Appendicular skeleton Questions in English

(B) The term $''Innominate''$ is used in two contexts in mammalian anatomy:
$1$. $Innominate$ $bone$: Each half of the pelvic girdle is known as the $innominate$ bone (or $coxal$ bone),which is formed by the fusion of the $ilium$,$ischium$,and $pubis$.
$2$. $Innominate$ $artery$: This is another name for the $brachiocephalic$ trunk,which is the first branch of the aortic arch.
Therefore,it refers to a part of the skeleton and an artery.

(D) The correct answer is $D$. The pelvic girdle of vertebrates consists of two coxal bones. Each coxal bone (innominate bone or hip bone) is formed by the fusion of three bones: the ilium,ischium,and pubis. These bones fuse together in the adult to form a single structure,which is a part of the appendicular skeleton.

(A) The $Scapula$ is a large,triangular bone situated in the dorsal part of the thorax between the $2^{nd}$ and the $7^{th}$ ribs.
Each $Scapula$ has a slightly elevated ridge called the spine which projects as a flat,expanded process called the $Acromion$ process.
The $Clavicle$ (collar bone) articulates with this $Acromion$ process to form the shoulder joint structure.

(D) In rabbit,the radius and ulna are separate bones,but they are united at both the proximal and distal ends by ligaments. This arrangement allows for limited rotation of the forearm.

(C) The scapula is a large,triangular,flat bone situated in the dorsal part of the thorax between the $2^{nd}$ and the $7^{th}$ ribs.
It contains a shallow articular surface called the glenoid cavity.
The glenoid cavity articulates with the head of the humerus (the upper arm bone) to form the shoulder joint.

(C) The patella, commonly known as the knee cap, is a classic example of a sesamoid bone.
Sesamoid bones are small, nodular bones embedded within tendons or joint capsules.
The patella develops within the tendon of the $quadriceps \text{ } femoris$ muscle, providing protection to the knee joint and increasing the leverage of the muscle.

(C) The correct answer is $C$.
Each upper arm or brachium of mammals contains a single long bone known as the $Humerus$.
The proximal end of the $Humerus$ is swollen,spherical,and smooth,forming the 'head' of the bone.
This head fits into the glenoid cavity of the pectoral girdle to form the shoulder joint.

(B) The $Acetabulum$ is a cup-shaped depression located on the lateral surface of the hip bone (pelvic girdle).
It is formed by the fusion of three bones: the $ilium$,$ischium$,and $pubis$.
This cavity provides the site for the articulation of the head of the $femur$ (thigh bone),forming the hip joint.

(A) sesamoid bone is a small,round bone embedded within a tendon or a muscle.
It develops through the process of ossification within the tendon where it passes over a joint,serving to reduce friction and modify pressure.
The most common example of a sesamoid bone in the human body is the patella (kneecap),which is embedded in the tendon of the quadriceps muscle.

(B) The pelvic girdle consists of two coxal bones. Each coxal bone is formed by the fusion of three bones: $Ilium$,$Ischium$,and $Pubis$. The sacrum is a large,triangular bone at the base of the spine,formed by the fusion of five sacral vertebrae. The transverse processes of the sacral vertebrae articulate with the $Ilium$ part of the pelvic girdle to form the sacro-iliac joint,which provides stability to the pelvic region.

(A) The pelvic girdle consists of two coxal bones. Each coxal bone is formed by the fusion of three bones: $Ilium$,$Ischium$,and $Pubis$.
At the point of fusion of these three bones,there is a cavity called the $Acetabulum$ to which the thigh bone (femur) articulates.

(B) The human skeletal system is divided into two parts: the axial skeleton and the appendicular skeleton.
$(1)$ The axial skeleton consists of the skull,vertebral column,ribs,and sternum.
$(2)$ The appendicular skeleton consists of the pectoral girdle,pelvic girdle,and the bones of the limbs (arms and legs).
Therefore,the pectoral and pelvic girdles and the bones of the limbs form the appendicular skeleton.

(C) The scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs. The dorsal,flat,triangular body of the scapula has a slightly elevated ridge called the spine which projects as a flat,expanded process called the acromion. Below the acromion is a depression called the glenoid cavity which articulates with the head of the humerus to form the shoulder joint. The coracoid process is a small hook-like structure on the lateral edge of the superior anterior portion of the scapula.

(A) The human arm consists of the following bones:
$1$ Humerus (upper arm bone),
$1$ Radius and $1$ Ulna (forearm bones),
$8$ Carpals (wrist bones),
$5$ Metacarpals (palm bones),and
$14$ Phalanges (finger bones).
Total = $1 + 1 + 1 + 8 + 5 + 14 = 30$ bones.
Therefore,the total number of bones in the right arm is $30$.

(C) $Sesamoid$ bone is a small,round bone that is embedded within a tendon or a muscle. These bones typically form in response to strain or friction,providing a smooth surface for tendons to slide over,which increases the mechanical advantage of the joint. The most common example of a $Sesamoid$ bone in the human body is the $Patella$ (kneecap),which develops within the tendon of the quadriceps femoris muscle.

(B) The pectoral girdle in mammals consists of two bones: the clavicle and the scapula.
Each scapula is a large,triangular,flat bone situated in the dorsal part of the thorax between the second and the seventh ribs.
The dorsal,flat,triangular body of the scapula has a slightly elevated ridge called the spine which projects as a flat,expanded process called the acromion process.
The clavicle articulates with this acromion process.

(D) The pectoral girdle (shoulder girdle) consists of two bones: the clavicle and the scapula.
Each scapula contains a depression called the glenoid cavity,which articulates with the head of the humerus to form the shoulder joint.
In contrast,the acetabulum is a cup-like depression found in the pelvic girdle that articulates with the head of the femur.
The sternum is a part of the axial skeleton,and the hilum is a general anatomical term for a depression or pit where vessels and nerves enter an organ.

(A) The $ulna$ bone of the forearm possesses a large,prominent projection at its proximal end known as the $olecranon$ $process$.
This process fits into the $olecranon$ $fossa$ of the $humerus$ when the elbow is extended,forming a hinge joint that allows for the movement of the forearm.

(C) The correct answer is $C$. The pelvic girdle in mammals consists of two coxal bones (hip bones). Each coxal bone is formed by the fusion of three bones: the $Ilium$,$Pubis$,and $Ischium$. Together,these two coxal bones form a single pair of bones that make up the pelvic girdle.

(D) In many vertebrates,particularly in amphibians and some reptiles,the ventral wall of the pubis possesses a small,cartilaginous or bony structure known as the $Epipubic$ bone (also called the $marsupial$ bone in some mammals). The other options provided are incorrect: $Coracoid$ is part of the pectoral girdle,$Cotyloid$ refers to the acetabulum cavity,and $Pubic$ $symphysis$ is the cartilaginous joint between the two pubic bones.

(D) . The $Humerus$ is differentiated into three parts: the head,the shaft,and the lower end. The shaft features a $V$-shaped deltoid ridge located at its middle,which serves as the attachment site for the deltoid muscle.

(A) The pelvic girdle of a rabbit,like other mammals,is composed of two symmetrical halves. Each half is formed by the fusion of three bones: the ilium,the ischium,and the pubis. These three bones fuse together to form a single structure known as the innominate bone or hip bone.

(B) In the hind limb of a rabbit,the tarsal bones are arranged in two rows. The proximal row consists of two large bones: the tibiale (astragalus) and the fibulare (calcaneum). The calcaneum is the largest tarsal bone and it projects backward to form the heel bone of the rabbit.

(B) The hip bone (coxal bone) is formed by the fusion of three bones: the ilium,the ischium,and the pubis.
These three bones fuse together at the acetabulum,which is a cup-like cavity that articulates with the head of the femur to form the hip joint.

(B) The correct option is $(B)$. The pelvic girdle in females is broader and shallower compared to males. This anatomical adaptation is essential to facilitate the process of parturition (childbirth) by providing a larger birth canal.

(C) The human hand consists of $5$ digits.
Each finger (index,middle,ring,and little finger) contains $3$ phalanges,while the thumb contains $2$ phalanges.
Therefore,the phalangeal formula for the human hand is $2, 3, 3, 3, 3$.

(D) The correct answer is $D$. The thumb (great finger) of the hand is known as the $Pollex$,whereas the great toe of the foot is known as the $Hallux$.

(D) The pelvic girdle of a mammal consists of two coxal bones. Each coxal bone is formed by the fusion of three bones: the $Ilium$,$Ischium$,and $Pubis$.
These three bones meet at a cavity called the acetabulum,to which the head of the femur articulates.
Between the $Pubis$ and the $Ischium$ bones,there is a large,oval-shaped opening known as the obturator foramen,which allows for the passage of nerves and blood vessels.

(C) The human skeletal system is divided into two main parts: the axial skeleton and the appendicular skeleton.
$1$. The axial skeleton consists of the skull,vertebral column,sternum,and ribs.
$2$. The appendicular skeleton consists of the bones of the limbs (fore limbs and hind limbs) along with their respective girdles (pectoral and pelvic girdles).
$3$. An amphicoelous vertebra is a part of the vertebral column,which belongs to the axial skeleton.
Therefore,the correct answer is $C$.

(D) The $Ulna$ is a bone in the forearm that is thicker and longer. It features a subterminal,cup-like receptacle known as the $sigmoid$ $notch$ (or $olecranon$ $notch$),which facilitates articulation with the distal end of the $Humerus$ to form the elbow joint.

(A) The ankle,also known as the tarsus,consists of $6$ tarsal bones arranged in three rows connected by gliding joints.
The $1^{st}$ (proximal) row contains two bones: the outer calcaneum (heel bone) and the inner talus (also known as the astragalus).
Therefore,the correct option is $A$.

(B) . The patella is a flat,triangular bone that covers and protects the knee joint. It is commonly known as the knee cap.

(C) The $Olecranon$ process is a large,thick,curved bony eminence at the proximal end of the $Ulna$ (the forearm bone).
It is formed through the process of endochondral ossification,where cartilage is replaced by bone tissue.
Therefore,it is classified as a cartilaginous bone.

(D) The correct answer is $D$. In mammals,each half of the pectoral girdle is composed of three primary skeletal components: the scapula,the supra scapula,and the coracoid process. These elements collectively form the structure that supports the forelimbs.

(D) Each half of the pelvic girdle (coxal bone) is formed by the fusion of three bones: the ilium,ischium,and pubis. These three bones fuse together during embryonic development to form a single coxal bone.

(D) The correct answer is $(d)$.
Each hind limb of a human consists of $30$ bones.
The distribution of these bones is as follows:
$1$ Femur (thigh bone),
$1$ Patella (knee cap),
$1$ Tibia (shin bone),
$1$ Fibula,
$7$ Tarsals (ankle bones),
$5$ Metatarsals (sole bones),
$14$ Phalanges (toe bones).
Total = $1 + 1 + 1 + 1 + 7 + 5 + 14 = 30$ bones.

(B) The $Astragalus$ (also known as the $talus$) and $calcaneum$ (heel bone) are tarsal bones found in the ankle region of the $Hind$ limb of humans and other mammals. These bones are part of the tarsus, which consists of $7$ bones in total.

(D) The human skeleton is divided into two parts: the axial skeleton and the appendicular skeleton.
$(1)$ The axial skeleton consists of the skull,vertebral column,sternum,and ribs.
$(2)$ The appendicular skeleton consists of the pectoral and pelvic girdles,along with the bones of the forelimbs (arms) and hind limbs (legs).
Therefore,the bones of the fore and hind limbs are part of the appendicular skeleton.

(A) The human skeletal system is divided into two main parts: the axial skeleton and the appendicular skeleton.
$1$. The axial skeleton consists of the skull,vertebral column,ribs,and sternum,which form the central axis of the body.
$2$. The appendicular skeleton consists of the limbs (arms and legs) and the girdles (pectoral and pelvic girdles) that attach the limbs to the axial skeleton.
Therefore,the correct option is $A$.

(D) The $Humerus$ is the bone of the upper arm. It articulates with the $Ulna$ of the forearm.
Two depressions located just above the $Trochlea$ on the anterior aspect are the $Coronoid$ $fossa$ and the $Radial$ $fossa$,which receive the $Coronoid$ $process$ of the $Ulna$ and the head of the $Radius$,respectively.
One large depression on the posterior aspect is the $Olecranon$ $fossa$,which receives the $Olecranon$ $process$ of the $Ulna$ during the extension of the elbow.

(C) The ulna bone in the forearm features a prominent projection known as the olecranon process. This process,along with the coronoid process,forms the deep,$C$-shaped depression called the sigmoid notch (or trochlear notch). This notch articulates with the trochlea of the humerus to form the elbow joint.

(B) The pelvic girdle consists of two coxal bones. Each coxal bone is formed by the fusion of three bones: ilium,ischium,and pubis. The pelvic girdle articulates with the sacral region of the vertebral column through the sacroiliac joint. The sacrum is a large,triangular bone at the base of the spine that connects the vertebral column to the pelvic girdle,providing stability to the lower body.

(B) In the provided diagram,the labels are as follows:
$1$. The thigh bone is labeled as 'Femu',which is a misspelling of 'Femur'.
$2$. The lateral bone of the lower leg is labeled as 'Fibul',which is a misspelling of 'Fibula'.
$3$. The medial bone of the lower leg is correctly labeled as 'Tibia'.
$4$. The ankle bones are labeled as 'Tarsa',which is a misspelling of 'Tarsals'.
$5$. The toe bones are correctly labeled as 'Phalanges'.
Comparing the labels with the anatomical positions:
- The label 'Femu' points to the Femur (correct bone,incorrect spelling).
- The label 'Fibul' points to the Fibula (correct bone,incorrect spelling).
- The label 'Tibia' points to the Tibia (correct bone,correct spelling).
- The label 'Tarsa' points to the Tarsals (correct bone,incorrect spelling).
- The label 'Phalanges' points to the Phalanges (correct bone,correct spelling).
However,looking at the anatomical orientation of the left hindlimb:
- The Fibula is the lateral bone,and the Tibia is the medial bone. In the diagram,the labels for 'Fibula' and 'Tibia' are swapped. The label 'Fibul' is pointing to the medial side (Tibia),and the label 'Tibia' is pointing to the lateral side (Fibula).
- Therefore,the bones that are wrongly labeled in terms of their anatomical position are the Fibula and the Tibia. Among the given options,the most appropriate choice identifying the mislabeled bones is 'Femur and fibula' (due to the spelling error and positional swap) or 'Tibia and tarsals'. Given the standard interpretation of this specific diagram in textbooks,the labels for 'Femur' and 'Fibula' are the ones typically highlighted as having errors.

(A) The greater trochanter and lesser trochanter are bony projections located at the proximal end of the $Femur$.
These structures serve as attachment sites for the tendons of various muscles of the thigh and buttock regions.
Therefore,the correct option is $A$.

(A) The shoulder joint is a ball-and-socket joint.
It is formed by the articulation of the head of the humerus with the glenoid cavity of the pectoral girdle (scapula).
The glenoid cavity is a shallow depression on the scapula that allows for a wide range of movement at the shoulder joint.

(A) The human appendicular skeleton consists of the limbs and their girdles.
The forelimb (arm) consists of the $Humerus$ (upper arm),$Radius$ and $Ulna$ (forearm),$Carpals$ (wrist bones),$Metacarpals$ (palm bones),and $Phalanges$ (digits).
The $Femur$ (thigh bone),$Tibia$,and $Fibula$ (lower leg bones) are components of the hindlimb.
Therefore,$Humerus$ is the correct bone belonging to the forelimb.

(C) The human skeletal system is divided into two main parts: the axial skeleton and the appendicular skeleton.
$1$. Malleus and Incus are ear ossicles,which is correct.
$2$. Sternum and Ribs are part of the axial skeleton,which is correct.
$3$. Clavicle and Scapula are part of the pectoral girdle (shoulder girdle),not the pelvic girdle. Therefore,this pair is incorrect.
$4$. Humerus and Ulna are bones of the forelimb,which is part of the appendicular skeleton,which is correct.

(A) The patellar groove,also known as the patellar surface or trochlear groove,is a smooth,articular depression located on the anterior distal end of the $Femur$. This groove allows the $Patella$ (kneecap) to glide smoothly during the flexion and extension of the knee joint. Therefore,the correct option is $A$.

(D) The pelvic girdle consists of two coxal bones. Each coxal bone is formed by the fusion of three bones: $Ilium$,$Ischium$,and $Pubis$. These three bones fuse together to form the acetabulum,which is a cavity to which the thigh bone $(femur)$ articulates. Therefore,all the given options are correct.

(A) The human skeletal system consists of $206$ bones. The longest,strongest,and heaviest bone in the human body is the femur,also known as the thigh bone. It extends from the hip to the knee and supports the weight of the body during movement.