Head and Neck Anatomy

Jake Pickering MS IV

Suprahyoid Neck

• Skull Base to Hyoid Bone (the different spaces)– Parapharyngeal Space– Pharyngeal Mucosal Space– Masticator Space– Parotid Space– Carotid Space– Retropharyngeal Space– Perivertebral Space– Posterior Cervical Space

Suprahyoid Spaces

Suprahyoid Spaces

Suprahyoid Spaces

Lateral Neck

CT of Suprahyoid Spaces

CT of Suprahyoid Spaces

CT of Suprahyoid Spaces

CT of Suprahyoid Spaces

Parapharyngeal Space

• Internal structures– Fat– Minor salivary glands– Internal maxillary artery– Ascending pharyngeal artery– Pterygoid venous plexus

Parapharyngeal Space

Parapharyngeal space

Parapharyngeal Space

Parapharyngeal Space

• Clinical implications– Direct extension from neoplasm

• From pharyngeal mucosal space (see neoplasm differential for pharyngeal mucosal space)

• From masticator space (see neoplasm differential)• From parotid space (see neoplasm differential)

– Direct extension from abscess• Tonsillar abscess• Acute Parotiditis

– Primary lesion• Lipoma• Venolymphatic malformation

Pharyngeal Mucosal Space

• Internal structures– Minor salivary glands– Torus tubarius: Cartilaginous end of eustachian tube – Muscles

• Superior, middle and inferior constrictor muscles• Salpingopharyngeus muscle• Levator palatini muscle

– Lymphatic ring (Waldeyer ring)• Nasopharynx: Adenoids• Oropharynx: Palantine tonsil• Oropharynx: Lingual tonsil

Pharyngeal Mucosal Space

Pharyngeal mucosal space

Adenoids

Torus tubarius

Pharyngeal muscoal space

Lingual tonsil

Palantine tonsil

Axial T1 MR

Nasopharyngeal mucosal space

Oropharyngeal mucosal space

Hypopharyngeal mucosal space

Pharyngeal Mucosal Space

• Clinical Implications– Differential diagnosis of lesion in Nasopharyngeal space

• Adenoid inflammation• Tornwaldt cyst• Retention cyst• Nasopharyngeal carcinoma• Non-Hodgkin lymphoma• Benign mixed tumor (uncommon)• Post-radiation mucositis (uncommon)• Minor salivary gland malignancy (rare)• Rhabdomyosarcoma (rare)• Extraosseous chordoma (rare)

Pharyngeal Mucosal Space

• Clinical implications– Differential diagnosis of lesion in oropharynx space

• Squamous cell carcinoma• Non-hodgkin lymphoma• Retention cyst• Palantine tonsil abscess• Tonsillar inflammation• Thryoglossal duct cyst (uncommon)• Post-radiation mucositis (uncommon)• Vallecular cyst (uncommon)• Minor salivary gland malignancy (uncommon)• Rhabdomyosarcoma (rare)

Masticator Space

• Internal contents– Muscles of Mastication

• Masseter• Temporalis• Medial pterygoid• Lateral pterygoid

– Mandibular division, trigeminal nerve (V3)• Masticator nerve branch• Mylohyoid nerve branch• Lingual nerve• Inferior alveolar nerve branch

– Ramus and posterior body of mandible– Pterygoid venous plexus

Masticator Space

Masticator Space

Masseter muscle

Temporalis muscle

Lateral pterygoid

muscle

Medial pterygoid

muscle

Axial T1 MR

Masticator Space• Clinical Implications

– Trismus– Differential diagnosis of masticator space lesion

• Abscess• Benign masticator muscle hypertrophy• Metastasis• Sarcoma• Osteosarcoma • Chondrosarcoma (uncommon)• Perineural tumor CNV3 (uncommon)• Schwannoma (uncommon)• Odontogenic keratocyst (uncommon)• Osteoradionecrosis (uncommon)• Pigmented villonodular synovitis (rare)• Synovial chondromatosis (rare)• Dentigerous cyst (rare)

Parotid Space

• Internal structures– Parotid Gland– Facial Nerve (CN7)– External carotid artery– Retromandibular vein– Intraparotid lymph nodes– Parotid Duct– Accessory parotid glands (20% of population)

Parotid space (green)

Parotid Space

Parotid space

Parotid gland

Retromandibular vein

External carotid artery

Axial T1 MR

Parotid Space• Clinical Implications

• Parotid Tumors benign mixed tumor (75%)• Warthin tumor (5%)• Adenoid cystic carcinoma (5%)• Mucoepidermoid carcinoma (5%)• Other (10%)

– Other masses in parotid space• Salivary gland malignancies (uncommon)• Non-Hodgkin lymphoma (uncommon)• Schwannoma (uncommon)• Infantile hemangioma (uncommon)• Lipoma (uncommon)• Oncocytoma (rare)• Venous malformation (rare)• Lymphatic malformation (rare)• 1st Branchial cleft cyst (rare)• Rhabdomyosarcoma (rare)

Carotid Space

• Internal structures– Suprahyoid• Internal carotid artery• Internal jugular vein• Cranial nerves 9-12• Sympathetic plexus

Carotid Space

Carotid Space

Internal carotid artery

Internal jugular vein

Carotid space

External carotid artery (not in carotid space)

Carotid Space• Clinical implications

– Differential diagnosis of carotid space lesion• Reactive lymph nodes• Atherosclerosis of carotid artery• Thrombosis of jugular vein• Squamous cell carcinoma• Dissection of carotid artery• Paraganglioma of carotid body• Schwannoma• Neurofibroma (uncommon)• Hodgkin and Non-Hodgkin lymphoma (uncommon)• Meningioma (rare)• Pseudoaneurysm of carotid artery (rare)• Metastases (rare)• Acute Idiopathic carotidynia (rare)

– CN 9-12 neuropathy• Vagus Nerve injury- vocal cord paralysis

Retropharyngeal Space

• Internal Structures – Suprahyoid• Fat • Lymph nodes (none below hyoid)

– Lateral group (nodes of Rouviere)– Medial group

Retropharyngeal space

Retropharyngeal space

Retropharyngeal Space

• Clinical Implications– Differential diagnosis of focal lesion

• Reactive adenopathy• Suppurative adenopathy• Squamous cell carcinoma• Metastatic node• Non-Hodgkin lymphoma• Tortuous carotid artery• Multinodular goiter (uncommon)• Lipoma (uncommon)• Schwannoma (rare)• Ectopic parathryoid adenoma (rare)

Retropharyngeal Space

• Clinical Implications– Differential diagnosis of diffuse space lesion• Abscess• Effusion• Longus colli tendonitis (uncommon)• Venous malformation (uncommon)• Lymphatic malformation (uncommon)• Multinodular goiter (uncommon)• Lipoma (rare)

Perivertebral Space

• Internal structures– Prevertrebral muscles-longus colli and capitis– Scalene muscles– Phrenic nerve– Vertebral artery and vein– Vertebral body– Paraspinal muscles– Brachial plexus

Perivertebral Space

Prevertebral portion of the perivertebral space

Perivertebral space

Paraspinal portion of the perivertebral space

Perivertebral Space

Perivertebral Space

• Clinical implications– Differential diagnosis of perivertebral space lesion

• Vertebral body metastasis• Infection • Schwannoma of brachial plexus• Longus colli tendinitis• Chordoma (uncommon)• Venous malformation (uncommon)• Lipoma (uncommon)• Non-Hodgkin lymphoma (uncommon)• Lymphatic malformation (rare)• Fibromatosis (rare)• Hemangiopericytoma (rare

Posterior Cervical Space

• Internal structures– Fat is primary occupant– Accessory nerve (CNII)– Spinal accessory lymph node chain– Pre-axillary brachial plexus– Dorsal scapular nerve

Posterior Cervical Space

Posterior Cervical Space

Posterior cervical space

Posterior Cervical Space• Clinical implications

– Differential diagnosis of cervical space lesion• Reactive lymph nodes• Squamous cell carcinoma • Non-hodgkin lymphoma• Suppurative lymph node• Thyroid carcinoma• Abscess (uncommon)• Metastases (uncommon)• Sarcoidosis (uncommon)• Tuberculosis (uncommon)• Lipoma (uncommon)• Venous Malformation (uncommon)• Schwannoma (rare)• Liposarcoma (rare)• Sinus histiocystois • 3rd Branchial cleft cyst• Giant lymph node hyperplasia

References• Harnsberger HR, Osborn AG, Ross JS. Diagnostic and Surgical Imaging

Anatomy: Brain, Head and Neck, Spine. 1st edition. Salt Lake City: Amirsys, 2006.

• Harnsberger HR, Koch BL, Phillips CD. EXPERTddx: Head and Neck. 1st edition. Salt Lake City: Amirsys, 2009.

• Neck CT. Retrieved Sept 11 2012. http://headneckbrainspine.com