Identifying Bones of the Trunk and Core - Anatomy

The 8th, 9th, and 10th ribs are false ribs in that they do not articulate directly with the sternum, but with a cartilage which articulates with the sternum. The first seven ribs are true ribs, in that they articulate with the sternum at the readily observable costal (rib) notches. The 11th and 12th ribs are floating ribs, in that they do not connect at all to the sternum.

The clavicles insert in the most superior portion of the sternum known as the manubrium. The clavicles do not insert into the body of the sternum, the xiphoid process, the humerus, or the supraspinatus muscle.

The sternal angle separates the manubrium and the body of the sternum.

The first rib inserts on the manubrium of the sternum.

The second rib inserts at the sternal angle. The first rib inserts on the manubrium and the third through six ribs insert on the body of the sternum.

The third through sixth ribs insert at the body of the sternum. They do not insert at the manubrium, xiphoid process, clavicle, or the humerus.

The jugular notch, also known as the suprasternal notch is located at the superior portion of the manubrium. It is not located on the body of the sternum, the xiphoid process, the clavicle or the humerus.

The xiphisternal joint separates the body of the sternum and the xiphoid process. The sternal angle separates the manubrium and the body of the sternum.

Primary curvature is found in newborns, whereas secondary curvature develops over time. The thoracic and sacral portions of the vertebral column are convex, giving babies a more hunched posture.

Atlas is another term for C1. Its superior articular facets receive the condyles of the occipital bone in the skull, which allows the neck to move backwards and forwards. The axis, or C2, has a superiorly projecting dens that distinguishes it from the atlas.

The hyoid bone acts as an attachment point for many muscles in the neck. When swallowing, the larynx is elevated and the epiglottis is removed from the glottis, allowing matter into the esophagus.

The top two cervical vertebrae (C1 and C2) are responsible for allowing the head to move in a nodding motion, as well as side to side. The atlas is the first cervical vertebra (C1), and attaches to the occipital condyles in order to allow a nodding motion. The axis is the second cervical vertebra (C2) and allows for twisting motion from side to side.

The thoracic vertebrae are located in the trunk and allow for twisting motion, and some bending (though this is mostly allowed by the lumbar region). The sacrum is located inferior to the lumbar vertebrae and does not substantially contribute to movement.

There are 33 vertebrae in the human body: 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 (fused) sacral vertebrae, 3-4 (fused) coccygeal vertebrae.

Primary curvatures of the spine reflect the original shape of the embryo, and are concave to the anterior. The thoracic and sacral curvatures are examples of primary spinal curvatures. Exaggeration of these curvatures is considered kyphosis.

The cervical and lumbar curvatures are examples of secondary curvatures and are concave to the posterior. Exaggeration of these curvatures is considered lordosis.

The spinous processes of the vertebrae largely dictate their range of motion and ability to interlock with adjacent vertebrae. Cervical vertebrae have short, bifid (split) spinous processes to facilitate a wide range of movement. The neck is capable of twisting, nodding, and lateral deviation. Thoracic vertebrae have long spinous processes that point to the inferior and align with the vertebra immediately inferior. This promotes anterior concavity, allowing the motion of bending forward. Lumbar vertebrae have shorter posterior spinous processes that do not interact with adjacent vertebrae. This allows for twisting motions, as well as anterior and posterior concavity. Next to the cervical vertebrae, the lumbar vertebrae have the largest range of articulation.

The sternum is a bone that is a part of the skeleton of the thorax. It is made of three components: the manubrium, the body, and the xiphoid process. The manubrium is the portion closest to the neck area and has articulations with the clavicle on both sides. It also has three additional articulations: the first rib cartilage, the second rib, and the body of the sternum. The last of these is called the manubriosternal joint, or the angle of Louis. The body of the sternum further articulates with the xiphoid process to form the xiphisternal joint. These angles are important landmarks in locating structures in the thoracic cavity. The xiphoid process can be felt in the epigastric quadrant of the abdomen.

The zygomatic process is a region of the skull. Technically, the zygomatic process is made of three components: the zygomatic process of the frontal bone, the zygomatic process of the maxilla, and the zygomatic process of the temporal bone.

In a human skeleton, there are twelve pairs of ribs found in the thoracic cavity. They extend from the vertebrae and some have attachments to the sternum in the anterior. The ribs provide protection for the organs in the thorax and aid in changing the anterior to posterior and transverse diameter of the chest.

There are three classifications of ribs: true, false, and floating. True ribs are ribs 1 to 7 and attach to the sternum directly. False ribs are ribs 8 to 10 and attach to the cartilage of the ribs above. Ribs 11 and 12 are floating ribs in that they have no anterior attachments.

The pelvic girdle is the combination of pelvis and the sacrum, which form a closed transverse ring. The ilium, the ischium, and the pubis form the pelvis. These three bones fuse together at the acetabulum. The femur articulates with the acetabulum, but is not considered part of the pelvic girdle.

The lower part of the pelvis is formed by the ileum, ishium, and pubic bones. These bones join to create a cavity. This cavity is larger in females to allow the passage of an infant during childbirth.

The pectoral girdle is made up of the scapulae (shoulder blades) and clavicles (collar bones). The coccyx, also referred to as the tailbone, is located at the inferior of the spinal column. The sacrum is a curved set of fused bones that forms part of the posterior pelvis. The tarsus is the collection of seven bones in the foot that form the ankle and instep.

There are twelve thoracic vertebrae, labeled T1 to T12. They have articulations (joints) that connect them with the rib cage. The cervical vertebrae, labeled C1-C7, are located in the neck. The lumbar vertebrae, labeled L1-L5, are located in the lower back. The sacrum is a segment of the vertebral column that forms part of the posterior pelvis. The coccyx, or tailbone, is the most inferior part of the vertebral column.