Submandibular region

Code: NS26

Lecturer: Dr. S. Kandiah

Date: 11th October 2013

Learning Objectives

The submandibular gland and duct

Facial artery

Hypoglossal nerve

Lymphatics of the head and neck

Mandible External Aspect

1

2

3

4

5

6

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Mandible External Aspect

Mandible Internal Aspect

1

2

Submandibular

fossa-

submandibular

gland;

Sublingual fossa-

sublingual gland

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2005 Elsevier

Medial Pterygoid

Superior and Inferior

Mental Spines

Mandible Internal Aspect

Hyoid bone supports the larynx

1) Stylohyoid

ligament

attaches to

lesser horn of

hyoid bone

2) Keeps airway

open

Suprahyoid Muscles

Digastric

Stylohyoid

Mylohyoid

Geniohyoid

Mylohyoid Muscle

Paired muscle, originates from the mylohyoid line on the internal aspect of the mandible

Anterior fibres insert into the midline raphe, posterior fibres insert onto the hyoid bone

Nerve supply = nerve to mylohyoid, branch of V3 (1st branchial derivative)

Action = to elevate the floor of the mouth in the first stage of swallowing. May also depress the mandible or raise the hyoid bone

Digastric Muscle Digastric = two bellies

connected by an intermediate tendon fastened to the hyoid bone by a band of fascia

Anterior belly = derivative of the first branchial arch (Trigeminal nerve)

Posterior belly = derivative of the second branchial arch (Facial nerve)

Digastric Muscle II

Posterior belly of digastric arises from a groove medial to the mastoid process; the stylohyoid muscle arises from the styloid process and runs alongside it (also CNVII nerve supply)

Posterior digastric is an important landmark as deep to it runs the internal jugular vein, the cranial nerves VII, X, XI and XII and the carotid arteries

Digastric Muscle III

The anterior belly of digastric arises from the intermediate tendon and inserts into the digastric fossa on the mandible

Actions = to depress the mandible and elevate the hyoid bone; paired digastrics are second to lateral pterygoid in mandibular depression. Posterior bellies active during chewing and swallowing

Mental Spines

Geniohyoid Muscle

Arises from the inferior mental spines on the internal aspect of the mandible

Inserts onto the anterior hyoid bone

Nerve supply = first cervical spinal nerve via hypoglossal

Actions = elevates the hyoid bone and draws it forward; when the hyoid is fixed it depresses the mandible

Support the tongue

Hyoglossus Muscle

One of the extrinsic muscles of the tongue others are styloglossus, genioglossus, palatoglossus

Hyoglossus attaches to the length of the greater cornu of the hyoid bone and front of the body of the hyoid bone

Action = to depress the tongue

Nerve supply to all extrinsic muscles of the tongue except for palatoglossus is Hypoglossal Nerve (CNXII)

Palatoglossus is innervated by the pharyngeal plexus(X nerve)

Muscles of floor of mouth

Anterior belly of digastric

Mylohyoid from mylohyoid line of mandible to hyoid bone

Branches of External Carotid

External Carotid Superior thyroid

Lingual

Facial

Occipital

Ascending Pharyngeal

Posterior auricular

Maxillary

Superficial temporal

Relations of hyoglossus

Lateral/superficial

Medial/deep

Lateral/Superficial

Lingual nerve

Submandibular gland and duct

XII

Medial/Deep

IX

Stylohyoid ligament

Lingual artery

Salivary Glands

Sublingual

Submandibular

Parotid

Why are stones more common in the first 2?

Why saliva?

Moisture

Food Lubrication

Prevents decay

Submandibular and Sublingual

Glands

Submandibular gland

Superficial and deep parts

Arranged like a C above, to the side of mylohyoid, and below

Superficial part inferior palpable

Deep part superior non palpable

Lymph to submandibular nodes

Submandibular Gland/Duct

Mucus/serous mixed secretions

Antigravity drainage

Swollen submandibular duct may damage lingual nerve

Lingual nerve passes lateral to submandibular duct, then below it, then

medial before it ascends into tongue

Lingual Nerve

Also damaged by careless dental procedures relating to lower teeth and

gums due to close relationship with inferior

alveolar nerve

Fractures of the mandible

Abcesses of 3rd lower molar tooth

Submandibular Duct

Whartons Duct

5cm long

Opens into the floor of the mouth on the sublingual papilla beside the frenulum of

the tongue, behind the incisor teeth

Sublingual Gland

Almond shaped

Lies above mylohyoid muscle

Mucus secretions

About 15 ducts

Half open into the submandibular duct

Rest open on the sublingual fold

Parotid duct opens

in vestibule opposite

upper 2nd molar

Submandibular

gland and duct

Sublingual gland

secretes via numerous

small ducts

Salivary glands and ducts

Sublingual papilla

(opening of duct)

Lingual frenulum

Parotid gland

sublingual and submandibular secrete into oral cavity proper

net61

Clinical Perspective

Stone in Whartons Duct

Most common disease of

salivary glands

Twice as common in males as females

80-95% occur in submandibular gland or duct

Stones are most common cause of acute and chronic

infection of salivary glands

Lingual Nerve/Chorda Tympani

Lingual nerve somatic sensation to anterior 2/3 of tongue

Chorda tympani of VII taste (visceral sensation) anterior 2/3 tongue and palatal

glands

Chorda tympani of VII parasympathetic secretory fibres to sublingual and

submandibular glands

Question

What happens when the lingual nerve is cut at point 1, and point 2?

Hypoglossal Nerve

CNXII

Motor to extrinsic muscles of the tongue except palatoglossus

Originates from medulla oblongata, exiting skull via hypoglossal canals in the occipital bone

Emerges medial to the IJV, ICA, CNIX, CNX, CNXI.

Becomes superficial below the posterior belly of digastric and emerges between the IJV and the ICA

Hypoglossal Nerve

Travels upwards and forwards on the hyoglossus muscle deep to the digastric tendon, stylohyoid and the posterior border of mylohyoid

Passes on the lateral aspect of genioglossus as far as the tip of the tongue

Communicates with the sympathetic trunk, the first and second cervical nerves and the lingual nerve

Branches of the Hypoglossal Nerve

1. Meningeal leave hypoglossal nerve in its canal, travelling back into the posterior cranial fossa. Contains mixed sensory and sympathetic fibres from upper cervical nerves and superior cervical sympathetic ganglion.

2. Descending Branch contains fibres only from C1 gives a branch to the superior belly of omohyoid. Then joined by the lower root of the ansa from C2 and C3. The conjunction of the two roots gives rise to the nerve to sternothyroid, sternohyoid and the inferior belly of omohyoid.

Question?

1. If the hypoglossal nerve is purely motor. What nerve contains the tongue muscle propioreceptors. What happens with accessory nerve?

Branches of the Hypoglossal Nerve

3. Nerves to thyrohyoid and geniohyoid these arise near the posterior border of the hyoglossus. Contain C1 fibres

4. Muscular branches these are all true hypoglossal nerve fibres, and motor to the extrinsic muscles of the tongue except palatoglossus

Lymphatics of the Head and Neck

Superficial and Deep lymphatics

Deep Cervical nodes

superior (jugulodigastric)

- inferior

(jugulo-omohyoid)

- others

Superficial Lymph Nodes

No lymph nodes in scalp

Ring of nodes around the skull/neck junction

In the head occipital, post-auricular, parotid

and buccal

In the neck submandibular,

submental, superficial

cervical

Sample Question

A patient presents with a submandibular swelling. Describe the anatomy of the

submandibular gland and duct. What is the

lymph drainage of the gland? Describe the

secretomotor pathway to the gland,

including nerves involved, synapes and

ganglia.