Musculoskeletal System and Anatomy - NCLEX-PN

The falx cerebri, the dura that separates the two hemispheres of the brain, attaches to a bony projection of the ethmoid bone called the crista galli, or "crest of the rooster." This projection is a distinct landmark that arises from the cribiform plate. The ethmoidal labyrinth and orbital plate do not form any attachments to the dura of the brain.

The scapula has multiple fossa that serve as attachment points of various bones and muscles of the shoulder. Among these are the glenoid fossa, where the head of the humerus articulates with the scapula, the subscapular fossa, which is an attachment for the subscapularis muscle, the infraspinous fossa, to which the infraspinatus attaches, and the supraspinous fossa, to which the supraspinatus muscle attaches. There is no suprascapular fossa on the scapula.

The supraspinatus tendon passes under the acromion, a bony hook-like process at the end of the scapular spine. Inflammation of the supraspinatus muscle or tendon can quickly lead to entrapment of this muscle under the acromion, causing pain and reduced mobility. The coracoid process, another projection from the anterior scapula, is an attachment point for several muscles and ligaments, including the pectoralis minor and the short head of the biceps brachii.

The pelvis is formed by the sacrum and coccyx and the three bones that come together to form the innominate: the ilium, ischium, and the pubis. The ileum is a part of the small intestine.

The large, fan-like ridge of bone that can be felt just under the waist is the iliac crest. The anterior superior iliac spine and the anterior inferior iliac spine are smaller protuberances on the ilium that are important landmarks for assessing malpositions of the bones of the sacroiliac joint. The greater sciatic notch is in the posterior ilium and serves as a passage for several muscles and nerves of the pelvic girdle.

The head of the femur rests in the acetabulum, a bony socket on the lateral pelvis that is formed by all three bones of the innominate (the ischium, ilium, and the pubis). The pubic symphysis is a midline cartilaginous joint between the pubic bones. The obturator foramen is an opening in the innominate through which multiple nerves and vessels pass. The pubic tubercle is a bony projection on the pubis that serves as an attachment point for inguinal ligament.

All of the bones listed form the posterior portion of the foot. The largest bone in the foot is the calcaneus. It forms the heel and articulates with the bones of the ankle.

The bones that form the anterior half of the foot (but not the toes) are the metatarsals. These are mirrored in the metacarpal bones of the hand. The carpal bones form the wrist, and the phalanges form the toes and the fingers.

Long bones are lengthened during childhood and adolescence via a process referred to as endochondral ossification. In this process, chondrocytes of the growth plate hypertrophy and eventual die, leaving cavities that are then colonized by osteoprogenitor cells. These osteoprogenitor cells then differentiate into osteoblasts, which mineralize the newly forming bone. None of the other answers are actual processes in bone formation or physiology.

There are five distinct zones in regions of endochondral ossification. These are the resting zone, the zone of proliferation, the zone of maturation, the zone of calcification, and the zone of ossification.

The behavior of cells in the zones of endochondral ossification is as follows:

• The resting zone: normal resting chondrocytes within hyaline cartilage
• The zone of proliferation: rapid mitosis of chondrocytes
• The zone of maturation: hypertrophy of chondrocytes
• The zone of calcification: the death of chondrocytes due to lack of nutrients and inability to eliminate cellular wastes
• The zone of ossification: migration of osteoprogenitor cells into the cavities left behind by dead chondrocytes and mineralization of newly formed bone

Variation in color of bone marrow cells is not related to their level of activity, calcification, or the types of blood cells they produce. Rather, "red marrow" is primarily hematopoietic cells (both red and white progenitor cells) while "yellow marrow" is primarily composed of fat cells.

In adults, hematopoietic bone marrow is generally confined to the flat bones, including the sternum, the skull, the ribs, and the pelvis. Hematopoietic bone marrow also exists in the proximal end of the femur in most adults, but is not generally found in the tibia or fibula.

Muscle attaches to bone via tendons, fibrous extensions of the sheath of the muscle body that are primarily composed of tightly packed collagen fibers. In comparison, ligaments attach bones to other bones without involvement with a muscle, such as the ligaments between the metacarpals of the wrist. Sutures are fibrous joints of the cranium, and hyaline cartilage is at the point of articulation of many bones but it is neither incorporated into muscle structure, nor does it attach to the bone with which it articulates. Rather, articular cartilage primarily serves to allow bones to glide more easily over each other during movement.

The structural classification of joints divides them according to the form of tissue that connects bones to each other. The three structural divisions of joints are fibrous, cartilaginous, and synovial. In contrast, synarthrosis, amphiarthrosis, and diarthrosis are all classifications of a joint's movement.

Condyloid, gliding, and hinge joints are all types of synovial joints, while sutures, syndesmosis, and gomphosis are all types of fibrous joints.

Gomphosis joints are fibrous joints that attach the root of the tooth to the bony socket of the mandible or maxilla.

Both the tibio-fibular joint and the joint between the radius and ulna are syndesmoses, while the joints between the bones of the skull are sutures.

The majority of joints of the human body are synovial joints. These joints are diarthrotic and include a synovial joint capsule that allows for greater freedom of movement. Examples include the fingers and the elbows, the knees, the temporomandibular joint, and the hips.

Fibrous and cartilagenous joints, all of which are either synarthrotic or amphiarthrotic, are relatively less common.

The intervertebral disc articulate with the vertebrae via cartilaginous symphysis joints. These joints are amphiarthrotic, meaning that they allow for slight mobility.

Synovial joints are all diarthrotic and characterized by a flexible joint capsule filled with synovial fluid. Synarthrotic joints have no movement - examples include the skull bones and the joints of the teeth to the jaw.

The head of the femur articulates with the acetabulum, a concave surface on the pelvis formed by the union of three bones: the ilium, the ischium, and the pubis.

The obturator foramen is a large opening in the pelvis formed by the pubis and the ischium bilaterally. It does not form any joints but rather allows the passage of the obturator artery, nerve, and vein.

The glenoid fossa is the surface onto which the head of the humerus articulates in the shoulder, and the patella is a part of the knee.