head and neck anatomy

Head and Neck Anatomy.

  Anatomy of the skull. The skull can be divided into three regions: Cranium - Enclosing the brain Face- Surrounding and supporting the eyes and the nose. Jaws- The upper and lower jaws, supporting teeth and the tongue and providing the openings for the respiratory tract and digestive tract.   The skull develops in the fetus as cartilage, which is gradually converted to bone during the growth of the body into adulthood. The outer layer of bone is called the compact bone, The inner layer is called cancellous bone.  

Cranium

The cranium is made up of relatively thin plates of bone surrounding the brain, At birth these plates are widely separated to allow growth of the brain as the baby grows, the gaps are called frontanelles .During growth, the space gets gradually filled with bone and close together to provide a protective helmet around the brain. The bony plates join together like a jigsaw at the Coronoid sutures. There are 4 major sutures. There are 8 cranial bones altogether  Frontal Bone: One plate forming the forehead/top section eye socket. Coronal suture - connect Frontal -Parietal. Temporal Bones: One plate on either side of the skull at the temples, they form part of TMJ (temporo-mandibular joint) of the lower jaw and provide muscle attachments. Connects by the squamous and zygmatic sutures. Has the mandibular fossa, auditory meatus(like a tunnel)- ear canal inter and external.Mastoid process - connects neck muscles helps move our heads. Styloid process - connects muscle to our voicebox. Parietal Bones: Two plates joined along the top of the suture skull and forming the majority of its side and back. Fused together by the sagittal suture and joins the frontal bone by the coronal suture  Occipital Bone:  Back and base of the skull, contains the large opening ( foramen magnum) throught which the spinal chord passes. Bump at the back of the skull. Sphenoid Bone: (batwing) Base and front of the cranium with a close relationship to facial.Touches every cranial bone .Single continuous bone.Wings called the pterygoid process.Forms anterior base of the skull behind orbit. Ethmoid Bone: Contains ethmoid tissue , thin and spongey in appearance. Has the Crista Galli (brain anchored by a little sail) a membrane around the midline towards the anterior.   

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Frontal Bone Anatomy Classification Of Bones (binary/octet-stream)

Facial Bones

14 facial bones - They give us our appearance. Made up with several pairs of bones. Most important are the Zygomatic bone, Zygomatic arches and nasal bones. Nasal bone x2: Bridge of the nose- rest of nose is cartilage. Vomer: Single bone on inside of the nasal cavity, This bone meets up with the inferior part of the nasal septum joining with the ethmoid bone to make the complete septum. Nasal septum- is a cartilage structure that divides the nasal cavities. Lacrimal Bones x2: anterior to the ethmoid bone. This bone lies on the medial aspect of the orbit near anterior border of the orbit.The tear duct passes through the orbit. Inferior nasal concha x2: On outside of nasal cavities, scroll like bones. Consist of think cancellous bone Zygomatic bone x2: Forms cheek bones. Palatine: These bones are found at the posterior border of the hard palate. Each bone made of horizontal plate. Joined at the midline, Forms hard palate, two formina are located in hard palate.  

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Maxilla (2)

Maxilla Largest of the facial bones, made up of two portions of bone joined by the median suture. Fixed to the other bones by the sutures and are immovable.Four Processes- Zygomatic process -meets frontal and zygomatic. Alveolar process -Supports the maxillary /mandibular teeth. Palatine process-Main portion of the hard palate. Frontal process- assists in forming the lateral margin of the nasal aperture and ends by articulating with the frontal bone. The maxillae are the paired facial bones which contain the upper dentition- forms upper jaw. Each are basically hallow with a large maxillary sinus. Orbital plate forms the floor of the eye orbit - while the zygomatic process articulates with the zygomatic bone. The alveolar process of the maxilla contains the upper dentition and assists in giving rise to the palatine portion which forms the anterior half of the hard palate.  

Processes of the Maxilla

Zygomatic process- This is at the apex of the pyramid, it projects into the cheek.It articulates with the zygomatic bone. It forms the anterior part of the zygomatic arch. The frontal Process-  Projects upwards and forms part of side if the nose. It articulates with the frontal bone. The palatine process-  Projects horizontally to form part of hard palate. It seperates the oral cavity from the nasal cavity.The incisive foramen is visible.This is where the palatine nerve pass through. The alveolar process- It projects downwards and supports the upper teeth. It resorbs when teeth are lost.The alveolar process ends at the back of the maxilla in a rounded buhe called maxillary tuberosity.  

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The Mandible

The Mandible  Horse shoe shaped bone, one body and two rami ( each ramus has two bony projections running upwards : A condyle- A conoroid process - A coronod, mandibular or sigmoid notch. The body of the mandible is the horizontal component it contains the teeth within the alveolar bone (the alveolar process)  The ramus is a vertical component and it joins the body at the angle of the mandible. Two raised ridges- 1- External oblique line. 2- Mylohyoid ridge. The mandible has many landmarks external and internally.