A cadaveric study of ulnar nerve innervation of the medial head of triceps brachii

Triceps and cutaneous radial nerve branches investigated via an axillary anterior arm approach: new findings in a fresh-cadaver anatomical study

OBJECTIVE

The authors sought to describe the anatomy of the radial nerve and its branches when exposed through an axillary anterior arm approach.

METHODS

Bilateral upper limbs of 10 fresh cadavers were dissected after dyed latex was injected into the axillary artery.

RESULTS

Via the anterior arm approach, all triceps muscle heads could be dissected and individualized. The radial nerve overlaid the latissimus dorsi tendon, bounded by the axillar artery on its superior surface, then passed around the humerus, together with the lower lateral arm and posterior antebrachial cutaneous nerve, between the lateral and medial heads of the triceps. No triceps motor branch accompanied the radial nerve's trajectory. Over the latissimus dorsi tendon, an antero-inferior bundle, containing all radial nerve branches to the triceps, was consistently observed. In the majority of the dissections, a single branch to the long head and dual innervations for the lateral and medial heads were observed. The triceps long and proximal lateral head branches entered the triceps muscle close to the latissimus dorsi tendon. The second branch to the lateral head stemmed from the triceps lower head motor branch. The triceps medial head was innervated by the upper medial head motor branch, which followed the ulnar nerve to enter the medial head on its anterior surface. The distal branch to the triceps medial head also originated near the distal border of the latissimus dorsi tendon. After a short trajectory, a branch went out that penetrated the medial head on its posterior surface. The triceps lower medial head motor branch ended in the anconeus muscle, after traveling inside the triceps medial head. The lower lateral arm and posterior antebrachial cutaneous nerve followed the radial nerve within the torsion canal. The lower lateral brachial cutaneous nerve innervated the skin over the biceps, while the posterior antebrachial cutaneous nerve innervated the skin over the lateral epicondyle and posterior surface of the forearm. The average numbers of myelinated fibers were 926 in the long and 439 in the upper lateral head and 658 in the upper and 1137 in the lower medial head motor branches.

CONCLUSIONS

The new understanding of radial nerve anatomy delineated in this study should aid surgeons during reconstructive surgery to treat upper-limb paralysis.

Comparison between long and lower medial head triceps branches in dual neurotization for shoulder function restoration in upper brachial plexus palsy

PURPOSE

In upper brachial plexus injury (UBPI), restoring shoulder function is crucial. This study compares the transfer of long and lower medial heads of triceps branches to the axillary nerve to achieve proper restoration of function.

PATIENTS AND METHODS

A retrospective comparative study was conducted between two groups of patients with (UBPI). Group I patients (10) [mean age: 19 ± 10.6 years] were managed by transferring triceps long head branch to axillary nerve while group II patients (8) [mean age: 26 ± 9.6 years] were managed by triceps lower medial head branch transfer. The mean time from injury to surgery was 6 ± 1.3 and 5 ± 1.7 months respectively. All patients were followed up for a minimum of 12 months with the assessment of VAS, DASH score, active range of motion (AROM) and strength of shoulder abduction and external rotation; in addition to shoulder endurance and strengths of donors. Postoperative, three-monthly, electrodiagnostic assessments were performed.

RESULTS

Postoperatively, the mean VAS and DASH scores; in addition to endurance time, showed significant enhancement in both groups. Patients in both groups have accomplished a mean abduction (AROM) of 98° ± 27.9 and 97° ± 11.9 respectively. The mean external rotation (AROM) was 48° ± 18.4 and 47° ± 9.2 respectively. Furthermore, group II patients had less triceps morbidity in addition to earlier and enhanced electrophysiological recovery.

CONCLUSIONS

Dual neurotization for shoulder function restoration in (UBPI) is capable of providing proper functional results with minimal donor morbidity. The triceps lower medial branch provides an excelling donor due to less triceps morbidity, extra length; yet, earlier and enhanced electrophysiological recovery.

Traumatic Partial Posterior Cord Brachial Plexus Injury in a Patient with Aberrant Innervation of the Long Head of the Triceps by the Axillary Nerve: Implications in Nerve Transfer Surgery

Brachial plexus repair forms an unmet need in terms of posttraumatic rehabilitation, especially the young population, wherein the incidence of accidents is high. This leads to decrease in the number of functionally active years after the accident. We encountered an interesting case of posttraumatic posterior cord injury predominantly affecting the shoulder abduction beyond 15°. An electrodiagnostic study showed a complete lack of conduction within the axillary nerve with reduced conduction velocity in the radial nerve. We took the patient up for the long head of the triceps transfer to the anterior division of the axillary nerve transfer. Intraoperatively, we found that the long head branch was originating from the axillary nerve at the point of division. As it could not be used for neurotization, we transferred the medial head branch of the radial nerve to the axillary nerve. The patient started to show electroclinical improvement after 3 months of the surgery. A few similar cases have been published, as a cadaveric finding. We report this case to highlight the possibility and need for a high clinical suspicion and also to provide a possible treatment option, in such aberrant anatomy.

Ulnar Nerve Innervation to Triceps: A Cadaveric Study and a Technical Note on Partial Triceps to Biceps Transfer

BACKGROUND

The loss of elbow flexion is a routinely encountered problem in clinical practice. There is no literature on ulnar nerve innervation to triceps in addition to the radial nerve which is dual nerve innervation to triceps in the Indian population. We intend to study the incidence of ulnar nerve innervation to the medial head of triceps in Indian population and also the clinical feasibility of transfer of long and medial head of triceps tendon to biceps around the medial aspect of humerus.

MATERIALS AND METHODS

A cross-sectional study was conducted using 32 fresh-frozen skeletally mature cadavers of Indian origin. The possible contribution of the ulnar nerve to medial head of triceps in addition to the radial nerve was recorded. The arm length, the distance where the ulnar nerve pierces the medial intermuscular septum from medial epicondyle; the distance of the ulnar nerve fascicle from the medial epicondyle was also measured.

RESULTS

The incidence of ulnar nerve innervation to the medial head of triceps was 43.8%. Mean arm length was 29.13 cm. Mean distance where the ulnar nerve pierced the medial intermuscular septum from medial epicondyle was 9.93 cm. Mean distance of the ulnar nerve branch to the triceps from medial epicondyle was 8.01 cm.

CONCLUSION

This study reveals the presence of dual nerve innervation to triceps in 43.8% of the Indian population. The clinical implication would be to look for the possible contribution of the ulnar nerve fascicle to the medial head of triceps, which will help us to include the medial head along with the long head of triceps while performing partial triceps-to-biceps tendon transfer, and the other use would be as a donor fascicle when performing a nerve transfer.

Relationship between the ulnar nerve and the branches of the radial nerve to the medial head of the triceps brachii muscle

One branch of the radial nerve to the medial head of the triceps brachii muscle (MHN) has been described as accompanying or joining the ulnar nerve. Mostly two MHN branches have been reported, with some reports of one; however, the topographical anatomy is not well documented. We dissected 52 upper limbs from adult cadavers and found one, two, and three MHN branches in 9.6%, 80.8%, and 9.6% of cases, respectively. The MHN accompanying the ulnar nerve was always the superior MHN. The relationship between the ulnar nerve and the MHN was classified into four types according to whether the MHN was enveloped along with the ulnar nerve in the connective tissue sheath and whether it was in contact with the ulnar nerve. It contacted the ulnar nerve in 75.0% of cases and accompanied it over a mean distance of 73.6 mm (range 36-116 mm). In all cases in which the connective tissue sheath enveloped the branch of the MHN and the ulnar nerve, removing the sheath confirmed that the MHN branch originated from the radial nerve. The detailed findings and anatomical measurements of the MHN in this study will help in identifying its branches during surgical procedures. Clin. Anat. 00:1-16, 2018. © 2018 Wiley Periodicals, Inc.

Surgical Implications of Innervation Pattern of the Triceps Muscle: A Cadaveric Study

The innervation pattern of triceps is complex and not fully comprehended. Anomalous innervations of triceps have been described by various authors. We have attempted to delineate the nerve supply of the triceps and documented the anomalous innervations of its different heads. The brachial plexus and its major branches (in the region of the axilla and arm) and triceps were dissected in 36 embalmed cadaver upper limbs. Long head received one branch from radial nerve in 31 (86%) specimens. Four (11%) specimens received two branches including one that had dual innervation from the radial and axillary nerves, and one (3%) specimen had exclusive innervation from a branch of the axillary nerve. Medial head received two branches arising from the radial nerve in 34 (94%) specimens. One (3%) specimen received three branches from the radial nerve whereas one (3%) had dual supply from the radial and ulnar nerves. Lateral head received multiple branches exclusively from the radial nerve, ranging from 2 to 5, in all (100%) specimens. Knowledge of the variations in innervation of the triceps would not only help the surgeon to avoid inadvertent injury to any of the nerve branches but also offers new options for nerve and free functional muscle transfers.

Connections between radial and ulnar nerve at high humeral level in cadavers: incidence, topography, and literature review

PURPOSE

Although communications between branches and cords of the brachial plexus have been extensively published, there is a scarcity of reports concerning radial and ulnar nerve (RN-UN) communication in the arm. The current study aims to demonstrate the incidence, topography, and length of communicating branches between RN and UN. Any additional coexisted variations were also recorded.

MATERIALS AND METHODS

Two hundred and sixty-six upper limbs collected from one hundred and thirty-three (81 males and 52 females) Greek cadavers were dissected.

RESULTS

Three out of one hundred and thirty-three cadavers, accounting for an incidence of up to 2.3%, were found to have an atypical communicating branch originating at a high humeral level from RN towards UN. In two cadavers, communicating branches were detected on the left side and in one cadaver bilaterally.

CONCLUSIONS

The study of atypical communications between RN and UN attracts great attention for its clinical importance, mainly in cases of peripheral neuropathies with diagnostic dilemma or upper limb nerve injury producing an otherwise unexpected symptomatology due to the aberrant nerve supply. Familiarity with these variations is crucial in avoiding misdiagnosis and preserving valuable communicating branches, thus achieving an uneventful outcome in cases of upper limb nerve injury repair.

A cadaveric study comparing the three approaches for ulnar nerve block at wrist

Background:

Ulnar nerve blockade as a component of wrist block is a promising technique for adequate anesthesia and analgesia for different surgeries of the hand. Due to anatomical variations in the location of ulnar nerve under the flexor carpi ulnaris (FCU) a technique with good results and minimal complications are required.

Aim:

The aim of the following study is to compare the three techniques (volar, transtendinous volar [TTV] and ulnar) for ulnar nerve block at the wrist in human cadaveric wrists.

Materials and Methods:

Our study was conducted using 40 cadaver wrists. After inserting standard hypodermic needles by three techniques for ulnar nerve blockade at the wrist, a detailed dissection of FCU was done. The mean distance from the tip of the needle to ulnar artery/nerve and number of instances in which the ulnar artery/nerve pierced were observed.

Results:

Inter-group statistical significance was observed in measurement of the mean distance (mm) from the tip of the needle to the ulnar artery (volar [0.92 ± 0.11], TTV [3.96 ± 0.14] and ulnar [7.14 ± 0.08] approaches) and ulnar nerve (volar/TTV/ulnar approaches were 0.71 ± 0.12/3.61 ± 0.10/6.31 ± 0.49, respectively) (P = 0.001). Inadvertent intra-arterial/intraneural injections was seen with volar approach in 14 (35%) and 16 (40%) of the cadaveric wrists respectively, statistically significant with transtendinous and ulnar techniques of ulnar nerve block.

Conclusion:

TTV approach could be a better technique of choice for ulnar nerve blockade at the wrist because of its ease to practice, safer profile and minimum chances of inadvertent intra-arterial/intraneural injection with adequate anesthesia/analgesia.

Ulnar nerve innervation of the triceps muscle: real or apparent? An anatomic study

BACKGROUND

Since the 18th century, the existence of ulnar nerve innervation of the medial head of the triceps brachii muscle has been controversial. The evidence for or against such innervation has been based on macroscopic dissection, an unsuitable method for studying intraneural topography or intramuscular branching. The study of smaller specimens (embryos or fetuses) by means of serial histologic sections may resolve the controversy.

QUESTIONS/PURPOSES

Using fetal specimens and histology we determined the contributions of the ulnar and radial nerves to innervation of the triceps brachii muscle.

METHODS

We histologically examined 15 embryonic and fetal arms. Radial nerve branches obtained from six adult arms were analyzed immunohistochemically to determine motor fiber content.

RESULTS

The medial head of the triceps brachii muscle was always innervated by the radial nerve (ulnar collateral branch). The branches seeming to leave the ulnar nerve at elbow level were the continuation of the radial nerve that had joined the ulnar nerve sheath via a connection in the axillary region. Immunohistochemistry revealed motor and nonmotor fibers in this radial nerve branch.

CONCLUSIONS

A connection between the radial and ulnar nerves sometimes may exist, resulting in an apparent ulnar nerve origin of muscular branches to the medial head of the triceps, even though in all our specimens the fibers could be traced back to the radial nerve.

CLINICAL RELEVANCE

Before performing or suggesting new muscle and nerve transpositions using this apparent ulnar innervation, the real origin should be confirmed to avoid failure.

Triceps brachii reinnervation in primary reconstruction of the adult brachial plexus: experience in 25 cases

BACKGROUND

Elbow flexion and shoulder abduction are the primary goals in brachial plexus surgery; however, reinnervation of the triceps is also an objective to be considered, as restoration of elbow extension improves the stabilization of the elbow and can provide a more powerful grasp. This study aims to demonstrate the author's experience with restoration of elbow extension function in cases of brachial plexus surgery in adults.

METHODS

Records of 25 patients sustaining traumatic brachial plexus injuries who were treated surgically with reinnervation of the triceps were reviewed. Nine techniques were employed, including posterior cord reconstruction and nerve transfers using donors such as the ipsilateral C7 root, phrenic nerve, medial pectoral nerve, intercostal nerves, the spinal accessory nerve, and a motor fascicle of the ulnar nerve. The targeted structure was the radial nerve or the branch to the long head of the triceps.

FINDINGS

Twenty-one subjects (83%) obtained triceps reinnervation, and good results (M3 or better) were observed in 19 cases (76%). M4 grade was noted in 36% of the cases, M3 grade in 40%, M2 grade in 8%, M1 grade in 8%, and M0 grade in 8% of the patients. The best outcomes were observed in the cases presenting a C5 to C7 palsy and those in which the nerve to the triceps was chosen as the transfer target.

CONCLUSIONS

Reinnervation of the triceps can be achieved in most patients if adequate donor and recipient nerves are carefully selected based on an individual case-specific decision.