Anatomy of bones and joints

Temporal Bones The temporal bone itself is comprised of five constituent parts. The squamous, tympanic and petromastoid parts make up the majority of the bone, with the zygomatic and styloid processes projecting outwards. The squamous is a large, flat plate, known as the squamous portion; as well as thickened, wedge-shaped area, the petrous portion respectively. Squamous portion makes up cranium for articulating with parietal bone as well as the sphenoid bone. The zygomatic process arises from the lower part of the squama temporalis. It projects anteriorly, articulating with the temporal process of the zygomatic bone. These two structures form the zygomatic arch. Petrous portion provides extensions with bones such as the cranium. It mainly provides housing for middle and inner ear structures. It has mastoid and styloid processes that project from inferior regions. Between the two processes exists the stylomastoid foramen where facial nerve passes through to the skull. It also has the petrous portion responsible for articulating various bones including occipital bone found on the floor of the skull. It has carotid canal running up and down the petrous portion. It enhances provision that allow entrance of inner carotid artery in the cranial cavity. Sphenoid Bone The sphenoid bone refers to a single bone that provides a surface that lies to the midline providing section for articulating with the occipital bone as well as the temporal bones forming the base of the cranium bone. It has a joining with zygomatic bones forming several lateral walls. In the anterior and inferior the it articulates with palatine and maxillary bones. It is located superior to parietal bone which is anterior and superior to ethmoid and frontal bones respectively. It allows a depression located on the surface of superior cranial found on the body of sphenoid bone. It has hypophyseal fossa also known as sella turcica responsible for housing pituitary gland. Part of its body is hollow in shape allowing formation of sphenoid sinus cavity. It has two pairs of wings projecting from the surface of the sphenoid bone. The lesser wings projecting from the anterior aspect of the surface becoming more superior as well as lesser compared to greater wings. The lesser wings get attached to the surface by small roots known as struts. There is a gap forming between lesser wings and the sphenoid surface forming a canal called optic foramen where optic nerve exits the orbit. The lesser wings have an articulation with frontal as well as ethmoid bones.