Distribution of the motoneuronal pools controlling the forelimb muscles in the cervical spinal cord of the Acomys cahirinus.

The spinal motoneuronal pools innervating forelimb muscles in Acomys cahirinus were mapped using Fast Blue retrograde fluorescent tracing. The spatial organization (dorsoventral, mediolateral, and rostrocaudal) of motoneuron pools controlling the targeted muscles was mapped in the cervical spinal cord: (i) motoneuronal pools innervating the m. levator claviculae extend from the rostral part of segment C3 to the caudal part of segment C4 and are located in the ventrolateral column; (ii) motoneuronal pools innervating the m. acromiodeltoideus extend from the rostral part of segment C5 to the caudal part of segment C6 and are located in the central column; (iii) motoneuronal pools innervating the m. spinodeltoideus extend from the middle part of segment C5 to the middle part of segment C7 and are located in the central column; (iv) motoneuronal pools innervating the m. triceps brachii extend from the rostral part of segment C7 to the middle part of segment T1 and are located in the central column; (v) motoneuronal pools innervating the m. biceps brachii extend from the rostral part of segment C5 to the middle part of segment C6 and are located in the dorsolateral column; (vi) motoneuronal pools innervating the m. brachialis extend from the rostral part of segment C5 to the middle part of segment C6 and are located in the dorsolateral column; (vii) motoneuronal pools innervating the m. extensor carpi radialis longus extend from the caudal part of segment C5 to the caudal part of segment C6 and are located in the dorsolateral column; (viii) motoneuronal pools innervating the m. flexor digitorum profundus extend from the middle part of segment C7 to the caudal part of segment T1 and are located in the dorsolateral column. These findings represent the first detailed mapping of cervical motoneuronal pools in A. cahirinus.