The cricoarytenoid ligament: its morphology and possible implications for vocal cord movements

Cricoarytenoid Articulation in Elderly Japanese With Special Reference to Morphology of the Synovial Tissue

Objective:

To clarify composite fibers and cells in the synovial tissues of the cricoarytenoid joint (CA joint).

Methods:

Routine histology and immunohistrochemistry using sagittal or nearly sagittal sections obtained from 18 elderly cadaveric specimens.

Results:

The CA joint capsule was thin and contained few elastic fibers. A limited supportive ligament, namely, a thickened fascia of the posterior cricoarytenoid muscles, was sometimes evident on the lateral aspect of the CA joint. However, even in the weaker medial aspect of the joint, no marked destruction of the synovial tissues was found. The CA joint always contained synovial folds—a short medial fold and long lateral folds—but these contained no or few macrophages, lymphocytes, and blood capillaries. In 2 exceptional specimens showing inflammatory cell infiltration in the submucosal tissue of the larynx, the macrophage-rich area extended toward the capsule and medial synovial fold.

Conclusions:

The lateral aspect of the CA joint was likely to be supported mechanically by the muscle-associated tissues. Strong support of the arytenoid by muscles might reduce the degree of CA joint injury with age. However, some patients with hoarseness due to mucosal inflammation of the larynx might have accompanying synovitis and subsequent cartilage injury in the CA joint.

Central nervous system control of the laryngeal muscles in humans

Laryngeal muscle control may vary for different functions such as: voice for speech communication, emotional expression during laughter and cry, breathing, swallowing, and cough. This review discusses the control of the human laryngeal muscles for some of these different functions. Sensori-motor aspects of laryngeal control have been studied by eliciting various laryngeal reflexes. The role of audition in learning and monitoring ongoing voice production for speech is well known; while the role of somatosensory feedback is less well understood. Reflexive control systems involving central pattern generators may contribute to swallowing, breathing and cough with greater cortical control during volitional tasks such as voice production for speech. Volitional control is much less well understood for each of these functions and likely involves the integration of cortical and subcortical circuits. The new frontier is the study of the central control of the laryngeal musculature for voice, swallowing and breathing and how volitional and reflexive control systems may interact in humans.

Anatomical bases of glottic widening surgery related to arytenoidectomy

Derived from arytenoidectomy, different surgical techniques have been developed for widening the glottis in cases of bilateral vocal cord paralysis. Their anatomical bases were reinvestigated in plastinated serial sections of 25 adult human larynges. At the anterolateral surface of the arytenoid cartilage, blood vessels crossing the crista arcuata may cause bleeding complications. The arytenoid cartilage is related to three major histologic complexes which must be taken into account during surgery. The dense connective tissue complex consists of the cricoarytenoid ligament and the conus elasticus, which are connected ventrocaudally. The cricoarytenoid ligament and the vocal cord are separated by the cartilaginous inscription of the vocal process. The muscular complex consists of the transverse arytenoid muscle, which is the posterior wall of the glottis, and the thyroarytenoid muscle, which is intimately fixed to the conus elasticus near the arytenoid cartilage. The loose connective tissue complex is represented by the vestibular fold, containing adipose tissue, mucous glands, few collagenous fiber septa, and at its posterior end, a small cranial extension of the vocal cord. For glottic widening surgery, the arytenoid cartilage must be regarded as an integrated component of an extended fibro-cartilaginous framework supporting the laryngeal airway. Shrinking processes of the dense connective tissue elements may complicate surgical interventions. Iatrogenic lesions of the posterior glottis should be avoided to prevent the development of synechia or insufficient closure of the larynx during swallowing.