What is Epiphysis?
A long bone's epiphysis is the rounded end. Its primary role is to connect neighboring bones to produce joints. The diaphysis, or shaft, of the long bone, is the other notable area. The metaphysis is the region of the long bone that lies between the epiphysis and the diaphysis. The metaphysis contains the epiphyseal plate or epiphyseal growth plate. The epiphysis is likewise covered by articular cartilage at the joint. Subchondral bone, on the other hand, is the bone beneath the articular cartilage and its development plate.
Epiphysis Definition - Epiphysis is the rounded end of a long bone, its primary function is to connect adjacent bones to form joints. The diaphysis, or shaft, of the long bone, is another prominent feature. There is another part of the long bone between the epiphysis and the diaphysis, which we call metaphysics. The epiphyseal plate, or growth plate of the epiphysis, is found in the metaphysis. At the joint, the epiphysis is also covered by articular cartilage. The subchondral bone, on the other hand, is the bone under the articular cartilage and its growth plate.
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Epiphysis Meaning - It is a part of the bone that ossifies separately and later becomes ankylosed to the main part of the bone especially at the end of the long bone.
Furthermore, the epiphysis is made up of trabecular tissue, which is a spongy bone. The trabecula, which forms the structural structure of the bone, is the main functional unit of this type of bone tissue. The red bone marrow that undergoes hematopoiesis is found between the trabeculae. Furthermore, the osteoblasts that cover the epiphysis are in charge of converting a spongy bone to compact bone.
Types of Bones
The bones in your body come in a variety of shapes and sizes. Bones, despite their differences in appearance, serve the same purpose: to support the body. The bones that are encircled by a tendon are known as sesamoid bones. The patella (knee cap) and a few tiny bones in your hands and feet are examples. Irregular bones, such as the vertebrae (bones in the spine), maxilla (upper jaw bone), and mandible (lower jaw bone), don't have a definite shape (lower jaw bone). Internal organs are protected by flat bones, which are flat in shape. The cranium (cranial bone) and scapula are two of them (shoulder blade). Short bones, such as those in the palm of your hand and the middle of your foot, give support and movement but are little, whereas long bones, such as the femur (thigh bone), humerus (upper arm bone), and tibia (shin bone), are the longest bones in your body.
Similarities between Epiphysis and Diaphysis
A long bone's epiphysis and diaphysis are two components.
Both of these sections are made up of bone tissues.
Their primary role is to provide shape and support to the animal's skeletal structure.
They also contain osteoblasts and osteoclasts, which are responsible for bone formation.
Nerves, blood arteries, and bone marrow are likewise found in both.
They are also covered by cartilage and membranes such as the endosteum and periosteum.
Difference between an Epiphysis and a Diaphysis
Shape
Occurrence
Comprised of
Unit of Function
The cavity of the Marrow
Bone Marrow Types
Calcium content
Porosity
Strength
Function
Types of Epiphysis
There are Four Types of the Epiphysis of Bones, Discussed below -
Pressure Epiphysis: A pressure epiphysis is the portion of the long bone that shapes the joint (e.g. the head of the femur, part of the hip joint complex). Pressure epiphyses are the regions of the bone that are under pressure during movement or locomotion and aid in transmitting the weight of the human body. The head of the humerus, which is part of the shoulder complex, is another example of a pressure epiphysis. The pressure epiphysis also involves the femur of tibia and condyles.
Traction Epiphysis: The non-articular regions of the long bone, which are not involved in joint formation. These areas, unlike pressure epiphyses, do not aid in weight transmission. The supporting ligaments and tendons bind to these areas of the bone due to their proximity to the pressure epiphysis site. Pressure epiphyses ossify first, followed by traction epiphyses. Tubercles of the humerus (greater tubercle and lesser tubercle) and trochanters of the femur are examples of traction epiphyses (greater and lesser).
Atavistic Epiphysis: A phylogenetically independent bone that has been fused with another bone. The coracoid process of the scapula, which has been fused in humans but is distinct in four-legged animals, is an example of atavistic fused bones. Another example of atavistic epiphysis is the os trigonum (posterior tubercle of the talus).
Aberrant Epiphysis: These epiphyses are not necessarily present and are deviated from the standard. The epiphysis at the head of the first metacarpal bone, as well as the epiphysis at the base of other metacarpal bones, are examples.
Pseudo Epiphysis
A pseudo-epiphysis is an epiphysis-looking end of a bone that isn't really an epiphysis, it is a transverse notch, which resembles a growth plate, defining a pseudo-epiphysis. These transverse notches, on the other hand, lack the usual cell columns found in normal growth plates and thus have little impact on longitudinal bone growth. Pseudo-epiphyses are present in 80 percent of the normal population at the distal end of the first metacarpal bone and 60 percent at the proximal end of the second metacarpal bone.
Bones With an Epiphysis
There are Many Bones That contain an Epiphysis:
Humerus - It is located between the shoulder and the elbow.
Radius - Is one of two bones located between the hand and the elbow and its anatomical position is the radius lateral to the ulna.
Ulna - This is one of two bones located between the hand and the elbow and the anatomical position of the ulna is medial to the radius.
Metacarpal - This is the bones of the hand, and they are proximal to the phalanges of the hand.
Phalanges - Is the bones of the fingers and toes and they are distal to the metacarpals in the hand and metatarsals in the foot.
Femur - It is the longest bone in the human body, and found in the thigh region, between the hip and the knee.
Fibula - This is one of two bones in the lower leg and It is lateral to the tibia and smaller in comparison.
Tibia - This is one of two bones in the lower leg and It is medial to the fibula and does most of the weight-bearing activities in the human body.
Metatarsal - It is the bones of the foot that are proximal to the medial cuneiform on the first metatarsal, and proximal to the phalanges for the other four.
Do You know?
What are the epiphyseal plates and epiphyseal line? Epiphyseal plate Definition - The epiphyseal plate (also known as the epiphyseal plate, physic, or growth plate) is a hyaline cartilage plate found at either end of a long bone in the metaphysis. The growth plate is the portion of a long bone where new bone growth occurs; the whole bone is alive, with maintenance remodeling occurring in its current bone tissue, but the growth plate is where the long bone grows larger (adds length).
Epiphyseal Line Definition - An ossified epiphyseal plate is referred to as an epiphyseal line. Epiphyseal closure is the process by which the formation of an epiphyseal layer takes place. It is the point of fusion between the Epiphysis and the Diaphysis in adult humans.
FAQs on Epiphysis
1. What is the epiphysis of a long bone as per the CBSE syllabus?
The epiphysis is the rounded end part of a long bone, which is crucial for forming joints with other bones. Each long bone has two epiphyses: a proximal epiphysis (closer to the body's torso) and a distal epiphysis (further from the torso). It is primarily composed of spongy (cancellous) bone and is covered by a thin layer of articular cartilage at the joint surface.
2. What are the main functions of the epiphysis?
The epiphysis serves several vital functions in the skeletal system:
- Articulation: Its smooth, cartilage-covered surface allows for smooth movement at the joints, reducing friction.
- Force Transmission: It effectively transmits the weight and forces from one bone to the next across a joint.
- Haematopoiesis: The spongy bone within the epiphysis contains red bone marrow, which is responsible for producing red blood cells, white blood cells, and platelets.
- Bone Growth: It contains the epiphyseal plate or growth plate, which is the site of longitudinal bone growth in children and adolescents.
3. How can you differentiate between the proximal and distal epiphysis?
The primary difference lies in their location relative to the body's trunk. The proximal epiphysis is the end of the long bone that is closer to the centre of the body (torso). For example, the proximal epiphysis of the femur articulates with the pelvis to form the hip joint. In contrast, the distal epiphysis is the end farther away from the torso. The distal epiphysis of the femur articulates with the tibia and patella to form the knee joint.
4. What are the different types of epiphysis found in the human body?
Epiphyses are classified based on their function and development into four main types:
- Pressure Epiphysis: This type is found at the ends of long bones that form joints. It is responsible for transmitting the body's weight and withstanding the pressure of movement. Examples include the head of the femur and humerus.
- Traction Epiphysis (Apophysis): This type is a non-articular part of the bone that serves as an attachment point for strong tendons and ligaments. The greater trochanter of the femur is a classic example.
- Atavistic Epiphysis: This represents a bone that was phylogenetically separate in ancestral species but has since fused to another bone in humans. The coracoid process of the scapula is an example.
- Aberrant Epiphysis: This is a type that is not consistently present in all individuals, such as the epiphysis at the head of the first metacarpal bone.
5. How do the structure and function of the epiphysis compare to the diaphysis?
The epiphysis and diaphysis are two distinct regions of a long bone with different structures and functions. The epiphysis is the expanded end, made of lightweight spongy bone, designed for articulation and housing red bone marrow for blood cell formation. In contrast, the diaphysis is the long, tubular shaft of the bone, composed of dense, strong compact bone. Its primary function is to provide structural support and leverage. The diaphysis also contains the medullary cavity, which is filled with yellow bone marrow (fat storage) in adults.
6. What is the epiphyseal plate, and why does it disappear in adults?
The epiphyseal plate, often called the growth plate, is a layer of hyaline cartilage located between the epiphysis and the diaphysis in growing bones. It is the primary site for the longitudinal growth of long bones. During childhood and adolescence, cartilage cells in this plate actively divide and are replaced by bone. This process stops at skeletal maturity (typically between ages 18-25). The cartilage is completely replaced by bone in a process called epiphyseal closure, fusing the epiphysis and diaphysis into a single structure. This fusion marks the end of growth in height, and the remnant of the plate is visible as the epiphyseal line in adults.
7. What is the anatomical composition of the epiphysis?
The epiphysis has a specific anatomical structure. It consists of an outer shell of compact bone that provides strength, while the interior is filled with spongy (cancellous) bone. This spongy bone has a trabecular, honeycomb-like structure that makes it lightweight yet strong enough to resist stresses from multiple directions. The spaces within this network are filled with red bone marrow. The part of the epiphysis that forms a joint is covered by a smooth, durable layer of articular cartilage.
8. What is the clinical significance of the epiphysis in medicine?
The epiphysis is clinically significant, especially in paediatrics and orthopaedics. Since the epiphyseal plate is the weakest part of a growing bone, it is highly susceptible to fractures, known as Salter-Harris fractures. An injury to the growth plate can disrupt normal bone growth, potentially leading to limb length discrepancy or angular deformities. Furthermore, the epiphysis's dedicated blood supply makes it vulnerable to conditions like avascular necrosis, where a loss of blood flow causes the bone tissue to die.
9. How does the blood supply to the epiphysis differ from other parts of a long bone?
The blood supply to the epiphysis is distinct, particularly during development. It is primarily supplied by epiphyseal arteries that enter the bone at its ends, independent of the main nutrient artery that supplies the diaphysis (shaft). Before the growth plate fuses, these two blood supplies are separate. This independent and rich vascular network is crucial for the high metabolic activity required for both ossification at the secondary centres and the production of blood cells in the red marrow.
