Scalp Temple And Face Anatomy

Modiolus

1. Modiolus (nave, pillar): It is a compact, mobile fibromuscular structure.

Modiolus  is present at about 1.25 cm lateral to the angle of the mouth opposite the upper 2nd premolar tooth.

2. The five muscles interlacing to form the modiolus are:

1. Buccinator,
2. Zygomaticus major,
3. Levator anguli oris,
4. Depressor anguli oris
5. Risorius.

3. Modiolus  Shape: Like a hub of a cart-wheel. The muscles radiate from it lie in different planes.

4. Modiolus  Palpation: It can be palpated between the opposed thumb compressing the skin at the angle of mouth and index finger simultaneously compressing the oral mucosa
at the same point.

Read and Learn More Head Anatomy

5. Modiolus  Applied anatomy: The complex integrated movements of modiolar muscles help in biting, chewing, drinking, sucking, swallowing and speaking apart from the facial expressions.

Describe scalp under the following headings:
1. scalp Layers,
2. scalp Blood supply,
3. scalp Nerve supply, and
4. scalp Applied anatomy

1. scalp Layers: I. SCALPI

Skin: Skin is hairy and exceptionally thick. It contains plenty of sebaceous glands.

scalp is adherentto the underlying epicranial aponeurosis through th dense superficial fascia.

Connective tissue (superficial fascia): It is very dense and contains plenty of blood vessels and nerves.

I has the richest cutaneous blood supply in the body.

C. Aponeurosis (galea aponeurotica or epicranial aponeurosis): This contains occipitofrontalis muscle. It has

1. Occipital, and
2. Frontal belly.
3. Occipital belly arises from

• • External occipital protuberance, and IL Highest nuchal lines and becomes continuous with epicranial aponeurosis.
  • Frontal belly arises from epicranial aponeurosis and merges with the procerus, corrugator supercilii and orbicularis oculi.
  • The direction of the fibres is anteroposterior. Thus, the occipital belly is attached to the bone and the frontal belly is attached to the dermis of skin.
  • Lose areolar tissue extends

1. 1. 1. Posteriorly from highest and superior nuchal lines,
      2. Laterally from superior temporal lines, and
      3. Anteriorly into the eyelids.

Fericranium: Fericranium is loosely attached to the surface of the bone except near sutures.
Hence, the fluid collected in this layer takes the shape of underlying bone.

2. Scalp Blood supply: Scalp has rich blood supply.

Scalp Arterial supply 

In front of the auricle, Supraorbital artery (branch of ophthalmic artery), and Supratrochlear artery (branch of ophthalmic artery).
Superficial temporal artery (branch of external carotid artery).
Behind the auricle, it is supplied by
Posterior auricular artery (branch of external carotid artery), and
Occipital artery (branch of external carotid artery).

Note: Scalp is a site of anastomosis between branches of external and internal carotid arteries.

Venous drainage

3. Scalp Nerve supply

Sensor
In front of auricle:
External jugular vein

Supraorbital and supratrochlear, branches of ophthalmic division of trigeminal nerve.

Zygomaticotemporal a branch of zygomatic nerve which is a branch of maxillary division of trigeminal nerve.

Auriculotemporal nerve-mandibular division of trigeminal.

• Behind the auricleI. Go To Posterior division of Great !!_icular nerve (ventral rami of C2-C3)
• Lesser Occipital nerve. Ventral rami of (C2)
• Greater Occipital nerve-dorsal ramus of C2 spinal nerve.
• Third Occipital nerve-dorsal ramus of C3 spinal nerve.

B. Motor
In front of the auricle: Temporal branch of facial nerve supplies frontal belly of occipitofrontalis.
Behind the auricle: Posterior auricular branch of facial nerve supplies occipital belly of occipitofrontalis.

Motor Applied anatomy

First layer
Skin is thick and hairy.

It is the common site of sebaceous cyst.

The infection of the scalp behind the ear may cause transverse venous sinus infection.

It can be dangerous or fatal.

Second layer
The bleeding in second layer is profuse. This is because of two reasons:- The scalp has rich blood supply (five arteries on each side),

The tom vessels are prevented from constriction because the walls of the blood vessels are adherent to the dense connective tissue.

This prevents constriction of vessels.

The bleeding can be immediately arrested by compressing against hard bone, i.e. cranium.
As all thblood vessels of th scalp run frm periphery to centre, bleeding frm th scalp can easily be arrested by applying a tournit around th head.

Third layer: The direction of injury to the scalp decides the rate of healing of the wound.

There is rapid healing of the wound in injury parallel to direction of muscle fibres.

There is delayed healing of wounds, in injury perpendicular to the muscle fibres.

Fourth layer
This is the dangerous area of scalp. The infection from this layer spreads to the brain through emissary vein.

Accumulation of blood in this layer results in black eye.

Fifth layer
Bleeding in 5th layer takes the shape of underlying bone.

The condition is called cephalohaematoma.

Caput succedaneum: It is oedema occurring in and around scalp of newborn during labour.

 

Deep facial vein

Deep Facial Vein Introduction: Deep Facial Vein is a communicating channel that conncts the facial vein to pterygoid venous plexus .
1. Deep Facial Vein Course: Deep Facial Vein leaves the facial vein before it crosses the lateral surface of masseter and to the ramus of mandible.
2. Deep Facial Vein Communications: It is connected to the cavernous sinus by the emissary veins passing through the

1. Foramen lacerum,
2. Foramen ovale, and
3. Foramen spinosum.

3. Deep Facial Vein Peculiarities: It has no valves.

4. Deep Facial Vein Applied anatomy
The dangerous area of face lies between angular and deep facial veins.

The infection from the upper lip and the lower part of the nose can spread through the deep facial vein and cause cavernous sinus thrombosis.

The movements of the facial muscles may facilitate the spread of septic emboli.

Dangerous area of face

Infection of the face can spread to intracranial venous sinus.

Hence, the veins draining the following area is called dangerous area of face.
1. Area:SAI Upper lip.
Septum of nose.
Adjoining part of nose and lip lying between angular and deep facial veins forms the dangerous area of the face.

2. Following are the routes for the spread of infection.

1. Facial vein + deep facial vein + pterygoid venous plexus + cavernous sinus.
2. Angular vein + superior ophthalmic vein + cavernous sinus.

3. The spread of septic emboli from the infected area to cavernous sinus can cause serious complications because of following reasons.

1. Veins of the face do not have valves.
2. Veins of the face directly lie on the muscles of face.
3. There is no deep fascia on the face.
4. The movements of the facial muscles may facilitate the spread of septic emboli to cavernous sinus.

 

 

Upper and lower motor neuron lesions of facial nerve

The difference in the upper and lower motor neuron lesions is displayed in Table 2.7.

Lower motor neuron lesion of facial nerve

The causes, and manifestation of lower motor lesion are described below.

1. Lesion of facial nerve distal to stylomastoid foramen: The lesion of facial nerve is due to vertical incision of the parotid gland.

2. Lesion of facial nerve at the stylomastoid foramen: It results in Bell’s palsy.
The ‘Bell’s palsy’ is the lower motor neuron type of facial palsy (paralysis of muscles of facial expression).
It occurs due to inflammation of facial nerve in the facial canal at the stylomastoid foramen.
The exact cause of inflammation is not known, but it is thought to be due to viral infection.
It causes inflammation and oedema of facial nerve.
It results in compression of facial nerve in the facial canal.
Pain of variable intensity behind the ear precedes facial weakness which develops over 48 hours period.

3. Characteristic features (All muscles of whole face are affected on the side of paralysis.)

1. Facial asymmetry: Due to unopposed action of muscles of opposite side.
2. Loss of wrinkles on forehead: Due to paralysis of fronto-occipitalis.
3. Inability to close the eye (wide palpebral fissure): Due to paralysis of orbicularis oculi.
4. Inability to move the angle of the mouth upwards and laterally during laughing due to paralysis of zygomaticus major.
5. Loss of nasolabial furrow due to paralysis of levator labii superioris alaeque nasi.
6. Accumulation of food in the vestibule of the mouth due to paralysis of the buccinator.
7. Dribbling of saliva: Due to paralysis of orbicularis oris.
8. Inability to inflate the cheek properly: Due to paralysis of buccinator muscle.

4. Lesion in the vertical course of the facial nerve within the mastoid bone results in the

1. Loss of taste sensation on the anterior two-thirds of the tongue on the side of the lesion.
2. There is loss of secretion from submandibular salivary gland; however, lacrimation and the stapedius reflex would be normal.
3. A lesion in the middle ear segment of the nerve (tympanic) does not affect lacrimation but results into ipsilateral hyperacusis due to paralysis of stapedius.

5. Lesion at or proximal to the geniculate ganglion (translabyrinthine) produces diminished lacrimation on the same side, as well as disturbance in function of the other branches.

After regeneration, th parasympathtic secretomotor fires intended for salivary glands grow, and join the secretomotor fibres intended to supply the lacrimal gland; the anticipation of food then produces lacrimation, instead of salivation (syndrome of crocodile tears or Bogard syndrome)NEET_ The specific feature of this syndrome is paroxysmal lacrimation during eating.

Exact cause of lesion is not known. Most often it is due to viral infection leading to ro oedema and inflammation of the nerve.
Upper motor neuron lesion

1. Causes: It is due to damage of corticonuclear fibres. The lesion may be

1. Facial nerve nucleus in the pons or
2.  Above the nucleus.
   The main cause is lesion in the internal capsule.

2. Manifestations:

1. Supranuclear lesions produce upper motor neuron type of paralysis.
   The muscles of the lower half of the face of opposite side are paralysed.
   The muscles of the upper half of the face are normal because they are bilaterally innervated.
2. Effects of upper motor neuron lesion: The patient is able to wrinkle the skin of his forehead, but he is not able to perform the actions of the muscles oflower 1/2 of these
   (as they have unilateral innervation from the cerebral hemisphere hence paralyzed).

Question 18: What are the functions of buccinator muscle?

Answer: 1. It flattens cheek against gums and teeth.
2. It prevents accumulation of food in the vestibule.
3. This is the whistling muscle.