University of Al-Ameed / College of Medicine
Department of Anatomy
M.B.Ch.B. M.Sc. Ph.D. Anatomy
1. Describe the anatomy of pharynx:
i. Nasopharynx
ii. Oropharynx
iii. Laryngopharynx
2. Demonstrate the anatomical structure of the Larynx:
i. Parts of larynx
ii. Cartilages of larynx
iii. Neurovascular supply
3. Elucidate the anatomical construction of Thyroid Gland.
PHARYNX
• It is a musculofascial half-cylinder that
links the oral and nasal cavities in the head
to the larynx and esophagus in the neck.
The pharyngeal cavity is a common
pathway for air and 'food'.
• Parts of Pharynx:
1. Nasopharynx
2. Oropharynx
3. Laryngopharynx
NASOPHARYNX
• It is situated above the soft palate behind the
nasal cavity.
• Boundaries:
 Superior – skull base
 Inferior – level of soft palate
 Anterior – choanae (posterior nasal
apertures)
 Posterior – nasopharyngeal tonsil
• Lined with respiratory ciliated stratified
squamous epithelium.
Contents
1. Nasopharyngeal tonsil (adenoids)
2. Part of Waldeyer’s ring
3. Eustachian tube orifice
OROPHARYNX
• Behind mouth and tongue
• Boundaries:
 Superior – level of soft palate
 Inferior – superior edge of epiglottis
 Anterior – oral cavity
 Posterior – C2 – C3
• Lined with stratified squamous epithelium
Contents
• Palatine tonsils
• Anterior and posterior tonsillar
pillars
3 Sets of tonsils:
1. Pharyngeal Tonsils
2. Palatine Tonsils
3. Lingual Tonsils
Palatine Tonsils
Lie in tonsillar fossa (between ant. and post.
pillars).
Anterior pillar (palatoglossal arch)
The boundary between buccal cavity and
oropharynx.
Fuses with lateral wall of tongue.
Contains palatoglossal muscle.
Posterior pillar (palatopharyngeal arch)
blends with wall of pharynx.
Contains palatopharyngeus muscle.
Blood Supply
- Tonsillar branch of facial artery (also lingual/ascending palatine/ascending
pharyngeal)
- Venous drainage pharyngeal plexus (also paratonsillar vein)
Lymph Drainage
Lymphatics pierce superior constrictor muscle pass to nodes along internal
jugular vein and Jugulo-digastric node (angle of mandible).
Laryngopharynx (Hypopharynx)
• Below epiglottis
• Boundaries:
 Superior – superior edge of epiglottis
 Inferior – level of inferior edge of
cricoid cartilage
 Anterior – larynx
 Posterior – C3 – C6 vertebrae
• Inferiorly opens into oesophagus
• Lined with stratified squamous
epithelium
Pharyngeal Musculature
They arranged into two groups;
Constrictors and Longitudinal.
1. Superior Constrictor
2. Middle Constrictor
3. Inferior Constrictor
• Overlap each other
• Open anteriorly
• Attached posteriorly by median
raphe
• Gaps provide important routes for muscles and
neurovascular tissues.
• Above the margin of superior constrictor, the
pharyngeal wall is deficient in muscle and
completed by pharyngeal fascia.
• The tensor and levator palatini muscles of the
soft palate descend from the base of the skull
and reinforce the pharyngeal fascia.
• Between the superior and middle constrictor muscles:
stylopharyngeus, muscles, nerves, and vessels between
regions lateral to the pharyngeal wall and the oral
cavity, particularly the tongue.
• The gap between the middle and inferior constrictor
muscles allows the internal laryngeal vessels and nerve
access to the aperture in the thyrohyoid membrane to
enter the larynx.
• The recurrent laryngeal nerves and accompanying
inferior laryngeal vessels enter the larynx deep to the
inferior margin of the inferior constrictor muscle.
Pharyngeal Musculature
The longitudinal muscles:
1. Stylopharyngeus
2. Salpingopharyngeus
3. Palatopharyngeus
Pharyngeal Musculature
Muscle
Origin
Insertion
Innervation
Function
Stylopharyngeus
Medial side of base of
styloid process
Pharyngeal wall
Glossopharyngeal
nerve
Elevation of the pharynx
Salpingopharyngeus
Inferior aspect of
pharyngeal end of
pharyngotympanic tube
Pharyngeal wall
Vagus nerve
Elevation of the pharynx
Palatopharyngeus
Upper surface of palatine
aponeurosis
Vagus nerve
Elevation of the pharynx;
closure of the
oropharyngeal isthmus
Pharyngeal wall
Pharyngeal Blood Supply
Arterial
– Superior Thyroid Artery
– Ascending Pharyngeal Artery
– Ascending And Descending Palatine Artery
– Branches of lingual, facial and maxillary arteries
– (External Carotid Artery)
Venous
– Pharyngeal Venous Plexus
– (Internal Jugular Vein)
Pharyngeal Nerve Supply
Motor
• Vagus (X)
• Glossopharyngeal (IX)
• All muscles of the pharynx are innervated by the vagus nerve [X], except for
the stylopharyngeus, which is innervated by a branch of the glossopharyngeal
nerve [IX].
Sensory
• Nasopharynx – Maxillary division of Trigeminal (V2)
• Oropharynx - Glossopharyngeal (IX)
• Laryngopharynx – Vagus (X)
• The larynx is a hollow musculoligamentous structure with a cartilaginous
framework that caps the lower respiratory
tract.
• The cavity of the larynx is continuous
below with the trachea, and above opens
into the pharynx.
Functions
Respiration (open valve)
Phonation (partially closes valve)
Protecting trachea/bronchial tree (swallowing)
Cough reflex
Parts of Larynx
1. Supraglottis
Inferior surface of epiglottis
Vestibular folds (false cords)
2. Glottis
Vocal cords (including 1cm inferiorly)
3. Subglottis
Down to lower border of cricoid cartilage
Larynx
 Main Structures
1) Epiglottis
2) Thyroid cartilage
3) Cricoid cartilage
4) Arytenoid cartilage (paired)
5) Cuneiform cartilage (paired)
6) Corniculate cartilage (paired)
– Vocal Cords
Epiglottis
• Leaf shaped plate of elastic fibrocartilage
• Attached posterior to thyroid cartilage by
thyroepiglottic ligament
• Vallecula – depression between tongue
base and epiglottis
Thyroid Cartilage
• Largest cartilage comprising two
lamina
• Laryngeal prominence (‘Adam’s
Apple’)
• Superior & inferior thyroid horns
(hyoid and cricoid respectively)
Cricoid Cartilage
• Most inferior cartilage, completely encircles
the airway
• Signet ring shape
• 2 articular facets on each side
– Superolateral surface for arytenoid
cartilage
– Lateral surface for the medial surface of
inferior horn of thyroid cartilage
Arytenoid Cartilage
• Pyramid shaped
• Concave base articulating with cricoid
• Involved in vocal cord movement
Vocal Cords
Laryngeal Blood Supply
Arterial
• Superior Laryngeal Artery (Superior Thyroid Artery)
• Inferior Laryngeal Artery (Inferior Thyroid Artery)
Venous
• Superior Laryngeal Vein
• Inferior Laryngeal Vein
Laryngeal Nerve Supply
 Superior laryngeal nerve
– Deep to carotid arteries
– Internal – pierces thyrohyoid membrane
– External – deep to superior thyroid artery, supplying cricothyroid muscle
 Recurrent laryngeal nerve
– Ascends in the tracheo-oesophageal groove
– Right – under subclavian artery
– Left – under aortic arch
– All muscles of the larynx are supplied by recurrent laryngeal nerve, except
the cricothyroid which is supplied by external laryngeal nerve.
Recurrent Laryngeal
Nerve
• It is endocrine gland located anteriorly in
the neck, begin as pharyngeal outgrowth
that migrate caudally to its final position as
development continue.
• It is large unpaired gland consists of two
lateral lobes and connecting isthmus in
front of 2nd. and 3rd. tracheal cartilage.
• Lying
deep
to
the
sternohyoid,
sternothyroid, and omohyoid muscles, the
thyroid gland is in the visceral
compartment of the neck.
• The lower pole of the thyroid
gland extends along the side of
the trachea as low as the sixth
tracheal ring
1
2
3
4
5
6
• The thyroid gland is very vascular
• The vessels lie between the capsule
and the pre-tracheal fascia.
• In some pathological conditions such
as thyrotoxicosis, owing to its high
vascularity, the blood flow can be
heard with a stethoscope as a bruit
• Two major arteries:
A. Superior thyroid A.: first branch of
external carotid A.
B. Inferior thyroid A.: branch of
thyrocervical trunk which arise from
the first part of subclavian A.
C. Occasionally a third small artery arise
from brachiocephalic trunk called
Thyroidea ima artery on the anterior
surface of trachea.
• Three veins drain the thyroid gland:
A. the superior thyroid vein primarily
drains the area supplied by the superior
thyroid artery.
B. the middle and inferior thyroid veins
drain the rest of the thyroid gland.
• The superior and middle thyroid veins
drain into the internal jugular vein and the
inferior thyroid veins empty into the right
and
left
brachiocephalic
veins,
respectively.
• The thyroid gland is closely related to
the recurrent laryngeal nerves.
• They pass deep to the posteromedial
surface of the lateral lobes of the thyroid
gland and enter the larynx by passing
deep to the lower margin of the inferior
constrictor of the pharynx.