Face and scalp

• External skull

  The muscles of facial expression attach to the bones of the skull and the fascia of the face

  
• The temporal bone provides attachment for temporalis but also forms important areas for muscle and ligament attachment – the mastoid and styloid processes

  
• Muscles of facial expression - most originate on facial bones and insert into the skin/connective tissue of face

  The facial muscles are small, thin and delicate.

  
• Fascia

  •Superficial fascia and fat

  •Fascia in scalp blends with superficial fascia in neck posteriorly and extends into the temporal regions laterally

  •A layer of deep cervical fascia (parotid fascia) covers masseter and invests the parotid gland

  The fascia of the parotid gland is thicker and is an extension of a layer of deep fascia

  
• Muscles of facial expression

  Fronto-occipitalis can also be called occipitofrontalis or divided into its two bellies of frontalis and occipitalis.

  
• Muscles of facial expression

  Although platysma is covering the neck, it inserts onto the face and so is said to contribute to facial expression as well as tightening the skin on the neck. This thin layer of subcutaneous muscle is said to be a remnant of the panniculus carnosis. Platysma also shares the innervation common to all of the muscles of facial expression – the facial nerve.

  
• A buccinator's actual function is to prevent food from collecting between the teeth and the cheek.

  
• Orbicularis oculi is one of two ‘orbicularis’ muscles of the face. As its name suggests it forms a circle around the eye. The muscle acts to close the eye.

  
• Orbicularis oris is the other ‘orbicularis’ muscle. It forms a circle of muscle around the mouth but forms a more complex sphincter than orbicularis oculi. The zygomaticus muscles act to raise the corners of the mouth and can be used to create a sneering expression.

  
• Two muscles that also insert into the lips lie above the lips. One acts to elevate the lip so is called levator (it elevates) labii (the lips) superioris (it lies above the lips). One acts to raise the corner (anguli) of the mouth and also lies above the mouth. Using the levator muscles above the mouth in combination with the depressor muscles below the mouth helps to open up the lips – they are dilators of the mouth.

  
• Mentalis is a small muscle that helps to pull down the lower lip.

  
• Risorius arises from the fascia over the parotid gland and attaches to the corner of the mouth, so is used to make a happy, smiling expression.

  Levator labii superioris alaeque nasi is yet another small muscle that helps to move the skin of the nasal area.

  
• the muscles of facial expression are small and fragile.

  
• Facial nerve

  The facial nerve supplies the muscles of facial expression and so is MOTOR supply to the face. The trigeminal nerve supplies sensory nerves to the face and motor innervation to temporalis and masseter.

  
• Facial nerve

  the muscles supplied by each branch of the facial nerve.

  
• Arteries

  The facial artery is the third anterior branch of the external carotid artery. It crosses the anterior surface of the mandible and forms branches that supply the face. The facial artery is usually described as ‘tortuous’  in shape – it forms many bends as it crosses the face.

  The transverse facial branch of the superficial temporal artery also supplies the face. The supratrochlear and supraorbital branches derived from branches of the internal carotid artery supply the forehead.

  
• Veins

  The face is drained by the facial vein, which is often slightly larger than the artery and much less tortuous as it crosses the face. It joins with the anterior part of the retromandibular vein and usually drains into the internal jugular vein. It communicates with vessels in the pterygoid venous plexus that lies inside the infratemporal fossa.

  
• Layers of the scalp

  Skin

  Connective tissue

  Aponeurosis (between frontalis and occipitalis)

  Loose areolar connective tissue

  Periosteum (pericranium)

  
• Blood supply

  •Supratrochlear (a), supraorbital (b)

  •Superficial temporal (c)

  •Posterior auricular (d)

  •Occipital (e)

  The supratrochlear and supraorbital arteries are derived from branches of the internal carotid artery and supply the anterior part of the scalp. The rest of the scalp is supplied by posterior branches of the external carotid artery and the superficial temporal artery (which is a terminal branch of the external carotid).

  
• Emissary veins

  •Communication between superficial veins of the scalp (in connective tissue layer) and dural venous sinuses

  •Potential route for infection

  
• Nerve supply

  •(a) Supratrochlear and (b) supraorbital (CNV1)

  •(c) Zygomaticotemporal (CNV•2)

  •(d) Auriculotemporal (CNV3)

  •(e) Lesser occipital (C2)

  •(f) Greater occipital (C2) and third occipital (C3)

  
• Nerve supply

  The superior, anterior and lateral surfaces of the scalp are innervated by branches of the trigeminal nerve (CN V). The ophthalmic (CNV1), maxillary (CNV2) and mandibular divisions (CNV3) all contribute to sensation from the scalp. Behind the auricle and the posterior surface of the head are innervated from local nerves derived from C2 and C3 nerve roots.

  
• Trigeminal nerve

  •Frontal (a)

  •Nasociliary (b)

  •Infraorbital (c)

  •Superior alveolar (d)

  •Lingual (e)

  •Inferior alveolar (f)

  •Auriculotemporal (g)

  
• Trigeminal nerve

  The trigeminal nerve supplies sensory nerves to the face.

  The supraorbital nerve exits the skull at the supraorbital notch/foramen to reach the forehead. The infraorbital nerve leaves the skull via the infraorbital foramen to reach the lateral sides of the nose and the upper lip. The inferior alveolar nerve ends as it passes through the mental foramen to form the mental nerve that passes onto the skin of the mandible.

  
• Trigeminal nerve

  The C2 dermatome covers the posterior part of the head and then C3 dermatome covers much of the neck.

  
• Lymphatics

  The face and scalp are drained to nodes in the occipital, mastoid, parotid, submandibular and submental areas. Lymph then passes to deep cervical nodes which lie close to the internal jugular vein.