The scalp is the area of the head where

head hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fin ...

grows. It is made up of skin, layers of connective and fibrous tissues, and the membrane of the skull. Anatomically, the scalp is part of the epicranium, a collection of structures covering the

cranium The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. The scalp is bordered by the

face The face is the front of the head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may affect th ...

at the front, and by the

neck The neck is the part of the body in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Addition ...

at the sides and back. The scientific study of hair and scalp is called

trichology Trichology is the study of the hair and scalp. The term derives from Ancient Greek θρίξ (''thríx''), "hair" and -λογία ''-logia''. In most jurisdictions the title of a ''trichologist'', not the field of trichology, is considered a par ...

Structure

Layers

The scalp is usually described as having five layers, which can be remembered using the

mnemonic A mnemonic device ( ), memory trick or memory device is any learning technique that aids information retention or retrieval in the human memory, often by associating the information with something that is easier to remember. It makes use of e ...

'SCALP': * S:

Skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

. The skin of the scalp contains numerous

hair follicle The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction betwee ...

s and sebaceous glands. * C:

Connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...

. A dense subcutaneous layer of

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...

and fibrous tissue that lies beneath the skin, containing the nerves and vessels of the scalp. * A:

Aponeurosis An aponeurosis (; : aponeuroses) is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerable ...

. The epicranial aponeurosis or galea aponeurotica is a tough layer of dense fibrous tissue which anchors the above layers in place. It runs from the

frontalis muscle The frontalis muscle () is a muscle which covers parts of the forehead of the skull. Some sources consider the frontalis muscle to be a distinct muscle. However, Terminologia Anatomica currently classifies it as part of the occipitofrontalis muscl ...

anteriorly to the

occipitalis The occipitalis muscle (occipital belly) is a muscle which covers parts of the skull. Some sources consider the occipital muscle to be a distinct muscle. However, Terminologia Anatomica currently classifies it as part of the occipitofrontalis musc ...

posteriorly. * L:

Loose areolar connective tissue Loose connective tissue, also known as areolar tissue, is a cellular connective tissue with thin and relatively sparse collagen fibers. They have a semi-fluid matrix with lesser proportions of fibers. Its ground substance occupies more volume ...

. This layer has a gel-like consistency, and allows the more superficial layers of the scalp to shift about in relation to the pericranium. It is constituted of more

matrix Matrix (: matrices or matrixes) or MATRIX may refer to: Science and mathematics * Matrix (mathematics), a rectangular array of numbers, symbols or expressions * Matrix (logic), part of a formula in prenex normal form * Matrix (biology), the m ...

than fibers. It contains and is rich in

glycosaminoglycans Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharides consisting of repeating disaccharide units (i.e. two-sugar units). The repeating two-sugar unit consists of a uronic acid, uronic sugar and an amino sugar, except i ...

(GAGs). In

craniofacial surgery Craniofacial surgery is a surgical subspecialty that deals with congenital disorder, congenital and acquired deformity, deformities of the human head, head, human skull, skull, face, neck, jaws and associated structures. Although craniofacial treat ...

and

neurosurgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the specialty (medicine), medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system ...

this layer provides an easy plane of separation between the upper three layers and the pericranium. In

scalping Scalping is the act of cutting or tearing a part of the human scalp, with hair attached, from the head, and generally occurred in warfare with the scalp being a trophy. Scalp-taking is considered part of the broader cultural practice of the taki ...

the scalp is also torn off through this layer. The layer is sometimes referred to as the "danger zone" because infectious agents can easily spread through it to

emissary veins The emissary veins connect the extracranial venous system with the intracranial venous sinuses. They connect the veins outside the cranium to the venous sinuses inside the cranium. They drain from the scalp, through the skull, into the larger men ...

which drain into the

. * P: Pericranium. This is the

periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. (At the joints of long bones the bone's outer surface is lined with "articular cartila ...

of the skull bones, a membrane that provides nutrition to the bone and the capacity for repair. During surgery it can be lifted from the bone to allow the removal of windows of bone (

craniotomy A craniotomy is a surgery, surgical operation in which a bone flap is temporarily removed from the Human skull, skull to access the Human brain, brain. Craniotomies are often critical operations, performed on patients who are suffering from brain ...

Blood supply

The blood supply of the scalp is via five pairs of arteries, three from the

external carotid The external carotid artery is the major artery of the head and upper neck. It arises from the common carotid artery. It terminates by splitting into the superficial temporal and maxillary artery within the parotid gland. Structure Origin Th ...

and two from the

internal carotid The internal carotid artery is an artery in the neck which supplies the anterior and middle cerebral circulation. In human anatomy, the internal and external carotid arise from the common carotid artery, where it bifurcates at cervical verteb ...

: * internal carotid ** the

supratrochlear artery The supratrochlear artery (or frontal artery) is one of the terminal branches of the ophthalmic artery. It arises within the orbit. It exits the orbit alongside the supratrochlear nerve. It contributes arterial supply to the skin, muscles and peri ...

to the midline forehead. The supratrochlear artery is a branch of the ophthalmic branch of the internal carotid artery. ** the

supraorbital artery The supraorbital artery is a branch of the ophthalmic artery. It passes anteriorly within the orbit to exit the orbit through the supraorbital foramen or notch alongside the supraorbital nerve, splitting into two terminal branches which go on to f ...

to the lateral forehead and scalp as far up as the vertex. The supraorbital artery is a branch of the ophthalmic branch of the internal carotid artery. * external carotid ** the

superficial temporal artery In human anatomy, the superficial temporal artery is a major artery of the head. It arises from the external carotid artery when it splits into the superficial temporal artery and maxillary artery. Its pulse can be felt above the zygomatic ar ...

gives off frontal and parietal branches to supply much of the scalp ** the

occipital artery The occipital artery is a branch of the external carotid artery that provides arterial supply to the back of the scalp, sternocleidomastoid muscles, and deep muscles of the back and neck. Structure Origin The occipital artery arises from (the ...

which runs posteriorly to supply much of the posterior aspect of the scalp ** the

posterior auricular artery The posterior auricular artery is a small artery that arises from the external carotid artery. It ascends along the side of the head. It supplies several muscles of the neck and several structures of the head. Structure Origin The artery ar ...

, a branch of the external carotid artery, ascends behind the auricle to supply the scalp above and behind the auricle. Because the walls of the blood vessels are firmly attached to the fibrous tissue of the superficial fascial layer, cut ends of vessels here do not readily retract; even a small scalp wound may bleed profusely. Venous drainage The veins of the scalp accompany the arteries and thus have similar names, e.g. Supratrochlear and supraorbital veins, which unite at the medial angle of the eye, and form the angular vein, which further continues as the facial vein. The superficial temporal vein descends in front of the tragus, enters the parotid gland, and then joins the maxillary vein to form the retromandibular vein. The anterior part of it unites with the facial vein to form the common facial vein, which drains into jugular vein, and ultimately to the subclavian vein. The occipital vein terminates to the sub-occipital plexus. There are other veins, like the emissary vein and frontal diploic vein, which also contribute to the venous drainage.

Nerve supply

Innervation is the connection of nerves to the scalp: the sensory and motor nerves innervating the scalp. The scalp is innervated by the following: *

Supratrochlear nerve The supratrochlear nerve is a branch of the frontal nerve, itself a branch of the ophthalmic nerve (CN V1) from the trigeminal nerve (CN V). It provides sensory innervation to the skin of the forehead and the upper eyelid. Structure Orig ...

and the

supraorbital nerve The supraorbital nerve is one of two terminal branches - the other being the supratrochlear nerve - of the frontal nerve (itself a branch of the ophthalmic nerve (CN V1)). It exits the orbit via the supraorbital foramen/notch before splitting ...

from the

ophthalmic division The ophthalmic nerve (CN V1) is a sensory nerve of the head. It is one of three divisions of the trigeminal nerve (CN V), a cranial nerve. It has three major branches which provide sensory innervation to the eye, and the skin of the upper face an ...

of the

trigeminal nerve In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions ...

Greater occipital nerve The greater occipital nerve is a nerve of the head. It is a spinal nerve, specifically the medial branch of the dorsal primary ramus of cervical spinal nerve 2. It arises from between the first and second cervical vertebrae, ascends, and then pa ...

(C2) posteriorly up to the vertex *

Lesser occipital nerve The lesser occipital nerve (or small occipital nerve) is a cutaneous spinal nerve of the cervical plexus. It arises from second cervical (spinal) nerve (C2) (along with the greater occipital nerve). It innervates the skin of the back of the up ...

(C2) behind the ear *

Zygomaticotemporal nerve The zygomaticotemporal nerve (zygomaticotemporal branch, temporal branch) is a cutaneous ( sensory) nerve of the head. It is a branch of the zygomatic nerve (itself a branch of the maxillary nerve (CN V2)). It arises in the orbit and exits the o ...

from the maxillary division of the

supplying the hairless temple *

Auriculotemporal nerve The auriculotemporal nerve is a sensory branch of the mandibular nerve (CN V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to parts of the external ear, scalp, and temporomandibular joint. The nerve a ...

from the

mandibular division In neuroanatomy, the mandibular nerve (V) is the largest of the three divisions of the trigeminal nerve, the fifth Cranial nerves, cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve (ophthalmic nerve, maxillary nerve) which ...

of the

The innervation of scalp can be remembered using the mnemonic 'Z-GLASS' for Zygomaticotemporal nerve, Greater occipital nerve, Lesser occipital nerve, Auriculotemporal nerve, Supratrochlear nerve, and Supraorbital nerve. The motor innervation of the scalp, specifically, the

occipitofrontalis The occipitofrontalis muscle (epicranius muscle) is a muscle which covers parts of the skull. It consists of two parts or bellies: the occipital belly, near the occipital bone, and the frontal belly, near the frontal bone. It is supplied by the ...

muscle, is split into two main factions: the frontal belly or

is supplied by the

temporal branch of facial nerve The temporal branches of the facial nerve (frontal branch of the facial nerve) crosses the zygomatic arch to the temporal region, supplying the auriculares anterior and superior, and joining with the zygomaticotemporal branch of the maxillary nerv ...

, while the occipital belly or

is supplied by the posterior auricular branch of facial nerve.

Lymphatic drainage

Lymphatic channels from the posterior half of the scalp drain to occipital and posterior auricular nodes. Lymphatic channels from the anterior half drain to the parotid nodes. The lymph eventually reaches the submandibular and deep cervical nodes.

Clinical significance

Infection

The 'danger area of the scalp' is the area of loose connective tissue. This is because pus and blood spread easily within it, and can pass into the cranial cavity along the emissary veins. Therefore, infection can spread from the scalp to the meninges, which could lead to meningitis.further studies are needed to conclude that it’s actually a “danger zone” though.

Injury

The clinically important layer is the aponeurosis. Scalp lacerations through this layer mean that the "anchoring" of the superficial layers is lost and gaping of the wound occurs which would require suturing. This can be achieved with simple or vertical mattress sutures using a non-absorbable material, which are subsequently removed at around days 7–10.

Hair transplantation

All the current

hair transplantation Hair transplantation is a surgery, surgical technique that removes hair follicles from one part of the body, called the 'donor site', to a bald or balding part of the body known as the 'recipient site'. The technique is primarily used to treat ...

techniques utilize the patient's existing hair. The aim of the

surgical Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery ...

procedure is to use such hair as efficiently as possible. The right candidates for this type of surgery are individuals who still have healthy hair on the sides and the back of the head in order that hair for the transplant may be harvested from those areas. Different techniques are utilized in order to obtain the desired cosmetic results; factors considered may include hair color, texture, curliness, etc. The most utilized technique is the one known as micro grafting because it produces naturalistic results. It is akin to

follicular unit extraction Follicular unit extraction (FUE; also follicular unit excision or follicular transfer, FT) Performed under local anaesthetic, FUE procedure involves the harvesting of individual hair follicles from the donor site at the back of the head using a t ...

, although less advanced. A knife with multiple blades is used to remove tissue from donor areas. The removed tissue is then fragmented into smaller chunks under direct vision inspection (i.e., without a microscope).

Disease

The scalp is a common site for the development of tumours including: *

Actinic keratosis Actinic keratosis (AK), sometimes called solar keratosis or senile keratosis, is a Premalignant condition, pre-cancerous area of thick, scaly, or crusty skin.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed. ...

Basal-cell carcinoma Basal-cell carcinoma (BCC), also known as basal-cell cancer, basalioma, or rodent ulcer, is the most common type of skin cancer. It often appears as a painless, raised area of skin, which may be shiny with small blood vessels running over it. ...

Epidermoid cyst An epidermoid cyst or epidermal inclusion cyst is a benign cyst usually found on the skin. The cyst develops out of ectodermal tissue. Histologically, it is made of a thin layer of squamous epithelium. Signs and symptoms The epidermoid cyst may ...

Merkel-cell carcinoma Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer occurring in about three people per million members of the population. It is also known as cutaneous APUDoma, primary neuroendocrine carcinoma of the skin, primary small cell ca ...

Pilar cyst A trichilemmal cyst (or pilar cyst) is a common cyst that forms from a hair follicle, most often on the scalp, and is smooth, mobile, and filled with keratin, a protein component found in hair, nail (anatomy), nails, skin, and horn (anatomy), ho ...

Squamous cell carcinoma Squamous-cell carcinoma (SCC), also known as epidermoid carcinoma, comprises a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the ...

Scalp conditions

Dandruff Dandruff is a skin condition of the scalp. Symptoms include flaking and sometimes mild itchiness. It can result in social or self-esteem problems. A more severe form of the condition, which includes inflammation of the skin, is known as s ...

– a common problem caused by excessive shedding of dead skin cells from the scalp *

Head lice infestation Head lice infestation, also known as pediculosis capitis, is the infection of the head hair and scalp by the head louse (''Pediculus humanus capitis''). Itching from lice bites is common. During a person's first infection, the itch may not devel ...

Excoriation disorder Excoriation disorder, more commonly known as dermatillomania, is a mental disorder on the obsessive–compulsive spectrum that is characterized by the repeated urge or impulse to pick at one's own skin, to the extent that either psychological or ...

– obsessive skin picking *

Trichotillomania Trichotillomania (TTM), also known as hair-pulling disorder or compulsive hair pulling, is a mental disorder characterized by a long-term urge that results in the pulling out of one's own hair. A brief positive feeling may occur as hair is rem ...

– obsessive hair pulling *

Seborrhoeic dermatitis Seborrhoeic dermatitis (also spelled seborrheic dermatitis in American English) is a long-term skin disorder. Symptoms include flaky, scaly, greasy, and occasionally itchy and inflamed skin. Areas of the skin rich in oil-producing glands are ...

– a skin disorder causing scaly, flaky, itchy, red skin *

Cradle cap Cradle cap is crusty or oily scaly patches on a baby's scalp. The condition is not painful or itchy, but it can cause thick white or yellow scales that are not easy to remove. Cradle cap most commonly begins sometime in the first three months b ...

– a form of seborrhoeic dermatitis which occurs in newborns *

Trichodynia Scalp dysesthesia is a cutaneous condition characterised by pain and burning sensations without objective physical examination findings. The pain sometimes is described as burning. Often there is an underlying psychosomatic cause, such as stress, ...

– burning scalp syndrome *

Tinea capitis Tinea capitis (also known as "herpes tonsurans", "ringworm of the hair", "ringworm of the scalp", "scalp ringworm", and "tinea tonsurans") is a cutaneous fungal infection ( dermatophytosis) of the scalp. The disease is primarily caused by dermato ...

- ringworm of the scalp, and its severe form Favus *

Cutis verticis gyrata Cutis verticis gyrata is a medical condition usually associated with thickening of the scalp. The condition is identified by excessive thickening of the soft tissues of the scalp and characterized by ridges and furrows, which give the scalp a cer ...

– a rare deformity of the scalp

Society and culture

The scalp plays an important role in the

aesthetics Aesthetics (also spelled esthetics) is the branch of philosophy concerned with the nature of beauty and taste (sociology), taste, which in a broad sense incorporates the philosophy of art.Slater, B. H.Aesthetics ''Internet Encyclopedia of Ph ...

of the face.

Androgenic alopecia Pattern hair loss (also known as androgenetic alopecia (AGA)) is a hair loss condition that primarily affects the top and front of the scalp. In male-pattern hair loss (MPHL), the hair loss typically presents itself as either a receding front ...

, or male pattern hair loss, is a common cause of concern to men. It may be treated with varying rates success by medication (e.g.

finasteride Finasteride, sold under the brand names Proscar and Propecia among others, is a medication used to treat pattern hair loss and benign prostatic hyperplasia (BPH) in men. It can also be used to treat hirsutism, excessive hair growth in women. It ...

minoxidil Minoxidil is a medication used for the treatment of high blood pressure and pattern hair loss. It is an antihypertensive and a vasodilator. It is available as a generic medication by prescription in oral administration, oral tablet (pharmacy), ...

) or hair transplantation. If the scalp is heavy and loose, a common change with

ageing Ageing (or aging in American English) is the process of becoming older until death. The term refers mainly to humans, many other animals, and fungi; whereas for example, bacteria, perennial plants and some simple animals are potentially biol ...

, the forehead may be low, heavy and deeply lined. The

brow lift A forehead lift, also known as a browlift or browplasty, is a cosmetic surgery procedure used to elevate a drooping eyebrow that may obstruct vision and/or to remove the deep "worry" lines that run across the forehead. History The first documente ...

procedure aims to address these concerns.

Scalping Scalping is the act of cutting or tearing a part of the human scalp, with hair attached, from the head, and generally occurred in warfare with the scalp being a trophy. Scalp-taking is considered part of the broader cultural practice of the taki ...

is the act of removing a human scalp, usually with hair, as a

trophy A trophy is a tangible, decorative item used to remind of a specific achievement, serving as recognition or evidence of merit. Trophies are most commonly awarded for sports, sporting events, ranging from youth sports to professional level athlet ...

. Often associated with the history of North America, scalping developed independently on multiple continents and dates back to antiquity.

References

External links

* - "Integument: scalp, transverse" * - "Integument: scalp" * * http://www.dartmouth.edu/~humananatomy/figures/chapter_47/47-1.HTM {{Authority control Human hair Human head and neck Human skin Medical mnemonics