This presentation is about the scalp in detail

1. Scalp

2. The Scalp
It is a soft tissue covering the calvaria of the skull.
Extent :
• Anteriorly - supraorbital margins
• Posteriorly - External occipital protuberance &
superior nuchal line
• Laterally - zygomatic arch, here it overlaps the
temporal region superficial to temporal fascia.
Layers :
1. Skin
2. Connective tissue layer
3. Aponeurotic layer - Galea aponeurotica with
occipitofrontalis muscle.
4. Loose areolar layer
5. Pericranium

3. Skin -
• Thick with numerous hairs, sweat and sebaceous
glands.
• It is one of the commonest site for sebaceous
cyst.
Connective tissue layer -
• It is composed of dense fibro - fatty layer.
• It connects the skin to the underlying galea.
• It contains large blood vessels and nerves.
• The walls of the blood vessels are closely adherent
to the fibrous tissue, so when the vessels are torn
in an open wound, produce profuse bleeding, as
the adherence prevent retraction. Bleeding can be
arrested by applying pressure against the
underlying bone.
• Subcutaneous haemorrhage in a closed wound is
localised in extent.
• Inflammation in this layer is so painful, due to
unyielding nature of the fibrous tissue.
• Rich blood supply of scalp ensure good healing
even a large area is avulsed with narrow pedicle,
when replaced and sutured.

4. Occipitofrontalis muscle or epicranius :
It consists of a pair of occipital bellies behind and a pair of
frontal bellies in front.
Occipital bellies - widely separated from each other.
• Origin - from lateral 2/3 of superior nuchal line
• Insertion - to epicranial aponeurosis or galea aponeurotica
• Nerve supply - by posterior auricular branch of facial nerve
Frontal bellies - have no bony origin. They are longer, wider
and approximated to each other in the median plane.
• Origin - from skin & subcutaneous tissue of eyebrow and
root of nose
• Insertion - to epicranial aponeurosis.
• Nerve supply - by temporal branch of facial nerve.
• Action - Alternate contraction of occipital and frontal bellies
move the entire scalp backward and forwards
Frontal bellies - acting from above - raises the eyebrow as in
surprise or horror.
acting from below - produces transverse
wrinkles on forehead as in freight.
Temporo-parietalis:
It is a variable slip of muscle between auricularis anterior and
auricularis superior.
• Origin - from galea aponeurosis
• Insertion - to the root of auricle.
• Nerve supply - by temporal branch of facial nerve
• Action - raises the auricle.

5. Galea aponeurotica or eicranial aponeurosis
:
• It is a sheet of fibrous tissue which connects
the occipitalis and frontalis muscles.
• Extent -
• Posterior - attached to external occipital
protuberance and highest nuchal lines.
• Anterior - sends narrow extension between
the two frontal bellies and blends with the
subcutaneous tissues at root of nose.
• On each side - it extends as a thin membrane
superficial to temporal fascia. It is attached to
zygomatic arch.
• It gives attachments to auricularis muscles
and temporo-parietalis muscles.
• When it is divided transversely, the wound will
gape.

6. Loose areolar layer or subaponerotic layer :
• It consists of loose areolar tissue and forms a
potential space.
• This has emissary veins, which are valveless,
connects the veins of scalp and intracranial
venous sinuses.
• Any infection in the scalp will be carried
intracranial,
• hence this layer is called dangerous area of
scalp.
Any blow on the skull produces collection of
blood, which is generalised affecting the whole
dome of skull.
The blood slowly gravitates into the eyelids, as
frontal bellies has no bony attachments.
This is called black eye.

7. Sometimes fracture of skull is associated with a tear in
pericranium and dura mater. In such cases the
intracranial haemorrhage communicates with the
subaponeurotic space through the fracture line. Signs of
cerebral compression does not develop until this space is
full. This is called as safety - valve haematoma.
Traumatic cephalo-hydrocoele is a condition in which
the space is filled with cerebrospinal fluid. This is due to
fracture of skull associated with tear in meninges of the
brain.
Caput succedaneum is present in newborn. It is a
temporary swelling, affecting the scalp due to
interference of venous return occurs during the process
of delivery.
Pericranium :
It is the outer periosteum of the skull.
It loosely covers the skull bones except at the sutures,
where it becomes continuous with endocranium derived
from the endosteal layer of dura mater through the
sutural ligaments.
Cephalhaematoma - collection of blood beneath the
pericranium, assume the shape of the affected bone.

8. Nerve Supply :
Scalp is supplied by ten nerves on each side, five in front of auricle and five behind the auricle
Source Infront of auricle Source Behind the auricle
Sensory Motor Sensory Motor
Ophthalmic division
of trigeminal nerve
Frontal Nerve Supratrochlear nerve Temporal branch of
facial nerve
C2,C3 of cervical
plexus
Posterior branch of
Great auricular nerve
Posterior auricular
branch pf facial
nerve
Supra orbital nerve C2 of cervical plexus Lesser occipital
nerve
Maxillary division of
trigeminal nerve
Zygomatic Nerve Zygomatico-
temporal nerve
dorsal ramus of C2
nerve
Greater occipital
nerve
Mandibular division of trigeminal nerve Auriculo-temporal
nerve
dorsal ramus of C3
nerve
third occipital nerve
Applied Anatomy - Surgeries on the scalp should be preferably done under general anaesthesia, as the dermatomes of trigeminal
and cervical nerves overlap considerably and the density of fibrous tissue prevents the diffusion of local anaesthetic in the scalp

9. Nerves and Arteries of Scalp

10. Arterial supply: Five sets of arteries supply on each side, three in front and two behind the auricle.
Source In front of auricle Source Behind the auricle
Internal carotid
artery
ophthalmic artery supra trochlear
artery
External carotid
artery
Posterior auricular
artery
supraorbital artery Occipital artery
External carotid
artery
terminal branch superficial
temporal artery
Importance: Scalp is the site where there is free anastomosis of branches of External and Internal carotid arteries.

11. Venous Drainage: Veins corresponds the arteries.
They drain as follows:
1. supra orbital vein joins with the supra trochlear vein to
form angular vein at the medial angle of eye.
2. Angular vein continues across down the face as facial
vein.
3. The superficial temporal vein enters the parotid gland,
joins with maxillary vein to form retromandibular vein.
This vein divides into anterior and posterior divisions.
4. The anterior division joins with facial vein forming the
common facial vein, terminating into internal jugular
vein.
5. The posterior division joins with posterior auricular
vein to form external jugular vein, terminating into
subclavian vein.
6. Occipital vein draining into sub occipital plexus of
veins.

12. Lymphatic drainage:
• Anterior part of scalp drains into pre
auricular or superficial parotid lymph nodes.
• Posterior part of scalp drains into post
auricular or mastoid group and occipital
group of lymph nodes.