Scalp Anatomy

Scalp

• The scalp extends posteriorly from the superior nuchal lines.
• The scalp extends anteriorly from the supraorbital margin of the frontal bone.
• The scalp extends laterally to the zygomatic arches.

Layers of the Scalp

• The layers of the scalp, from superficial to deep, are Skin, Connective tissue, Aponeurosis, Loose connective tissue, and Pericranium.
• The skin contains hair.
• The connective tissue contains the nerves and blood supply of the scalp.
• The aponeurosis contains the occipitofrontalis muscle.
• The loose connective tissue is a dangerous layer because it contains emissary veins, so infection here can reach the brain.
• The pericranium is the periosteum which is adherent to the bone.

Occipitofrontalis Muscle

• The frontalis part originates from the skin and superficial fascia of eyebrows and inserts into the aponeurosis.
• The frontalis part raises the eyebrows and moves the scalp forward.
• The occipitalis part originates from the superior nuchal line and inserts into the aponeurosis.
• The occipitalis moves the scalp backwards.
• Nerve supply: facial nerve.

Clinical Anatomy and Scalp Wounds

• Deep scalp wounds gape widely when the epicranial aponeurosis is lacerated in the coronal plane.
• This is due to the pull of the frontal and occipital bellies of the occipitofrontalis muscle in opposite directions.
• Reasons wounds bleed profusely:
  • The scalp is highly vascular.
  • Vessels lie superficially in the 2nd layer.
  • Wound gaps.
  • Vessel walls fail to retract.

Clinical Anatomy and Black Eyes

• An infection or fluid can enter the eyelids and root of the nose because the occipitofrontalis is attached to the skin and subcutaneous tissue and not to the bone.

Muscles of Facial Expression

• These muscles are derived from the 2nd pharyngeal arch.
• These muscles are supplied by the facial nerve.

Orbicularis Oculi

• Orbicularis oculi is composed of the orbital part, the palpebral part, and the lacrimal part.
• The orbital part is around the orbital margin and does a firm closure of the eye.
• The palpebral part is within the eyelids and does a gentle closure of the eye (sleep).
• The lacrimal part is in the free margin of the eyelid, around the lacrimal sac, and helps tear drainage.
• Nerve supply: temporal and upper zygomatic branches of the facial nerve.

Buccinator

• Origin: Maxilla opposite molar teeth, Mandible opposite molar teeth, Pterygomandibular ligament.
• Insertion is the upper and lower lips.
• Nerve supply: facial nerve.
• Action: Blowing.
• Action: Prevent accumulation of food in the vestibule of the mouth.

Orbicularis Oris

• In the lips.
• Surrounds the mouth.
• Nerve supply: facial nerve.
• Action: whistling and kissing.

Ear Muscles

• Auricularis anterior
• Auricularis superior
• Auricularis posterior

Platysma

• Origin: from the deep fascia and skin over pectoralis major and deltoid.
• Insertion: inferior border of the mandible, skin of the face inferior to the mouth.
• Nerve supply: Facial nerve.
• Action: Depresses the angle of the mandible.
• Action: Tenses the skin of the neck.

Facial Nerve Injury

• Injury to the facial nerve (CN VII) or its branches produces paralysis of some or all facial muscles on the affected side (Bell palsy).
• The affected area sags.
• Facial expression is distorted, making it appear passive or sad.