Test: Skeletal System - NEET MCQ

Number of bones in the adult human body:
The correct answer is A: 206.
Explanation:
The human skeleton is made up of a complex structure of bones that provide support, protection, and movement. The number of bones in the adult human body is generally fixed at 206, although there can be slight variations from person to person due to the presence of extra bones or the fusion of certain bones.
Here is a breakdown of the bones in the adult human body:
1. Axial Skeleton:
- Skull: 22 bones
- Vertebral Column: 26 bones (including 24 individual vertebrae, the sacrum, and the coccyx)
- Ribs: 24 bones (12 pairs)
- Sternum: 1 bone
Total bones in the axial skeleton: 73
2. Appendicular Skeleton:
- Upper Extremities:
- Shoulder Girdle: 4 bones (2 clavicles and 2 scapulae)
- Arms: 6 bones (2 humeri, 2 radii, and 2 ulnae)
- Hands: 54 bones (27 bones in each hand)
- Lower Extremities:
- Pelvic Girdle: 2 bones (1 sacrum and 1 coccyx)
- Legs: 8 bones (2 femora, 2 patellae, 2 tibiae, and 2 fibulae)
- Feet: 52 bones (26 bones in each foot)
Total bones in the appendicular skeleton: 133
Adding the bones from the axial and appendicular skeletons, we get a total of 73 + 133 = 206 bones in the adult human body.
Therefore, the correct answer is A: 206.

Comparative study of skulls is called Craniology.
Craniology is a branch of anthropology that focuses on the study of skulls and their characteristics. It involves analyzing and comparing skulls from different species or individuals to understand their anatomical variations and evolutionary relationships. Here is a detailed explanation of Craniology:
Definition of Craniology:
- Craniology is the scientific study of skulls, their structure, and their variations.
Key points about Craniology:
- It is a branch of anthropology that focuses on the study of skulls.
- The study of skulls can provide valuable insights into the evolution, development, and characteristics of different species.
- Craniology involves analyzing the shape, size, and structure of skulls, as well as the variations in different populations or individuals.
- It can help in understanding the anatomical differences between species, identifying evolutionary relationships, and studying human evolution.
- Craniology is often used in forensic anthropology to identify human remains or determine the cause of death based on skull analysis.
- It can also be applied in paleontology to study extinct species and reconstruct their features.
- The study of skulls is important in various fields such as archaeology, anatomy, medicine, and zoology.
Conclusion:
- Craniology is the branch of anthropology that deals with the comparative study of skulls.
- It plays a crucial role in understanding the diversity and evolution of different species, including humans.
- By analyzing and comparing skulls, researchers can gain valuable insights into the anatomical variations and evolutionary relationships between species.

A flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone.is called a tendon.

Bone formed by ossification of the tendon is called as the sesamoid bone.

Sesamoids are found in several joints in the body. In the normal foot, the sesamoids are two pea-shaped bones located in the ball of the foot, beneath the big toe joint. Their functions of sesamoid bone include modify pressure, to diminish friction, and occasionally to alter the direction of a muscle pull. So, the correct answer is 'Sesamoid bone'.

Hyaline cartilage is the most abundant cartilage. It forms the cushions or pads upon the articular surfaces at joints of long bones, known as articular cartilage. It forms the costal cartilage at the ventral ends of ribs, and also helps to form the nose, larynx, trachea, bronchi and bronchial tubes.

The correct option is C 80

The total number of bones in the axial skeleton of a man is 80.

There are
1. 29 bones in the skull.
2. 25 bones of the thorax (the sternum and 24 ribs).
3. 26 bones in the vertebral column.
In total, there are 80 bones (29+25+26) in the axial skeleton of a man.

Epiphyseal plates at the extremities of long bones help in elongation of bone:
The epiphyseal plates, also known as growth plates, are found at the extremities of long bones, such as the femur and tibia. These plates are responsible for the lengthening of bones during childhood and adolescence. Here's how they contribute to the elongation of bone:
1. Structure: Epiphyseal plates are made up of cartilage and are located between the epiphysis (end of the bone) and the diaphysis (shaft of the bone). They act as a bridge between these two regions.
2. Growth process: The growth of long bones occurs at the epiphyseal plates through a process called endochondral ossification. This process involves the replacement of cartilage with bone tissue.
3. Cartilage proliferation: The epiphyseal plates contain chondrocytes (cartilage cells) that continuously divide and multiply. This proliferation of cartilage cells leads to the lengthening of the bone.
4. Ossification: As the cartilage cells divide, new cartilage is formed on the epiphyseal side of the plate. On the diaphyseal side, the cartilage is gradually replaced by bone tissue through ossification.
5. Closure: During late adolescence or early adulthood, the epiphyseal plates close, which marks the end of longitudinal bone growth. At this point, the cartilage is completely replaced by bone, and the bone reaches its maximum length.
In summary, the epiphyseal plates play a crucial role in the elongation of bones by promoting the proliferation of cartilage cells and the subsequent replacement with bone tissue. This process allows for the growth and development of the skeletal system during childhood and adolescence.

The patella is also known as the kneecap. It sits in front of the knee joint and protects the joint from damage. It is the largest sesamoid bone in the body, and lies within the quadriceps tendon. The kneecap is an example of a bone we are all familiar with, and which has a significant functional role.

Human Vertebra: Irregular Bone

• The human vertebra is an example of an irregular bone.


• Irregular bones are bones that do not fit into any other category of bone shape.


• They have complex shapes and do not have a consistent length, width, or thickness.


• The vertebrae are the individual bones that make up the vertebral column or spine.


• They are responsible for providing support and protection to the spinal cord.


• Each vertebra has a unique shape and structure, consisting of a body, arch, processes, and spinal canal.


• These irregular bones allow for flexibility and movement of the spine.


• Unlike long bones or flat bones, the vertebrae have a more irregular and specialized shape to fulfill their specific function.


• Other examples of irregular bones in the human body include the hip bones (ilium, ischium, and pubis) and the facial bones.

Therefore, the correct answer is D: Irregular bone.

The smallest irregular bone in man is the Stapes.
Explanation:
The stapes is a small bone located in the middle ear. It is commonly known as the stirrup bone and is one of the three ossicles, along with the malleus (hammer) and incus (anvil), that transmit sound vibrations from the eardrum to the inner ear.
Here are some key points about the stapes bone:
- Size: The stapes is the smallest bone in the human body, measuring only about 2.8 to 3.3 millimeters in length.
- Shape: It has a unique shape resembling a stirrup, with a head, neck, two crura (arms), and a footplate.
- Function: The stapes plays a vital role in the process of hearing. When sound waves enter the ear, they cause the eardrum to vibrate. These vibrations are then transmitted to the ossicles, with the stapes specifically transferring the vibrations to the oval window of the cochlea.
- Composition: Like other bones, the stapes is primarily composed of calcium and collagen, giving it strength and flexibility.
In conclusion, the stapes is the smallest irregular bone in the human body, playing a crucial role in the transmission of sound vibrations for hearing.

It consists of 14 individual bones, which fuse to house the orbits of the eyes, nasal and oral cavities, as well as the sinuses. The frontal bone, typically a bone of the calvaria, is sometimes included as part of the facial skeleton.

Foramen magnum is present at the base of the skull.
The foramen magnum is a large opening located at the base of the skull. It is the largest opening in the skull and serves as a passageway for important structures such as the spinal cord, blood vessels, and nerves. Here is a detailed explanation of the location and function of the foramen magnum:
- Location: The foramen magnum is located at the base of the skull. It is positioned between the occipital bone and the atlas, which is the first cervical vertebra.
- Function: The primary function of the foramen magnum is to provide a passage for the spinal cord to connect with the brain. The spinal cord passes through the foramen magnum and continues up into the cranial cavity. Additionally, important blood vessels such as the vertebral arteries and the spinal accessory nerve also pass through this opening.
- Protection: The foramen magnum is surrounded by the occipital bone, which helps protect the delicate structures that pass through it. The position at the base of the skull offers a strong and stable support for the weight of the skull and helps protect the spinal cord from injury.
- Relations: The foramen magnum is surrounded by various structures, including the occipital condyles, which articulate with the atlas vertebra. It is also in close proximity to the brainstem and cerebellum.
In summary, the foramen magnum is a crucial anatomical feature located at the base of the skull. Its primary function is to allow the passage of the spinal cord, blood vessels, and nerves between the brain and the rest of the body.

The only movable bone in the skull is the Mandible.
Here is a detailed explanation:
1. Introduction:
The skull is made up of several bones that protect the brain and provide structural support to the face. While most of the bones in the skull are fixed and immovable, there is one bone that is an exception.
2. The Mandible:
The mandible, also known as the lower jaw, is the only movable bone in the skull. It is a U-shaped bone that forms the lower part of the face and supports the lower teeth. The mandible is attached to the skull via the temporomandibular joint (TMJ), allowing it to move up and down as well as side to side.
3. Functions of the Mandible:
The mandible serves several important functions in the body:
- It plays a crucial role in chewing, biting, and speaking.
- It supports the lower teeth and provides a base for the muscles of mastication.
- The movement of the mandible allows for proper articulation of speech sounds.
- It helps in maintaining the shape and structure of the face.
4. Other Bones in the Skull:
While the mandible is the only movable bone in the skull, there are several other bones that make up the skull structure. These include:
- Maxilla: The maxilla is the upper jaw bone and is fixed in place, forming the upper part of the face.
- Ethmoid: The ethmoid bone is located between the eyes and forms part of the nasal cavity and eye sockets. It is also a fixed bone and does not move.
5. Conclusion:
In conclusion, the only movable bone in the skull is the mandible. It is essential for various functions such as chewing, speaking, and maintaining the shape of the face. The maxilla and ethmoid bones, on the other hand, are fixed and do not have the ability to move.

The four coccygeal vertebrae fuse together in adult to form a single small triangular bone called coccyx. It articulates with the tip of the sacrum.

Total Number of Vertebrae in Man
There are 33 vertebrae in the human body, which are divided into different regions:
1. Cervical Vertebrae (C1-C7)
- These are the vertebrae in the neck region.
- There are 7 cervical vertebrae in total.
2. Thoracic Vertebrae (T1-T12)
- These are the vertebrae in the upper back region, corresponding to the twelve pairs of ribs.
- There are 12 thoracic vertebrae in total.
3. Lumbar Vertebrae (L1-L5)
- These are the vertebrae in the lower back region, supporting the weight of the upper body.
- There are 5 lumbar vertebrae in total.
4. Sacral Vertebrae (S1-S5)
- These are fused vertebrae located at the base of the spine, forming the sacrum.
- There are 5 sacral vertebrae in total.
5. Coccygeal Vertebrae (Co1-Co4)
- These are the smallest and most inferior vertebrae at the end of the spine, forming the coccyx or tailbone.
- There are 4 coccygeal vertebrae in total.
Adding up all these regions, we get a total of 7 cervical vertebrae + 12 thoracic vertebrae + 5 lumbar vertebrae + 5 sacral vertebrae + 4 coccygeal vertebrae, which equals 33 vertebrae in total.
Therefore, the correct answer is A: 33 vertebrae.

To determine the number of ribs in the human body, we need to consider the rib cage. The rib cage is a bony structure that surrounds and protects the organs of the thoracic cavity, including the heart and lungs. Here is a breakdown of the number of ribs in the human body:
1. True Ribs:
- There are 12 pairs of ribs in the human body.
- These ribs are called "true ribs" because they are directly attached to the sternum (breastbone) via their own costal cartilage.
2. False Ribs:
- There are 5 pairs of false ribs in the human body.
- The first 3 pairs of false ribs are indirectly attached to the sternum via the costal cartilage of the rib above.
- The last 2 pairs of false ribs are also known as "floating ribs" because they do not attach to the sternum at all.
3. Total Ribs:
- Adding the true ribs and false ribs together, we get a total of 12 true ribs + 5 false ribs = 17 pairs of ribs.
- Since we have two ribs per pair, the total number of ribs in the human body is 17 pairs x 2 ribs per pair = 34 ribs.
Therefore, the correct answer is C: 24.

Number of 'True Ribs' in a Man:
The number of 'true ribs' in a man is 7 pairs.
Explanation:
- The rib cage is composed of a series of bones called ribs, which surround and protect the chest cavity.
- There are 12 pairs of ribs in total, but only the first 7 pairs are considered 'true ribs'.
- The true ribs are directly attached to the sternum (breastbone) by their own costal cartilage.
- The remaining 5 pairs of ribs are called 'false ribs' or 'floating ribs' because they do not attach directly to the sternum.
- The false ribs either attach indirectly to the sternum or do not attach to the sternum at all.
- The last 2 pairs of ribs, known as 'floating ribs', do not have any attachment to the sternum and are only connected to the vertebrae.
- Therefore, the correct answer is B: 7 pairs.

The ribs in a human are attached to the sternum.
- The sternum, also known as the breastbone, is a flat bone located in the center of the chest.
- It connects the ribs through a series of cartilages called costal cartilages.
- The rib cage is formed by the sternum and the ribs, providing protection to vital organs in the chest such as the heart and lungs.
- There are 12 pairs of ribs in a human body, and each rib is attached to the sternum via its own costal cartilage.
- The first seven pairs of ribs are directly attached to the sternum through their own cartilages, known as true ribs.
- The next three pairs of ribs are indirectly attached to the sternum through a shared cartilage, known as false ribs.
- The last two pairs of ribs are floating ribs, which are not attached to the sternum and only connect to the vertebrae in the back.
- The attachment of the ribs to the sternum allows for the flexibility and movement of the rib cage during breathing.
In conclusion, the ribs in a human body are attached to the sternum through costal cartilages.

Movable joints are called synovial joints.
Synovial joints are the most common type of joint in the human body and are responsible for the majority of our movements. They are characterized by their ability to move freely and are classified based on their structure and function. Here are some key points about synovial joints:
- Structure: Synovial joints are composed of two or more bones that are held together by a joint capsule. The joint capsule is made up of a tough outer layer called the fibrous capsule and an inner layer called the synovial membrane. The synovial membrane produces synovial fluid, which lubricates the joint and allows for smooth movement.
- Function: Synovial joints are designed to allow for a wide range of movements, including flexion, extension, rotation, abduction, and adduction. They are found in the knees, elbows, shoulders, hips, and many other areas of the body.
- Types of synovial joints: There are several types of synovial joints, including hinge joints (e.g., elbow), ball-and-socket joints (e.g., shoulder), pivot joints (e.g., neck), saddle joints (e.g., thumb), condyloid joints (e.g., wrist), and gliding joints (e.g., between the vertebrae).
- Articular cartilage: The ends of the bones in synovial joints are covered with a smooth, slippery substance called articular cartilage. This cartilage helps to reduce friction and absorb shock during movement.
- Ligaments: Synovial joints are reinforced by ligaments, which are tough bands of connective tissue that help to stabilize the joint and prevent excessive movement.
In summary, movable joints are called synovial joints. They are characterized by their structure, function, and ability to allow for a wide range of movements.

The synovial fluid serves a vital function at the articular surface of the bones. It is responsible for lubricating and nourishing the joints, allowing them to move smoothly and reducing friction between the bones.
Here is a detailed explanation of how synovial fluid serves these purposes:
Lubrication:
- The synovial fluid acts as a lubricant, reducing friction between the articular surfaces of the bones.
- It forms a thin film over the cartilage, allowing the bones to glide smoothly against each other during movement.
- This lubrication is essential for maintaining the integrity and function of the joints.
Nourishment:
- Synovial fluid provides nourishment to the articular cartilage, which has no direct blood supply of its own.
- It delivers nutrients to the cartilage cells and removes waste products, ensuring the health and longevity of the joint.
Shock absorption:
- Synovial fluid also serves as a shock absorber, cushioning the joints against impact and reducing the risk of damage.
- It helps distribute the load evenly across the joint surface, preventing excessive stress and strain on the bones.
In conclusion, synovial fluid primarily functions to lubricate the joints, reducing friction and allowing smooth movement. Additionally, it nourishes the articular cartilage and provides shock absorption, contributing to the overall health and function of the joints.

Articulation of ulna with humerus at the elbow joint is a hinge joint.
The elbow joint is a synovial joint formed by the articulation of the humerus, radius, and ulna bones. The specific articulation between the ulna and humerus is known as the ulnohumeral joint. Here's a detailed explanation of why it is classified as a hinge joint:
Hinge joint characteristics:
1. Uniaxial movement: Hinge joints allow movement along a single axis, typically flexion and extension.
2. Articular surfaces: The ulna and humerus have specific anatomical features that allow them to interlock and form a stable hinge joint.
3. Range of motion: The ulnohumeral joint primarily allows flexion and extension movements, resembling the opening and closing of a hinge.
4. Limited rotation: Hinge joints have limited rotational movement compared to other types of joints, such as ball and socket joints.
5. Stability: Hinge joints are relatively stable due to the close fit between the articulating surfaces and the presence of strong supporting ligaments.
Considering these characteristics, the articulation of the ulna with the humerus at the elbow joint fits the criteria for a hinge joint. It allows primarily flexion and extension movements while providing stability and limited rotation.

Pivot joint occurs between the atlas and the adontoid process of axis.

According to functional classification, joints may be immovable (synarthroses), slightly movable (amphiarthroses) and freely movable (diarthrosis). According to structure, joints can be classified into fibrous, cartilaginous and synovial.

The pivot joint is a synovial joint, which permits the movement of bone about one axis of rotation. In pivot, the joint central bony pivot of one bone is surrounded by a collar of bone and ligaments. The types of movement possible are rotation, pronation, supination. An example of pivot joints is proximal radioulnar and atlantoaxial joints.

Synovial Fluid
Synovial fluid is a clear, viscous fluid that is found in freely movable joints. It plays a crucial role in lubricating and nourishing the joints, allowing for smooth and pain-free movement. Here's a detailed explanation of synovial fluid:
1. Definition:
- Synovial fluid is a gel-like substance that fills the synovial cavity, which is the space between the articulating bones in freely movable joints.
2. Composition:
- Synovial fluid is primarily composed of water, accounting for about 80% of its total volume.
- It also contains hyaluronic acid, which provides viscosity and elasticity to the fluid.
- Other components include proteins, electrolytes, and cells such as synoviocytes and leukocytes.
3. Function:
- Lubrication: Synovial fluid acts as a lubricant, allowing the smooth movement of the joint surfaces. It reduces friction and minimizes wear and tear on the cartilage.
- Shock absorption: The fluid's viscosity helps absorb shocks and distribute forces evenly across the joint, protecting the bones and cartilage.
- Nutrient supply: Synovial fluid delivers nutrients to the articular cartilage, which lacks a direct blood supply. It also removes waste products from the cartilage.
4. Production and circulation:
- Synovial fluid is produced by the synovial membrane, which lines the joint cavity.
- The fluid circulates within the joint cavity, bathing the articular surfaces and ensuring their proper functioning.
5. Joint disorders:
- Imbalances in synovial fluid production or composition can lead to joint disorders such as osteoarthritis or rheumatoid arthritis.
- In these conditions, the synovial fluid may become thinner or thicker, affecting joint mobility and causing pain.
In conclusion, synovial fluid is found in freely movable joints and plays a crucial role in lubricating, cushioning, and nourishing the joints. Its composition and functions contribute to the overall health and functionality of the joints.

If synovial fluid get decrease it causes friction bones and causes stifness.

Given below is a detailed explanation of the disease associated with joint:
Arthritis is the disease associated with joints. It is a broad term that refers to inflammation or swelling of the joints, causing pain and stiffness. There are several types of arthritis, including:
- Osteoarthritis: This is the most common type of arthritis, often referred to as "wear and tear" arthritis. It occurs when the protective cartilage that cushions the ends of bones wears down over time.
- Rheumatoid arthritis: This is an autoimmune disease that causes chronic inflammation in the joints. It occurs when the immune system mistakenly attacks the lining of the joints, leading to pain, swelling, and joint damage.
- Gout: Gout is a form of arthritis that occurs when uric acid crystals build up in the joints, causing sudden and severe pain, swelling, and redness.
- Juvenile arthritis: This type of arthritis affects children and adolescents. It can cause joint pain, swelling, and stiffness, and may also result in growth problems.
- Ankylosing spondylitis: This is a type of arthritis that primarily affects the spine, causing pain and stiffness. Over time, it can lead to fusion of the vertebrae, resulting in a rigid spine.
- Psoriatic arthritis: Psoriatic arthritis is a type of arthritis that often occurs in people with psoriasis, a skin condition. It can cause joint pain, stiffness, and swelling, as well as skin and nail changes.
It is important to consult a healthcare professional for an accurate diagnosis and appropriate treatment if you suspect you have arthritis or any joint-related issues. Treatment options may include medication, physical therapy, lifestyle changes, and in some cases, surgery.

Explanation:
Bone dissolving cells are known as osteoclasts. Here is a detailed explanation of each option:
A: Osteoblasts
- Osteoblasts are responsible for bone formation.
- They secrete matrix proteins and minerals to build new bone.
- Osteoblasts are involved in bone remodeling and repair.
B: Chondroblasts
- Chondroblasts are responsible for cartilage formation.
- They secrete the matrix of cartilage.
- Chondroblasts are involved in cartilage growth and repair.
C: Osteoclasts
- Osteoclasts are specialized cells that break down bone tissue.
- They are derived from monocytes and macrophages.
- Osteoclasts secrete enzymes that dissolve the mineralized matrix of bone.
- Their activity is important for bone remodeling, growth, and repair.
D: Chondroclasts
- Chondroclasts are not bone cells but rather cells involved in the breakdown of cartilage.
- They are responsible for removing old or damaged cartilage tissue.
- Chondroclasts are involved in the process of endochondral ossification, where cartilage is replaced by bone.
Therefore, the correct answer is C: Osteoclasts. Osteoclasts are the bone dissolving cells responsible for breaking down bone tissue.

Answer:
The bone Ilium is a part of the Pelvic Girdle. Here is a detailed explanation:
The Pelvic Girdle:
- The pelvic girdle is a ring-like structure composed of several bones that connect the lower limbs to the axial skeleton.
- It consists of two hip bones, also known as coxal bones or innominate bones, which fuse with the sacrum posteriorly.
- Each hip bone is formed by the fusion of three bones: ilium, ischium, and pubis.
- The ilium is the largest and most superiorly positioned bone of the pelvic girdle.
The Ilium Bone:
- The ilium is located on each side of the pelvis, forming the upper and widest part of the hip bone.
- It has a wing-like shape and contributes to the anterior and superior aspects of the hip bone.
- The ilium forms the greater part of the acetabulum, which is the socket for the head of the femur (thigh bone).
- It also provides attachment sites for various muscles, including the gluteal muscles that control hip movement and stability.
Therefore, the correct answer is C: Pelvic girdle. The ilium bone is a key component of the pelvic girdle, which forms the bony structure of the pelvis.

The vertebral column is composed of smaller vertebrae which are classified as per their location.
The vertebrae in the neck region are known as the cervical vertebrae.
There are seven cervical vertebrae that connect the brain with the spinal cord.
The human spinal column is made up of 33 bones: 7 vertebrae in the cervical region, 12 in the thoracic region, 5 in the lumbar region, 5 in the sacral region and 4 in the coccygeal region. Thus, the correct answer is option C.

Clavicle is a bone of the Shoulder.

• The clavicle, also known as the collarbone, is a long bone that connects the sternum (breastbone) to the scapula (shoulder blade).


• It is located at the base of the neck and is easily visible and palpable on the surface of the body.


• The clavicle plays an important role in supporting the shoulder and allowing for the movement and flexibility of the upper limb.


• It acts as a strut or a strut-like bone, providing strength and stability to the shoulder joint.


• The clavicle also protects important structures, such as blood vessels and nerves, that pass through the area.


• Fractures of the clavicle are relatively common and can occur due to various reasons, such as falls, sports injuries, or trauma.


• Treatment for clavicle fractures may involve immobilization with a sling or surgical intervention, depending on the severity of the fracture.

Therefore, the correct answer is B: Shoulder. The clavicle is a bone of the shoulder.

Ankle joint is a hinge joint.
The ankle joint is the joint connecting the foot and the leg. It allows for movement between the talus bone of the foot and the tibia and fibula bones of the leg. The ankle joint is classified as a hinge joint due to its structure and range of motion.
Characteristics of a hinge joint:
- Hinge joints allow movement in only one plane, like a door hinge.
- They have a convex and concave surface that fit together, allowing for flexion and extension movements.
- Hinge joints do not allow for rotation or side-to-side movement.
Specific features of the ankle joint:
- The ankle joint is formed by the articulation of the talus bone with the tibia and fibula bones.
- It allows for dorsiflexion (movement of the foot towards the shin) and plantarflexion (movement of the foot away from the shin).
- The joint is supported by ligaments, tendons, and muscles, which provide stability and control movement.
Function of the ankle joint:
- The ankle joint plays a crucial role in walking, running, jumping, and other weight-bearing activities.
- It absorbs forces during movement and helps maintain balance and stability.
- The range of motion in the ankle joint allows for adaptation to various surfaces and terrains.
In conclusion, the ankle joint is classified as a hinge joint due to its structure and range of motion, allowing for flexion and extension movements in one plane.

Astragalus and calcaneum occurs in the hind limb.
The astragalus and calcaneum are two bones that are found in the hind limb of animals. Here is a detailed explanation of their location and function:
1. Location:
- The astragalus is a bone that is located in the ankle joint of the hind limb.
- The calcaneum is a bone that is located in the heel region of the hind limb.
2. Function:
- The astragalus plays a crucial role in the movement and stability of the ankle joint.
- It helps to transmit forces from the leg to the foot, allowing for movement and weight-bearing.
- The calcaneum, also known as the heel bone, provides support and stability to the hind limb.
- It is the largest bone in the foot and plays a significant role in walking, running, and jumping.
In conclusion, the astragalus and calcaneum are two bones that are found in the hind limb. They play important roles in supporting the hind limb and enabling movement in animals.