HEAD AND NECK

• The head and neck region of the body contains many important structures compressed into a small area including the skull, brain and meninges, nerves, special senses (eye, ear, olfactory area, taste receptors), digestive system, respiratory system, key endocrine organs, and many others.
• Many signs and symptoms related to the head and neck are determined by the anatomic arrangement of various structures.
• Head injuries from blunt trauma and penetrating missiles are associated with high mortality and severe disability.
• Headaches may be caused by unserious conditions but can also be early manifestations of a life-threatening disease.
• Facial, scalp, and mouth injuries vary in seriousness.
• Facial paralysis and unequal pupils may indicate a serious neurologic deficit.
• Larynx or trachea injuries or pressure can compromise airway.
• Swellings may indicate a tumor of the thyroid gland or a malignant secondary lesion in a lymph node.
• The posterior cranial fossa is separated from the anterior cranial fossa by the petrous part of the temporal bone.
• Anterior Ethmoidal Nerve passes through the narrow slit in the cribriform plate alongside the crista galli and into the nasal cavity.
• The middle cranial fossa is separated from the anterior cranial fossa by the lesser wing of the sphenoid.
• Crista Galli is a sharp upward projection of the ethmoid bone in the midline with a narrow slit in the cribriform plate alongside it.
• The anterior cranial fossa meets the anteroinferior angle of the parietal bone at the pterion.
• The median part of the anterior cranial fossa is limited posteriorly by the groove for the optic chiasm.
• The anterior cranial fossa is anteriorly bounded by the inner surface of the frontal lobe and posteriorly by the sharp lesser wing of the sphenoid.
• Cribriform Plate of the Ethmoid forms the floor medially, supports the olfactory bulbs, and its small perforations permit passage of the olfactory nerves.
• The anterior cranial fossa is medially bounded by the medial end of the lesser wing of the sphenoid which forms the anterior clinoid process on each side, giving attachment to the tentorium cerebelli.
• Falx Cerebri is attached to the crista galli.
• The cribriform plate of the ethmoid forms the floor medially in the anterior cranial fossa.
• The lateral floor of the anterior cranial fossa is formed by the ridged orbital plates of the frontal bone.
• The anterior cranial fossa, also known as the Anterior Cranial Fossa, lodges the frontal lobes of the cerebral hemispheres.
• The Squamotympanic Fissure separates the mandibular fossa from the tympanic plate posterior.
• The Anterior Part of the Skull is formed by the frontal bone, articulating with the parietal bones at the coronal suture, and sometimes, the two halves of the frontal bone fail to fuse which leaves a midline metopic suture.
• The Inferior Orbital Fissure is a horizontal opening between the greater wing of the sphenoid bone and the maxilla, leading forward into the orbit.
• The Pterygopalatine Fossa is a small space behind and below the orbital cavity, laterally communicating with the infratemporal fossa through the pterygomaxillary fissure, medially communicating with the nasal cavity through the sphenopalatine foramen, and superiorly communicating with the cranial cavity through the foramen rotundum.
• The Groove for the Cartilaginous Part of the Auditory Tube lies behind the spine of the sphenoid, located in the interval between the greater wing of the sphenoid and the petrous part of the temporal bone, and leads into the opening of the bony part of the tube.
• The Mandibular Fossa forms the upper articular surfaces for the temporomandibular joint, and the articular tubercle forms the upper articular surfaces for the temporomandibular joint.
• The Greater and Lesser Palatine Foramina lay posterolaterally, and the choanae (posterior nasal apertures) are above the posterior edge of the hard palate.
• The Posterior Parts of the 2 Parietal Bones are superiorly the parietal bones with the intervening sagittal suture, inferiorly the parietal bones articulate with the squamous part of the occipital bone at the lambdoid suture, and externally the occipital protuberance gives attachment to muscles and the ligamentum nuchae.
• The Median Pterygoid Plates of the Sphenoid Bone laterally bound the choanae, and the pterygoid hamulus is the inferior end of the medial pterygoid plate that is prolonged as a curved spike of bone.
• The Inferior View of the Skull is formed by the hard palate, composed of the palatal processes of the maxillae and horizontal plates (palatal processes) of the palatine bones, and the incisive foramen is located in the anterior midline.
• The Large Foramen Ovale and Small Foramen Spinosum pierce the greater wing of the sphenoid posterior to the lateral pterygoid plate, and the spine of the sphenoid is posterior to the foramen spinosum.
• The Frontal Bone articulates with the 2 parietal bones at the coronal suture, and the two parietal bones articulate in the midline at the sagittal suture.
• The inferior conchae are separate bones.
• The mandible, also known as the lower jaw, consists of the horizontal body, 2 vertical rami, and forms the lower margin of the mouth.
• The maxillae form the lower margin of the nasal aperture.
• The frontal bone forms the anterior part of the side of the skull, articulates with the parietal bone at the coronal suture, and is pierced by the superior sagittal sinus.
• The superior and middle conchae are shelves of bone that project into the nasal cavity from the ethmoid on each side.
• The maxillary sinus is a large, pyramid-shaped cavity in the maxilla, lined with mucous membrane, communicates with the nasal cavity, serves to lighten the facial skeleton, and acts as a voice resonator.
• The perpendicular plate of the ethmoid forms the nasal septum along with the vomer.