![]() Most individuals usually have five sesamoid bones in each hand. In the upper extremities, notable sesamoid bones are found in the hand and wrist. This type of sesamoid allows the maintenance of tendon structure and provides immense flexibility from the fibrous component and elasticity via the cartilage tissue. Both types of sesamoid bones serve unique functions and biomechanical properties.Īnother type of sesamoid bone is the fibrocartilaginous sesamoid. An example of a Type B sesamoid bone is the sesamoid of the peroneus (fibularis) longus tendon. Type B sesamoid bones overlie a bony prominence and are separated by an underlying bursa. Common examples of this type include the hallucis and pollicis sesamoids along with the patella, allowing for increased leverage. Type A sesamoid bones are adjacent to a joint, becoming a part of the joint capsule. Together a sesamoid bone and its relation to other tendons form a joint. Bony surfaces are surrounded by cartilage and incorporated within the cavity, forming the synovium. īased on their positioning and attachment, sesamoid bones can be divided into two broad categories, type A and B. Injuries to the patella greatly reduce its leverage and extensor capabilities these injuries commonly result from trauma and increased tension. This unique mechanism allows for the knee's range of motion and increased weight-bearing activities. For example, the patella increases joint leverage and contributes to our knee's extensor properties. The body contains many sesamoid bones, often offering an added strength advantage to the muscles and supporting tendon stability. While most sesamoid bones are small, these bones play a critical role in our body in leverage, decreasing overall friction and allowing for our body's unique biomechanics and distinct range of motion. Sesamoid bones relieve tension within muscles and tendons, allowing for increased weight-bearing and tolerance by redistributing forces throughout a muscle or tendon, thereby protecting them from significant strain and injury. These bones are often formed in response to added strain to muscles and tendons but can also be normal variants, most commonly present in the hand. There are many sesamoid bones in a person, with up to 42 reportedly found in an individual. Sesamoid bones are most commonly located in the foot, hand, and wrist the largest and most well-known is the patella. The word "sesamoid" derives from the Arabic word 'sesamum' translating to sesame, given that many sesamoid bones are small. Unlike standard bones, which connect via joints, sesamoid bones connect to muscles via tendons. Sutures are firm and immovable joints but allow for expansion of the skull in a growing animal.A sesamoid bone is a small bone commonly found embedded within a muscle or tendon near joint surfaces, existing as focal areas of ossification and functioning as a pulley to alleviate stress on that particular muscle or tendon. Many of the bones of the skull are joined together by fibrous joints called sutures (p 41). The incisive bone is the most rostral and carries the incisor teeth (Fig. The roof of the mouth is called the hard palate and is formed from three bones on the ventral aspect of the skull: the incisive bone or premaxilla, part of the maxilla and the palatine. In the centre of this bone is the cribriform plate – a sieve-like area perforated by numerous foramina through which the olfactory nerves pass from the nasal mucosa to the olfactory bulbs of the brain (see Ch. At the back of the nasal chamber, forming a boundary between the nasal and cranial cavities, is the ethmoid bone. These are covered in ciliated mucous epithelium (see Ch. Each of the chambers is filled with delicate scrolls of bone called the nasal turbinates or conchae. The nasal chamber is divided lengthways into two by a cartilaginous plate called the nasal septum. The most rostral part of the skull carries the nasal chamber, the sides of which are formed by the maxilla and the roof by the nasal bone.
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