Scalp
The scalp is the skin and subcutaneous tissue covering the neurocranium. It is composed of five layers and has a rich vascular supply which explains why it bleeds profusely and heals well.
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Layers
The scalp is composed of five layers which are easily remembered with this mnemonic. From external to internal the layers are:
- skin
- usually covered in hair
- thicker over the occiput
- rich arterial supply and venolymphatic drainage
- connective tissue
- a thick layer which has a rich vascular supply
- contains numerous cutaneous nerves
-
galeal aponeurosis (also known as the galea aponeurotica or epicranial aponeurosis)
- strong aponeurosis that allows attachment for muscles of the scalp (occipitofrontalis, temporoparietalis and superior auricular muscles), all innervated by the facial nerve
- loose areolar tissue
- a sponge-like layer of areolar tissue which allows the free movement of the first three layers over the underlying pericranium and skull
- being so loose it is a potential space for collections and hematomas
- pericranium
- a dense layer of fibrous connective tissue that is the external periosteum of the neurocranium (firmly attached)
- extends into the cranial sutures
Boundaries
- posterior: superior nuchal lines of the occipital bone
- anterior: supraorbital margins of the frontal bone
- lateral: zygomas
Arterial supply
Numerous arteries supply the scalp, contributing to its rich vascular supply.
The arteries arise from both the internal and external carotid circulations:
- external carotid artery branches
- internal carotid artery branches
Venous drainage
- venous drainage is via veins that correspond to the named arteries and via emissary veins to dural venous sinuses
Lymphatic drainage
Like the face, the scalp does not have lymph nodes. Lymph drains via small lymphatic channels to the submandibular, parotid, mastoid and occipital nodes. These form a collar of nodes at the junction of the head and neck.
Innervation
Numerous cutaneous nerves supply sensation to the scalp depending on the location:
- anterior scalp (branches of the ophthalmic division of the trigeminal nerve)
- superior scalp towards the vertex
- posterior scalp
- greater occipital nerve (from C2)
- third occipital nerve (C3)
- lateral scalp (from anterior to posterior)
- zygomaticotemporal nerve
- zygomaticofacial nerve
- auriculotemporal nerve (branch of the mandibular division of trigeminal nerve)
- lesser occipital nerve (C2, C3 from the cervical plexus)
The muscles of the scalp (see above) are considered muscles of facial expression and therefore are all innervated by the facial nerve.
Related pathology
Related Radiopaedia articles
Anatomy: Head and neck
- skeleton of the head and neck
-
cranial vault
- scalp (mnemonic)
- fontanelle
-
sutures
- calvarial
- facial
- frontozygomatic suture
- frontomaxillary suture
- frontolacrimal suture
- frontonasal suture
- temporozygomatic suture
- zygomaticomaxillary suture
- parietotemporal suture (parietomastoid suture)
- occipitotemporal suture (occipitomastoid suture)
- sphenofrontal suture
- sphenozygomatic suture
- spheno-occipital suture (not a true suture)
- lacrimomaxillary suture
- nasomaxillary suture
- internasal suture
- basal/internal
- skull landmarks
- frontal bone
- temporal bone
- parietal bone
- occipital bone
- skull base (foramina)
-
facial bones
- midline single bones
- paired bilateral bones
- cervical spine
- hyoid bone
- laryngeal cartilages
-
cranial vault
- muscles of the head and neck
- muscles of the tongue (mnemonic)
- muscles of mastication
-
muscles of facial expression
- occipitalis muscle
- circumorbital and palpebral muscles
- nasal muscles
- buccolabial muscles
- elevators, retractors and evertors of the upper lip
- levator labii superioris alaeque nasalis muscle
- levator labii superioris muscle
- zygomaticus major muscle
- zygomaticus minor muscle
- malaris muscle
- levator anguli oris muscle
- risorius muscle
- depressors, retractors and evertors of the lower lip
- depressor labii inferioris muscle
- depressor anguli oris muscle
- mentalis muscle
- compound sphincter
- orbicularis oris muscle
- incisivus superior muscle
- incisivus inferior muscle
- muscle of mastication:
- elevators, retractors and evertors of the upper lip
- muscles of the middle ear
- orbital muscles
- muscles of the soft palate
- pharyngeal muscles
- suprahyoid muscles
- infrahyoid muscles
- intrinsic muscles of the larynx
- muscles of the neck
- accessory muscles of the neck
- deep cervical fascia
-
deep spaces of the neck
- anterior cervical space
- buccal space
- carotid space
- danger space
- deep cervical fascia
- infratemporal fossa
- masticator space
- parapharyngeal space
- stylomandibular tunnel
- parotid space
- pharyngeal (superficial) mucosal space
- perivertebral space
- posterior cervical space
- pterygopalatine fossa
- retropharyngeal space
- suprasternal space (of Burns)
- visceral space
- surgical triangles of the neck
- orbit
- ear
- paranasal sinuses
- nose
- oral cavity
- pharynx
- larynx
- viscera of the neck
- blood supply of the head and neck
-
arterial supply
-
common carotid artery
- carotid body
- carotid bifurcation
- subclavian artery
- variants
-
common carotid artery
- venous drainage
-
arterial supply
- innervation of the head and neck
-
cranial nerves
- olfactory nerve (CN I)
- optic nerve (CN II)
- oculomotor nerve (CN III)
- trochlear nerve (CN IV)
-
trigeminal nerve (CN V) (mnemonic)
- trigeminal ganglion
- ophthalmic division
- maxillary division
- mandibular division
- abducens nerve (CN VI)
- facial nerve (CN VII)
-
vestibulocochlear nerve (CN VIII)
- vestibular ganglion (Scarpa's ganglion)
- glossopharyngeal nerve (CN IX)
-
vagus nerve (CN X)
- superior laryngeal nerve
- recurrent laryngeal nerve (inferior laryngeal nerve)
- (spinal) accessory nerve (CN XI)
- hypoglossal nerve (CN XII)
- parasympathetic ganglia of the head and neck
- greater occipital nerve
- third occipital nerve
-
cervical plexus
- muscular branches
- longus capitis
- longus colli
- scalenes
- geniohyoid
- thyrohyoid
-
ansa cervicalis
- omohyoid (superior and inferior bellies separately)
- sternothyroid
- sternohyoid
- phrenic nerve
- contribution to the accessory nerve (CN XI)
- cutaneous branches
- muscular branches
- brachial plexus
- pharyngeal plexus
-
cranial nerves
- lymphatic drainage of the head and neck
- embryological development of the head and neck
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