Trunk Extension Muscles and Motion Quiz

Trunk Extension Muscles

• The erector spinae muscles are composed of the iliocostalis, longissimus, and spinalis muscles
• These muscles run parallel along the sides of the vertebrae, extending from the lower back of the skull to the pelvis
• The iliocostalis muscles originate from the lumbosacral fascia and insert into the angles of ribs 7-12 (inferior 6 ribs) and ribs 1-6 (superior 6 ribs).
• The longissiumus originate from the transverse processes of the lumbar vertebrae and inserts into the transverse processes of the cervical vertebrae .
• The spinalis originates from the transverse processes, and inserts around the spinous processes of the thoracic and cervical vertebrae.
• The accessory muscles involved in trunk extension include the semispinalis, rotatores, and multifidus muscles.

Range of Motion

• Thoracic spine extension is limited, approximately straight line.
• Lumbar spine extension is more extensive.
• Range of motion is affected by the tension on the anterior longitudinal ligament, anterior abdominal muscles, contact of the spinous processes, and contact of inferior articular margins of the laminae.

Trunk Extension Anatomy (Iliocostalis)

• The iliocostalis muscles are the furthest from the vertebrae in the erector spinae group
• They originate from the lumbosacral fascia
• Iliocostalis lumborum originates from the lumbosacral fascia, and its insertion point is the angles of ribs 7-12.
• Iliocostalis thoracis originates from the angles of ribs 7-12, and its insertion point is the angles of ribs 1-6.
• Iliocostalis cervicis originates from the ribs 3-6, and its insertion point is the transverse processes of the cervical vertebrae C6-C4.
• The actions of the iliocostalis group include flexing the spine and laterally flexing it towards the relevant side

Trunk Extension Anatomy (Longissimus)

• The Longissimus muscles are the longest of the erector spinae group
• The longissimus muscle is comprised of three components: capitis, cervicis, and thoracis
• Longissimus capitis originates from the transverse processes of the upper thoracic vertebrae and inserts into the mastoid process of the temporal bone.
• Longissimus cervicis originates from the transverse processes of the upper 4 thoracic vertebrae and inserts into the transverse processes of the cervical vertebrae (C2-C6).
• Longissimus thoracis originates from the lumbosacral fascia and inserts into the transverse processes of the 12th thoracic vertebrae.
• Its action includes holding the head erect, rotating the head to the same side, bending the neck and keeping the cervical spine erect.

Trunk Extension Anatomy (Spinalis)

• The spinalis muscles are closest to the vertebrae and consist of the cervicis and thoracis muscles
• Spinalis cervicis arises from the lower ligamentum nuchae and the spinous processes of C6-C7, and inserts into the spinous processes of C2.
• Spinalis thoracis originates from the spinous processes of T11-L2 and inserts into the spinous processes of T2-T8.
• The actions of the spinalis group include extending and laterally flexing the vertebral column.