13.5
结构关节：软骨关节
顾名思义，在软骨关节处，相邻的骨头通过软骨连接在一起，软骨是一种坚韧且柔韧的结缔组织。与滑膜关节不同，这些类型的关节没有关节腔，并且涉及到通过透明软骨或纤维软骨连接在一起的骨骼。
软骨关节有两种类型：
软骨病
软骨联合（“通过软骨连接”）是一种软骨关节，其中骨骼能够通过透明的软骨来进行连接。软骨联合…
软骨连结是由软骨——一种强韧而富有弹性的结缔组织——将骨骼连接而成的关节。这类关节可有轻微活动性，且无关节腔。
根据连接软骨的类型，软骨性关节可分为两种——透明软骨连接骨骼的称为软骨结合（synchondroses），纤维软骨连接骨骼的称为联合（symphyses）。
软骨结合大多是不可动关节或不动关节，可以是暂时性的，也可以是永久性的。
儿童骨骼中干骺端与骨骺之间的关节是一种由骺软骨连接的暂时性软骨结合。青春期后，骺软骨被骨组织取代，干骺端与骨骺随之融合。
相比之下，第一肋骨与胸骨柄之间的关节是由肋软骨连接的永久性软骨结合。
联合关节属于微动关节，这意味着它们只允许有限的运动。
例如，通过可压缩且具有减震作用的纤维软骨盘连接耻骨的关节属于联合关节（symphysis）。
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Q1: What are the two main types of cartilaginous joints?
Cartilaginous joints are classified into synchondroses and symphyses based on the connecting cartilage type. Synchondroses use hyaline cartilage to join bones and are mostly immovable. Symphyses use fibrocartilage to connect bones and allow limited movement. Both types lack a synovial cavity, distinguishing them from other structural joints.
Q2: How do temporary and permanent synchondroses differ?
Temporary synchondroses, like epiphyseal plates in growing bones, connect the metaphysis to the epiphysis with hyaline cartilage. After puberty, this cartilage ossifies and the bones fuse. Permanent synchondroses, such as the first sternocostal joint, retain their hyaline cartilage throughout life and do not ossify with age.
Q3: Why is fibrocartilage better suited for symphyses than hyaline cartilage?
Fibrocartilage contains numerous bundles of thick collagen fibers, giving it greater ability to resist pulling and bending forces compared to hyaline cartilage. This strength allows symphyses to unite adjacent bones firmly while permitting limited movement, making fibrocartilage ideal for joints requiring both stability and flexibility.
Q4: What role do intervertebral discs play in the vertebral column?
Intervertebral discs are thick pads of fibrocartilage that form symphyses between adjacent vertebrae. They strongly unite the vertebrae while allowing small movements between them. The discs also provide crucial cushioning during weight-bearing and high-impact activities like running or jumping, protecting the vertebral column from injury.
Q5: How are cartilaginous joints functionally classified?
Synchondroses are functionally classified as synarthrotic joints because they lack movement between bone and cartilage. Symphyses are classified as amphiarthrotic joints because they allow limited movement. This functional classification reflects the degree of mobility permitted at each joint type based on their structural composition.
Q6: What happens to the epiphyseal plate during bone growth and maturation?
The epiphyseal plate is a temporary synchondrosis of hyaline cartilage that unites the metaphysis to the epiphysis in growing long bones. As the bone lengthens, the cartilage grows and is progressively replaced by bone, adding to the diaphysis. After puberty, the epiphyseal cartilage completely ossifies, fusing the metaphysis and epiphysis permanently.
Q7: How do cartilaginous joints differ from synovial joints?
Cartilaginous joints lack a synovial cavity and are connected by cartilage rather than a synovial membrane. They are generally less mobile than synovial joints, with synchondroses being immovable and symphyses allowing only limited movement. This structural difference makes cartilaginous joints better suited for stability and support rather than extensive mobility.