Head and Neck Anatomy Lesson: Key Concepts

Lesson Overview

• Key Landmarks and Openings of the Skull
• The Nasal Cavity and Sinuses
• The Oral Cavity: Hard Palate, Teeth, and Jaw
• Neck and Throat Structures (Hyoid, Larynx, Pharynx)
• The Eye and Orbit
• The Ear
• Cranial Nerves: The Brain's Connections to Head and Neck
• Major Blood Vessels of the Head and Neck

The head and neck contain many structures packed into a small space, which can make this region one of the most challenging areas in anatomy. However, by breaking it down into bones, landmarks, and key organs, it becomes much easier to understand. 

In this lesson, we'll explore the major components of head and neck anatomy – from the skull bones and facial features to important nerves and blood vessels. 

The Skull: Bones and Structure

The human skull is like a 3D puzzle made of 22 bones that protect the brain and form the face. These bones are divided into two groups:

• Cranial bones (Neurocranium): 8 bones that enclose the brain.
  
• Facial bones (Viscerocranium): 14 bones that shape the face, jaw, and nasal cavity.
  

The cranial bones are eight in number (frontal, occipital, sphenoid, ethmoid, and pairs of parietals and temporals). 

The facial bones are fourteen (the mandible and vomer, plus pairs of maxillae, zygomatics, nasals, lacrimals, palatines, and inferior conchae). These are summarized in the table below:

The bones of the skull are joined by sutures, which are immovable joints (like puzzle seams). For instance, the parietal bones meet the frontal bone at the coronal suture across the top of the head. 

These junctions make the skull rigid to protect the brain. Inside, the cranial bones form the large cranial cavity housing the brain. The facial bones create cavities for the eyes (orbits), nose, and mouth, and provide anchor points for the teeth and facial muscles.

Key Landmarks and Openings of the Skull

The skull has many distinct features that serve as landmarks:

• Processes (bony projections): The temporal bone has a round mastoid process (the bump behind your ear) for muscle attachment, and a pointed styloid process just below the ear for ligament and muscle attachments. The cheek arch, or zygomatic arch, is formed by the connection of the temporal bone to the zygomatic bone. At the base of the skull, the occipital bone has two smooth occipital condyles – these articulate with the first neck vertebra (atlas) to support the head and allow the nodding "yes" motion.
  
• Foramina (openings): These are holes that allow nerves and blood vessels to pass through. The largest is the foramen magnum in the occipital bone, where the spinal cord exits the skull to connect with the brain. Many smaller holes exist as well. For example, the cribriform plate of the ethmoid (in the nasal roof) is perforated with tiny holes for the olfactory nerves (smell) to reach the brain. The stylomastoid foramen (between the styloid and mastoid processes of the temporal bone) is where the facial nerve (CN VII) exits the skull to reach the face. There are numerous other foramina and canals (for the optic nerve, trigeminal nerve branches, and others), but focusing on a few major ones first makes it easier to learn their locations and what passes through them.
  

The Nasal Cavity and Sinuses

Inside the nose, the nasal cavity is divided by the nasal septum (made of the ethmoid's perpendicular plate, the vomer, and cartilage). The side walls have three curled bony shelves: the superior, middle, and inferior nasal conchae (also called turbinates). Beneath each concha is a passageway or meatus. 

These structures create channels that swirl and condition the air as we breathe in – increasing the surface area to warm, humidify, and filter the air before it reaches our lungs. The nasal cavity connects to air-filled spaces in surrounding bones called the paranasal sinuses. There are sinuses in the frontal bone (forehead), maxillae (cheeks), ethmoid bone (between the eyes), and sphenoid bone (deep center of skull). 

These hollow spaces lighten the skull and produce mucus that drains into the nasal passages. (For example, a "sinus headache" often results from fluid buildup or inflammation in these sinuses.)

High in the roof of the nasal cavity is the region for smell: olfactory receptors send nerve fibers through the cribriform plate (ethmoid) up to the brain's olfactory bulbs. The floor of the nasal cavity is the hard palate – which is also the bony roof of the mouth (formed by the maxilla and palatine bones).

Take This Quiz:

head and neck anatomy quiz

The Oral Cavity: Hard Palate, Teeth, and Jaw

The oral cavity (mouth) has a bony roof and floor. The roof is the hard palate, which separates the mouth from the nasal cavity. It is formed by the palatine processes of the maxillae in front and the horizontal plates of the palatine bones at the back. (Behind the hard palate is the soft palate, which is muscular – but here we focus on the bones.)

The upper jaw (maxilla) and lower jaw (mandible) house the teeth in two arches. Adults have 32 permanent teeth rooted in these jaws. The maxillae hold the upper teeth and also form much of the nose and the floor of each eye socket. Just behind the last upper molar, the maxilla has a rounded area called the maxillary tuberosity (an important landmark for dental procedures).

The mandible (lower jaw) is the only skull bone that moves significantly, allowing us to chew and speak. It connects with the temporal bone at the temporomandibular joint (TMJ), located just in front of each ear. The mandible's horizontal part (the body) forms the chin and supports the lower teeth, while the upright part on each side (the ramus) extends upward. At the top of each ramus are two processes:

• the coronoid process (in the front) where a major chewing muscle attaches,
  
• the condylar process (in the back) which has the condyle that fits into the temporal bone's socket to form the TMJ.
  

Between these two processes is the mandibular notch, a curved depression. On the front border of the ramus, near where it meets the body, there is a slight inward curve called the coronoid notch (just below the coronoid process).

Neck and Throat Structures (Hyoid, Larynx, Pharynx)

At the top of the neck, just below the jaw, lies the hyoid bone. Interestingly, the hyoid is not attached to any other bone – it "floats" in the neck, anchored by muscles. It sits above (superior to) and in front of (anterior to) the thyroid cartilage of the larynx. The hyoid supports the tongue and provides attachment for muscles that aid in swallowing and speech.

Below the hyoid is the larynx (voice box), which you can feel as the "Adam's apple" (thyroid cartilage) in the middle of your neck. The larynx is a cartilage structure that contains the vocal cords and connects downward to the trachea (windpipe). Behind it is the pharynx (throat), a muscular passage for air from the nose and mouth to the larynx, and for food to the esophagus. During swallowing, a flap called the epiglottis closes over the larynx to prevent food from entering the airway.

The neck also houses major blood vessels and glands. On either side of the larynx is the thyroid gland (which regulates metabolism). Running alongside the throat are the carotid arteries and jugular veins (described later). All these structures are tightly packed in a relatively small area, so injuries to the neck can potentially affect breathing, circulation, or nerve function.

The Eye and Orbit

Our eyes sit in the orbits (eye sockets) on either side of the skull. Each orbit is formed by parts of seven bones (frontal, sphenoid, zygomatic, maxilla, ethmoid, lacrimal, and palatine) that together create a protective hollow for the eyeball and its associated structures. The orbit not only holds the eye, but also contains muscles, nerves, and blood vessels that support eye function.

At the back of each orbit are openings that connect to the cranial cavity. The round optic canal in the sphenoid bone allows the optic nerve (CN II) to pass through, carrying visual information from the eye to the brain. Next to it, a larger slit-like superior orbital fissure allows nerves that control eye movements (CN III, IV, VI) and a branch of the trigeminal nerve (CN V1) to enter. Another opening, the inferior orbital fissure, lets nerves and vessels pass to the face from the orbit.

Inside the orbit, the eye is moved by six tiny extraocular muscles. These muscles attach to the eyeball and enable us to look in different directions. They are controlled by three cranial nerves (oculomotor III, trochlear IV, and abducens VI). For example, when you look toward your nose or roll your eyes, specific pairs of these muscles coordinate under nerve control.

The orbit also contains the lacrimal gland (in the upper outer corner), which produces tears. Tears moisten the eye and then drain through the nasolacrimal duct into the nasal cavity (which is why your nose can run when you cry).

The Ear

The ear has external, middle, and inner parts. The external ear includes the auricle (the ear flap) and the external acoustic meatus (ear canal) leading to the tympanic membrane (eardrum). The middle ear is an air-filled chamber behind the eardrum containing three tiny bones (malleus, incus, stapes) that amplify sound vibrations and transmit them to the inner ear. It connects to the throat via the Eustachian tube to equalize pressure. The inner ear has the fluid-filled cochlea (for hearing) and semicircular canals (for balance), which send nerve signals to the brain via the vestibulocochlear nerve (VIII).

Cranial Nerves: The Brain's Connections to Head and Neck

Twelve pairs of cranial nerves (CN I–XII) emerge from the brain to supply the head and neck (and one of them extends down to the chest and abdomen). They carry sensory information and motor commands for our head and neck functions. Here is a quick overview of the 12 cranial nerves, their type, and primary functions:

Memorizing all 12 cranial nerves can be challenging. A popular mnemonic for the nerve names in order is: "Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH!" – where each word's first letter corresponds to each nerve (Olfactory, Optic, Oculomotor, and so on through Hypoglossal). 

To remember which nerves are Sensory, Motor, or Both, students often use: "Some Say Marry Money, But My Brother Says Big Brains Matter Most." In this phrase, the first letter of each word gives you the function for CN I through XII. For example, using this mnemonic, Olfactory (I) is Sensory, Trigeminal (V) is Both, and Hypoglossal (XII) is Motor.

Understanding the cranial nerves is key to explaining many head and neck functions. For instance, knowing that the facial nerve (VII) controls facial muscles will tell you that an inability to smile on one side could relate to a problem with that nerve. Or if a question asks which nerve passes through the cribriform plate, you'll remember it's the olfactory nerve (I) for smell.

Take This Quiz:

Head & Neck anatomy quiz

Major Blood Vessels of the Head and Neck

Blood supply to the head and neck comes mainly from the carotid arteries, and it drains out through the jugular veins:

• Arteries: The right and left common carotid arteries run up the sides of your neck. Each splits into an internal carotid artery (goes inside the skull to supply the brain) and an external carotid artery (stays outside to supply the face and scalp). You can feel a carotid pulse by gently pressing your fingertip to the side of your windpipe. The internal carotids supply the brain (joining with other arteries at the base of the brain), while the external carotids branch into arteries like the facial artery (to the face) and maxillary artery (to deep face and jaw).
  
• Veins: Most blood from the brain drains into the internal jugular veins (one on each side). Each internal jugular joins the vein from the arm (subclavian vein), and they continue to the heart. More superficial parts of the face and scalp are drained by the external jugular veins, which run down the sides of the neck and empty into the subclavian veins.
  

These blood vessels are vital for delivering nutrients and oxygen to the brain and head. The carotid arteries supply blood to the brain – if one is blocked or cut, it can cause loss of consciousness or a stroke. The jugular veins carry blood away from the brain – injury to a jugular vein can lead to serious bleeding. Fortunately, in our daily lives, these vessels are well protected by the neck's muscles and our body's sturdy anatomy.