Intertransversarii
The intertransversarii muscles (Latin: musculi intertransversarii) are small muscles that stretch between the transverse processes of vertebrae. Most of these muscles lie in the cervical and lumbar parts of the spine; however, small muscular slips are present in the lower thoracic region. Along with interspinales and levatores costarum the intertransversarii comprise the deepest layer of the deep back muscles.
Intertransversarii cervicis
The intertransversarii cervicis (also known as intertransversarii colli; Latin: musculi intertransversarii cervicis) are more developed than the intertransversarii lumborum. They consist of seven pairs of anterior and posterior intertransversarii colli muscles.
Origin
The origin site of each anterior intertransversarii cervicis muscle is on an anterior tubercle of a cervical vertebra.
Each posterior intertransversarii cervicis muscle originates from a posterior tubercle of a vertebra.
Insertion
Each anterior intertransversarii inserts onto the anterior tubercle of the adjacent vertebra above the insertion site.
The insertion site of each posterior intertransversarii muscle is on the posterior tubercle of the vertebra above.
Action
The anterior and posterior intertransversarii cervicis have a proprioceptive function in controlling the vertebral column position and its movements.
Innervation
The intertransversarii cervicis are innervated by the anterior and posterior rami of spinal nerves.
Blood supply
The arterial blood to the anterior intertransversarii cervicis muscles is supplied via the occipital, deep cervical, and vertebral arteries. The ascending cervical artery supplies the posterior intertransversarii cervicis.
Intertransversarii lumborum
The intertransversarii lumborum (Latin: musculi intertransversarii lumborum) consists of four pairs of muscles located on each side of the lumbar spine, extending between transverse processes of two adjacent lumbar vertebrae. Each pair consists of a medial and lateral component, namely, medial and lateral intertransversarii lumborum.
Origin
The lateral intertransversarii lumborum originates from the transverse and accessory processes of the first to fourth lumbar vertebrae (L1 - L4).
The medial intertransversarii lumborum muscles arise from the accessory processes of the first four lumbar vertebrae (L1 - L4).
Insertion
The muscle fibers of the lateral intertransversarii lumborum insert into the transverse process of the succeeding vertebra.
The medial intertransversarii lumborum insert into the mammillary process of the succeeding vertebra.
Action
The intertransversarii lumborum muscles aid in lateral flexion of the lumbar spine and also stabilizes the spine.
Innervation
The anterior rami of spinal nerves innervate the medial and lateral intertransversarii lumborum.
Blood supply
The intertransversarii lumborum muscles are supplied by the dorsal branches of the lumbar arteries.