FACE
“The Face”
extends from the rots of hair above to the chin below and from one auricle to
the other auricle at the sides. The forehead stands therefore common to the
face and scalp; but for the sake of convenience the incisions are made in the
dissection of face excluding the forehead.
N.B. Before
staring the dissection, see that the lips, cheeks and eyelids and distended by
placing cotton wool inside the vestibule of month and the conjunctival sacs and
the margins of the lips & eyelids are stitched up.
Skin
Incisions
1.
A longitudinal incision in the median plan from the root of the nose to the
symphysis menti.
2.
A slight curved incision from the root of the nose to the upper & front
part of the auricle passing along superciliary arch.
3.
An oblique incision from the symphysis menti along the lower border of the body
of the mandible to its angle.
4.
One semicircular incision along the muco-cutaneous junction of the upper and
lower lips.
5.
One circular incision along the margin of the upper and lower eyelids.
To be retlected
as a single flap laterally over the auricle. It is not uniform all over the face;
thin & lax over the eyelids but fairly thick elsewhere. On the tip and the
alae of the nose the skin is fused with the underlying cartilage in such a way
that some portion of the cartilage is inevitable taken away with the skin.
After removal of
the skin fibres of the Superficial
Muscles of the face will come into view but as most of them are inserted
into the skin, their surfaces become somewhat lacerated in appearance.
Skin of the Face
is very vascular, so wounds bleed freely but heal quickly.
Superficial Fascia
Very than and is
generally taken away with the skin. Carefully clean the sub-cutaneous fat and
areolar tissue without injury to the vessels & nerves.
Then note the
position of the Facial muscles and define their outlines as clearly as
possible. Preserve some portion of the Buccal
pad of fat at about the middle of the cheek.
Deep Fascia
There is no deep
fascia in the face except posteriorly over the parotid gland and the Masseter
where it is known as the Parotido
Masseteric Fascia. It is derived from the deep fascia of the neck and after
ensheathing the parotid gland, is attached above to the zygomatic arch. It has
to be reflected backwards avoiding injury to the vessels & nerves. Facial
expression has become easy due to the absence of deep fascia in the face.
Vessels
& Nerves of the Face
A)
Nerves of the face: 13 in number on each side, of which only one is motor and
twelve are sensory. Motor Nerve of the face is the facial nerve and the Sensory
Nerves are all derived from the trigeminal nerve except one which is derived
from the cervical plexus.
a) Sensory Nerves: Are the following :
Derived from the ophthalmic division of the trigeminal nerve.
1. Supra orbital.
2. Supra trochlear.
3. Infra trochlear.
4. Lacrimal.
5. External nasal.
Derived from the maxillary division of the trigeminal nerve.
6.
Zygomatico facial.
7.
Zygomatic temporal.
8. Infra orbital.
Derived from the mandibular divison of the trigeminal nerve.
9. Buccal.
10. Mental.
11. Auriculo temporal
Derived from the cervical plexus.
b)
Motor Nerve: It the Facial nerve
with its following terminal branches:
1) Temporal.
2) Zygomatic.
3) Buccal.
4) Mandibular.
5) Cervical.
B)
Arteries of the face
1) Facial artery with its branches.
2) Transverse facial artery, a branch of
the superficial temporal artery.
3) Smaller arteries that usually accompany
the cutaneous branches of the trigeminal nerve having identical names such as
supra-orbital, infra orbital, mental etc, being derived from the external
carotid and ophthalmic arteries.
They freely anastomose with one another, so that a network of arteries is
formed in the face.
C)
Veins
of the face
They form a
plexus in the superficial fascia & muscles of the face and are drained by
the veins which accompany the arteries. Facial vein is important of these
veins. It has no valves.
DISSECTION NOTE: In dissecting the vessels and nerves of the face, firs of all the
nerves (motor then sensory) have to be traced, then followed by the arteries
& veins. Clean the outer surface and the anterior border of the parotid
gland, that trace The branches of the facial nerve which emerge from its deep
surface in a radiating manner to the muscles of their supply. Cervical branch
of the facial nerve goes downwards behind the angle of the mandible to the neck
to supply the Platysma.
Then trace all the twelve sensory nerves with great care as they are very
delicate: of them the following Nerves are more or less stronger and must be
detected at their respective sites: (a) Supraorbital, (b) Infra orbital, (c)
Zyomatico temporal, (d) Zygomatico facial, (e) Mental, (f) Auriculo temporal.
In
the dissection of the face, only small proximal parts of the supratrochlear,
Surpaorbital, Zygomatyico temporal and Auriculotemporal nerves are exposed but
their terminal parts are distributed to the Scalp & Temporal region, where
those four sensory nerves have been described.
Other Eight Sensory Nerves are distributed as
follows:
1)
Infra
trochlear nerve : Is a branch
of the nasociliary, which is a branch of the ophthalmic division of Trigeminal
nerve. It comes out of the orbit above the medial angle of the eye and supplies
the skin and conjunctiva of the medial part of the eyelids. skin of the root of
the nose, lacrimal sac and caruncul lacrimalis.
2)
External
nasal nerve: Is the continuation of
the Anterior ethmoidal nerve, which is continued behind with the nasociliary.
It emerges out of the nasal cavity between the lower border of the nasal bone
and the upper nasal cartilage and supplies the skin of the lip & vestibule
of the nose.
3)
Lacrimal
nerve: Is the smallest branch of the ophthalmic division of Trigeminal
nerve. It enters the orbit through the superior orbital fissure and supplies
the larcimal gland and conjunctiva, then piercing the orbital septum it ends by
supplying the skin of the upper eyelid. Sometimes this nerve may be absent.
4)
Zygomatico
facial nerve: Is a branch of the zygomatic branch of the maxillary nerve. It
comes out of the zygomatico facial foramen of the zygomatic bone and supplies
the skin over the prominence of the cheek (malar prominence).
5)
Infra
orbital nerve: Is the
continuation of the maxillary nerve. It traverses the infra orbital groove,
then infra orbital canal and appears in the face through the infra orbital
foramen under cover of the Levator labii superiors and ends by dividing into
three sets of branches:
a)Palperbral
branches: Supply the skin and conjunctiva of the lower eyelid
b) Nasal
branches: Supply the skin of the side of the nose.
c) Supply the
skin and mucous membrane of the cheek and upper lip.
These branches
communicate with the zygomatic and upper deep buccal branches of the facial
nerve. forming a network, called the infra orbital plexus.
6)
Buccal
nerve : Is a branch of the anterior
trunk of the mandibular nerve. It passes between the two heads of the lateral
pterygoid muscle and appears in the face from under cover under cover of the
masseter to the outer surface of the Buccinators where it supplies the skin and
mucous membrane for the cheek.
7)
Mental
nerve: Is one of the terminal
branches of the inferior dental nerve. It appears in the face through the
mental foreman
8)
and under cover of the Depressor
anguli oris divides into branches which supply the skin & mucous membrane
of the lower lip and the skin over the body of the mandible.
9)
Anterior
branch of the great auricular nerve:
It supplies the skin of the face over the parotid gland. The great auricular
nerve is formed by the anterior primary rami of the 2nd and 3rd cervical spinal
nerves.
