Where skeletal muscle is voluntary, cardiac muscle is autorhythmic (beats involuntarily; generates its own action potentials). 3. Smooth muscle: refers to the muscles that are controlled involuntarily by the brain, like those attached to the base of hair follicles or in the walls of the gastro-intestinal tract.The muscle has a single nucleus in the middle of the cell. Skeletal and cardiac muscle are types of straited muscle.here skeletal muscle is voluntary, cardiac muscle is autorhythmic (beats involuntarily; generates its own action potentials). 3. Smooth muscle: refers to the muscles that are controlled involuntarily by the brain, like those attached to the base of hair follicles or in the walls of the gastro-intestinal tract.
When this results in irritation or damage to the adjacent nerves at the T4 level and the patient experiences diffuse arm pain, pins and needles or numbness in the upper arm the condition is known as T4 syndrome. Causes of T4 syndrome. T4 syndrome typically occurs due to injury to the facet joints or disc at T4 which then affects the nerve root at that level. Injury to these structures can occur during excessive bending, lifting, arching, or twisting movements or due to poor posture.
1 Fifth thoracic vertebrae (T5) : The T5 and T4 vertebrae are at the same levels as the sternal angle. 2  The trachea branches into the two main bronchi at the level of T5. 3  The thoracic spinal nerve 5 passes through underneath T5. 4  Sixth thoracic vertebrae (T6) : The thoracic spinal nerve 6 passes through underneath T6.here are 12 thoracic vertebrae (denoted as T1-T12) found in adult humans, and they are situated in between the cervical and lumbar vertebrae, with a general sizing larger than the cervical but smaller than the lumbar vertebrae.