How do the cervical plexus and the spinal accessory nerve contribute to the innervation of the trapezius muscle? As seen from within using Sihler's stain.

OBJECTIVE: To determine how the spinal accessory nerve and the trapezius branches of the cervical plexus contribute to the innervation of each of the 3 parts of the trapezius muscle. Special emphasis was placed on the nerve supply of the clinically most important descending part of the muscle. DESIGN: Anatomical analysis of the distribution of the cervical plexus and spinal accessory nerve branches in the human trapezius muscle. MATERIALS: Twenty-two trapezius muscles from 11 perfusion-fixed human cadavers ranging in age from 66 to 92 years (mean, 81.7 years). INTERVENTIONS: The specimens were dissected free and macerated, decalcified, and stained according to Sihler's technique for about 6 weeks. The translucent, stained muscles were then backlit, and the findings were documented photographically and by schematic drawings. RESULTS: In all 22 muscles, the innervation of each of the 3 parts of the trapezius muscle was seen. In all muscles investigated, the nerve supply to the descending part of the muscle consisted of a single fine branch of the spinal accessory nerve, whereas the transverse and ascending parts were innervated by both the spinal accessory nerve and the trapezius branches of the cervical plexus. CONCLUSION: Our results, especially those involving the descending part of the trapezius muscle, may help to minimize the rate of unexpected trapezius muscle paresis after surgery of the neck.

The sternocleidomastoid flap--its indications and limitations.

HYPOTHESIS: The sternocleidomastoid (SCM) flap seems to be a practicable but underestimated flap for reconstructive and plastic surgery of the head and neck. OBJECTIVES: To determine in which situations the SCM flap may represent a reliable alternative to other flaps used in head and neck surgery. STUDY DESIGN: Meta-analysis of the complete literature on the SCM flap. SETTING: All literature found dealing with the SCM flap was reviewed, with special emphasis placed on the indications and success rates reported. The data presented are compared with our own morphologic findings and their putative clinical implications. RESULTS: Four types of SCM flap have been described: the muscle flap, the myocutaneous flap, the myoperiosteal flap, and the myosseus or osteomuscular flap. The SCM flap was either superiorly or inferiorly based. The SCM muscle flap was used in a total of 72 patients with only 1 major complication and 7 minor complications. The complication rate, therefore, is 11%. The applications of the muscle flap involved prevention of Frey's syndrome, closure of orocutaneous fistulae and soft tissue deficiencies, closure of pharyngocutaneous and cervical esophageal fistulae, and reconstruction of the tongue. Furthermore, Conley reported on the use of the SCM muscle flap in a group of 30 patients to reanimate the face, reconstruct oral cavity defects, protect the carotid and innominate artery, and even to aid shoulder elevation after poliomyelitis. The SCM myocutaneous flap seems to be the most common application, with a total of 138 patients. All in all, a total of 29 complications (21%) was reported, with partial skin necrosis by far the most frequent. Total failure of the flap has been described in 10 patients (7%). The SCM myocutaneous flap was used for closure of defects of the mouth as well as oro-, pharyngo-, and tracheocutaneous fistulae, facial reconstruction, reconstruction of mastoid defects, and reconstruction of the laryngotracheal complex in children. The SCM myosseus or osteomuscular flap was reported in 23 patients. Flap necrosis is reported in 1 case (4%). The SCM osteomuscular flap was used to reconstruct defects of the lower jaw in all patients. The SCM myoperiosteal flap was used in a total of 49 patients. The complication rate reported is 6% (3 cases). The myoperiosteal flap was used for reconstruction of the laryngotracheal complex in adults and for esophagopharyngeal reconstruction and fistula repair. CONCLUSIONS: The data presented in previous literature is well correlated with our own morphologic findings. In comparison of the different techniques applied with the assumptions drawn on the basis of our own anatomic findings, it becomes evident that the SCM flap is only a useful tool in limited indications and under certain precautions.

Surgical anatomy of the spinal accessory nerve and the trapezius branches of the cervical plexus.

BACKGROUND: A thorough understanding of the topographical anatomy of the spinal accessory nerve and the cervical plexus branches is a basic prerequisite for positive results when operating on the neck. OBJECTIVE: To give an exact description of the topographical and surgical anatomy of the spinal accessory nerve (SAN) and the trapezius branches of the cervical plexus. DESIGN: Anatomic analysis of the SAN and the trapezius branches of the cervical plexus. SETTING: The topographical anatomy of the SAN and the cervical plexus branches were studied in the anterior and posterior triangles of the necks of 46 perfusion-fixed human cadavers of both sexes, which ranged in age from 55 to 97 years (mean age, 83 years). RESULTS: The SAN can be identified on the posterior border of the sternocleidomastoid (SCM) muscle, 8.2 + 1.01 cm cranial to the clavicle. In 37% of cases, the SAN enters the posterior triangle of the neck dorsal to the SCM muscle, where it passes through the muscle in 63% of these cases. In the anterior triangle of the neck, the SAN crosses the internal jugular vein ventrally in 56% of the cases and dorsally in 44%. Regarding the cervical plexus, 1 trapezius branch could be found in 9% of the specimens, 2 in 61%, and 3 in 30%. None of the branches merged with the SAN medial to the anterior border of the trapezius muscle. In most cases, a tiny additional branch could be found arising from the SAN about 2 cm medial to the trapezius muscle. This branch enters the descendant part of the muscle approximately 2 to 3 cm cranial to the main nerve. CONCLUSIONS: Surprisingly, available data on topographical as well as surgical anatomy of the SAN and the trapezius branches of the cervical plexus are confusing and often wrong. The descriptions given herein can help to minimize the risk of injuring the SAN during neck surgery and preserve the additional innervation of the trapezius muscle granted by the rami trapezii of the cervical plexus.

Observations on the number, distribution and morphological peculiarities of muscle spindles in the tensor tympani and stapedius muscle of man.

Although the middle ear muscles have been described for the first time more than four hundred years ago their role in modulation and transmission of sound is not yet fully understood. Surprisingly very little is known about proprioceptors in these muscles, especially in man, although this seems to be the key to the understanding of their various functions. Therefore, the question for proprioceptive sensory organs in these muscles is still relevant. The tensor tympani and stapedius muscles of four women who had donated their bodies to our institute were taken. Complete serial sections of these muscles were made which were either impregnated with silver, stained with ferric oxide for acidic polysaccharides or incubated with antibodies against S-100 protein. Thereby four to eight (mean five) muscle spindles distributed along the whole muscle could be detected in the tensor tympani muscles. These spindles contain one to three intrafusal muscle fibres and their length ranges from 140 to 4270 microm (mean 1492.8 microm). Furthermore, in three stapedius muscles one to two (mean 1.7) muscle spindles were found. They were from 350 to 500 microm (mean 482 microm) long and contained only one intrafusal muscle fiber. Regarding the diameter of intrafusal muscle fibers in both, the tensor tympani as well as the stapedius muscle, no difference to extrafusal muscle fibers of these muscles could be detected. The structure of these spindles differs considerably from those found in skeletal muscles. The morphological findings presented strongly suggest that muscle spindles occur regularly in both middle ear muscles. The results presented herein are consistent with clinical findings obtained from electromyographic studies and may help to elucidate all functions the middle ear muscles might serve in man.

The blood supply of the sternocleidomastoid muscle and its clinical implications.

BACKGROUND: The knowledge of the exact anatomy of the sternocleidomastoid (SCM) muscle and its nerve and blood supply must be considered a basic prerequisite for its use as a pedicle muscle flap. OBJECTIVE: To give an exact description of the courses and variability of all vessels supplying the SCM muscle. DESIGN: Anatomic analysis of all arteries supplying the SCM muscle. SETTING: The blood supply of the SCM muscle was studied by dissecting bilaterally the anterior regions of the neck of 31 perfusion-fixed human cadavers of both sexes aged 50 to 94 years (mean, 78 years). RESULTS: The blood supply to the SCM muscle can be divided into 3 parts: upper, middle, and lower. The upper third of the SCM muscle was found to be constantly supplied by branches of the occipital artery. According to their courses, these branches are categorized into types 1, 2a, 2b, and 3. The middle third of the SCM muscle receives its blood supply from a branch of the superior thyroid artery (42%), the external carotid artery (23%), or branches of both (27%). In most cases, the lower third of the muscle was supplied by a branch arising from the suprascapular artery (>80%), which has not been described until now. CONCLUSIONS: In contrast to available data, the arterial blood supply of the lower third of the SCM muscle is constantly provided by a branch of the suprascapular artery. Since the SCM muscle flap is used in reconstructive surgery of the neck, the exact knowledge of its blood supply may help to minimize the risk of flap necrosis after surgical procedures.