Tag: joints in the human body

The human skull is a bony structure that supports the face and creates a cavity for the brain and protects it. The skull is made up of 8 cranial bones, 14 facial bones and 6 middle ears and 1 hyoid bones. So, the total number of bones in the skull are 29 bones.

The hypopharynx is an appendage or thickened fold on the floor of the mouth of many insects, that resembles a tongue. Thus, option B is correct.
The labium is a fused mouth part, which forms the floor of the mouth of an insect. Thus, option C is wrong.
The labrum is a structure corresponding to a lip, especially the upper border of the mouth parts of a crustacean or insect. Thus, option D is wrong.
The maxilla is the jaw or jawbone, specifically the upper jaw in most vertebrates. In humans, it also forms part of the nose and eye socket. Thus, option A is wrong.

The box enclosing and protecting the brain is called as the cranium. The cranium is the part of the skull, that encloses the brain. It is sometimes called as the braincase.

The lower jaw of mammals consists of only one bone, the dentary whereas jaws of other vertebrates are composed of more than one bone. This bone joins the skull at the squamosal bone. This anterior bone of the lower jaw bears the teeth. Hence option A is correct.

The sella turcica forms a bony seat for the pituitary gland. The sella turcica is a saddle-shaped depression in the body of the sphenoid bone of the human skull.

The atlas ($C _1$) is the most superior (first) cervical vertebra of the spine. The atlas's chief peculiarity is that it has no body. It is ring like and consists of an anterior and a posterior arch and two lateral masses. The coccyx commonly referred to as the tailbone is the final segment of the vertebral column in humans and apes. It comprises of three to five separate or fused coccygeal vertebrae below the sacrum. As, both atlas and coccyx are the two first and last bones respectively of the vertebral column they do not have corresponding bones.

Of the 206 bones in the human body, 22 bones are in the skull. The skull consists of 8 cranial bones and 14 facial bones. The hyoid bone (lingual bone) is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes.

Skull is the part of bony endoskeleton, which protects the brain. Skull is made up of two parts- cranial and facial. In humans, skull consists of 29 bones. Rabbit skull is made up of 53 bones.

There are 7 cervical vertebrae, $C _1$ - $C _7$.  First cervical vertebrae, i.e., atlas and second cervical vertebrae, i.e., axis, and seventh vertebrae are modified; third through sixth are typical; all contain transverse foramina. Atlas supports head, permits "yes" motion of head at joint between skull and atlas; axis permits "no" motion, i.e., rotation movement at joint between axis and atlas.

• Flat bones are made up of a layer of spongy bone between two thin layers of compact bone. They have a flat shape, not rounded
  
• The flat bones are the occipital, parietal, frontal, nasal, lacrimal, vomer, hip bone (coxal bone), sternum, ribs, and scapulae.
  
• Hence ribs are flat bones.
• So, the correct answer is'Ribs'.