Lecture7.pdf

Lecture: 7 Head and neck Dr. Omar Riadh The objectives: 1. To get knowledge about the normal anatomy of the parotid gland. 2. Understanding the normal position of lymph nodes is necessary in practicing surgery. 3. Knowing the anatomical basis is ver...

Lecture: 7 Head and neck Dr. Omar Riadh The objectives: 1. To get knowledge about the normal anatomy of the parotid gland. 2. Understanding the normal position of lymph nodes is necessary in practicing surgery. 3. Knowing the anatomical basis is very important in solving the clinical problems. Lymphatic drainage of head and neck: Divided into two groups:- 1- Circular groups around the base of skull. 2- Cervical groups along the superficial and deep veins of the neck. Circular groups include- 1- Occipital group:- lies along occipital vessels and drains the back of scalp and upper part of the neck. 2- Retroauricular group:- drains the back of the auricle, external acoustic meatus and nearby part of scalp. 3- Superficial parotid group:- it lies on the fascia of parotid gland and drains the anterior part of auricle, external acoustic meatus and temporal region. 4- Deep parotid group:- lies in the sheath of parotid gland, it drains the anterior part of scalp, orbit, parotid gland and part of the face. 5- Retropharyngeal group:- between pharynx and prevertebral muscles, it drains vertebral region and pharynx. 6- Submandibular group:- lies in the submandibular triangle, drain submandibular and lingual salivary glands, tongue, gum, tonsil and cheek. 7- Submental group:- lies in submental triangle and drains the tip of tongue, lower lip and the floor of mouth. 1 Cervical groups:- Formed of superficial group lies along external jugular vein and anterior jugular vein, they drain superficial structures of neck. The deep group lies along the internal jugular vein and drain the deep structure in neck (pharynx, larynx, esophagus, trachea and thyroid gland) it also receives vessels from superficial and circular groups. The lymphatic in the right side of neck differs from the left side, in the left side there is the thoracic duct which receives jugular and subclavian lymph trunk and opens at the junction of internal jugular vein and subclavian vein, while in the right side the jugular and subclavian trunk join together and open in brachiocephalic vein and sometimes open separately in their corresponding vein. Parotid gland:- Is the largest salivary gland lies behind the ramus of mandible and it extends to mastoid process posteriorly. Medially it reaches up to the styloid process of skull; bellow it sometimes reaches the carotid triangle. It is irregular in shape and part of gland passes over the masseter muscle which is called the accessory parotid gland. From the upper part of the gland a duct passes anteriorly and crosses the masseter muscle then pierce the cheek to opens in the vestibule of mouth opposite the upper second molar tooth, the duct in relation with transverse facial artery superiorly and buccal branch of facial nerve inferiorly. The gland is traverses deeply by external carotid artery with its upper end divided into two terminal branches (maxillary artery and superficial temporal artery), while superficially it traverses by retromandibular vein and through the gland the facial nerve and its branches passes to the muscles of the face. Blood supply of the parotid gland:- 1- External carotid artery (superficial temporal and maxillary artery). 2- Transverse facial artery (branch of superficial temporal artery). 3- Deep auricular artery (branch of maxillary artery). 2 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:- It is a small parasympathetic ganglia lies below the foramen ovale. Components:- 1- Preganglionic parasympathetic fibers from glossopharyngeal nerve through lesser petrosal nerve to the ganglia, then postganglionic parasympathetic secretomotor fibers carried from the ganglia by auriculotemporal nerve to the parotid gland, it is the only nerve which synapses in the ganglia. Others pass without synapses. 2- Motor fibers to tensor palate and tensor tympani muscles from nerve to medial pterygoid muscle (branch of mandibular division of trigeminal nerve). 3- Sympathetic fibers from plexus around middle meningeal artery. 4- Sensory fibers from glossopharyngeal nerve and distributed through the branches of the ganglia. Muscles of mastication These are four muscles:- 1- Masseter muscle. 2- Temporalis muscle. 3- Medial pterygoid muscle. 4- Lateral pterygoid muscle. 3 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:-It is a fan shape muscle arises from medial wall of temporal fossa and from the temporal fascia, it inserted into the coronoid process of mandible and anterior border of ramus of mandible. Nerve supply:- deep temporal nerve which is branch of mandibular division of trigeminal nerve. Action:- rises and retracts the mandible. Lateral pterygoid muscle:-Arises by two heads, the smaller upper head arises from the infratemporal surface of greater wing of sphenoid, the lower large head arises from the lateral surface of lateral pterygoid plate. This muscle 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:-It 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 unit forming one tendon which passes downward, backward and laterally to be inserted in the medial surface of the angle and ramus of mandible. Nerve supply:- mandibular division of trigeminal nerve. Action:- rises and protracts the mandible. 4 Temporal and infratemporal fossa Temporal fossa:- it situated in the side of head and bounded by:- 1- From above:- superior temporal line. 2- In front:- frontal process of zygomatic bone. 3- Below:- zygomatic arch. Contents of temporal fossa:- 1- Temporalis muscle and covering fascia. 2- Deep temporal nerves and vessels. 3- Auriculotemporal nerve. 4- Superficial temporal artery. Infratemporal fossa:- irregular space presents below and deep to zygomatic arch medial to the ramus of mandible. It is bounded by:- 1- Superiorly:- infratemporal surface of greater wing of sphenoid. 2- Inferiorly:- alveolar margin of maxilla. 3- Medially:- lateral pterygoid plate. 4- Laterally:- ramus of mandible. 5- Anteriorly:- posterior surface of maxilla. 6- Posteriorly:- styloid process. The fossa communicates with the orbit through infraorbital fissure and with pterygopalatine fossa through pterygomaxillary fissure, in the roof there is foramen ovale and spinosum. Contents of infratemporal fossa:- 1- Muscles of mastication (medial pterygoid and lateral pterygoid muscle). 2- Branches of mandibular division of trigeminal nerve. 5  3- Chorda tympani nerve. 4- Otic ganglia. 5- Maxillary artery and its branches. 6- Pterygoid venous plexus. Summary: 1- Lymphatic drainage of head and neck divided into circular and cervical, the circular include: occipital, retroauricular, superficial parotid, deep parotid, retropharyngeal, submandibular and submental group. The cervical include superficial and deep group. 2- The parotid gland is the largest salivary gland lies behind the ramus of mandible. Blood supply include external carotid artery, transverse facial artery and deep auicular artery. Lymphatic drainage to the deep parotid lymph nodes. Nerve supply: parasympathetic from glossopharyngeal nerve while sympathetic from sympathetic plexus around external carotid artery. 3- Muscles of mastication include masseter, temporalis, medial pterygoid and lateral pterygoid muscle, all innervated by mandibular division of trigeminal nerve. 4- Temporal fossa contain temporalis muscle and the covering fascia, deep temporal nerves and vessels, auriculotemporal nerve and superficial temporal artery. 5- Infratemporal fossa contain muscles of mastication, branches of mandibular division of trigeminal nerve, chorda tympani nerve, otic ganglia, maxillary artery and its branches and pterygoid venous plexus. 6