brachial plexus anatomy, etiology, mechanism of injury, classifications, clinical features, diagnosis and management. surgical management of brachial plexus

1. BRACHIAL PLEXUS INJURIES
Dr. CH ADITYA
DNB RESIDENT
Care hospitals, Hyderabad
OBJECTIVES
ANATOMY
ETIOLOGY
MECHANISM OF INJURY
CLASSIFICATION
CLINICAL FEATURES
INVESTIGATIONS
MANAGEMENT

3. ANATOMY
• it is a network of nerves passing through the cervico-axillary canal
to reach axilla and innervates brachium (upper arm), antebrachium
(forearm) and hand.
• Brachial plexus is a somatic nerve plexus formed by the union of
anterior rami of C5,C6,C7,C8 and T1.
• The formation of brachial plexus begins just distal to the scalenus
muscles.
• Function:
The brachial plexus is responsible for cutaneous and muscular
innervation of the entire upper limb, with two exceptions: the
trapezius muscle innervated by the spinal accessory nerve (CN XI)
and an area of skin near the axilla innervated by the
intercostobrachial nerve.

5. CLINICAL ANATOMY
The plexus consists of roots, trunks, divisions, cords and
branches.
• Roots : Lower 4 cervical (C5-8) and the 1st thoracic.
 Situated between the scalenus anterior and medius muscle
deep to sternocleidomastoid muscle.
 The origin of the plexus may shift one segment either upward
or downward resulting in a PRE FIXED PLEXUS or POST FIXED
PLEXUS respectively.
 In a prefixed plexus, the contribution by C4 is large and in that
from T2 is often absent. In a post fixed plexus, the
contribution by T1 is large, T2 is always present, C4 is absent,
and C5 is reduced in size.

8. • Trunks :
 Derived from roots
 Located in the antero-inferior portion of post triangle of
neck
C5-6  ant primary rami unite  upper trunk.
C8-T1  ant primary rami unite  lower trunk.
C7 – ant primary rami continues as  middle trunk.
Each trunk ends by splitting into 1) Ant. 2) Post -
divisions.

9. • CORDS: it forms 3 cords
• The Posterior Cord is formed from the three posterior
divisions of the trunks (C5-C8,T1)
• The Lateral Cord is the anterior divisions from the
upper and middle trunks (C5-C7)
• The Medial Cord is simply a continuation of the
anterior division of the lower trunk (C8,T1)

11. • BRANCHES:
• Branches of the brachial plexus may be described as
supraclavicular and infraclavicular.
Supraclavicular branches
• Supraclavicular branches arise from roots or from trunks as
follows:
From roots
• 1. Dorsal scapular nerve C5
• 2. Long thoracic nerve C5, 6 (7)
From trunks
• 1. Nerve to subclavius C5, 6
• 2. Suprascapular nerve C5, 6 :
NOTE: SUPRASCAPULAR NERVE IS THE FIRST IMPORTANT BRANCH
SEEN WHEN THE PLEXUS IS EXPLORED SUPERIOR TO THE CLAVICLE

12. Infraclavicular branches
• branches come from the cords,
Lateral cord
• Lateral pectoral C5, 6, 7
• Musculocutaneous C5, 6 7
• Lateral root of median C(5), 6, 7
Medial cord
• Medial pectoral C8, T1
• Medial cutaneous of forearm C8, T1
• Medial cutaneous of arm C8, T1
• Ulnar C(7), 8, T1
Posterior cord
• Upper subscapular C5, 6
• Thoracodorsal C6, 7,8
• Lower subscapular C5, 6
• Axillary C5, 6
• Radial C5, 6, 7, 8, (T1)

13. ETIOLOGY
• penetrating wounds
• Missiles
• Stab wounds
• Injuries related to birth
• Traction applied to the plexus during
falls
• Vehicular accidents
• Sports activities and
• Radiation

14. • In most large series, motorcycle accidents are the most common
cause 70%.
• In 20% cases a/w rupture of subclavian or axillary artery.
• Spinal cord injury is reported in 2% - 5% cases.
• COMMON ASSOCIATED INJURIES
• Fractures of the proximal humerus
• Scapula fractures
• Rib fractures
• Clavicle fractures
• Fracture of the transverse process of cervical vertebrae
• Dislocations of the shoulder, acromioclavicular and sternoclavicular
joints

15. Mechanisms of
Injury to the Brachial Plexus
A. Traction: direct blow to the
shoulder with the neck laterally
flexed toward the unaffected
shoulder (gymnast falls on beam)
B. Direct trauma: direct blow to the
supraclavicular fossa over Erb’s point
C. Compression: Occurs when the
neck is flexed laterally toward the
patient’s affected shoulder,
compressing / irritating the nerves,
resulting in point tenderness over
involved vertebrae of affected
nerve(s)
(Troub, 2001)

17. Mechanisms of
Injury to the Brachial Plexus

18. CLASSIFICATION OF BRACHIAL PLEXUS
INJURIES:
• Classification of injuries
• The various classifications of brachial plexus injury are as follows:
1. Leffert classification of brachial plexus injury
2. Millesi classification of brachial plexus injury
3 . Classification on anatomical location of injury
1. Leffert classification of brachial plexus injury: It is based on mechanism
and level of injury and is as follows
• I Open (usually from stabbing)
• II Closed (usually from motorcycle accident)
• IIa Supraclavicular

19. – preganglionic:
• avulsion of nerve roots, usually from high speed injuries
• no proximal stump, no neuroma formation (neg Tinel's)
• pseudomeningocele, denervation of neck muscles are common
• horner's sign (ptosis, miosis, anhydrosis)
– postgangionic:
• roots remain intact;
• usually from traction injuries;
• there are proximal stump and neuroma formation (pos Tinel's)
• deep dorsal neck muscles are intact, and pseudomeningoceles will not
develop;
– IIb Infraclavicular Lesion:
• usually involves branches from the trunks (supraclavicular);
• function is affected based on trunk involved;
• III Radiation induced
• IV Obstetric
• IVa Erb's (upper root)
• IVb Klumpke (lower root)

20. • 2. Millesi classification of brachial plexus injury: It is mainly divided into 4
• I: supraganglionic/preganglionic.
• II: infraganglionic/postganglionic
• III: trunk.
• IV: cord.
• 3. Classification on anatomical location of injury:
• Upper plexus palsy (Erb’s palsy in the OBPI cases) involves C5-C6+/-
C7roots.
• Lower plexus palsy (Klumpke’s palsy) involves C8-T1 roots (and sometimes
also C7)
• Total plexus lesions involve all nerve roots C5-T1

21. Lower brachial
plexus injuries
Upper brachial
plexus injuries

22. ERB'S PARALYSIS:
• Site of injury: The region of the upper trunk of the
brachial plexus is called Erb's point. Injury to the upper
trunk causes Erb's Paralysis.
• Causes of injury: Undue separation of the head from
the shoulder, which is commonly encountered in
1)birth injury 2) fall on shoulder, and 3)during
anaesthesia
• Nerve roots involved: Mainly C5 and partly C6.
• Muscles paralysed: Mainly biceps, deltoid, brachilais
and brachioradialis.Partly supraspinatus, infraspinatus
and supinator

23. • Deformity
• Arm: Hangs by the side, it is adducted and
medially rotated
• Forearm: Extended and pronated
• Abduction impossible because of paralysis of
deltoid & supraspinatus m/s.
• ER impossible because of paralysis of
infraspinatus & teres minor m/s.

24. • Active flexion
impossible because of
paralysis biceps,
brachialis &
brachioradialis.
• Paralysis of supinator
m/s causes pronation
deformity of forearm.
• The deformity is known
as "Policeman's tip
hand" or "Porter's tip
hand".

26. KLUMPKE’S PALSY
• Site of injury: Lower trunk of the brachial plexus.
• Cause of injury: Undue abduction of the arm, as in clutching
something with the hand after a fall from a height, or sometimes in
birth injury.
• Nerve roots involved: Mainly T1 and partly C8.
• Muscles paralysed:
• Intrinsic muscles of the hand (T1)
• Ulnar flexors of the wrist and fingers (C8).
• Deformity: (position of the hand): claw hand due to the unopposed
action of the long flexors and extensors of the fingers. in a claw
hand there is hyperextension at the metacarpophalangeal joints
and flexion at the interphalangeal joints.

27. • Disability:
• Claw hand
• Cutaneous anaesthesia and analgesia in a narrow zone along the
ulnar border of the forearm and hand.
• Horner's syndrome: ptosis, miosis, anhydrosis, enophthalmos and
loss of ciliospinal reflex- may be associated. This is because of
injury to sympathetic fibres to the head and neck that leave the
spinal cord through nerve T1.
• Vasomotor changes: The skin areas with sensory loss is warmer due
to arteriolar dilation. skin is dry due to the absence of sweating as
there is loss of sympathetic activity.
• Tropic changes: Long standing case of paralysis leads to dry and
scaly skin.The nails crack easily with atrophy of the pulp of fingers.

30. Clinical features :
History :
 The mechanism of injury should be considered.
 Birth injury : Usually 5th and 6th root.
 Motor cycle accidents.
 Stab and bullet wounds.
Symptoms vary depending upon the type and
location of the injury to the brachial plexus.
The most common symptoms of BPI include:
-Weakness or numbness
-Loss of sensation
-Loss of movement (paralysis)
-Pain
.

31. CLINICAL FEATURES
• The pain from brachial plexus injuries results
from injury to the spinal cord where the nerve
rootlets are avulsed from the cord. This pain is
neuropathic in nature. The pain can last for a very
long time.
• Brachial plexus injuries that occur at the level of
the spinal cord often produce greater pain than
injuries more distant from the spinal cord.
• In addition, injuries nearer the spinal cord may
cause a burning numbness, which is called
paresthesias or dysesthesias.

32. Physical examination :
Examination of all nerve groups controlled by the brachial
plexus to identify the specific location of the nerve injury and its
severity.
In addition, some patients display specific signs that help
determine the location of the nerve injury:
 Narrowing of the eye pupils, drooping of the eyelid, and lack
of ability for the face to sweat (Horner's syndrome) is a sign
that the injury is close to the spinal cord.
 A shooting nerve-like pain on taping along the affected
nerves (Tinel sign) suggests an injury farther from the spinal
cord. Over time, if the location of the Tinel sign moves down
the arm toward the hand, it is a sign that the injury is
repairing itself.
During the physical examination, assess the arm and shoulder
for stability and range of motion

33. INVESTIGATIONS
• Imaging Studies
• Electromyogram
• Nerve Conduction Velocity
• Intraoperative Nerve Action Potential
• Myelography
• CT scan for any tumours
• MRI

34. Imaging studies :
X-ray of cervical spine :
 Fracture of lateral masses of cervical vertebrae are
strongly associated with pre-ganglionic injuries.
Chest x-ray :
 May show 1st and 2nd rib fracture or an elevated
hemidiaphragm, which denotes phrenic nerve
paralysis and proximal injury to upper plexus.
 Fractures of scapula and clavicle and Humerus may
indicate infraclavicular plexus injuries.

35. INVESTIGATIONS
EMG :
 Most important use of EMG studies is for serial evaluation
of injury to search for signs of re innervation.
 A decreased in number of fibrillation potentials and positive
sharp potentials  typically seen in dennervated
muscles  regenerating axons have reached the motor
end plates.
 The appearance of prolonged, polyphasic and low-amp
indicated  re-innervation.
 Seen several weeks before the onset of voluntary muscle
contraction and signify that a further period of
observation is in order.

39. Intra operative nerve action potential (NAP) :
 This study is performed during surgical exploration of the
plexus, which is usually done 3-4 months after injury.
 If a nerve action potential can be recorded.
Substantial number of regenerating axons have
traversed the lesion site.
 Conversely if an action potential cannot be elicited  the
abnormal segment is resected because spontaneous
recovery is likely to be poor.
NAP is best for evaluating a neuroma in continuity. If an
NAP can be transmitted across the area of injury, the
patient has 93% chance of useful motor function
will develop in the muscles supplied by that nerve.

40. Direct
Intraoperative
nerve stimulation
No nerve action
potentials are
recorded
Excision and
nerve grafting
Nerve action
potentials are
obtained
Simple neurolysis
is indicated

41. CT Myelography :
 If plexus injury is strongly suspected a myelogram and
subsequent CT scan should be obtained 2-3 months
after injury.
It may be inaccurate early after the injury because clotted
blood may occlude the opening into the pseudomeningocele.
A delay of 6-12 weeks is recommended before myelogram is
advised.
Advantages:
-detect partial root avulsion
-excellent visualization of bony structures
-no CSF flow artifacts and
-multiplanar reconstruction.
Disadvantages:
- high radiation dose
-poor visualization of lower brachial plexus
due to bony artifacts.

44. CT myelogram showing a normal brachial plexus (left) and injured brachial plexus
(right)

45. • Nagano et al . classified myelographic findings into six
types; N, A1, A2, A3, D, and M .
• N is a normal shadow;
• A1 is a slightly abnormal root sleeve shadow in which
shadows of roots and rootlets can be recognized but
appear different from those on the unaffected side;
• A2 is obliteration of the tip of the root sleeve with the
shadows of roots or rootlets visible;
• A3 is obliteration of the tip of the root sleeve with no
shadows of roots or rootlets visible;
• D is a defect instead of a root sleeve shadow; and
• M is a traumatic meningocele.

46. • N is the sign of normality or a postganglionic
lesion.
• A1 is observed in either a preganglionic or a
postganglionic lesion; thus, detailed evaluation
with CT myelography is necessary for this kind of
finding.
• A2, A3, D, and M are indicative of a preganglionic
lesion.
• A traumatic meningocele is a valuable sign of a
preganglionic lesion, although it is not
pathognomonic.

47. CONVENTIONAL MRI
• MRI provides additional anatomic and
physiologic information on injuries.
1. Signal intensity changes in the spinal cord
2. Enhancement of nerve roots and
3. Enhancement of paraspinal muscles

48. 1. Signal intensity changes in the spinal cord
• Hyperintense areas on T2-weighted images
suggest edema in the acute phase and
myelomalacia in the chronic phase.
• Hypointense lesions on T2-weighted images
reflect hemosiderin deposition on account of
hemorrhage .

49. 2. Enhancement of nerve roots
• Enhancement of intradural nerve roots and
root stumps suggests functional impairment
of nerve roots despite morphologic continuity
• Breakdown of the blood-nerve barrier and
dilatation of radicular veins are postulated as
the mechanisms of intradural nerve root
enhancement.

50. 3. Enhancement of paraspinal muscles
• Abnormal enhancement of paraspinal muscles is
an accurate indirect sign of root avulsion injury.
• Denervated muscles show enhancement as early
as 24 hours after a nerve is injured.
• The presumed mechanisms for muscle
enhancement are
1. dilatation of the vascular bed and
2. enlargement of the extracellular space.

52. Nerve root avulsion. Axial T2-weighted (A) and
coronal MIP 3D STIR SPACE (B) images show the
avulsed left T1 nerve root (large arrows) and C8
nerve root (small arrow) with
pseudomeningocele formation

54. MANAGEMENT
• Closed Brachial Plexus Injury
• Open Brachial Plexus Injury

55. Closed injury
• In the case of closed BPI wounds and when
there are no other emergent injuries, surgical
exploration and recovery may not take place
immediately. Recommendations include
• managing pain, and
• starting rehabilitation.

56. Closed Brachial Plexus Injury
• Barnes divided Upper & Lower Plexuses injuries caused
by traction into four groups
• 1)Injuries at C5 & C6
• 2)Injuries at C5,C6 & C7
• 3)Degenerative lesions of entire plexus
• 4)Injuries at C7,C8 & T1 (rare)

57. • Barnes reported that spontaneous recovery in group 1 & 2
cases
• But in case of Degenerative plexus injuries there is partial
recovery.
• EMG should be done at 3 to 4 wks.
• At 6 to 8wks additional studies like myelography & axon
reflex evaluation can be done if return of functions not
seen.
• Exploration is justified at 3 to 6 months after injury if
function has not returned.

58. OPEN INJURIES
• Open wounds in BPI are uncommon and vary from small
penetrating injuries to high energy injuries.
• INDICATIONS OF SURGERY:
• Injuries caused by sharp objects or missiles.
• When patient seen soon after injury & pt's general condition
permits exploration & primary repair can be done
• When patient not seen soon after injury but only after initial
management, It is best to wait for wound healing &
stabilization of any other injuries.

59. • During this period locate neurological deficit for level of injury.
• EMG performed 3 to 4 wks after injury.
• Exploration of plexus & neurorrhaphy, autogenous
interfascicular nerve grafting or neurolysis is indicated 3 to
6wks after injury.
• Motor function recovered to a grade of 3 or better in half of
pts.
• Best results obtained in upper trunk & lateral cord & posterior
cord injuries.
• Poor prognosis can be expected in lower trunk injuries.

60. CONSERVATIVE TREATMENT
• AIMS:
• to maintain the range of motion of the extremity
• to strengthen the remaining functional muscles
• to protect the denervated dermatomes, and
• to manage pain.

61. • Pain management:
• Significant pain is observed in complete palsy especially in root
avulsions.
• Pain Is excruciating and exhausting for the patient but it can
affect the rehabilitation procedure .
• NSAIDs and opioid drugs useful during the first stages but do not
appear to help with neuropathic pain, which requires careful
use of antiepileptic drugs (gabapentin and carbamazepine) or
antidepressants such as amitriptyline.
• About 30% of patients report significant pain relief with this
type of treatment.

62. SURGICAL GOALS
In order of priority as follows:
1)Restoration of elbow flexion
2)Restoration of shoulder abduction
3)Restoration of sensation of medial border of
forearm & hand.

63. • Depending on extent of injury various surgical
techniques may be required:
• Primary neurorrhaphy
• Neurolysis
• Nerve grafting
• Neurotization

64. NEUROLYSIS
• When the nerve lesion is in continuity, neurolysis may
help. It is of great importance to maintain the
interfascicular structure and the nerve sheath.
• Because of the risk of vascular damage interfascicular
neurolysis not done. instead an anterior
epineurectomy is performed, excising the fibrous
tissue.
• Use of direct nerve stimulation before and after
neurolysis helps us demonstrate the improvement in
nerve conductance.

65. NERVE GRAFTING
• Nerve grafting is the predominant technique for
clear cut injuries with a healthy proximal stump
and with no axial damage.
• The outcome is influenced by
1. the length of the nerve graft
2. the presence of scar tissue at the wound site
3. the number of grafts used
4. the presence of a healthy proximal stump
available for grafting and
5. the nerve gap to be covered.

66. • The sural nerve, the sensory branch of ulnar
nerve, and the medial cutaneous nerve of the
forearm are the usual donor nerves.
• Generally, use of nerve grafts shorter than
10 cm results in better functional and clinical
outcomes compared with longer grafts

67. NEUROTIZATION
• This type of procedure is used for preganglionic root injury
• The nerve transfer may be extraplexus or intraplexus.
• Intraplexus transfer options include intact nerve roots. Other
choices include the use of the medial thoracic nerve and
inferior medial cord/ulnar nerve.
• Oberlin et al. described nerve transfer to the biceps muscle
using part of the ulnar nerve for C5-C6 avulsion of the brachial
plexus
• Extraplexus transfer options include the use of intercostal and
spinal accessory nerves. The phrenic nerve and deep motor
branches of the cervical plexus (C3-C4) may be used as donor
nerves.

68. • In ROOT avulsion of upper plexus in which no
proximal neural stump is available for nerve
grafting, neurotization between intercostal
nerves or FCU motor fascicles of ulnar nerve &
musculocutaneous nerve to restore the
ELBOW FLEXION may be considered.

69. • NEUROTIZATION of the suprascapular nerve
using the spinal accessory nerve and
neurotization of the axillary nerve with
fascicles of radial nerve innervating the lateral,
medial, or long head of triceps can be used to
restore SHOULDER ABDUCTION AND
EXTERNAL ROTATION

70. After Brachial plexus repair & regeneration 12
to 18 mths required to determine extent of
neural regeneration.
If recovery inadequate
Peripheral reconstruction considered

71. Secondary Operations
• In the absence of spontaneous recovery or when the first
surgical procedure does not provide satisfactory outcomes
then a second operation may be required.
• In such cases there should be specific signs of neurological
denervation or no possibility of neurological recovery, or
sufficient time should have passed with no functional
improvement.
• Secondary options include
1. Arthrodesis
2. Tendon transfer and
3. Functional free muscle transplantation are
favoured treatment options.

72. ARTHRODESIS
• INDICATIONS
• In complete brachial plexus traumatic injuries
• unstable and painful shoulders
• When planning shoulder arthrodesis certain parameters should be
taken into consideration.
1. good thoracic-shoulder functionality .
2. the mobility of the peripheral hand is important as shoulder
arthrodesis has no clinical effect on a paralytic hand.
3. The acromioclavicular joint, sterno-clavicular joint, and
scapulothoracic joint should be intact. Any dysfunction may affect the
success of arthrodesis.
• NOTE: The shoulder should be fused with only 20 degrees of
abduction, 30 degrees flexion, and 30 degrees of internal rotation to
allow the patient to be independent in his daily life with a mean range
of 60 degrees abduction and flexion through the scapulothoracic joint.

73. TENDON TRANSFERS
• Tendon transfers are useful in restoring upper
extremity function after BPI.
• An absolute indication for tendon transfer is
upper or lower brachial plexus traumatic
injury with only partial paralysis.

74. TENDON TRANSFERS
• Many tendon transfer techniques have been described for
treating partial shoulder paralysis.
• the most common procedures are the following:
1.Trapezius to deltoid transfer as described by Elhassan et al.
in 2000 to restore abduction of the shoulder
2.Latissimus dorsi transfer as described by L’ Episcopo,
to improve external rotation.
3. Anterior transfer of the posterior branch of the deltoid
muscle to restore nonfunctional anterior segment.

75. Restoration of elbow flexion
• The surgical goal is to restore good muscle strength through a range
of elbow motion (30 to 130 degrees).
• The most commonly used procedures are as follows:
• i)transfer of the common origin of the flexor forearm muscles to a
proximal section as described by Steindler (1918) . The Steindler
technique may lead to disappointing outcomes such as elbow
stiffness or over pronation;
• (ii)transfer of latissimus dorsi muscle to the tendon of the biceps
brachialis provides great muscle strength, but this muscle is often
denervated
• (iii)transfer of pectoralis major brachial branch tendon to brachial
biceps (Clark technique). A fused shoulder is required for the best
postoperative result;
• (iv)transfer of triceps tendon to biceps provides good results

76. • Anterior shoulder release:
• First described by Fairbanks & modified by
Sever
• Main indication is iatrogenic internal rotation
contracture & imbalance between shoulder
internal & external rotation.

82. Guidelines for arthroscopic treatment of contractures &
deformity sec to brachial plexus birth palsy

83. RECOVERY AND REHABILITATION
• Because nerve regeneration occurs slowly at a rate of
approximately 1 mm/day, recovery from a brachial
plexus injury takes time, and patients may not
experience results for several months. A positive
mindset and the support of family, friends, and
healthcare professionals are important to recovery and
rehabilitation.
• During this recovery process, occupational therapists
teach patients how to use the unaffected arm to
perform daily activities like eating and personal
hygiene.

84. • Physical therapy of the shoulder, elbow, wrist, and
fingers involves specific exercises to prevent stiffness,
contractures, or muscle atrophy.
• A physical therapist can also recommend assistive
devices, such as splinting or supportive bracing to help
support a limp arm and joints. Compression gloves and
sleeves may be used to prevent swelling in the affected
arm, which can lead to pain and joint contractures.
• Pain may be managed with medications, therapy, and
assistive devices.
• In addition, patients will require healthy coping skills in
order to make adjustments in their lives.

85. THANK YOU

86. OBERLIN TECHNIQUE
• Christophe Oberlin described transfer of one or more ulnar nerve fascicles
to the motor branches of the biceps muscle .
• This is performed to restore elbow flexion in patients who have an
irreparable upper trunk injury or avulsion, and an intact lower trunk .
• Careful selection of ulnar nerve fascicles using intraoperative nerve
stimulation enables one to perform this transfer without a donor motor or
sensory deficit.
• Technique A 15-cm incision is made along the medial arm beginning at the
pectoralis and coursing distally along the neurovascular bundle.
• The biceps fascia is opened and the musculocutaneous nerve identified.
The motor branches to both heads of the biceps are identified
approximately 12 cm distal to the acromion and stimulated to ensure
complete denervation;

87. • the branches are traced proximally where they usually
coalesce into a single motor branch from the parent
musculocutaneous nerve, and then divided sharply for
transfer to the ulnar nerve.
• The ulnar nerve is identified by external neurolysis, and the
epineurium is opened. Several fascicles of the ulnar nerve
are chosen 3–4 cm distal to the level of the MC branch to
the biceps and stimulated with a portable nerve stimulation
unit. A single large fascicle can usually be identified to
produce maximal contraction of the flexor carpi ulnaris
without significant contraction of the ulnar intrinsic
muscles. This fascicle (or fascicles) are divided far enough
distally to transfer directly to the motor branch(es) of the
musculocutaneous nerve .

88. Ulnar nerve fascicle was transferred to the musculocutaneous nerve (Oberlin
transfer) to achieve biceps function