In this post we have discussed all the head-neck anatomy important topics. This topics are very very important for your viva and theory exam.
Meaning/ Definition :
In this section we study about the Head and Neck part of the human body.
What are the important topics :
1. Bones of the Skull :
Cranial Skeleton :
|Paired Bones||Unpaired Bones|
|1. Parietal||1. Frontal|
|2. Temporal||2. Occipital|
Facial Skeleton :
|Paired Bones||Unpaired Bones|
|1. Maxilla||1. Mandible|
|2. Zygomatic||2. Vomer|
|6. Inferior nasal concha||—-|
2. Layers of the Scalp :
Mnemonics – SCALP
- S – Skin
- C – Connective Tissue/Superficial fascia
- A – Aponeurosis
- L – Loose areolar tissue
- P – Pearicardium
3. Bell’s Palsy :
–> Lower Motor Neuron type paralysis
Cause : Compression of the facial nerve in the facial canal near the stylomastoid foramen causes lower motor neuron type facial muscle paralysis. Although the exact cause is unknown, it is most likely due to viral infection.
- Facial Asymmetry
- Foods gets stored in the vestibule of the mouth.
- Dribbling of saliva
4. Branches of the Trigeminal nerve :
Mainly divided into 3 divisions : Ophthalmic, Maxillary, Mandibular
- External nasal
5. Facial vein :
It is the face’s largest vein. It is created by the union of supratrochlear and supraorbital veins at the medial angle of the eye. It runs straight down and backwards behind the facial artery after forming to meet the masseter’s anteroinferior angle. The typical facial vein pierces the deep fascia, crosses the submandibular gland superficially, and joins the anterior division of the retromandibular vein below the angle of the mandible to form the internal jugular vein.
Deep Connections :
- At the point of commencement : It connects with the superior ophthalmic vein
- In the cheek : The facial vein gets connected with the pterygoid venous plexus through the deep facial vein.
6. Dangerous Area of the Face :
The lumens of the facial vein and its communications are empty of valves. Since the facial vein is directly attached to the muscles of facial expression, the movements of these muscles may facilitate the spread of septic emboli from an infected area of the lower part of the nose, upper lip, and adjoining part of the cheek in a retrograde direction through the deep facial vein, pterygoid venous plexus, and emissary vein into the cavernous sinus, resulting in meningitis and cavernous sinus thrombosis. As a result, this part of the face is known as the dangerous area of the face.
7. Ptosis :
The upper eyelid droops due to paralysis of the levator palpebrae superioris muscle caused by a lesion of the occulomotor nerve, which supplies this muscle.
8. Lacrimal Apparatus :
The lacrimal apparatus consists of mainly 7 structures :
- Lacrimal Gland
- Ducts of lacrimal gland
- Nasolacrimal duct
- Lacrimal sac
- Conjunctival sac
- Lacrimal puncta
- Lacrimal canaliculi
- Prevention of infections by secreting lysozyme over the eyeball
- Supplying Nutritions to the eye
- Provides moisture by flushing the conjunctiva
- Shredding of tears during express of any emotions
- Shredding tears during automatic removal of foreign body from the eye
9. Deep Cervical Fascia(Fascia Colli):
This is a deep fascia of the neck
It contains three layers :
- Investing layer of deep cervical fascia
- Pretracheal fascia
- Prevertebral fascia
10. Sternocleidomastoid Muscle :
This is the main muscle of the neck, which divides the neck into posterior and anterior triangles by extending obliquely across the side.
By two ends – Sternal and Clavicular
- A thin tendon that runs from the tip of the mastoid process to its base on the lateral surface of the process.
- A thin aponeurosis is inserted into the lateral half of the occipital bone’s superior nuchal axis.
Others – Arterial Supply, Nerve supply
11. Ansa Cervicalis :
The ansa cervicalis is a U-shaped nerve loop embedded in the anterior wall of the carotid sheath in the area of the carotid trianlgle.
The ventral rami of the C1, C2, and C3 spinal nerves are used to make it. It also supplies all of the infrahyoid muscles, with the exception of the thyrohyoid, which is supplied by the hypoglossal nerve’s nerve to the thyrohyoid(C1).
12. Parotid Gland :
In between the three pairs of salivary glands, the Parotid gland is the largest one.
Lobules are present, with yellowish-brown color and weighs about 25g.
Structures present within the Parotid Gland :
- Facial Nerve
- Retromandibular vein
- External carotid artery
Parotid Duct :
- It is about 5cm long, which originates from the middle of the anterior border of the gland and opens into the vestibule of the mouth.
Nerve Supply :
- Parasympathetic supply – Inferior salivatory Nucleus —> Glossopharyngeal nerve —> Jacobson’s Nucleus(Tympanic branch of IX) —> Lesser petrosal nerve —> Otic Ganglion —> Auriculotemporal Nerve(Post ganglionic) –> Parotid Gland
- Sympathetic : Vasomotor, Derived from PLEXUS around “External carotid artery”
- Sensory : Auriculotemporal nerve, Great auricular nerve (C2 & C3)
13. Mandibular Nerve :
This is the largest nerve among all the divisions of the Trigeminal nerve
—> Nerve of 1st pharyngeal arch so supplies all the structures derived from the 1st pharyngeal arch.
14. Otic Ganglion :
It’s a small parasympathetic ganglion that’s attached to the trigeminal nerve’s mandibular division and serves as a relay station for the parotid gland’s secretomotor fibres. It is 2-3mm in size and is located in Infratemporal fossa, just below the foramen oval.
- Postganglionic parasympathetic
- Postganglionic sympathetic
15. Temporomandibular Joint :
This is the joint between the temporal bone and the mandible that enables the mandible to pass for speech and mastication. It is present on both sides of the head.
Joint Cavity :
This is cavity which is divided into mainly two parts by and intra-articular disc of fibrocartilage.
- Upper menisco-temporal
- Lower menisci-mandibular
- Fibrous capsule
- Lateral (Temporomandibular) Ligement
- Sphenomandibular Ligament
- Stylomandibular Ligament
Laterally : Skin, fascia, Parotid Gland, Temporal branches of the 7th cranial nerve
Medially : Tympanic plate separates TMJ from internal carotid artery, spine of sphenoid with upper end of sphenomandibular ligament, Auriculotemporal and chords tympani nerve, and Middle meningeal artery
Anterior : Masseteric nerve and vessels, Tendon of lateral pterygoid
Posterior : Superficial temporal vessels, Auriculotemporal nerve, Postglenoid part of parotid gland separating it from external auditory meatus.
Nerve Supply :
Auriculotemporal nerve and Masseteric nerve
Blood Supply :
Maxillary artery and Superficial temporal artery
Lymphatic Drainage :
Superficial and Deep parotid nodes, Upper deep cervical nodes.
When the mouth is closed (i.e., when the teeth are in occlusion), the joint is much more secure than when it is open. When the mandible is in occlusion, the teeth themselves support the mandible on the maxilla, and no pressure is placed on the joints when the mandible is struck upward.
Movements of the Mandible :
- Side to side
16. Pterygopalatine Fossa :
This is a pyramidal space located deep below the orbit’s apex, between the sphenoid’s Pterygoid process and the palatine’s perpendicular plate in front.
17. Thyroid Gland :
This is the largest Endocrine gland of the body, this gland secretes mainly 3 hormones:
- Triiodo thyroxine(T3)
Relations, Arterial supply, Nerve supply
18. Horner’s Syndrome :
- The sympathetic fibres that originate in the upper thoracic spinal segments supply the head and neck area.
- These preganglionic fibres travel through the stellate ganglion to the superior cervical sympathetic ganglion, where they are relayed.
- The postganglionic fibres emerge from the cells of this ganglion and supply the head and neck structures.
- Partial ptosis
- Loss of ciliospinal reflex
19. Muscles of the Tongue :
|Intrinsic Muscles||Extrinsic Muscles|
|1. Superior longitudinal||1. Genioglossus|
|2. Inferior longitudinal||2. Hyoglossus|
|3. Transverse||3. Styloglossus|
|4. Vertical||4. Palatoglossus|
Lymphatic Drainage :
- Apical vessels
- Marginal vessels
- Central vessels
- Basal vessels
Nerve Supply :
|Sensory Supply||Motor Supply|
|Anterior 2/3rd of the Tongue : lingual nerve and chords tympani nerve||Hypoglossal nerve|
|Posterior 1/3rd of the Tongue : Glossopharyngeal nerve, Internal laryngeal branch of superior laryngeal.|
20. Safety muscle of the tongue :
Genioglossus : Two Genioglossi form the main portion of the muscular tongue and are responsible for the protrusion of the tongue.
21. Nasopharynx :
This lies behind the nasal cavities and above the soft palate.
|Roof||Floor||Anterior Wall||Posterior Wall||Lateral Wall|
|1. Body of sphenoid|
2. Basilar part of the occipital bone
|1. Soft palate|
2. Pharyngeal isthmus
|1. Posterior nasal apertures||1. Anterior arch of C1 vertebra||1. Medial Pterygoid plate of the Sphenoid bone|
22. Piriform Fossa :
On either side of the laryngeal inlet, it is a deep recess long above and narrow below in the anterior part of the lateral wall of the laryngopharynx. The bulging of the larynx into the laryngopharynx causes these recesses.
|1. Aryepiglottic fold|
2. Quadrangular membrane of larynx
|1. The mucous membrane that protects the|
medial surface of the thyroid cartilage lamina as well as the thyrohyoid membrane.
|1. Epiglottic vallecula by lateral glossoepiglottic fold|
23. Deglutition(Swallowing) :
This is the method of transferring food from the mouth to the stomach.
Three Phases :
- First stage(mouth) which is Voluntary
- Second stage(in the pharynx) which is involuntary
- Third stage(in the oesophagus) which is involuntary
24. Pharyngeal Spaces :
In relation to the pharynx, these are possible spaces :
- Retropharyngeal space
- Parapharyngeal space
25. Palatine Tonsils :
These are almond shaped mass of lymphoid tissue located in the tonsillar fossa, and are 2 in numbers.
Two pillars : Anterior pillar by Palatoglossal arch and Posterior pillar by Palatopharyngeal arch.
26. Pharyngotympanic Tube :
The osseocartilaginous channel that links the nasopharynx and the tympanic cavity is mucous-lined. It keeps air pressure balanced on both sides of the tympanic membrane so that it can vibrate properly.
- Length : It is about 36 mm long in adults and
- : Extends from the tympanic end downwards, forwards, and medially.
27. Muscles of the Soft Palate :
- Tensor palati or tensor veli palatini
- Levator palate or levator deli palatini
- Musculus Uvulae
Paralysis of Soft palate :
The paralysis of the soft palate muscles (due to a vagus nerve lesion) results in:
- Liquid regurgitation through the nose,
- Nasal twang in speech,
- Flattening of the palatal arch on the side of the lesion,
- Uvula divergence on the opposite side of the lesion.
28. Muscles of the Larynx :
—> Makes the Larynx movable as a whole
- Opening and closing the laryngeal inlet
- Adduction and abduction of the Vocal cords
- Increasing and Decreasing the tension of the vocal cords.
|Laryngeal Inlet – Opening & closing||Vocal Cords – Abduction & Adduction||Vocal Cords – Increase & Decrease Tension|
|1. Oblique Arytenoids||1. Posterior Cricoarytenoids||1. Thyroarytenoid|
|2. Aryepiglotticus||2. Transverse cricoarytenoids||2. Vocalis|
|3. Thyroepiglotticus||3. Lateral cricoarytenoids||3. Cricothyroid|
29. Laryngeal Inlet :
This cavity runs from the laryngeal inlet, where it connects to the laryngopharyngeal lumen, to the lower boundary of the cricoid cartilage, where it connects to the tracheal lumen.
|Epiglottis||Interarytenoid fold of the mucous membrane||Aryepiglottic fold of the mucous membrane|
30. RIma Glottidis and Phonation :
This is a narrow anteroposterior cleft of the laryngeal inlet. Adult males have a 24mm anteroposterior glottis diameter, while adult females have a 16mm anteroposterior glottis diameter.
|Angle of thyroid cartilage||Interarytenoid folds of the mucous membrane||Vocal fold – anterior 3/5th|
Vocal process of arytenoid cartilage – posterior 2/5th
Sub-Divisions – Intercartilaginous part & Intermembranous part
31. Nose :
- Taking smell
- Hairs prevents insertion of any foreign body
- air conditioning of the inspired air
- Vocal resonance
- Nasal reflex action like sneezing
Others important topics :
- Lateral wall of the nose
- The nasal septum
- Arterial supply of Nasal septum
- Nerve supply of Nasal Septum
- Little’s area
32. Paranasal Air Sinuses :
These are air-containing cavities in the bones surround the nasal cavity and they are lined by Pseudostratified ciliated columnar epithelium.
Four Paranasal Air Sinuses :
- Frontal air sinuses
- Ethmoidal air sinuses
- Maxillary air sinuses
- Sphenoid air sinuses
33. Ear :
This is an organ helps in hearing and also plays an important role in maintaining body balance.
There are 3 parts of the ear :
- External ear
- Middle ear
- Inner ear
External Auditory Meatus/ Auditory Canal :
It measures about 24mm along its posterior wall and stretches from the bottom of the concha to the tympanic membrane.
Two parts : Cartilaginous part & Bony part
Tympanic Membrane :
Oval in shape, 9-10mm in length, and 8-9mm in width.
Placed obliquely with the floor of the external acoustic meatus, forming a 55° angle.
Others Important Topics : Nerve supply, Mastoid Antrum
34. Orbit and Eyeball :
Extraocular Muscles :
|Recti Muscles||Oblique Muscles||Other|
|1. Superior Rectus||1. Superior Oblique||1. Levator palpeerde superioris|
|2. Inferior Rectus||2. Inferior Oblique|
|3. Medial Rectus|
|4. Lateral Rectus|
Involuntary Muscles :
- Superior tarsal/Muller’s muscle
- Inferior Tarsal
Owing to nerve involvement, unilateral paralysis of an individual muscle causes strabismus or squint (eye deviation to the opposite side) and can result in diplopia (double vision).
The light from an object does not focuss on the same areas of both retinae in diplopia. The true image falls on the macula of the unaffected eye, while the false image falls on the paralysed eye’s peripheral retina.