Anatomy basics bones

How many bones are in the human body?

206 bones ( over 300 at birth that fuse together)

uniaxial joint

allows for a motion in a single plane (around a single axis). The elbow joint, which only allows for bending or straightening,

All bones in the body are connected to another bone except?

hyoid bone in the neck

sutures joint

narrow fibrous connective tissue joint found between most bones of the skull. skull sutures are functionally classified as a synarthrosis

multiaxial joint (polyaxial or triaxial joint).

shoulder and hip joints are multiaxial joints. They allow the upper or lower limb to move in an anterior-posterior direction and a medial-lateral direction. In addition, the limb can also be rotated around its long axis. This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body.

tubercle

small rounded projection or nodule on bone for attachment of muscle or ligament

3 types of fibrous joints

sutures, syndesmoses, gomphoses

joints united by fibrous connective tissue

synarthrosis (no movement) allow for very little movement -most of the joints of the skull are held together by fibrous connective tissue and do not allow for movement between the adjacent bones. This lack of mobility is important, because the skull bones serve to protect the brain

There are two types of cartilaginous joints.

synchondrosis symphysis

synostosis

synostosis ("joined by bone"). Examples of synostosis fusions between cranial bones are found both early and late in life

diarthrosis

synovial joints bones are free to move. the joint is less stable. enclosed within a space filled with lubricating fluid Most of the joints between the bones of the appendicular skeleton are this freely moveable type of joint

biaxial joint

type of diarthrosis; a joint that allows for movements within two planes (two axes) metacarpophalangeal joint (knuckle joint) of the hand. The joint allows for movement along one axis to produce bending or straightening of the finger, and movement along a second axis, which allows for spreading of the fingers away from each other and bringing them together.

Joint

where two or more bones or cartilage meet "articulations"

symphysis

A type of joint that has grown together forming a very stable connection bones are joined by fibrocartilage. Fibrocartilage is very strong because it contains numerous bundles of thick collagen fibers, thus giving it a much greater ability to resist pulling and bending forces when compared with hyaline cartilage. This gives symphyses the ability to strongly unite the adjacent bones, but can still allow for limited movement to occur. Thus, a symphysis is functionally classified as an amphiarthrosis. The gap separating the bones at a symphysis may be narrow or wide. Examples in which the gap between the bones is narrow include the pubic symphysis and the manubriosternal joint. At the pubic symphysis, the pubic portions of the right and left hip bones of the pelvis are joined together by fibrocartilage across a narrow gap. Similarly, at the manubriosternal joint, fibrocartilage unites the manubrium and body portions of the sternum. The intervertebral symphysis is a wide symphysis located between the bodies of adjacent vertebrae of the vertebral column. Here a thick pad of fibrocartilage called an intervertebral disc strongly unites the adjacent vertebrae by filling the gap between them. The width of the intervertebral symphysis is important because it allows for small movements between the adjacent vertebrae. In addition, the thick intervertebral disc provides cushioning between the vertebrae, which is important when carrying heavy objects or during high-impact activities such as running or jumping.

synchondrosis

almost immovable A synchondrosis is a cartilaginous joint where the bones are joined by hyaline cartilage. Also classified as a synchondrosis are places where bone is united to a cartilage structure, such as between the anterior end of a rib and the costal cartilage of the thoracic cage A synchondrosis may be temporary or permanent. A temporary synchondrosis is the epiphyseal plate (growth plate) of a growing long bone. The epiphyseal plate is the region of growing hyaline cartilage that unites the diaphysis (shaft) of the bone to the epiphysis (end of the bone). Bone lengthening involves growth of the epiphyseal plate cartilage and its replacement by bone, which adds to the diaphysis. Examples of permanent synchondroses are found in the thoracic cage. One example is the first sternocostal joint, where the first rib is anchored to the manubrium by its costal cartilage. (The articulations of the remaining costal cartilages to the sternum are all synovial joints.) Additional synchondroses are formed where the anterior end of the other 11 ribs is joined to its costal cartilage. Unlike the temporary synchondroses of the epiphyseal plate, these permanent synchondroses retain their hyaline cartilage and thus do not ossify with age. Due to the lack of movement between the bone and cartilage, both temporary and permanent synchondroses are functionally classified as a synarthrosis.

joints held together by cartilage

amphiarthrosis (little movement) also can be synarthrosis (no movement) little movements between the bones -the joints of the vertebral column only allow for small movements between adjacent vertebrae, but when added together, these movements provide the flexibility that allows your body to twist, or bend to the front, back, or side. united by cartilage, a tough but flexible type of connective tissue. These types of joints lack a joint cavity and involve bones that are joined together by either hyaline cartilage or fibrocartilage

syndesmoses joint

bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a ligament or a wide sheet of connective tissue called an interosseous membrane. This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg slightly movable. two bones bound by a ligament (tibia/fibula, radius/ulna) unite parallel bones and prevent their separation. However, a syndesmosis does not prevent all movement between the bones, and thus this type of fibrous joint is functionally classified as an amphiarthrosis. In the leg, the syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint. This provides strength and stability to the leg and ankle, which are important during weight bearing. In the forearm, the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements. Thus in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the antebrachial interosseous membrane allows for the much greater mobility of the forearm. The interosseous membranes of the leg and forearm also provide areas for muscle attachment. Damage to a syndesmotic joint, which usually results from a fracture of the bone with an accompanying tear of the interosseous membrane, will produce pain, loss of stability of the bones, and may damage the muscles attached to the interosseous membrane. If the fracture site is not properly immobilized with a cast or splint, contractile activity by these muscles can cause improper alignment of the broken bones during healing.

synarthrosis joint

immovable joint -sutures: --the fibrous joints --> b/t bones of the skull the --the cartilaginous joint -->manubriosternal joint, unites the manubrium and body of the sternum for protection of the heart.

All the bones of the skull, except for the__________, are joined to each other by a fibrous joint called a suture.

mandible

Purpose of Joints

movement, the functional unit of musculoskeletal system -muscles contract across bone allowing one bone to move towards another

gomphoses joint

narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits. fibrous joint that anchors the root of a tooth into its bony socket within the maxillary bone (upper jaw) or mandible bone (lower jaw) of the skull. A gomphosis is also known as a peg-andsocket joint. Spanning between the bony walls of the socket and the root of the tooth are numerous short bands of dense connective tissue, each of which is called a periodontal ligament (see Figure 9.5c). Due to the immobility of a gomphosis, this type of joint is functionally classified as a synarthrosis