Al- Muthanna University

j General Human Anatomy for

College of Dentistry Human Anatomy Dentistry
Dept. Oral Surgery Lecture.2

2nd. Stage-Semester:1 -‫مخلد االسدي‬.‫د‬

SCALP-2 ‫دكتوراه(بوردعربي) زراعة‬
‫االسنان وجراحة الفم‬
Arterial Supply of SCALP: ‫والوجه والفكين‬
The scalp has a rich supply of blood to nourish the hair follicles, and, for this reason, the
smallest cut bleeds profusely. The arteries lie in the superficial fascia. Moving laterally from
the midline anteriorly, Highly vascularized; the vessels anastomose freely on the scalp
Arteries are derived from the external and the internal carotid arteries The neurovascular
supply arises from the anterior, lateral, and posterior scalp regions. the following
arteries are present:

In front of the ear

1. The supratrochlear and the supraorbital arteries , branches of the ophthalmic artery,
ascend over the forehead in company with the supratrochlear and supraorbital
nerves.
2. The superficial temporal artery, the smaller terminal branch of the external carotid
artery, ascends in front of the auricle in company with the auriculotemporal nerve.
It divides into anterior and posterior branches, which supply the skin over the
frontal and temporal regions.

Behind the ear

3. The posterior auricular artery, a branch of the external carotid artery, ascends
behind the auricle to supply the scalp above and behind the auricle.
4. The occipital artery, a branch of the external carotid artery,ascends from the apex
of the posterior triangle, in company with the greater occipital nerve. It supplies the
skin over the back of the scalp and reaches as high as the vertex of the skull.

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 Venous Drainage of SCALP:

1. The supratrochlear and supraorbital veins unite at the medial margin of the orbit to
form the angular vein and further continue as the facial vein.
2. The superficial temporal vein unites with the maxillary vein in the substance of the
parotid gland to form the retromandibular vein.
3. The posterior auricular vein unites with the posterior division of the
retromandibular vein, just below the parotid gland, to form the external jugular
vein.
4. The occipital vein drains into the suboccipital venous plexus, which lies beneath
the floor of the upper part of the posterior triangle; the plexus in turn drains into the
vertebral veins or the internal jugular vein. The veins of the scalp freely
anastomose with one another and are connected to the diploic veins of the skull
bones and the intracranial venous sinuses by the valveless emissary veins.

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 Lymphatic Drainage of SCALP:

Lymph vessels in the anterior part of the scalp and forehead drain into the submandibular
lymph nodes. Drainage from the lateral part of the scalp above the ear is into the superficial
parotid (preauricular) nodes; lymph vessels in the part of the scalp above and behind the ear
drain into the mastoid nodes. Vessels in the back of the scalp drain into the occipital nodes.

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 Clinical Significance of the Scalp Structure
It is important to realize that the skin, the subcutaneous tissue, and the epicranial
aponeurosis are closely united to one another and are separated from the periosteum
by loose areolar tissue. The skin of the scalp possesses numerous sebaceous glands,
the ducts of which are prone to infection and damage by combs. For this reason,
sebaceous cysts of the scalp are common.

Lacerations of the Scalp

The scalp has a profuse blood supply to nourish the hair follicles. Even a small
laceration of the scalp can cause severe blood loss. It is often difficult to stop the
bleeding of a scalp wound because the arterial walls are attached to fibrous septa in the
subcutaneous tissue and are unable to contract or retract to allow blood clotting to take
place. Local pressure applied to the scalp is the only satisfactory method of stopping
the bleeding.
Because of the profuse blood supply, it is often possible to replace large areas of scalp
that are only hanging to the skull by a narrow pedicle. Suture them in place, and
necrosis will not occur. The tension of the epicranial aponeurosis, produced by the
tone of the occipitofrontalis muscles, is important in all deep wounds of the scalp. If
the aponeurosis has been divided, the wound will gape open. For satisfactory healing
to take place, the opening in the aponeurosis must be closed with sutures. Often, a
wound caused by a blunt object such as a baseball bat closely resembles an incised
wound. This is because the scalp is split against the unyielding skull, and the pull of
the occipitofrontalis muscles causes a gaping wound.

Head injury resulting in soft tissue damage can cause collection of blood in the loose
subaponeurotic layer of scalp which is continuous with the upper eye lid. The blood
easily tracks down anteriorly over the eyelids leading to discoloration of the eye
known as black eye. The spread of this collection is limited posteriorly and laterally
due to attachment of the aponeurosis to the supranuchal lines and to the zygomatic
arches at these points.

Infections of the scalp tend to remain localized and are usually painful because of the
abundant fibrous tissue in the subcutaneous layer. Occasionally, an infection of the
scalp spreads by the emissary veins, which are valveless, to the skull bones, causing
osteomyelitis. Infected blood in the diploic veins may travel by the emissary veins
farther into the venous sinuses and produce venous sinus thrombosis. Blood or pus
may collect in the potential space beneath the epicranial aponeurosis. It tends to spread
over the skull, being limited in front by the orbital margin, behind by the nuchal lines,
and laterally by the temporal lines. On the other hand, subperiosteal blood or pus is
limited to one bone because of the attachment of the periosteum to the sutural
ligaments.

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  Cephalhaematoma: It is the collection of blood below the periosteal layer of scalp due
to an injury.The swelling due to the haematoma is localized over the particular bone
involved as the periosteum is adherent to the underlying bone at the sutures which
limits its spread. In a new born, this has to be differentiated from caput formation.

 Caput is the collection of fluid in the loose areolar tissue of scalp due to forces of
labour. The swelling due to caput is generally diffuse and more on the dependant areas
instead of a particular bone. The collection of caput crosses the sutures and the midline
as it is not limited by sutures. Caput disappears in 24 to 48 hours of birth while
cephalhaematoma may take upto 4 to 7 days to disappear.

• Dangerous layer of the scalp: The layer of loose areolar tissue is often called as
dangerous layer of the scalp because it lodges the emissary veins. These veins do not
have any valves. Hence, if there is any infection of scalp it can travel along the
emissary veins into the intracranial dural venous sinuses leading to thrombosis of the
sinuses.

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