Trunk Extension - 29th Lecture PDF

# 29^th lecture - Theoretical Part: Trunk Extension ## Objectives At the end of this lecture the student will be able to: 1. Identify the primary muscles involved in trunk extension. 2. Identify the range of motion of trunk extension. ## Content: 1. Primary muscles involved in trun...

# 29^th lecture - Theoretical Part: Trunk Extension ## Objectives At the end of this lecture the student will be able to: 1. Identify the primary muscles involved in trunk extension. 2. Identify the range of motion of trunk extension. ## Content: 1. Primary muscles involved in trunk extension. 2. Range of motion of trunk extension. ## Trunk Extension Motion ### Primary Muscle: - **Erector spinae muscle:** It consists of three columns of muscles, the Iliocostalis, Longissimus, and Spinalis, each running parallel on either outer side of the Vertebra and extending from the lower back of the skull all the way down to the Pelvis. - **Iliocostalis.** - **Longissimus.** - **Spinalis**. ### Accessory Muscles: - Semispinalis. - Rotatores. - Multifidus ### Range of Motion: - Thoracic spine extends only to approximately a straight line. - Lumbar spine extends freely (Fig.1) ### Range Limiting Factors: 1. Tension of anterior longitudinal ligament of spine. 2. Tension of anterior abdominal muscles. 3. Contact of spinous processes. 4. Contact of inferior articular margins with laminae. ## Anatomy of Iliocostalis The furthest from the vertebra of all the erector spinae muscles and originates from: - **Iliocostalis lumborum:** - *Origin:* From lumbosacral fascia. - *Insertion:* The angles of ribs 7 to 12 (inferior 6 ribs) - **Iliocostalis thoracis:** - *Origin:* From the angles of ribs 7 to 12 (inferior 6 ribs) - *Insertion:* The angles of ribs 1 to 6 (upper 6 ribs) - **Iliocostalis cervicis:** (Fig. 2) - *Origin:* From ribs 3 to 6. - *Insertion:* Transverse processes of cervical C6-C4. ## Action: - Extension and laterally flex of the vertebral column. - Maintaining erect posture. - Bending the vertebral column to the same side. ## Nerve Supply: Adjacent spinal nerves ## Anatomy of Longissimus The longissimus is the longest of the back and is made up of 3 distinct parts, the Capitis, the Cervicis and the Thoracis (Fig 3). - **Longissimus capitis:** - *Origin:* From the transverse processes of the four thoracic vertebrae. - *Insertion:* Mastoid process of the skull. - *Action:* It holds the head erect as well as rotating toward the same side of the muscle that is contracting. - **Longissimus cervicis:** - *Origin:* From the transverse processes of the four thoracic vertebrae. - *Insertion:* Lateral of the cervical vertebra 2 through till 6. - *Action:* Bending the neck and assist in keeping the cervical spine erect. - **Longissimus Thoracis** - *Origin:* Lumbosacral fascia. - *Insertion:* 1. Transverse processes of the middle thoracic vertebrae 2. The lower nine or ten ribs. ## Action: It assists in the motion of backward and side wards bending. - Keeping the spine erect and pulling the ribs downward to help with breathing. ## Anatomy of Spinalis The Spinalis muscles are the closest to the vertebrae of all the Erector Spinae muscles and consists of two muscles, the Cervicis and the Thoracis. - **Spinalis cervicis:** - *Origin:* From the lower ligamentum nuchae and spinous processes of C6 or C7 (Fig. 4). - *Insertion:* Spinous process of the axis (C2). - *Action:* Extend and laterally flex vertebral column. - **Spinalis Thoracis:** - *Origin:* 1. Lumbosacral fascia. 2. The spinous processes of T11 to L2. - *Insertion:* All the spinous processes of the upper from T2 to T8. - *Action:* Extend and laterally flex vertebral column. ## Description of Image The image shows a series of anatomical diagrams relating to the muscles involved in trunk extension. The diagrams show the locations and attachments of the: - Iliocostalis - Longissimus - Spinalis muscles of the back. The diagrams are labeled with details about their origin, insertion, and action which are explained in the document. The diagrams also reference other bones and structures of the spine and skull. The images are labeled as "Figure 1", "Figure 2", "Figure 3", and "Figure 4".