REVIEW
The surgical anatomy of the
scalp
of the scalp lie in this layer (see below) and the scalp has,
indeed, the richest blood supply of any area of the skin in the
body. When the scalp is lacerated, the divided vessels retract
between the fibrous septa and therefore cannot be picked up
by artery forceps in the usual way e precious time will be
wasted if you try to do so. Two techniques are employed to
stem the bleeding that results from lacerations to the scalp;
the surgeon or his assistant presses firmly down on the underlying skull with his fingers, thus compressing the spurting vessels, or he places a series of artery forceps on the
underlying third, aponeurotic, layer and flips them backwards on either side of the wound, again compressing the
vessels. In closing the wound, the surgeon sutures the
laceration firmly in two layers e aponeurosis and skin. A
consequence of this excellent blood supply is that a flap of
scalp with even a narrow pedicle has a high chance of survival compared with a similar cutaneous flap elsewhere.
Aponeurosis e this fibrous sheet is found over much of the
vertex of the skull, where it connects the occipitalis muscle
posteriorly, (arising from the superior nuchal line), to the
frontalis muscle, which inserts into the dermis of the skin
in the region of the eyebrows and bridge of the nose.
Laterally, the aponeurosis extends as a thin sheet overlying
the temporalis fascia and becomes indistinct over the
zygomatic arch.
Loose connective tissue e this thin layer accounts for the
mobility of the scalp on the underlying skull. It is in this
layer that:
the surgeon is able to mobilize a scalp flap
machinery which has caught the hair may avulse the
scalp
Native Americans once ‘scalped’ their victims
As noted above, an extensive torn flap of scalp, because of its
superb blood supply, may well survive, where a similar flap
elsewhere would be non-viable. Blood which collects in this
loose connective tissue layer tracks freely under the scalp, but
cannot pass into the occipital or temporal regions because of
the posterior attachment of occipito-frontalis and the lateral
attachment of the temporalis fascia. It therefore tracks forwards and accounts for the bilateral orbital haematomas that
develops rapidly after a skull fracture or a cranial operation.
Periosteum e this adheres to the suture lines of the skull, in
the scalp region these are the coronal, saggital, temporal and
lambdoid sutures. A collection of blood beneath this layer will
therefore outline the affected bone. This is seen especially in
birth injuries affecting the skull, (cephalohaematoma).
Harold Ellis
Vishy Mahadevan
Abstract
The scalp denotes the soft tissue that covers the cranial vault. It is a multilayered structure with a good blood supply and a rich cutaneous innervation.
Scalp injuries including accidental lacerations are commonly encountered
clinical problems in A & E departments. A proper understanding of the anatomy of the scalp is required for the appropriate management of such injuries,
as it is for the design of craniectomies in neurosurgical practice.
Full-thickness scalp flaps are frequently used in reconstructive surgery to
provide soft tissue cover for facial defects. A proper appreciation of the
blood supply and innervation of the scalp is a prerequisite to the design
of such flaps.
Keywords Cranial vault; occipito-frontalis and aponeurosis; pericranium;
sebaceous cysts
A good knowledge of the anatomy of the scalp and its layers is
essential for a clear understanding of the management of injuries
and pathologies in this region.
The scalp denotes the soft tissues which cover the cranial
vault. It extends from the eyebrows covering the supra-ciliary
line of the frontal bone anteriorly to the superior nuchal line
posteriorly. The latter is a low ridge which extends on either side
from the midline external occipital protuberance of the occipital
bone to the corresponding mastoid process. Laterally the scalp
extends down to the level of the zygomatic arch and the external
auditory meatus (Figure 1).
The layers of the scalp
The scalp is made up of five tissue layers, which can be
remembered by the convenient mnemonic SCALP (Figure 2).
The skin e is thick, variably hair-bearing and is the area of
skin most richly endowed with sebaceous glands, hence its
greasy feel. In consequence of this concentration of sebaceous glands, the scalp is the commonest site for sebaceous cysts, which are often multiple.
Connective tissue e this is made up of fat lobules bound in
tough fibrous septa. The principal blood vessels and nerves
Blood supply
Each side of the scalp is supplied by a total of five arteries
(Figure 3). From the external carotid artery derive:
occipital, whose pulse can usually be felt careful palpation
above the superior nuchal line
posterior auricular
superficial temporal, whose pulse can be felt over the
zygomatic arch immediately in front of the tragus of the ear
From the internal carotid artery derive:
the supraorbital artery
the more medial supratrochlear artery
Harold Ellis CBE MCh FRCS was Professor of Surgery at Westminster
Medical School until 1989, Since then he has taught anatomy, first in
Cambridge and now at Guy’s Hospital, London, UK. Conflicts of interest:
none declared.
Vishy Mahadevan MBBS PhD FRCS is Barbers’ Company Professor of
Anatomy at the Royal College of Surgeons of England, London, UK.
Conflicts of interest: none declared.
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Epicranial aponeurosis
Auricularis anterior
Occipitofrontalis, frontal belly
Orbicularis oculi, palpebral part
Auricularis superior
Depressor supercilii
Occipitofrontalis,
occipital belly
Procerus
Orbicularis oculi, orbital part
Auricularis posterior
Levator labii superioris alaeque nasi
Nasalis
Sternocleidomastoid
Levator labii superioris
Semispinalis capitis
Zygomaticus minor
Orbicularis oris
Splenius capitis
Zygomaticus major
Orbicularis oris
Trapezius
Depressor labii inferioris
Cervical fascia, investing layer
(superficial layer)
Mentalis
Depressor anguli oris
Parotid fascia
Platysma
Risorius
Figure 1 Left lateral view of head showing layers of scalp.
From the ophthalmic V0 e the supratrochlear and supraorbital
nerves.
From the maxillary V00 e the zygomaticotemporal nerve.
From the mandibular V000 e the auriculotemporal nerve.
The lesser occipital nerve (C2).
The greater occipital nerve (C2, 3).
The third occipital nerve (C3).
Both of these derive from the ophthalmic artery.
All these vessels are accompanied by their corresponding
veins.
Owing to the rich anastomoses between these vessels, the
viability of the scalp may be retained when only one artery
survives a major scalp avulsion.
Sensory innervation (Figure 4)
The cutaneous nerve supply of the scalp is derived from all three
diversions of the trigeminal (V) nerve and from the second and
third cervical nerves:
The skull vault
This comprises the frontal, parietal, occipital and squamous part
of the temporal bone (Figure 5).
The layers of the scalp and skull
Blood vessel
Hair
Skin
Connective tissue
Aponeurosis
Loose areolar tissue
Periosteum
Diploë of skull
Dura
Source: Ellis H. Clinical anatomy. 10th edition. Oxford: Blackwell Science, 2002.
Reproduced with permission.
Figure 2
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Zygomaticotemporal
artery and vein
Zygomaticofacial
artery and vein
Supratrochlear
artery and vein
Transverse facial
artery and vein
Supra-orbital
artery and vein
Superficial temporal
artery and vein
Angular artery
and vein
Occipital artery and vein
Lateral nasal
artery and vein
Posterior auricular vein
Superior labial
artery and vein
Posterior auricular artery
Occipital vein
Occipital artery
Inferior labial
artery and vein
External jugular vein
Facial artery
Internal jugular vein
Facial vein
External carotid artery
Figure 3 Left lateral view of head showing blood supply of scalp.
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Ophthalmic nerve [v1]
Greater occipital
(C2 dorsal ramus)
Zygomaticotemporal nerves
Supratrochlear nerve
Supraorbital nerve
Auriculotemporal nerve
Infratrochlear nerve
Maxillary nerve [v2]
Greater occipital nerve
External nasal nerve
C3 dorsal ramus
Infraorbital nerve
Lesser occipital nerve
Zygomaticofacial nerve
Lesser occipital
and greater auricular
C4 dorsal ramus
Mental nerve
Greater auricular nerve
Buccal nerve
Transverse cervical nerve
Mandibular nerve [v3]
Transverse cervical
Figure 4 Left lateral view of head showing cutaneous innervation of scalp.
Coronal suture
Parietal bone
Frontal bone
Pterion
Superior and
inferior temporal
lines
Greater wing of
sphenoid bone
Squamous part of
temporal bone
Nasal bone
Lacrimal bone
Lambdoid suture
Zygomatic bone
Occipital bone
Maxilla
Mastoid process
Mandible Tympanic part of
temporal bone
Figure 5 Bones of the cranial vault.
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The skull vault has an adherent outer periosteal layer, or
pericranium, and an inner endocranial layer. The latter is firmly
fused with the dura mater (the outermost of the three meningeal
layers). These two adherent layers are separated by the sagittal
and the lateral venous sinuses. The periosteal and endocranial
layers meet at the suture lines between the individual bones. The
medullary cavities of the vault bones (the diploe) contain red
bone marrow and are not uncommon sites of deposits of
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secondary tumours and are often involved in multiple myelomatosis.
The blood vessels which supply the meninges, of which the
largest are the middle meningeal artery and vein, groove the
inner aspect of the skull vault and lie between the bone and the
dura. In addition to supplying the meninges, these vessels also
supply the overlying bone and the diploe.
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