Scalp Anatomy and Drainage

Structure

• The scalp has five layers

• Skin is thick, contains hair, and has numerous sebaceous glands

• Connective tissue is fibrofatty and contains fibrous septa that connects the skin to the underlying aponeurosis of the occipitofrontalis muscle

• Numerous arteries and veins are found in the connective tissue

• Arteries are branches of the external and internal carotid arteries, and a free anastomosis occurs between them

• Aponeurosis (epicranial) is a thin, tendinous sheet connecting the occipital and frontal bellies of the occipito frontalis muscle

• The lateral margins of the aponeurosis are attached to temporal fascia

• The subaponeurotic space beneath the epicranial aponeurosis is a potential space

• It is limited in front and behind by the origins of the occipitofrontalis muscle, and extends laterally as the attachment of the aponeurosis to the temporal fascia

• Loose areolar tissue occupies the subaponeurotic space and connects epicranial aponeurosis to the periosteum of the skull

• The areolar tissue includes some small arteries and contains some important emissary veins

• Emissary veins are valveless, connecting superficial scalp veins with the diploic veins of the skull bones and intracranial venous sinuses

• Pericranium is the periosteum that covers the outer surface of the skull bones

• At the sutures between individual skull bones, the periosteum on the outer surface of the bones becomes continuous with the periosteum on the inner surface of the skull bones

Muscles

• Occipitofrontalis muscles are a part the scalp
• The occipital belly originates from the highest nuchal line of the occipital bone, and inserts on the epicranial aponeurosis
• The occipital belly is supplied by the facial nerve
• The frontal belly originates from skin and superficial fascia of the eyebrow, inserting on the epicranial aponeurosis
• The frontal belly is supplied by the facial nerve

Nerve Supply

• Sensory nerves that supply the scalp lie in the superficial fascia

• Supratrochlear Nerve branches from the ophthalmic division of the trigeminal nerve and supplies the scalp

• The Supratrochlear Nerve winds around the superior orbital margin, passes backward near the median plane, and reaches the vertex of skull

• Supra Orbital Nerve is a Trigeminal nerve branch, opthalmic division and supplies the scalp

• It winds around the superior orbital margin and ascends over the forehead and supplies the scalp as far back as the vertex

• The zygomaticotemporal nerve is a maxillary division branch of the trigeminal nerve, supplying the scalp over the temple

• The auriculotemporal nerve is a mandibular division branch of the trigeminal nerve, it ascends over the side of the head from in front of the auricle, its terminal branch supplies skin over temporal region

• The lesser occipital nerve is a a branch of cervical plexus (C2), supplying the scalp over the lateral part of occipital region and skin over the medial surface of the auricle

• The greater occipital nerve is the posterior ramus branch of the 2nd cervical nerve, ascending over the back of the scalp and supplying the skin as far forward as the vertex of skull

Arterial Supply

• The scalp has a rich blood supply nourishing hair follicles, that results in profuse bleeding if cut

• Arteries lie in the superficial fascia and are located laterally from the midline anteriorly

• The Supratrochlear and Supraorbital artery are branches of the ophthalmic artery, ascending over the forehead in company with the supratrochlear and supraorbital nerves

• The superficial temporal artery is the smaller terminal branch of the external carotid artery, ascending in front of the auricle with the auriculotemporal nerve

• The superficial temporal artery divides into anterior and posterior branches, which supply the skin over frontal and temporal region

• The posterior auricular artery is the external carotid artery branch, ascends behind the auricle and supply the scalp above and behind the auricle

• Occipital artery is an branch of the external carotid artery, ascends from the apex of the posterior triangle with the greater occipital nerve

• The occipital artery supplies skin of the back of the scalp and reaches as high as the vertex of the skull

Venous Drainage

• The Supratrochlear and Supraorbital Veins unite at the medial margin of orbit forming the angular vein which continues as the facial vein
• Superficial Temporal Vein unites with the maxillary vein within the parotid gland to form the retromandibular vein
• Posterior Auricular Vein unites with the posterior division of the retromandibular vein below the parotid gland forming the external jugular vein
• Occipital Vein drains into the suboccipital plexus under the floor of the upper part of posterior triangle and drains into the vertebral or internal jugular vein

Lymphatic Drainage

• Lymph vessels from the anterior part of the scalp and forehead drain into the submandibular lymph nodes
• Lymph drainage of the lateral part of the scalp above the ear is superficial parotid nodes
• Lymph vessels of the scalp part above and behind the ear, drain into the mastoid nodes
• Vessels in the scalp's back drain into the occipital nodes

Questions cover venous and lymphatic drainage of the scalp, impact of blockages, and risks associated with scalp injuries. Includes the layers of the scalp and potential complications of damage. Crucial aspects of scalp anatomy are emphasized.