Characteristics of Tetanic Force Produced by the Sternomastoid Muscle of the Rat

Abstract

The sternomastoid (SM) muscle plays an important role in supporting breathing. It also has unique anatomical advantages that allow its wide use in head and neck tissue reconstruction and muscle reinnervation. However, little is known about its contractile properties. The experiments were run on rats and designed to determine in vivo the relationship between muscle force (active muscle contraction to electrical stimulation) with passive tension (passive force changing muscle length) and two parameters (intensity and frequency) of electrical stimulation. The threshold current for initiating noticeable muscle contraction was 0.03 mA. Maximal muscle force (0.94 N) was produced by using moderate muscle length/tension (28 mm/0.08 N), 0.2 mA stimulation current, and 150 Hz stimulation frequency. These data are important not only to better understand the contractile properties of the rat SM muscle, but also to provide normative values which are critical to reliably assess the extent of functional recovery following muscle reinnervation.

Muscle reinnervation with nerve-muscle-endplate band grafting technique: correlation between force recovery and axonal regeneration

“…Muscle force measurement is widely used to assess the mechanical function and contractile properties of a muscle [35–41]. Our studies [28,30–33] and others [23,25,42,43] have demonstrated that force measurement is a reliable technique in determining the degree of functional recovery of a reinnervated muscle. The denervated muscle is characterized by reduced muscle mass, decreased fiber size, increased connective tissue, and reduced metabolic capacity [44,45] which can be reversed by reinnervation [28,33,46].…”

“…At the end of the 3-month recovery period, the muscle force of the reinnervated SM was measured by using a stimulation and recording system as described in our publications [28,30–33]. Briefly, the SM muscle was dissected free from surrounding tissue without damaging the SH nerve branch innervating the implanted NMEG.…”

Nerve-Muscle-Endplate Band Grafting

“…58 Briefly, the SM muscle examined was dissected free from the surrounding tissue. The rostral tendon of the muscle was cut close to the insertion, tied together with a 2-0 suture, and connected to a servomotor lever arm (Model 305B Dual-Mode Lever Arm System, Aurora Scientific Inc., Aurora, Ontario, Canada).…”

“…At the moment of force measurement, the lever arm was stationary and the muscle was stretched to the optimal length for the development of maximum force as described. 58 During experiment, the rat was placed supine on a heating pad (homoeothermic blanket system, Stoelting, Wood Dale, IL) and the core body temperature was monitored with a rectal thermistor and maintained at 36°C. The muscle and nerve examined were regularly bathed with warmed mineral oil throughout the testing to maintain muscle temperature between 35-36°C.…”

Histochemical and ultrastructural changes of sternomastoid muscle in aged wistar rats

“…The sternocleidomastoid muscle in humans is located in the cervical region, which consists of two bellies and insertion in the mastoid process, with many functions in the craniovertebral joints movement, and during the inspiration process (Sobotka and Mu, 2010). In rodent's mammals, Rattus norvegicus, homologous muscles to sternocleidomastoid are distinct and parallel, separated by a thin membrane of connective tissue, being the SM disposed medially and the cleidomastoid muscle disposed posterolaterally.…”