HEAD AND NECK (GEN ANA 2)

• The skeleton of the head and neck includes the skull, middle ear ossicles, hyoid bone, and cervical vertebrae.
• Numerous structures in the head and neck are readily palpable and/or have distinctive surface landmarks that mark their underlying location, lending themselves well for orientation in physical examination.
• The skull bones join at fibrous sutural joints, except the mandible, which articulates with the skull via the synovial temporomandibular joint.
• Opening the mouth consists of both protrusion and depression of the mandible.
• Closing requires both retraction and elevation.
• The muscles of mastication include the masseter, temporalis, medial pterygoid, lateral pterygoid, and digastric.
• The neonatal skull has a small face relative to cranium and six fontanelles, which allow molding of the head during birth.
• The scalp consists of five layers that spell out SCALP: skin, connective tissue, aponeurosis, loose areolar tissue, and pericranium.
• The occipitofrontalis is the sole muscle of the scalp.
• Sensory nerves include branches of the trigeminal nerve anterior to the ear and cervical spinal nerves posterior to the ear.
• The external and internal carotid arteries provide blood to the scalp.
• Venous drainage is to the facial and external jugular veins.
• Lymph drainage is to the pericervical collar of nodes.
• The facial muscles (all supplied by CN VII) are organized around the facial orifices and act to regulate those openings.
• Five terminal branches of CN VIl emerge from the parotid gland and spread across the face.
• The meninges (dura mater, arachnoid mater, pia mater) surround the brain.
• The dura has extensions (falx cerebri, falx cerebelli, tentorium cerebelli, diaphragma sellae) that partition the cranial cavity around parts of the brain.
• The subarachnoid space is filled with cerebrospinal fluid.
• The dura receives a rich sensory supply from the trigeminal nerve above the tentorium and from cervical nerves below the tentorium.
• The dural venous blood sinuses collect blood from the brain and run between the layers of the dura.
• Most blood in this system drains to the internal jugular veins.
• The cavernous sinuses sit on the sides of the sella turcica.
• The internal carotid artery and cranial nerves III, IV, V1, V2, and VI pass through the sinus or its wall.
• The brain lies within the cranial cavity and has three main parts: forebrain, midbrain, and hindbrain.
• The internal carotid and vertebral arteries supply the brain.
• The levator palpebrae superioris and the superior tarsal muscle insert into the upper eyelid and open the eye.
• The orbicularis oculi closes the eye.
• The lacrimal apparatus consists of the structures that secrete and collect tears, that is, the lacrimal gland and the lacrimal ducts.
• The nasolacrimal duct drains into the inferior nasal meatus.
• The orbit has four walls and several openings.
• The optic canal and the superior orbital fissure are key in that they convey critical neurovascular structures.
• The eyeball has three layers: an external fibrous coat (sclera and cornea), a middle vascular coat (choroid, ciliary body, and iris), and an inner nervous coat (retina).
• The superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique, and inferior oblique are the extrinsic muscles that move the eye.
• The temporal fossa is an oval area on the side of the head.
• The external carotid has several branches in the neck and terminates in the head into the superficial temporal and maxillary arteries.
• The phrenic nerve is the only motor nerve supply to the diaphragm.
• The maxillary and mandibular nerves run into the pterygopalatine and infratemporal fossae and distribute widely from those spaces.
• The veins of the head and neck are organized in two groups: intracranial veins inside the cranium and extracranial veins outside the skull.
• Intracranial veins include the veins of the brain and the dural sinuses.
• The internal carotid has no branches in the neck but has an extensive distribution in the cranial cavity.