Upper Extremity Landmarks



Upper Extremity Landmarks











DERMATOMES







MYOTOMES







OSTEOTOMES



BRACHIAL PLEXUS BLOCK



  • Formed from anterior primary rami of C5-T1.


  • 5 roots, 3 trunks, 3 cords, 5 nerves.


  • 3 trunks: upper (C5, C6), middle (C7), and lower (C8, T1) in the interscalene space, anterior to scalenus medius and posterior to scalenus anterior.


  • The trunks pass over the lateral border of the first rib and under the clavicle; each trunk (superior, middle, and inferior) divides into anterior and posterior branches. The branches reunite to form cords.


  • 3 cords around the axillary artery:



    • Lateral cord: lateral portion of the median nerve and musculocutaneous nerve.


    • Medial cord: medial portion of the median nerve, ulnar nerve, medial cutaneous nerve of the forearm, and medial cutaneous nerve of the arm.


    • Posterior cord: axillary and radial nerves.



AXILLARY














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  • Cervical C5, C6.



  • Posterior to the third part of axillary artery.



  • Run laterally to the surgical neck of the humerus.



  • Posterior branch gives off the upper lateral nerve of the arm.


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  • Cutaneous innervation of the shoulder.



  • Deltoid.



  • Shoulder joint.


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  • Contraction of the deltoid.


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MUSCULOCUTANEOUS

















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  • Cervical C5, C6.


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  • Cutaneous innervation of the lateral part of the forearm.



  • Ventral musculature of the arm.


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  • Flexion of the forearm by contraction of the biceps (long and short head).



  • Possible confusion with a radial stimulation. The contraction of the supinator and brachioradialis muscles innervated by the radial gives a flexion and supination of the forearm.


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The contraction of the supinator and brachioradialis muscles innervated by the radial gives a flexion and supination of the forearm.


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RADIAL














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  • Cervical C6, C8.



  • Posterior to the axillary and brachial arteries.



  • Run with the profunda brachii artery between the long and medial heads of triceps.



  • Before leaving the axilla, the radial nerve gives the posterior cutaneous nerve of arm that innervates the posterior upper arm skin.



  • The posterior cutaneous nerve of forearm innerves the posterior forearm skin.



  • The deep radial branch innerves the forearm musculature and posterior part of carpal bones.



  • The superficial radial nerve passes over the tendons of the snuff box and terminates as cutaneous branches to the dorsum of the hand.


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  • Cutaneous innervation of the posterior part of the arm, forearm, and posterolateral part of the hand.



  • Extensor muscles (dorsal musculature in the upper extremity below the shoulder).



  • Radioulnar joint and wrist joint.


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  • Extension and supination of forearm.



  • Extension of the wrist and the fingers.



  • Abduction and extension of the thumb.


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MEDIAN














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  • Cervical C6, thoracic T1.



  • The median nerve lies lateral to the axillary artery and then lateral to the brachial artery before crossing the artery at the level of the midhumerus.



  • Gives branch to elbow joint (superior portion of the radioulnar joint): capitulum of humerus, radial head, and epitrochlea of humerus.



  • Gives branch to pronator muscles at level of forearm (one of the terminal branches is the anterior interosseous n.).




    • Arises just below the two heads of pronator teres m.



    • Contraction of flexor digitorum superficialis = flexion of proximal interphalangeal (IP) joints and secondary metacarpophalangeal (MCP) joints and wrist.



    • Contraction of flexor digitorum profundus (60% to 70% median and 30% to 40% ulnar) = flexion of distal IP joints and secondary flexion of proximal IP and MCP joints and wrist.


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  • Elbow joint (radioulnar joint).



  • Cutaneous innervation of the lateral palmar skin.



  • Ventral musculature of the forearm (flexor and pronator muscles).



  • Wrist and lower radioulnar joint (sensory supply to the anterior part of carpal bones).


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  • Flexion of the fingers and wrist.



  • Pronation of the wrist.



  • Opposition of the thumb (adductor pollicis brevis and opponens pollicis).


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Martin and Gruber Anastomosis

Median and ulnar anastomosis at forearm.

Present in 20% of patients.

Median and ulnar stimulations give the same flexion of the digits (flexion of the last 2 digits and adduction of the thumb) but adduction and flexion of the wrist are exclusively obtained with ulnar stimulation (no anastomosis with flexor carpi ulnaris).





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ULNAR












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  • Cervical C8, thoracic T1.



  • Medial to the axillary and brachial arteries.



  • Gives a branch to elbow joint: olecranon and medial epicondyle of humerus.



  • Divides into terminal branches at the pisiform bone.



  • Dorsal cutaneous branch arises 5 cm proximal to the wrist; passes deep to flexor carpi ulnaris.


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  • Cutaneous innervation of the medial part of the hand.



  • Ventral musculature of the hand.



  • Deep terminal branch: wrist joint, interossei, lumbricals, adductor pollicis, flexor pollicis brevis.


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  • Adduction of the thumb and little finger.



  • Prehension by the little finger and thumb.



  • Adduction and supination of the wrist.



  • Martin and Gruber anastomosis: see median.



Tips:



  • Elbow joint innervation = radial, median, and ulnar.


  • Wrist joint innervation = radial (posterior interosseous), median, and ulnar (deep terminal branch).


  • Medial cutaneous nerve of arm and forearm arise from the medial cord (C8-T1 roots).







UPPER EXTREMITY: DERMATOMES

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Jul 20, 2016 | Posted by in ANESTHESIA | Comments Off on Upper Extremity Landmarks

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