Unit Ii Anatomy Lecture 7

Front 1

Describe, in general, lesions of the brachial plexus

Back 1

Complete lesions of all roots are rare
Incomplete nerve injuries are common and are usually caused by traction or pressure on nerves or nerve roots

Front 2

What is the syndrome associated with the upper brachial plexus segment (upper trunk injury)

Back 2

Upper trunk syndrome (C5-C6) or Erb-Duchenne Palsy

Front 3

Describe Upper Trunk Syndrome

Back 3

Injuries to superior part of bracial plexus result from excessive increase in angle between neck and shoulder
Example, landing on shoulder in manner that widely separates shoulder from neck
Axillary nerve is derived from similar spinal cord segments and is included
Lesion often occurs at Erb's point

Front 4

What are some examples of mode of injury of upper trunk syndrome?

Back 4

Displacement of head toward contralateral side and depression of shoulder to ipsilateral side may result when newborn's neck is excessively stretched during delivery, fall from horse or motorcycle, prolapsed intervertebral disc (roots of C5-C6, upper radicular syndrome)
Roots may be irritated by arthritic changes in either synovial joint between vertebrae or in incovertebral joints (frequent sites for bone sprus)

Front 5

What are the myotomes of the upper limb affected by upper trunk syndrome?

Back 5

C5- at shoulder, abduction and lateral rotation
C5, C6- at elbow, flexion
Nerve damage will cause paralysis of muscles of shoulder, arm, and forearm supplied by C5-C6 (deltoid, biceps, brachialis, brachioradialis)

Front 6

What are some clinical features of upper trunk syndrome?

Back 6

1) Arm is adducted and medially rotated at shoulder
2) Arm hangs at side in medial position and is extended at elbow
3) Forearm is rotated medially and palm of hand faces superiorly
Collectively, commonly known as "waiters tip"

Front 7

Describe lower brachial plexus segment, or lower trunk injury

Back 7

Injuries to inferior part of brachial plexus less common
May occur when upper limb is suddenly pulled superiorly over head
May injure inferior trunk of plexus (C8-T1) and may place traction on or separate dorsal and ventral roots of spinal nerves from spinal cord
Short muscles of hand are affected, resulting in claw-hand deformity

Front 8

Describe Palsy of Klumpke

Back 8

Involvement of C8-T1
AKA Thoracic outlet syndrome
Invloves superior thoracic aperature and is general term for several conditions attributed to compromrise of blood vessels or nerve fibers at any location between base of neck and axilla
Classification based on structure known or presumed to be compromised, two main groups (vascular and neurologic)
Usually involved upper limb
Various types exist

Front 9

Describe costoclavicular syndrome

Back 9

Coldness of skin of upper limb and diminished radial pulse
Results from compression of subclavian artery between clavicle and first rib

Front 10

What is upper radicular syndrome?

Back 10

Roots of C8-T1 injured by prolapsed intervertebral disc

Front 11

What are the myotomes and action of upper limbs affected by thoracic outlet syndrome?

Back 11

1) C8- flexion of wrist and fingers
2) T1- intrinsic muscle function of hand

Front 12

Describe Horner's syndrome

Back 12

Proximal injury that cause serious damage to cervicothoracic ganglion (stellate) producing sympathetic denervation to head

Front 13

Describe clinical features of injury to C8 and T1

Back 13

Combined "claw-hand" (ulnar nerve) and "simian-hand" (median nerve, cannot oppose thumb)
Intrinsic muscle wasting and includes thenar and hypothenar muscles
Hyperextension at MCP joints, little clawing of IP joints because of weak flexor muscles of forearm
Loss of opposition for thumb
If C8 involved, flexion is weak for wrist and finger

Front 14

Describe damage to the ulnar nerve

Back 14

Prevents thumb from being adducted because nerve loss to adductor pollicis

Front 15

Describe damage to the median nerve

Back 15

Holds thumb in same plane as palm because of motor loss to thenar muscles

Front 16

Describe middle brachial plexus segment syndrome

Back 16

C7 may be involved in both upper and lower segment injuries (uncommon)
May be injured by prolapsed intervertebral disck (upper radicular syndrome)

Front 17

What are the myotomes and actions of upper limb affected by middle brachial plexus segment syndrome?

Back 17

C7- extension of elby, wrist and digits

Front 18

What are the clinical features of middle brachial plexus segment syndrome?

Back 18

C7 gives similar scenario to radial nerve palsy
Brachioradialis and its reflex escapes but there is loss of triceps reflex
Loss of extension at elbow and wrist drop occurs

Front 19

What does the musculocutaneous nerve supply?

Back 19

Supplies all muscles in the anterior compartment of the arm
These muscles cause flextion of elbow joint and supination of forearm

Front 20

What is the pathway of the musculocutaneous nerve?

Back 20

Pierces medial aspect of coracobrachialis muscle and exits lateral side
Occurs between biceps brachii and brachialis muscles

Front 21

What would injury to the musculocutaneous nerve cause?

Back 21

Flexion of elbow and supination of forearm greatly weakened

Front 22

Describe the median nerve of the upper limb

Back 22

Supplies most of muscles in anterior compartment of forearm, muscles of thenar eminenct, and radial-most two lumbrical muscles
Sensation to area of skin used in precision gripping over pulps (distal anterior aspect of digit) of thumb and index finger are affected
May be injured at several points along its path including at elbow or wrist, as it passes the carpal tunnel

Front 23

What is the pathway of the median nerve?

Back 23

It passes between the two heads of pronator teres (radial, ulnar)
Its deep branch (anterior interosseus nerve) arises in cubital fossa
It occurs between superficial and deep flexors of forearm
It occurs between superficial to flexor tendons at level of wrist
It passes through carpal tunnel to enter palm
A short, stubby muscular branch is given off from radial side (motor recurrent branch)

Front 24

Describe injury to the median nerve of upper limb

Back 24

May occur when median nerve is injured at or above elbow regioin
Forearm is supinated and index finger is extended and there is serial flexion of digits IV-V
Position of supination with an extended index finger is termed "Benediction Attitude"
Loss of thenar musculature results in palmar surface of thumb being placed in same plane as that of palm, "Simian hand". This is a deformity of the hand marked by thumb movements being limited to flexion and extension of the thumb in the plane of the palm b/c of the inability to oppose the thumb. Adduction of digit I is possible
Loss of thenar musculature would limit abduction and precision pad-to-pad and nail-to-nail opposition of the thumb toward digits II-V
Distal phalanx of thumb and distal joints of index and middle fingers are extended because of the loss of flexor pollicis longus and flexor digitorum superficialis and flexor digitorum profundus
Inability to clasp both hands firmly together with fingers interlocked
An attempt to flex wrist causes ulnar deviation

Front 25

What are four common sites of ulnar nerve lesions or compression?

Back 25

1) Posterior to medial epicondyle
2) Cubital tunnel
3) Wrist
4) Hand

Front 26

Describe ulnar canal syndrome

Back 26

Also called Guyson's Canal Syndrome
Cubital tunnel is formed by a tendinour arch connecting humeral and ulnar heads of flexor carpi radialis
Compression of ulnar nerve occurs where is passes between pisiform and hook of hamate
Depression between these bones is converted by pisohamate ligament into an osseofibrous tunnel (ulnar tunnel)
Condition may result in hypoesthesia in the medial one and one-half digits and weakness of the intrinsic muscles of hand

Front 27

What are some areas supplied by the ulnar nerve?

Back 27

Some musculature on ulnar side of forearm
Most of the intrinsic muscles of hand
Sensory supply to ulnar side of hand

Front 28

What is the pathway of the ulnar nerve?

Back 28

Passes posterior to medial epicondyle
Passes between two heads of flexor carpi ulnaris
Lies between flexor carpi ulnaris and flexor digitorum profundus
Occurs superficially at level of wrist
Lies lateral to pisiform bone and passes in passageway referred to as Ulnar canal

Front 29

What are some results of injury to the ulnar nerve at or above the elbow region?

Back 29

1) Flattening of ulnar forearm musculature and hyperextension of MCP joints of digits IV-V
2) Wasting of hypothenar muscles and interossei between metacarpals
3) Inability to hold a piece of paper between the pulp of a straight thumb and curled index finger
4) Weakness of key grip due to loss of first dorsal interosseous and adductor pollicis muscles
5) Inability to flex distal joints of ring and little fingers
6) Flexion of wrist produces radial deviation
7) Clawing deformity of ring and little fingers; higher the injury, less obvious "clawing"; ulnar nerve paradox

Front 30

Describe the radial nerve

Back 30

Supplies the muscles of posterior compartments of arm and forearm
Only exception is brachioradialis which occurs in anterior compartment and is a flexor of forearm
Does not directly supply intrinsic muscles of hand, but an injury can affect the hand

Front 31

What is the pathway of the radial nerve?

Back 31

Runs along posterior aspect of humerus within radial groove
Lies anterior to lateral epicondyle between brachialis and brachioradilis muscles
Divides into superficial and deep branches
Superficial branch is sensory and lies deep to brachioradialis
Deep branch penetrates the supinator muscle and emerges between it and abductor pollicis longus, where it quickly supplies EDC, ECU, and EDM muscles
Posterior interosseous is continuation of deep branch that supplies ABPL, EPB, EPL, and EI

Front 32

Describe injury to the radial nerve

Back 32

May occur in arm by compression or fractures of humerus
Compression results in transient paralysis, which may occur as result of poor-fitting crutches creating pressure on nerve in axilla area or in radial groove by arm of chair while subject is asleep (Saturday Night Palsy)
Fractures of surgical neck or shaft of humerus can damage nerve; considerable overlap of cutaneous nerves; elbow extension may be obtained if patient not bothered by pain
Gravity acting as an extensor must be ruled out and movement should be tested while limb is in abducted position; if nerve is injured, wrist extensors will be paralyzed, wrist-drop

Front 33

Describe radial nerve injury in axilla area or at elbow

Back 33

Loss of ability to flex and extend forearm at elbow
Loss of extension of wrist, wrist is flexed and fingers straight (wrist-drop)
Wrist-drop may result from paralysis of extensor muscles of forearm
Loss of supination of extended forearm
Loss of extension of IP and MCP joints of thumb and MCP joints of digits II-IV

Front 34

Describe injuery to the deep branch of the radial nerve

Back 34

Results in inability to extend thumb and MP joints of other digits
Digits remain flexed at MCP joints
IP joints (PIP and DIP) can be slightly extended because of action of intact lumbricals and interossei (supplied by ulnar and median nerves)