Scalp And Face
- The scalp is soft tissue which covers the calvaria of skull. It consists of five layers and can be memorised by a mnemonic using the initial letters of the word. SCALP :- (a) Skin; (b) Close network of connective tissue (superficial fascia); (c) Aponeurosis (galea aponeurotica) with occipitofrontalis muscles; (d) Loose areolar (subaponeurotic) tissue; (e) Pericranium (outer periosteum of skull). First three layers are intimately connected and move as one unit, and are called surgical layers of scalp or scalp proper.
- Connective tissue (superficial fascia) contains large blood vessels and nerves of the scalp. The walls of the vessels are adherent to the fibrous network, so that when the vessels are tom in an open wound they are unable to retract and produce profuse bleeding. Bleeding can be arrested by pressure against the underlying bone.
- Loose subaponeurotic areolar tissue (4th layer) is called dangerous area of scalp because it contains emissary veins through which infection in subaponeurotic space may spread readily to intracranial venous sinuses.
- Arterial supply of scalp is as follows ;-
- Infront of auricle:-Supratrochlear and supraorbital branches of ophthalmic artery (a branch ofICA); and superficial temporal artery, a branch of ECA.
- Beingauricle:-Posterior auricular artery and occipital artery, both are branches ofECA.
- Therefore scalp is the site of free anastomosis between the branches of external and internal carotid arteries.
- Nerve supply is as follows ;-
- In front of auricle: - Supratrochlear (sensory), supraorbital (sensory), zygomaticotemporal (sensory), aurlculotemporal (sensory) and temporal branch of facial nerve (motor).
- Behind auricle: - Posterior branch of great auricular: C2, C3 (sensory), lesser occipital: C2(sensory), greater occipital: C2 (sensory), third occipital: C2 (sensory), and posterior auricular branch offacialnerve (motor).
The face is provided with mouth, eyes and nose. The face is limited above by hair line of scalp, below by chin and base of mandible, and on each side by auricle.
Each half of the face is supplied by fourteen nerves, one is motor and the rest are sensory. Motor supply is derived from facial (7th) nerve which supplies all facial muscles except levator palpeprae superioris, which is supplied by sympathetic fibers and 3rd cranial nerve. Eleven sensorynerves are derived from branches of trigeminal (5th) nerve and only two sensory are derived from great auricular nerve and transverse (anterior) cutaneous nerve of neck.
- Face is supplied by facial artery (chief arteryof face), transverse facial artery and arteries that accompany cutaneous nerves.
- Facial artery is the chief artery of face. It arises from external carotid arteryabove the level of tip of greater cornu of hyoid bone, in carotid triangle. The facial artery enters the face by winding around the base of the mandible and by piercing the deep cervical fascia, at the anteroinferior angle of masseter: It can be palpated here and is called anaesthetist artery. Branches of facial artery are (i) inferior labial, (ii) superior labial, (iii) lateral nasal, and (iv) posterior (unnamed) branches.
- Transverse facial artery is a branch of superficial temporal artery, emerges from parotid gland. It supplies parotid gland, overlying skin, masseter, and ends by anastomosing with neighbouring arteries.
Veins of face
- The facial vein is the largest vein of the face with no valves. It begins as the angular vein at the medial angle of the eye. Angular vein is formed by the union of supraorbital and supratrochlear veins. The angular vein continues as facial veins. Which joins the anterior division of retromandibular vein (i.e. deep facial vein) below the angle of the mandible to form common facial vein. Common facial vein drains into the internal jugular vein.
- Facial vein communicates with cavernous sinus through deep connections :-
- A communication between supraorbital and superior ophthalmicveins.
- With the pterygoid plexus through deep facial vein.
- Therefore, infection from the face can spread in retrograde direction and cause caveronus sinus thrombosis (CVT). This is especially likely to occur in the presence of infection in the upper lip and in lower part of the nose. This area istherefore called dangerous area of the face.
The face possesses three areas from which lymphatic drainage is as follows:-
- Upper area, comprising greater part of forehead, lateral half of eyelids, conjunctiva, lateral part of cheek and parotid area, drains into preauricular (superficial) parotid nodes.
- Middle area, comprising central part of forehead, external nose, upper lip, lateral part of lower lip, medial halves ofeyelids, medial part of cheek, and greater part of lower jaw, drains into submandibular nodes.
- Lower area, including central part of lowerIipand the chin, drains into submental nodes.