Overview of the head and neck region

Abstract

This chapter gives an overview of the important structures, muscles, fasciae, and vessels (arteries, veins, lymph, nerves) of the head and neck region. The brain, one of the most important organs, is protected by the skull, both of which are covered in other learning cards. There are also individual learning cards for the organs of perception as well as for the thyroid gland, the salivary glands, teeth and oral cavity. The head and neck region is the beginning of the respiratory and digestive tract, both of which also have their own learning cards.

Organs

Organs of the head

Organs of the neck

Regions

Regions of the head

The head is divided into 14 regions:

  1. Frontal region
  2. Parietal region
  3. Occipital region
  4. Temporal region
  5. Auricular region
  6. Mastoid region
  7. Facial region
    1. Orbital region
    2. Infraorbital region
    3. Nasal region
    4. Zygomatic region
    5. Buccal region
    6. Parotid region
    7. Oral region
    8. Mental region

Regions of the neck

Anterior cervical triangle

Posterior cervical triangle

References:[1]

Musculature

Head muscles

Muscles of facial expression

  • Move the skin of the face, the alar wings of the nose, the eyelids, and lips
  • Enable us to express emotions
  • Not connected to bones but only to the skin
  • Do not have fasciae
  • All innervated by the facial nerve

Muscles of the cranium

Muscle Function
Occipitofrontalis muscle
  • Movement of the forehead and the brow
Temporoparietal muscle
  • Pulls the ears cranial and dorsal

Muscles of the ear

Muscle Function
Anterior auricular muscle
Superior auricular muscle
Posterior auricular muscle

Muscles of the eye

Muscle Function
Orbicularis oculi
Corrugator supercilii
  • Draw eyebrows together creating vertical fold (frown line)

Muscles of the nose

Muscle Function
Nasalis
  • Has two parts with opposing functions: tightening and widening of the nostrils
  • Draws the tip of the nose caudal
Depressor septi nasi
  • Pulls the nose inferiorly; opening the nostrils
Procerus
  • Pulls the skin between the eyebrows caudal

Muscles of the mouth

Muscle Function
Orbicularis oris
  • Closes the mouth
  • Purses the lips
Buccinator
  • Pulls cheeks inwards against the teeth while chewing

Upper group

Levator labii superioris, levator labii superioris alaeque nasi muscle, risorius, levator anguli oris, zygomaticus major, zygomaticus minor
  • Lift upper lip and draw the corners of the mouth upwards (smiling)

Lower group

Depressor anguli oris, depressor labii inferioris, mentalis
  • Draw down the lower lip and the corners of the mouth
  • Mentalis: raises lower lip and chin of the skin (pouting muscle)

For mastication muscles and muscles of the tongue, see oral cavity and mouth.

The facial nerve (VII) innervates all muscles of facial expression.

Hyoid bone and hyoid muscles

Muscle Function Innervation

Suprahyoid muscles

(Digastric, stylohyoid, mylohyoid, geniohyoid)

  • Form the bottom of the mouth
  • Elevate the hyoid bone during swallowing
  • Support the opening of the jaw
  • Inferior alveolar nerve (mylohyoid and anterior belly of digastric)
  • Facial nerve (stylohyoid and posterior belly of digastric)
  • Hypoglossal nerve (geniohyoid)

Infrahyoid muscles

(Sternohyoid, infrahyoid, sternothyroid, thyrohyoid, omohyoid)

Neck muscles

The musculature of the neck can be differentiated into superficial and deep muscles.

Superficial muscles of the neck

Muscle Characteristics Function Innervation
Sternocleidomastoid
  • Unilateral contraction
    • Flexes the head laterally on the ipsilateral side
    • Rotates the head to the contralateral side
  • Bilateral contraction: flexes neck dorsally
  • Accessory respiratory muscle
Platysma
  • Broad superficial muscle that runs subcutaneously from the upper chest area to the lower jawbone (mandible)
  • Reinforces the skin of the neck
  • Pulls lips to the sides and down
  • Opens jaw

An abnormal tone or length of the sternocleidomastoid muscle has a variety of mechanisms (e.g., trauma, muscle tone disorders, congenital muscle tightness, extrinsic masses, ocular, etc.) and is referred to as torticollis (wry neck).

Deep muscles of the neck

Group Function Innervation
Scalene muscles Anterior scalene, middle scalene, posterior scalene
  • Arise from the cervical vertebrae and attach to the first or second rib
  • Accessory respiratory muscles: lift the upper rips
Prevertebral muscles Longus colli muscle, longus capitis muscle, rectus capitis anterior, rectus capitis lateralis
  • Antagonist muscles at the back of the neck
  • Flex head, rotate head, restore head to original position after it has been drawn backward
Suboccipital muscles Rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis inferior, obliquus capitis superior
  • Draw the head backward (rectus muscles)
  • Help rotate the head
  • Suboccipital nerve (C1)

An abnormal position or insertion of the anterior or middle scalene muscle may result in compression of the brachial plexus and the subclavian vessels, causing thoracic outlet syndrome.

References:[1]

Fascias

Fascias of the head

  • Temporal fascia: covers temporal muscle
  • Parotid fascia: covers the parotid gland
  • Chewing fascia (masseteric fascia): covers muscles of mastication
  • Schechnoglotochnaya fascia (buccopharyngeal fascia): covers the cheek muscles

Muscles of facial expression do not have a fascia as they are placed directly under the skin.

Fascias of the neck

Because the structures in the neck region are very close to each other, there are many fasciae that ensheath and separate (compartmentalize) the different structures.

Superficial cervical fascia

Deep cervical fascia

The prevertebral layer of the deep cervical fascia extends from the skull via the mediastinum to the diaphragm. Therefore, infections in this layer can cause great harm.

Vasculature and innervation

Arteries

Subclavian artery

  • Origin
    • Left side: direct branch of the aorta
    • Right side: a branch from the brachiocephalic artery
  • Branches
    • Internal thoracic artery
    • Vertebral artery
    • Thyrocervical trunk
    • Costocervical trunk

In stenosis of the coronary arteries, the internal thoracic artery can be used as a natural coronary artery bypass graft.

A stenosis of the subclavian artery proximal to the origin of the vertebral artery may result in subclavian steal syndrome.

Common carotid arteries

An increased carotid sinus sensitivity can result in syncopes due to low systolic blood pressure when pressure is applied to the carotid sinus. It is frequently associated with arteriosclerotic changes in the carotid sinus.

Internal carotid artery

External carotid artery

  • Origin: arises from the common carotid at the level of the upper border of the thyroid cartilage
  • Branches
    • Superior thyroid artery
    • Lingual artery
    • Facial artery
    • Ascending pharyngeal artery
    • Occipital artery
    • Posterior auricular artery
    • Maxillary arteries
    • Superficial temporal artery

The temporal artery is involved in giant cell arteritis.

A branch of the maxillary artery is the middle meningeal artery. It enters the skull through the foramen spinosum and mostly supplies the meninges and the skull. A craniocerebral injury can result in rupture or laceration of the middle meningeal artery, leading to the life-threatening condition of an epidural hematoma.

Veins

Superficial veins

External jugular vein

  • Collects blood from the exterior cranium and parts of the face
  • Begins at the parotid gland and extends downwards
  • Runs along the side of the neck
  • Covered by the platysma
  • Pierces through the superficial layer of the fascia of the neck
  • Ends in the venous angle or in the internal jugular vein

Deep veins

Internal jugular vein

Subclavian vein

Lymphatics

  • About one-third of the lymph nodes of the body are located in the head and neck area as the beginning of the respiratory and digestive tract is prone to many pathogens.
  • All lymphatic drainage ends in the left and right jugular lymph trunk.
Characteristics
Superficial cervical lymph nodes
Deep cervical lymph nodes Superior
Inferior

Nerves

Cervical plexus

Nerve Spinal segment Innervation
Ansa cervicalis C1–C3
Phrenic nerve C3–C5
Lesser occipital nerve C2, C3
  • Sensory
    • Scalp
    • Ear
    • Neck
    • Upper thorax
Great auricular nerve C2, C3
Transverse cervical nerve C2, C3
Supraclavicular nerve C3, C4

Posterior branches of cervical nerves

Suboccipital nerve, Greater occipital nerve, Third occipital nerve

C1–C3

Phrenic nerve: C3, C4, C5 – keep the diaphragm alive!

A mediastinal tumor can present with shortness of breath, shoulder pain, and hiccups due to irritation of the phrenic nerve.References:[1]

Embryology

Many structures in the head and neck have their origin in the pharyngeal arches, pharyngeal pouches, and pharyngeal grooves. For a detailed description of these see branchial apparatus.

Clinical significance

Head

Neck

  • 1. Panchbhavi VK. Neck Anatomy. In: Gest TR. Neck Anatomy. New York, NY: WebMD. https://reference.medscape.com/article/1968303-overview. Updated November 30, 2017. Accessed June 7, 2018.
  • Standring S. Gray's Anatomy: The Anatomical Basis of Clinical Practice. Elsevier Health Sciences; 2015.
last updated 11/20/2018
{{uncollapseSections(['FCcgFe0', 'uCcpFe0', '9CcN8e0', 'ECc8Fe0', '-CcDue0', 'ZxcZEe0', 'cxcave0', 'Xxc9Ee0'])}}