Head and Neck Anatomy

A surgeon must have a thorough understanding of the anatomy of the head and neck region.
The scalp is divided into layers of skin and subcutaneous tissue, galea aponeurotica, loose connective tissue, and periosteum or pericranium.
The blood supply of the scalp comes from the paired supraorbital and supratrochlear arteries anteriorly, the terminal branches of the superficial temporal arteries laterally, and the occipital vessels posteriorly.
The calvaria consists of the unpaired frontal bone, the paired parietal bones, and the unpaired occipital bone.
The intracranial cavity is roughly divided into three fossae: anterior, middle, and posterior.
The arterial supply of the eyelids is provided by the angular branch of the facial artery.
The veins of the eyelids are larger and more numerous than the arteries and drain into the ophthalmic and angular veins medially and the superficial temporal vein laterally.
The lacrimal apparatus consists of a secretory portion, the lacrimal gland, its ducts, the drainage apparatus, the lacrimal canaliculi and sac, and the nasolacrimal duct.
The lacrimal gland is partially divided into two portions by the lateral horn of the aponeurosis of the levator palpebrae.
The excretory ductules of the lacrimal gland run through the orbital part of the gland, run through or close to the posterior part of the palpebral portion, and are joined by ducts from this portion.

The lacrimal gland and ducts drain into the lacrimal sac, which eventually drains into the nasal lacrimal duct and the inferior meatus of the nose.
The bony orbit consists of the medial wall occupied largely by the ethmoid bone, lacrimal bone, and a portion of the nasal process of the maxilla.
The eye consists of the cornea and sclera in the anterior aspect, with the retina resting on the choroid.
The seven voluntary muscles of the orbit are the levator palpebrae superioris; the superior, inferior, medial, and lateral rectus muscles; and the superior and inferior oblique muscles.
The external part of the nose is a roughly pyramidal shape, with the skeleton of the external nose being partly bony and partly cartilaginous and membranous.
The nasal cavities are also known as the nasal fossae, with the nasal septum consisting of the nasal septal cartilage, the nasal crest of the maxilla, the nasal crest of the palatine bone, the vomer, and the perpendicular plate of the ethmoid bone.
The paranasal sinuses consist of the paired frontal, ethmoid, maxillary, and sphenoid sinuses.
The frontal sinus develops as one of several outgrowths from the region of the frontal recess, with the frontal sinuses draining into the anterior aspect of the middle meatus.
The ethmoid sinuses consist of a variable number of separate cavities that honeycomb the ethmoid bone between the upper part of the lateral nasal wall and the medial wall of the orbit.
The sphenoid sinus usually opens into the sphenoethmoidal recess of the superior meatus.

The head and neck consist of various structures, including sinuses, facial bones and muscles, oral structures, and the hyoid bone and tongue.
The paranasal sinuses include the frontal, ethmoid, sphenoid, and maxillary sinuses, and their degree of pneumatization varies.
The sphenoid sinus is important in surgical approaches to the pituitary gland and is related to the optic nerves, internal carotid artery, and maxillary nerve.
The maxillary sinus is usually the largest and drains into the middle meatus of the nasal cavity.
The face includes the frontal and nasal bones, and the facial bones proper (maxilla, mandible, zygomatic, and palatine bones), as well as facial and mimetic muscles innervated by the facial nerve.
The parotid gland is anterior to and below the lower part of the ear and is divided into a lateral and medial portion by the course of the facial nerve.
The maxilla houses the dental apparatus and the maxillary sinus and provides sensation to the upper teeth.
The palate intervenes between the nasal and oral cavities and consists of the maxilla, the horizontal process of the palatine bone, and the pterygoid plates.
The mandible consists of the tooth-bearing body and the ramus and is covered externally by the masseter muscle.
The hyoid bone separates the anterior suprahyoid and infrahyoid fascial compartments and is attached to various muscles, including the suprahyoid and intrinsic and extrinsic muscles of the tongue.

The submandibular gland occupies most of the submandibular triangle and is crossed by the facial vein and sometimes by the ramus mandibularis branch of the facial nerve.
The pharynx consists of mucosa and voluntary muscle, and the muscular wall of the pharynx with its thin covering of buccal pharyngeal or visceral fascia is separated from the prevertebral fascia by an area of loose connective tissue that constitutes the retropharyngeal space.
The nasopharynx is continuous anteriorly through the choanae with the nasal cavities and the oropharynx is continuous anteriorly through the fauces, or oral pharyngeal isthmus, with the oral cavity.
The hypopharynx extends from just above the level of the hyoid bone superiorly to the lower border of the cricoid cartilage inferiorly, narrowing rapidly to become continuous with the esophagus.
The muscles of the pharynx are the superior, middle, and inferior constrictors, which are innervated by cranial nerve X through the pharyngeal plexus.
The major structural elements of the larynx are the shield-shaped thyroid cartilage and cricoid cartilages.
The epiglottis is formed of fibroelastic cartilage and has multiple perforations that allow free access of lymphatic drainage or tumor to the preepiglottic space.
The intrinsic muscles of the larynx are innervated by the recurrent laryngeal nerve.
The neck is divided into two major triangles, anterior and posterior, by the sternocleidomastoid muscles.
The anterior triangle of the neck may be further delimited by the strap muscles into the superior and inferior carotid triangles.