EXERCISES

Q1. How many bones constitute the human skeleton?
Answer: The human skeleton is composed of around 270 bones at birth, which decreases to 206 bones by adulthood after some bones get fused together.

Q2. Name the bone where foramen magnum is present?
Answer: The foramen magnum is a large oval-shaped opening present in the occipital bone.

Q3. How many bones are there in the human skull?
Answer: The human skull consists of twenty-two bones.

Q4. What is suture? Name the bones which are joined by coronal suture.
Answer: A suture is a type of fibrous joint or synarthrosis that only occurs in the skull. The parietal bone joins to form the coronal suture in the front with the frontal bone.

Q5. Name the longest and strongest bone of the human skeleton?
Answer: The femur or thigh bone is the largest and strongest bone present between the hip and knee joint of the human skeleton.

Q6. Name the bone where auditory meatus is present?
Answer: The tympanic part of the temporal bone surrounds the external auditory opening, which leads into the external auditory meatus of the external ear.

Q7. In which bone linea aspera is present?
Answer: Linea aspera, a rough ridge which is the site of attachment of muscles, is present on the posterior surface of the shaft of the femur bone.

Q8. How many bones constitute the vertebral column? What is the shape of the vertebral column?
Answer: The vertebral column is composed of thirty-three bones or vertebrae. The vertebral column presents four curves and resembles somewhat an ‘s’ shaped structure.

Q9. Name the parts of a tooth?
Answer: The three parts of a tooth are crown, neck, and root.

Q10. Name the first and second vertebrae of the vertebral column?
Answer: The first cervical vertebra of the vertebral column is the atlas and the second is the axis.

Q11. How many parietal bones are there in the cranium? Name the bones that are joined by the sagittal suture?
Answer: There are two parietal bones in the cranium. The two parietal bones join at the sagittal suture.

Q12. Write the dental formula of permanent teeth?
Answer: The dental formula of permanent teeth is 2.1.2.3 / 2.1.2.3.

Q13. Name the two main parts of human skull?
Answer: The human skull is divided into two parts: a cranial part or cranium, which forms the brain box, and a facial part.

Q14. Name the different parts of the innominate bone?
Answer: Each innominate bone comprises of three parts, namely ilium, ischium, and pubis.

Q15. Name the bones that constitute the forearm and the leg?
Answer: The radius and ulna bones of the skeleton constitute the forearm. Each leg consists of the tibia and fibula bone.

Q16. Name the different shaped bones in the human skeleton? Give example.
Answer: The five types of bones in the human skeleton are long, short, flat, irregular, and sesamoid bones.
Long bone: Femur, tibia, humerus.
Short bone: Carpals and tarsals.
Flat bone: Sternum, ribs, scapula, frontal, lacrimal.
Irregular bone: Vertebrae, temporal, ethmoid.
Sesamoid bone: Patella.

Q17. Write short notes on: Cranium, Mandible, Vertebral Column, Ribs, Femur, Norma frontalis, Norma lateralis, Humerus, Pelvic girdle, Human teeth, Hand, Foot.
Answer:

Cranium: The cranium is the upper part of the human skull that encloses and protects the brain. It forms the brain box and consists of eight bones — one frontal, two parietal, two temporal, one occipital, one sphenoid, and one ethmoid bone. These bones are tightly joined together by sutures, which are immovable joints. The cranium provides protection to the brain, support to the face, and serves as an attachment point for muscles involved in chewing and head movement.

Mandible: The mandible, or lower jawbone, is the only movable bone of the skull. It is the largest, strongest, and lowest bone of the facial skeleton. It holds the lower teeth and plays a vital role in chewing (mastication) and speech. The mandible consists of a curved horizontal body and two vertical extensions called rami. Each ramus has two processes — the coronoid process for muscle attachment and the condyloid process which forms a joint with the temporal bone (temporomandibular joint).

Vertebral Column: The vertebral column, also known as the spine or backbone, extends from the base of the skull (foramen magnum) to the pelvis. It is composed of 33 vertebrae arranged in five regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), and 4 coccygeal (fused). It forms the main axial support for the body, protects the spinal cord, and provides flexibility and movement. The column has four natural curves that help balance and absorb shock during movement.

Ribs: The ribs are slender, curved bones forming the rib cage of the thorax. Humans have 12 pairs of ribs. The first seven pairs are called true ribs as they are directly attached to the sternum. The next three pairs are false ribs, indirectly attached to the sternum through the costal cartilage, and the last two pairs are floating ribs as they are not attached to the sternum at all. The rib cage protects vital organs such as the heart and lungs and assists in the process of breathing by expanding and contracting.

Femur: The femur, or thigh bone, is the longest and strongest bone in the human skeleton. It extends from the hip to the knee joint and supports most of the body’s weight during standing, walking, and running. The upper part (proximal end) has a rounded head that fits into the acetabulum of the pelvis, forming the hip joint. The shaft has a ridge called the linea aspera for muscle attachment, and the lower part (distal end) forms the knee joint by articulating with the tibia and patella.

Norma frontalis: Norma frontalis is the anterior (front) view of the human skull. It appears roughly oval and broader at the top than the bottom. In this view, the frontal, nasal, zygomatic, maxilla, mandible, and vomer bones are visible. Important features include the glabella (smooth area between eyebrows), nasion (junction of frontal and nasal bones), orbits (eye sockets), and nasal aperture. It shows the symmetry and proportions of the human face and is used in anatomical and forensic studies.

Norma lateralis: Norma lateralis refers to the side (lateral) view of the skull. This view displays bones such as the frontal, parietal, temporal, occipital, nasal, zygomatic, maxilla, and mandible. Prominent features visible include the external auditory meatus, zygomatic arch, mastoid process, and various sutures like coronal, squamosal, and lambdoid sutures. This view helps study the skull’s profile, muscle attachments, and the relationship between facial and cranial bones.

Humerus: The humerus is the long bone of the upper arm that connects the shoulder to the elbow. Its proximal end has a head that fits into the glenoid cavity of the scapula, forming the shoulder joint. The shaft features a deltoid tuberosity for muscle attachment, and the distal end articulates with the radius and ulna to form the elbow joint. The humerus is essential for arm movement and muscle attachment, allowing lifting, rotation, and bending of the arm.

Pelvic girdle: The pelvic girdle forms the base of the trunk and supports the spinal column. It consists of two hip (innominate) bones, each made up of three fused parts — ilium, ischium, and pubis. These bones join at the pubic symphysis in the front and articulate with the sacrum at the back. The pelvic girdle supports and protects organs like the bladder, intestines, and reproductive organs, and provides attachment for lower limb muscles. It also plays an important role in walking and maintaining balance.

Human teeth: Human teeth are hard structures embedded in the jaws, used for cutting, tearing, and grinding food. There are two sets of teeth — deciduous (milk teeth, 20 in number) and permanent (32 in number). The permanent teeth include four types: incisors for cutting, canines for tearing, premolars and molars for crushing and grinding. Teeth also play a vital role in speech and facial appearance. Each tooth has three parts — crown, neck, and root.

Hand: The human hand is a highly flexible structure made up of 27 bones, divided into three regions: the carpus (8 carpal bones forming the wrist), the metacarpus (5 metacarpal bones forming the palm), and the phalanges (14 bones forming the fingers). The thumb has two phalanges, while each of the other fingers has three. The hand allows precise movements and grasping ability, making humans capable of performing complex tasks.

Foot: The human foot is a strong, arched structure composed of 26 bones, divided into three parts: the tarsus (7 tarsal bones including the calcaneus and talus), the metatarsus (5 metatarsal bones), and the phalanges (14 toe bones). The arches of the foot help in supporting body weight and absorbing shock during standing, walking, and running. The foot provides stability, balance, and mobility to the body.