REVIEW

The surgical anatomy of thescalpHarold Ellis

Vishy Mahadevan

AbstractThe scalp denotes the soft tissue that covers the cranial vault. It is a multi-

layered structurewith a goodblood 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 anat-

omy of the scalp is required for the appropriatemanagement 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 seba-

ceous glands, the scalp is the commonest site for seba-

ceous 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

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.

SURGERY 32:S1 e1

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 un-

derlying skull with his fingers, thus compressing the spurt-

ing vessels, or he places a series of artery forceps on the

underlying third, aponeurotic, layer and flips them back-

wards 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 sur-

vival 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 for-

wards 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

lambdoidsutures.Acollectionofbloodbeneath this layerwill

therefore outline the affected bone. This is seen especially in

birth injuries affecting the skull, (cephalohaematoma).

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

� 2013 Published by Elsevier Ltd.

Auricularis anterior Epicranial aponeurosis

Auricularis superior

Auricularis posterior

Sternocleidomastoid

Semispinalis capitis

Splenius capitis

Trapezius

Parotid fascia

Platysma

Cervical fascia, investing layer(superficial layer)

Occipitofrontalis,occipital belly

Occipitofrontalis, frontal belly

Orbicularis oculi, palpebral part

Orbicularis oculi, orbital part

Levator labii superioris alaeque nasi

Levator labii superioris

Zygomaticus minor

Orbicularis oris

Zygomaticus major

Orbicularis oris

Depressor labii inferioris

Depressor anguli oris

Risorius

Mentalis

Nasalis

Depressor supercilii

Procerus

Figure 1 Left lateral view of head showing layers of scalp.

REVIEW

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 layers of the scalp and sku

HairBlood vessel

Source: Ellis H. Clinical anatomy. 10th edReproduced with permission.

Figure 2

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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).

The skull vault

This comprises the frontal, parietal, occipital and squamous part

of the temporal bone (Figure 5).

ll

Skin

Connective tissue

Loose areolar tissue

Aponeurosis

Periosteum

Diploë of skull

Dura

ition. Oxford: Blackwell Science, 2002.

� 2013 Published by Elsevier Ltd.

Zygomaticotemporalartery and vein

Supratrochlearartery and vein

Supra-orbitalartery and vein

Angular arteryand vein

Lateral nasalartery and vein

Superior labialartery and vein

Inferior labialartery and vein

Facial artery

Facial veinExternal carotid artery

Internal jugular vein

External jugular vein

Occipital artery

Occipital vein

Posterior auricular vein

Posterior auricular artery

Occipital artery and vein

Superficial temporalartery and vein

Transverse facialartery and vein

Zygomaticofacialartery and vein

Figure 3 Left lateral view of head showing blood supply of scalp.

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Ophthalmic nerve [v1]

Maxillary nerve [v2]

Mandibular nerve [v3]

Transverse cervical

Transverse cervical nerve

Greater auricular nerve

C4 dorsal ramus

Lesser occipitaland greater auricular

Lesser occipital nerve

C3 dorsal ramus

Greater occipital nerve

Auriculotemporal nerve

Greater occipital(C2 dorsal ramus)

External nasal nerve

Infraorbital nerve

Zygomaticofacial nerve

Mental nerve

Buccal nerve

Zygomaticotemporal nerves

Supratrochlear nerve

Supraorbital nerve

Infratrochlear nerve

Figure 4 Left lateral view of head showing cutaneous innervation of scalp.

Coronal suture

Frontal bone

Pterion

Lacrimal bone

Zygomatic bone

Maxilla

Mandible Tympanic part oftemporal bone

Mastoid process

Occipital bone

Lambdoid suture

Squamous part oftemporal bone

Superior andinferior temporallines

Parietal bone

Nasal bone

Greater wing ofsphenoid 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

SURGERY 32:S1 e5

secondary tumours and are often involved in multiple myelo-

matosis.

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. A

� 2013 Published by Elsevier Ltd.