The serratus ventralis muscle is a large fleshy muscle placed on the lateral side of the neck and thorax and is named as serratus thoracis and serratus cervicis according to the region covered.
It is a large, thick muscle extends from the level of the second cervical vertebra to the fifth rib. The posterior part of this muscle is overlapped by the two anterior digitations of the succeeding. It lies partly on the neck and partly on the lateral wall of the thorax.
Origin: From the transverse process of the second or third cervical vertebra to seventh cervical vertebra and the lateral face of ribs from first to the fifth rib.
Insertion: The triangular rough area at the dorso-anterior part of the ventral surface of the scapula.
Action: To pull the scapula towards the neck. Two side muscles acting together to extend the neck and singly inclines the neck to its own side.
Blood supply: Superior cervical, dorsal and vertebral arteries.
Nerve supply: Fourth, fifth and sixth cervical spinal nerves and long thoracic nerve.
Serratus thoracis
This muscle is thin and flat muscle covered by a strong glistening aponeurosis. It overlaps the serratus cervicis. Its ventral border is serrated and shows six digitations.
Origin: External surfaces of ribs from 4 th to the 9 th .
Insertion: The rough line at the dorso-posterior part of the ventral surface of the scapula. (See the picture at the top)
Action: The two muscles act together as a sling to suspend the trunk between the two forelimbs. Acting singly it pulls the scapula upwards and backwards. When the limb is fixed, each side muscle acts as an extra-ordinary muscle of inspiration in respiratory exertions.
