lateral to psoas •The femoral (L2-L4) •Iliohypogastric •Ilioinguinal •Lateral cutaneousnerve of the thigh •Nerves emerging medial to psoas •The obturatornerve •The lumbosacraltrunk |
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State the composition and formation of a mixed spinal nerve.
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A mixed spinal nerve is one of a pair of segmental nerves from a vertebral level.
1 mixed spinal nerve leaves the vertebrae column on the right and the other on the left via the intervertebral foramina. Each mixed spinal nerve comprises of - Dorsal root ( sensory or afferent) - Ventral root ( efferent: motor – skeletal muscle, autonomic – smooth muscle, glands) |
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Draw the brachial plexus.
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Really tired? Drink coffee or tea.
Roots: C5,C6,C7,C8,T1 Trunks: superior, ( C5 & C6) middle (C7), inferior ( C8 & T1) Divisions: posterior and anterior divisions of each trunk Cords: named in relation to axillary artery. Lateral, posterior, medial Terminal branches: lateral – musculocutaneous nerve ( C5,C6 |
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Which muscle of the upper limb is the only one not to be supplied by the brachial plexus
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The trapezius – accessory nerve from cranial spinal nerves |
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What are the spinal root values of the nerves of the brachial plexus?
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Musculocutaneous – lateral cord – C5-C7
- Anterior muscles of arm – bicep brachii, coracobrachialis, brachialis - Lateral cutaneous nerve of forearm -> skin of lateral forearm Median – lateral and medial cords – C6-T1 - Flexor compartment of forearm: pronator teres, pronator quadratus, flexor carpis radialis, FDS, Palmaris longus, lateral half of FDP ( NOT flexor carpis ulnaris & ulnar half of FDP) - Intrinsic muscles of palmar thenar compartment – abductor policis brecis, opponens pollicis, flexor pollicis brevis and lumbricals- 1& 2 - Palm of hand – branch goes over carpal tunnel - Palmar Skin of hand and fingers lateral to axial line of digit 4 Ulnar – medial cord –C8-T1 - Passes medial epicondyle - Flexor carpis ulnaris, ulnar half of FDP - Most intrinsic muscles of hand - Palmar Skin of hand medial to axial line of digit 4 Radial – posterior cord – C5-T1 - All muscles of posterior compartments of arm and forearm - Skin of posterior arm and forearm and dorsum of hand except for nail beds and half of digit 4 and digit 5 Axillary – Posterior cord –C5,C6 - Glenohumeral joint: Deltoid, Teres minor - Skin over deltoid – regimental badge Thoracodorsal - side branch of posterior cord – C6,C7,C8 - Latissimus dorsi Long thoracic – C5-C7 - Seratus anterior – winged scapula Upper, middle, lower subscapular – posterior cord – c5-t1 - Subscapularis and teres major |
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Draw the path of the cords and terminal branches of the brachial plexus and the arteries along the humerus.
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Cords are named according to position in relation to axillary artery.
Lateral cord – musculocutaneous- runs down the anterior centre of the humerus and innervates biceps brachii, coracobrachialis and brachialis. Passes into the forarm as the lateral cutaneous branch, supplying the sensory innervations to the lateral aspect of the forearm. Posterior cord – behind axillary artery – branches into axillary nerve which circles the surgical neck of the humerus, along with the posterior and anterior circumflex humeral arteries. Also branches into radial nerve which crosses the posterior aspect of the humerus, in the radial groove with the deep brachial artery ( radial collateral arteries )and innervates triceps brachii- long, short, middle heads. The radial nerve passes anterior to the lateral epicondyle into the forearm. Medial cord – joins with lateral cord to form median nerve which lies anterior to axillary artery and then lies medial to the brachial artery and enters the cubital fossa with it. The medial cord also forms the ulnar nerve which lies medial to the median nerve and does not pass over the humerus until passing posterior to the medial epicondyle on entering the forearm. |
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Which muscles could be affected in a superior brachial plexus injury?
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Excessive increase in angle between neck and shoulder
- Thrown from a motorbike or horse landing on shoulder - In newborns when excessive stretching of the neck occurs during delivery Stretches or ruptures superior parts of the brachial plexus ( C5 C6). SIGNS of superior brachial plexus injury: ERB DUCHENNE PALSY - Waiters tip: arm is medially rotated, adducted shoulder, extended elbow Axillary nerve – C5-C6 – deltoid paralysed, loss of sensation in regimental badge area Musculocutanous nerve – C5-C7 – biceps brachii, coracobrachialis and brachialis are paralysed. Long thoracic nerve – C5-C7 – winged scapula – paralysis of seratus anterior |
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Describe the consequences of chronic microtrauma to the superior part of the brachial plexus.
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Chronic microtrauma can be achieved from wearing a heavy backpack eg hikers and can produce motor and sensory deficits in musculocutaneous and radial nerves. This may produce muscle spasms and a severe disability in hikers.
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Describe acute brachial plexus neuritis.
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Acute brachial plexus neuritis is a neurological condition of unknown cause that results in the sudden onset of severe pain around the shoulder region. The pain starts at night and is followed by muscle weakness and sometimes muscular atrophy.
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Describe hyperabduction syndrome.
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Hyperabduction of the arm due to performing manual tasks over the head causes the cords of the brachial plexus to become compressed between the corocoid process of the scapula and the pectoralis minor tendon.
Symptoms: pain radiating down arm, numbness, parresthesia ( tingling), erythema ( redness of the skin – capillary dilation) and weakness of the hands. The symptoms are caused by compression of the axillary vessels – ischaemia of upper limb and distension of superficial veins, and of axilary nerves. |
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Describe the consequences of injuries to the inferior part of the brachial plexus ( c7-t1)
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Injuries to inferior parts of brachial plexus are far less common and occur when the upper limb is suddenly pulled superiorly
- When a person grabs something to break a fall - When a parent swings a child by their arm - When a baby’s upper limb is pulled excessively during delivery Klumpke paralysis – C8,T1 Radial nerve – weakened but still supplied from C5, C6, C7 – so posterior arm and forearm is fine! Ulnar nerve – C7,T1 – paralysis of flexor carpis ulnaris, ulnar half of FDP, hypothenar intrinsic muscles, 4th and 5th lumbricals - Claw hand – metacarpal phalangeal joints are extended and IP joints are flexed ( usually other way around – due to paralysis of lumbricals) similar to hand of benediction caused by loss of median nerve but only occurs when asked to make a fist. decreased grip strength. |
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What is proprioception?
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The unconscious perception of movement and spatial orientation arising from stimuli within the body itself.
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Describe fractures of the ulna and radius.
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Transverse fracture at same level
- Direct injury Because the radius and ulna are firmly bound by interosseous membrane, the fracture of one bone is likely to be associated with dislocation of the nearest joint. Fracture of distal end of radius - Fall on outstretched upper limb – forced dorsiflexion of hand - in elderly > 50 yrs - Women more susceptible – more weekend bones by osteoporosis. Colles fracture (Dinner fork deformity) - Distal fragment of radius overrides the rest of the bone - Distal fragment may be comminuted - Ulnar styloid process may break off – avulsion In children, the epiphysial plate may be damaged – the healing process may cause malalignment of the epiphyseal growth plate and thus disturbance of radial growth |
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How does a fracture of scaphoid occur. |
Fracture of scaphoid occurs from a fall on the palm when the hand is abducted.
Pain on lateral side of wrist, particularly on dorsiflexion and abduction of the hand. - Inital radiographs of the wrist may not reveal the fracture – mis-diagnosed as severely sprained wrist. - Radiographs 10-14 days later reveal fracture because bone resorption has occurred. - Union of fractured parts may take at least 3 months – due to poor blood supply to proximal part. |
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What may occur after a fracture of scaphoid.
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Avascular necrosis of the proximal fragment of scaphoid due to the poor blood supply to the proximal part.
- Degenerative joint disease of the wrist may result. - It may be necessary to fuse the carpals surgically – arthrodesis. |
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What nerve is at risk in a hammate fracture?
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The ulnar nerve is at risk as it lies close to the hook of hammate – decreased grip strength the hand.
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Describe fracture of metacarpals.
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Metacarpals are closely bound together ( except thumb) – isolated fractures are stable – good blood supply = heal rapidly.
Severe crushing injuries of the hand -> multiple metacarpal injuries -> instability of hand Boxer’s fracture – fracture of 5th metacarpal ( pinkie) -> flexion deformity. |
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Describe fracture of phalanges.
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Distal phalanx – crushing injury eg caught in a door – extremely painful haematoma and comminuted bone.
Proximal and middle plalanx – crushing or hyperextension - close relationship to flexor tendons so must be carefully realigned. |
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Describe the muscles of the anterior arm.
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All muscle of anterior arm are innervated by musclocutaneous nerve
Biceps brachii - Long head – supraglenoid tubercle via intertubercular groove under transverse humeral ligament., short head – corocoid process of scapula - flexor of elbow joint – when arm is suppinated - Suppination – when arm is pronated - Attaches to tuberosity of radius and fascia of forearm via bicipital aponeurosis – covers the cubital fossa protecting the brachial artery and median nerve Coracobrachialis - Corocoid process of scapula -> middle third of medial surface of humerus - Flexion and adduction of arm - Resists dislocation of shoulder Brachialis - Distal half of anterior surface of humerus -> coronoid process and tuberosity of ulna - MAIN Flexion of forearm |
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Describe the muscles of the posterior arm.
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The muscles of the anterior arm are innervated by the radial nerve.
Triceps brachii – long and lateral heads are innervated above radial groove so midshaft fractures do not usually effect extension of elbow - Long head – infraglenoid tubercle of scapula – RESISTS DISLOCATION OF HUMERUS – important in adduction!! - Lateral head – posterior surface of humerus superior to radial groove - Medial head – posterior surface of humerus inferior to radial groove - Attach to proximal end of olecranon of ulna and fascia of forarm. - EXTENSION of forearm. Anconeus - Lateral epicondyle -> lateral suface of olecranon and superior and posterior part of ulna - Assists triceps with extension - Stabilises elbow joint. |
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How do you test for the triceps and biceps of the arm.
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Biceps brachii – flexion against resistance when forearm is suppinated
Triceps brachii – extension against resistance when arm is abducted 90 degrees. Brachialis – forearm is semipronated and flexed against resistance |
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Describe the boundaries of the cubital fossa.
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Upper boundary: imaginary line between medial and lateral epicondyles of humeru
Medial boundary: pronator teres Lateral boundary: brachioradialis Roof: bicipital aponeurosis connected tendon of biceps brachii and anterior fascia of forearm Floor: brachialis of arm attaching to coronoid process and ulnar tuberosity and suppinator originating from lateral epicondyle ( extensor compartment of forearm) |
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Describe the course of the nerve, veins and arteries that pass through or near the cubital fossa.
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The superficial veins begin on either side of the dorsal venous arch of the hand and extend up through the foream, cephalic vein on the lateral side and basilic vein on the medial side.
The median cubital vein forms an anastomose between the cephalic and basilic veins, which crosses over the cubital fossa – blood is taken from this vein!! Contents of the cubital fossae: - The brachial artery, lying between the biceps tendon and the medial nerve, which bifurcates into the radial and ulnar arteries - Deep accompanying veins of the arteries - Biceps brachii tendon - Median nerve Radial nerve – deep between muscles forming the lateral boundary – the extensor muscles of the forearm |
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Describe venepuncture at the cubital fossa.
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Venipuncture – the puncture of a vein to draw blood or inject solution.
- Apply a tourniquet to the arm which occludes venous return and the vein becomes distended and usually visible and palpable - Median cubital vein – most commonly used - Once punctured the tourniquet is removed to prevent extensive bleeding. - Median cubital vein |
