Head and Neck AnatomyThe head and neck are two examples of the perfect anatomical marriage between form and function, mixed with a dash of complexity. The head is resilient enough to sustain a five kilogram weight 24/7, yet sufficiently mobile to move it in several directions. On the other end, the head is durable enough to protect the fragile brain but intricately designed to facilitate the passage of the complex neurovascular network.
In this topic page, we’ll learn about various anatomical aspects of the head and neck, such as the skull, eyes, teeth, nose, ears, and neck. In addition, we’ll also cover the most important blood vessels and nerves supplying each region.
The skull is a strong, bony capsule that rests on the neck and encloses the brain. It consists of two major parts: the neurocranium (cranial vault) and the viscerocranium (facial skeleton). The neurocranium is the part enveloping the brain and is formed out of two parts; the skull base that supports the brain and the calvaria (skullcap) that sits on top of the base, covering the brain. The viscerocranium supports mainly the facial muscles and a variety of anatomical structures.
As you can see from the above skull diagram, there are quite a lot of skull bones. In fact, there are twenty three in total, some of which are paired:
- Ethmoid bone
- Frontal bone
- Inferior nasal concha
- Lacrimal bone (s)
- Maxillary bone (s)
- Nasal bone (s)
- Occipital bone
- Palatine bones (s)
- Parietal bone (s)
- Sphenoid bone
- Temporal bone (s)
- Zygomatic bone (s)
To make the skull an enclosed and resilient structure, those bones are connected together via joints called sutures. There are quite a few skull sutures in total, each one named according to the bones that form it. The most important ones are the coronal, sagittal, squamous, lambdoid, and palatine sutures, together with the lambda, bregma, and pterion landmarks.Watch the following videos and read the article to learn more about the bones of the skull and how they fit together.
Sticking out from the middle of your face is your nose, a structure that allows you to smell and breathe. It is composed of the nasal bones and cartilage that has two openings called nostrils.Behind the nose is the nasal cavity. There are two cavities in total, separated by the nasal septum. Each cavity contains three seashell-like structures called nasal conchae that drain the nasal openings (meatuses) and the various paranasal sinuses located within your head and skull. Watch the following videos to find out more details about the walls and structures of the nasal cavities.
The main arteries supplying the nose are the facial, sphenopalatine, greater palatine, and ophthalmic arteries. While the main nerves are the olfactory (CN I), ophthalmic (CN V1), and maxillary (CN V2) cranial nerves, all of which are branches of the trigeminal nerve (CN V).
The nose is flanked by two anatomical structures called the eyes. Each one consists of an eyeball suspended inside a bony socket within the skull, named the orbit. The eyeball itself has an extremely intricate and complex anatomy in order to provide you with vision. Broadly speaking, it consists of three layers enveloping two jelly filled compartments into which a lens is suspended. The entrance is provided by the pupil, which is a black central hole that is controlled by the iris. The pupil allows light to enter the eye and fall on the retina, ultimately allowing you to see.
There are also several eye adnexa that essentially protect the eyeball, as well as help it to move and perform its functions. Those are the eyelids, conjunctiva, lacrimal apparatus, and the seven extraocular muscles. Watch the following videos and read the articles to learn more about those structures.
The main artery supplying the eye is the ophthalmic artery, while the main nerves are the optic (CN II), oculomotor (CN III), trochlear (CN IV), trigeminal (CN V), and abducens (CN VI) cranial nerves. They reach the eye via three holes located at the back wall of the orbit.
Found on either side of the head are your ears . In fact, the only things visible are the auricle and the opening of the ear canal (external auditory canal) because the intricate anatomy is actually hidden inside your skull. The ear consists of three major regions:
- Outer ear - picks up the sound
- Middle ear - transmits the sound to the inner ear via the eardrum and three ossicles (incus, malleus, stapes)
- Inner ear - transforms the sound into nervous impulses via the cochlea and maintains balance via the semicircular canals
The ear anatomy doesn’t finish here. In addition to the above, there are other structures that surround the ear and help its function. Those are the Eustachian tube, tegmen tympani, and the labyrinth. The latter structure also helps to maintain the overall balance of the body.
The most important arteries supplying the ear are the external carotid, maxillary, and basilar arteries, while the main nerves are the facial (CN VII) and vestibulocochlear (CN VIII) cranial nerves. Read the following articles and watch again the previous video to learn the specific arteries and nerves supplying the ear.
Another major facial feature of the head that is clearly visible, and also heard, is the mouth. Anatomically called the oral cavity . It is the first component of the digestive system and takes a major role in the mechanical digestion and mixing of food. It consists of two major parts: the vestibule found between the teeth and the lips, and the oral cavity proper located posteriorly, which is what everyone thinks of when they hear the word ‘mouth’. The latter contains several important structures:
- Roof of the mouth (hard and soft palates)
- Opening into the oropharynx and the surrounding arches
As you might guess, the most complex and voluminous structure found inside the oral cavity is the tongue. It takes part in almost all the functions of the mouth, from chewing to mixing and swallowing. In addition, it consists of two sets of muscles that allow it to move in any direction within the mouth and to take various shapes, as needed. Watch the following videos to learn everything about the tongue.
The main arteries supplying the oral cavity are the descending palatine, facial, lingual, and maxillary arteries. In turn, the major nerves are the maxillary (CN V2), mandibular (CN V3), vagus (CN X), hypoglossal (CN XII), and facial (CN VII) cranial nerves. Check out the following video and articles to learn more about the neurovasculature of the oral cavity.
Even though the teeth are part of the oral cavity, their intricate anatomy obliges us to reserve their own specific section. Throughout a human’s life, there are two sets of teeth growing: deciduous which are shed around six years of age; and permanent, which remain with you for the rest of your life. The oral cavity of a human adult contains thirty two teeth organized into two arches, each one having sixteen teeth.
Their role is pure biting and mechanical digestion of food. There are four types of teeth:
If you open your mouth in front of a mirror, the visible part of every tooth is the crown, which is composed of a resistant, calcified material for strength. The crown is covered by enamel and contains the pulp within. Each tooth is anchored in the gum (gingiva) via its dental root, which can vary in number depending on the type of tooth.The teeth receive their blood supply from the maxillary artery, while their innervation is provided by the maxillary (CN V2) and mandibular (CN V3) cranial nerves. Take a look at the following resources to study the entire tooth anatomy.
If you think the previous structures were complex, wait until you see the neck. This structure is sufficiently strong to anchor the head, but also mobile enough to turn it around. From the outside, the neck is divided into triangles, each one containing specific muscles, vessels, and nerves. In turn, however, the neck also has an internal division in the form of compartments, which are delimited by various layers cervical of fascia.Take a look at the following resources to learn all about the triangles and compartments of the neck and test your knowledge about them.
The anchor point of the neck is the hyoid bone, which is situated at the level of the ‘Adam’s apple’ (laryngeal prominence) in males. The majority of neck muscles attach to the hyoid, separating them into two groups: the suprahyoid and infrahyoid muscles. However, other muscles also constitute the neck.
The neck also harbours four major structures deep within; two organs and two tubes or passageways. They are named as follows:
- Thyroid gland
- Parathyroid glands
The two glands are responsible for the normal endocrine homeostasis of the body. The pharynx is a muscular passageway for food and air, connecting the nasal and oral cavities with the esophagus and the larynx. The latter is more commonly known as the voice box and it consists of various cartilages, membranes, ligaments, and muscles. It is responsible for speaking.Take a look at the following resources to learn more about each of these structures:
The four main arteries passing through the neck and/or supplying it are the common carotid, external carotid, internal carotid, and facial arteries together with the thyrocervical trunk. The cervical plexus is the main structure innervating or passing through the neck.