Muscles of the face and scalp

Humans make many different facial expressions and they are an extremely important way that we communicate. They let people know when you are happy, like after getting a good mark on an anatomy test, or curious like when you learn something new about the human body. Let’s learn about the muscles responsible for our facial expressions!

First, let’s start with the scalp which is a layer of skin and subcutaneous tissue that covers the cranium. It extends from the supraorbital margins on the frontal bone to the superior nuchal line on the occipital bone.

Laterally, it covers the temporal fascia and extends to the zygomatic arches on each side. The scalp is made of five layers, which can be remembered easily as the first letter of each spells out the word SCALP.

Going in the order from superficial to deep: S stands for skin, C stands for connective tissue, A stands for aponeurosis or epicranial aponeurosis, L stands for loose connective tissue, and P stands for pericranium, which is the periosteum on the external surface of the cranium.

The first three layers - skin, connective tissue, and the aponeurosis - are connected tightly together, forming a single unit called the scalp proper.

Muscles of facial expression, simply known as the facial muscles are found deep to the skin of the scalp, face, and neck.

Most facial muscles are attached to bones or fascia on one end, and skin on the other, so that when they contract they create facial expressions.

All facial muscles originate from the mesoderm of the second pharyngeal arch, along with the facial nerve. During embryological development, a muscular sheet forms and begins to spread over the scalp, face and neck which later forms the facial muscles.

This spreading carries the branches of the nerve of the second arch with it, which is the facial nerve, or cranial nerve seven.

So, all facial muscles are innervated by the branches of the facial nerve which are the posterior auricular, temporal, zygomatic, buccal, marginal mandibular, and cervical nerves.

A way to remember these last five branches that emerge from the parotid gland is by using the mnemonic “To Zanzibar By Motor Car!”