This session is about the spine. There are different regions of the spine. We can refer to the cervical, thoracic, lumbar, sacral, and coccygeal. For the cervical spine, there are seven vertebrae; for the thoracic, there are a total of twelve vertebrae; for the lumbar, there are a total of five vertebrae; for the sacral, there are five vertebrae fused to form the sacrum; for the coccygeal, which refers to the tailbone. It may vary from three to five depending on the individuals. These are the general structures of each vertebra. It involved the vertebral body, two pedicles, two laminae on the side, two transverse processes and one single spinous process. You may see there is a hole in the middle. We call it the vertebral canal or the spinal canal. This is where the spinal cord passed through within the vertebral column. This is how it looks like for the vertebral column. The facet joint, it's a synovial joint. It is formed between the superior and the inferior articular processes of the adjacent vertebrae. We also have an intervertebral disc between each vertebra. The intervertebral disc is fibrocartilage located between adjacent vertebrae. Its function is shock absorption for the spine. For each spinal column for the adults, we have two natural curves located in the thoracic region as well as the lumbar region. For the thoracic region, the curve is concave anteriorly. We call it the kyphotic curve. For the lumbar region, the curve is concave posteriorly. We call it the lordotic curve. These are the common movements of the spine. This one is the trunk flexion. The second one is the trunk extension. This one is the trunk lateral flexion. The one on the right, when we see it from the top, it is the trunk rotation. This is just what we see from the front, from the anterior of the body. It is the trunk rotation. Now we look into the cervical vertebrae. We have C1 to C7. These vertebrae have some distinctive characteristics. The spine has short bifid spines and transverse processes. For the vertebral bodies, it curves upwards at the lateral edges. For the facet joints on the superior articular process, it faces obliquely backward and upwards, which allows rotation and lateral flexion together. The cervical vertebra is a more flexible joint of the region. It allows neck movement. If we look into some modified cervical vertebrae which are the C1, C2, and C7. For the C1, we call it the atlas. It's a relatively large transverse process with two lateral masses. Atlas has no body and its’ concave facets on the superior surface of each lateral mass are articulated with the skull. When the C1 and the skull they articulate together, we call it the atlantooccipital joint. This joint permits flexion and extension, which is the nodding movement of our head. For the C2, we call it the axis. The axis has a unique vertical projection. We call it the dens or the odontoid process. The dens project superiorly from the upper surface of its body and represent the body of the atlas. The dens allow the rotation of the head as we look from side to side. For the C7, the feature is that it possesses a long, non-bifid spine. We can palpate this spinous process and we refer it as the prominent vertebra. We move on to the thoracic region. We have T1 to 1T2. The body is heart-shaped. The sizes increase as we proceeded down to the spine. We have a costal facet for these thoracic vertebrae because it provides an articulation surface for the head of the ribs. The spinous process is more pointed, and the angle is sharply downwards. For the lumbar vertebrae, we have L1 to L5. The body of the lumbar vertebrae is kidney in shape. It is larger because it allows us to carry the load of our body. That is why the diameter of each lumbar vertebra from L1 to L5 of increases. The L5 lumbar vertebra, there are some features for it. The transverse processes are shorter and it has a less angular spinous process. The inferior articular facets are widely separated and face anteriorly. It's also articulated with the sacrum. Lastly we have the sacral and the coccygeal vertebrae. The sacrum is a triangular bone. It is formed by the fusion of five vertebrae. The coccyx, we refer it as the tailbone. It locates below the apex of the sacrum. It could be a small single bone or up to 4 rudimentary vertebrae. The coccyx and sacrum are usually articulate together via a small intervertebral disc. Here is the summary of the features of a typical vertebra in different regions of the vertebral column for your reference. Now we will move on to the muscle of the back. We can divide the muscles into the superficial layer, the intermediate layer and the deep layer. For the superficial layer, the main function is to allow the movement of the upper limb. The intermediate layer attaches to the ribs and may serve as a respiratory function. For the deep layer, it acts on the vertebral column and the main function is for postural maintenance. You may see the superficial muscle of the back in this photo. They are the trapezius, the latissimus dorsi, the levator scapulae which connects the spine of the scapula to the vertebral column, as well as the rhomboid major and minor. These five muscles mainly act on their shoulder girdles. These muscles are the deep muscles of the back that help maintains our posture. They are the splenius, the erector spinae, and the transversospinalis. All these muscles interconnect with the base of the skull all the way to the sacrum and the vertebrae in between. For the erector spinae, it includes three muscles, the iliocostalis, the longissimus and the spinalis. For the transversospinalis, it includes the semispinalis, multifidus and rotators, which involve the movement in the vertebrae. Now we move on to the anterior parts of the trunk. These are the muscles of the abdomen. There are four principle muscles on each side of the midline. The rectus abdominis is located in the center. The external oblique is the most superficial one on the side. The muscle lying deep to the external oblique would be the internal oblique. The transversus abdominis would be the deepest layers. The rectus abdominis is the top layer of the abdominal muscles and we always refer it as the “six-pack”. They are two flats and parallel muscles separated by the linea alba. Its function is to flex the spinal column, to tense the anterior wall of the abdomen as well as to assist in compressing the content of the abdomen. Next to it will be the external oblique. The muscle fibers travel downwards and forwards which extends from the lower half of the ribs down to the pelvis. Its functions are to help in trunk rotation, stabilize the core, assist with forced expiration in breathing and assist with bending from side to side, which we refer as the lateral flexion of the trunk. For the internal oblique the muscle fibers travel forwards and upwards. With the external oblique on the outer side and the transverse abdominis on the inner sides, the internal oblique lies between these two muscles. It helps to maintain the abdominal pressure as well as the movement of the trunk. Lastly, we have the transversus abdominis. It is the deepest abdominal muscle extends between the ribs and the pelvis. These muscles wrap around the trunk from front to back as a back-support belt. The function of it is to maintain proper placement of the abdominal content as well as to support our lower back. Lastly, we have this graph, the cross-sectional area of the abdomen muscles. The rectus abdominis muscles located at the center, while the external oblique, internal oblique and the transversus abdominis on the side. You may see the external oblique muscles are more superficial while the internal oblique lies in the middle and the transversus abdominis are dominant at the bottom. Now we will move on to the surface anatomy of the spine. We should be able to locate the anatomical landmark of the spine by palpation. If we find the spine of the scapula, that usually refers to the level of thoracic 3, the T3 of the spine. Then we move on and move down, we will find the inferior angle of the scapula that refers to the T7, the thoracic 7. A little bit downward would be where the pelvis is. With the iliac crest, it refers to the level of lumbar 4, the L4 vertebra. The posterior superior iliac spine (PSIS) is, we call it the dimples, this is where the S2 is. We are done with this session. Than