NS26_2013
description
Transcript of NS26_2013
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Submandibular region
Code: NS26
Lecturer: Dr. S. Kandiah
Date: 11th October 2013
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Learning Objectives
The submandibular gland and duct
Facial artery
Hypoglossal nerve
Lymphatics of the head and neck
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Mandible External Aspect
1
2
3
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6
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2005 Elsevier
Mandible External Aspect
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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
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Hyoid bone supports the larynx
1) Stylohyoid
ligament
attaches to
lesser horn of
hyoid bone
2) Keeps airway
open
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Suprahyoid Muscles
Digastric
Stylohyoid
Mylohyoid
Geniohyoid
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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
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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)
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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
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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
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Mental Spines
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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
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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)
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Muscles of floor of mouth
Anterior belly of digastric
Mylohyoid from mylohyoid line of mandible to hyoid bone
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Branches of External Carotid
External Carotid Superior thyroid
Lingual
Facial
Occipital
Ascending Pharyngeal
Posterior auricular
Maxillary
Superficial temporal
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Relations of hyoglossus
Lateral/superficial
Medial/deep
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Lateral/Superficial
Lingual nerve
Submandibular gland and duct
XII
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Medial/Deep
IX
Stylohyoid ligament
Lingual artery
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Salivary Glands
Sublingual
Submandibular
Parotid
Why are stones more common in the first 2?
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Why saliva?
Moisture
Food Lubrication
Prevents decay
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Submandibular and Sublingual
Glands
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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
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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
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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
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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
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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
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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
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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
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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
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Question
What happens when the lingual nerve is cut at point 1, and point 2?
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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
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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
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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?
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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
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Lymphatics of the Head and Neck
Superficial and Deep lymphatics
Deep Cervical nodes
superior (jugulodigastric)
- inferior
(jugulo-omohyoid)
- others
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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
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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.