Anatomy of Head and Neck

Lymphatic Drainage of Head and Neck

• Lymphatic drainage of head and neck is divided into two groups: circular and cervical groups
• Circular groups include:
• Occipital group: lies along occipital vessels and drains the back of scalp and upper part of neck
• Retroauricular group: drains the back of the auricle, external acoustic meatus and nearby part of scalp
• Superficial parotid group: lies on the fascia of parotid gland and drains the anterior part of auricle, external acoustic meatus and temporal region
• Deep parotid group: lies in the sheath of parotid gland and drains the anterior part of scalp, orbit, parotid gland and part of the face
• Retropharyngeal group: lies between pharynx and prevertebral muscles, and drains vertebral region and pharynx
• Submandibular group: lies in the submandibular triangle and drains submandibular and lingual salivary glands, tongue, gum, tonsil and cheek
• Submental group: lies in submental triangle and drains the tip of tongue, lower lip and the floor of mouth

Cervical Groups

• Cervical groups are formed of superficial and deep groups
• Superficial group: lies along external jugular vein and anterior jugular vein, and drains superficial structures of neck
• Deep group: lies along the internal jugular vein and drains the deep structure in neck (pharynx, larynx, esophagus, trachea and thyroid gland)

Parotid Gland

• The parotid gland is the largest salivary gland
• It lies behind the ramus of mandible and extends to the mastoid process posteriorly
• Medially, it reaches up to the styloid process of the skull
• The gland is irregular in shape and part of it passes over the masseter muscle, which is called the accessory parotid gland
• The parotid gland has a duct that passes anteriorly and crosses the masseter muscle, then pierces the cheek to open in the vestibule of the mouth opposite the upper second molar tooth

Blood Supply of Parotid Gland

• External carotid artery (superficial temporal and maxillary artery)
• Transverse facial artery (branch of superficial temporal artery)
• Deep auricular artery (branch of maxillary artery)

Lymphatic Drainage of Parotid Gland

• To the deep parotid lymph nodes, which pass to the deep cervical lymph nodes

Nerve Supply of Parotid Gland

• Parasympathetic from glossopharyngeal nerve through otic ganglia, carried to the gland via auriculotemporal nerve
• Sympathetic from sympathetic plexus around external carotid artery

Otic Ganglia

• The otic ganglia is a small parasympathetic ganglia that lies below the foramen ovale
• Components:
• Preganglionic parasympathetic fibers from glossopharyngeal nerve through lesser petrosal nerve to the ganglia
• Postganglionic parasympathetic secretomotor fibers carried from the ganglia by auriculotemporal nerve to the parotid gland
• Motor fibers to tensor palate and tensor tympani muscles from nerve to medial pterygoid muscle (branch of mandibular division of trigeminal nerve)
• Sympathetic fibers from plexus around middle meningeal artery
• Sensory fibers from glossopharyngeal nerve and distributed through the branches of the ganglia

Muscles of Mastication

• There are four muscles of mastication:
• Masseter muscle
• Temporalis muscle
• Medial pterygoid muscle
• Lateral pterygoid muscle

Masseter Muscle

• The masseter muscle arises from the lower border and deep surface of zygomatic arch
• It runs downward to be inserted into the lateral aspect of ramus of mandible
• Nerve supply: mandibular division of trigeminal nerve
• Action: rises and protracts the mandible

Temporalis Muscle

• The temporalis muscle is a fan-shaped muscle that arises from the medial wall of temporal fossa and from the temporal fascia
• It is inserted into the coronoid process of mandible and anterior border of ramus of mandible
• Nerve supply: deep temporal nerve which is a branch of mandibular division of trigeminal nerve
• Action: rises and retracts the mandible

Lateral Pterygoid Muscle

• The lateral pterygoid muscle arises by two heads, the smaller upper head arises from the infratemporal surface of greater wing of sphenoid, and the lower large head arises from the lateral surface of lateral pterygoid plate
• It is inserted into the front of neck of mandible and articular disc through temporomandibular joint
• Nerve supply: mandibular division of trigeminal nerve
• Action: protracts the mandible and depresses the chin

Medial Pterygoid Muscle

• The medial pterygoid muscle has two heads, superficial small head arises from maxillary tuberosity, and deep head which forms nearly the whole muscle arises deep to the lateral pterygoid from medial surface of lateral pterygoid plate
• The two heads unite to form one tendon which passes downward, backward, and laterally to be inserted into the medial surface of the angle and ramus of mandible
• Nerve supply: mandibular division of trigeminal nerve
• Action: rises and protracts the mandible

Temporal and Infratemporal Fossa

• Temporal fossa: situated in the side of the head and bounded by superior temporal line, frontal process of zygomatic bone, and zygomatic arch
• Contents of temporal fossa:
• Temporalis muscle and covering fascia
• Deep temporal nerves and vessels
• Auriculotemporal nerve
• Superficial temporal artery

Infratemporal Fossa

• Infratemporal fossa: irregular space presents below and deep to zygomatic arch, medial to the ramus of mandible
• Boundaries:
• Superiorly: infratemporal surface of greater wing of sphenoid
• Inferiorly: alveolar margin of maxilla
• Medially: lateral pterygoid plate
• Laterally: ramus of mandible
• Anteriorly: posterior surface of maxilla
• Posteriorly: styloid process
• Contents of infratemporal fossa:
• Muscles of mastication (medial pterygoid and lateral pterygoid muscle)
• Branches of mandibular division of trigeminal nerve
• Chorda tympani nerve
• Otic ganglia
• Maxillary artery and its branches
• Pterygoid venous plexus