Chapter 8 (3)

• Abnormalities of spinal curvatures may result from disease, paralysis of the trunk muscles, poor posture, pregnancy, or congenital defects.
• Scoliosis is an abnormal lateral curvature, a developmental abnormality in which the body and arch fail to develop on one side of thevertebrae. It is the most common one and usually happens in the thoracic region, particularly in adolescent girls.

  
• Kyphosis (hunchback) is an exaggerated thoracic curvature usually from osteoporosis, osteomalacia, or spinal tuberculosis, wrestling, or weight lifting in young boys.

  
• Lordosis (swayback) is an exaggerated lumbar curvature that can come from pregnancy or obesity.

  
• The vertebra has a general structure that includes several key components. The Body, also known as the centrum, is made up of spongy bone with red marrow and is covered by a compact bone shell. The surface of the body is rough, which helps intervertebral discs to attach and bear weight. The Vertebral foramina collectively form the vertebral canal that houses the spinal cord. The Vertebral arch includes the Pedicle, which is pillar-like, and the Lamina, which is plate-like. The Spinal process, which projects from the arch, is the bump that is visible under the skin.
• The intervertebral foramen is an opening between the pedicles of two adjoining vertebrae. It is the passageway for spinal nerves.

  
• The intervertebral discs, which total 23, are important structures in our spine. They are made up of a gelatinous inner mass called the nucleus pulposus and an outer ring of fibrocartilage called the annulus fibrosus. These pads serve multiple functions such as binding the vertebrae together, supporting the weight of the body, and absorbing shock. However, in cases where the disc is herniated (also known as "ruptured" or "slipped"), it puts painful pressure on the spinal nerve or spinal cord.

  
• The thoracic cage consists of the thoracic vertebrae, sternum, and ribs. It encloses the lungs and the heart. It also provides some protection for the spleen, liver, and kidneys. It provides attachment for the pectoral girdle and upper limbs. It has a broad base and narrower apex. It is rhythmically expanded by respiratory muscles to draw air into lungs.
• The sternum, also known as the breastbone, is a bony plate located at the front of the heart
• During CPR, no pressure should be applied to the xiphoid to avoid internal bleeding
• The sternum is divided into three regions:

  • Manubrium: broad superior part with a suprasternal (jugular) notch and clavicular notches that articulate with the clavicle
  • Body (gladiolus): longest part with a sternal angle where it joins the manubrium, ribs attach along the scalloped lateral margins
  • Xiphoid: inferior point, attachment site for some abdominal muscles

  
• There are 12 pairs of ribs. The posterior (proximal) ends of the ribs are attached to the vertebral column, while most ribs' anterior (distal) ends are attached to the sternum. Costal cartilages, made of hyaline cartilage, attach the ribs to the sternum.

  
• The head of a rib is the portion of the rib that articulates with the bodies of thoracic vertebrae. There are the superior and inferior articular facets of the head of the rib. The neck is the narrow portion distal to the head. The tubercle is the wider, rough area that is distal to the neck, it articulates with the transverse costal facet of the vertebra. The angle is the lateral curve of the rib. The shaft is the long, gentle sloping, blade-like portion of the rib. The costal groove is on the inferior margin of the shaft.

  
• The human rib cage is composed of true ribs (ribs 1-7) and false ribs (ribs 8-12). True ribs are connected to the sternum directly, while false ribs do not have independent connections to the sternum. Ribs 11-12 are known as floating ribs, as they lack a cartilaginous connection to the sternum or higher costal cartilages, and they do not have tubercles or attachments to transverse processes of vertebrae.

  
• The Pectoral girdle (shoulder girdle) supports the arm. It consists of two bones on each side of the body; the clavicle (collarbone) and the scapula (shoulder blade). The clavicle articulates medially to the sternum and laterally to the scapula. It is made up of the Sternoclavicular joint and the Acromioclavicular joint. The scapula articulates with the clavicle and the humerus. The glenohumeral joint is the shoulder joint it can easily dislocated due to loose attachment.

  
• The clavicle is the collarbone and it is an S-shaped somewhat flattened bone. It has a sternal end that looks like a hammer-like head and an acromial end that is flattened. The clavicle braces the shoulders and keeps the arms away from the midline. It is also one of the bones that are unfortunately often fractured.

  
• The scapula is named for its resemblance to a shovel. It is a triangular plate that posteriorly overlies ribs 2 to 7. The suprascapular notch is a conspicuous notch on the superior border of the scapula that provides passage for a nerve. The spine of the scapula is a transverse ridge on the posterior surface.

  
• The scapula's lateral angle can be divided into three main features. Firstly, the acromion, which is a plate-like extension of the spine that forms the shoulder's apex. It also articulates with the clavicle, which is the sole point of attachment of the scapula and upper limb to the rest of the skeleton. Secondly, the coracoid process, which is shaped like a bent finger, provides an attachment point for the tendons of the biceps brachii, and other arm muscles. Finally, the glenoid cavity is a shallow socket that articulates with the head of the humerus and helps form the glenohumeral joint.