Transcript 13. submandibular-M.N.V2010-10

Submandibular Region
It lies under cover of the body of the mandible between the mandible and the
hyoid bone.
It contains muscles; salivary glands; nerves; parasympathetic ganglion; blood
vessels and lymph nodes.
Digastric Muscle
Origin and Insertion:
The posterior belly arises from the medial surface of the mastoid process of the temporal
bone. It passes downward and forward across the carotid sheath. It ends in the intermediate
tendon. This tendon pierces the stylohyoid insertion and is held in position by a loop of
deep fascia which binds the tendon down to the junction of the body and greater cornu of
the hyoid bone.
The anterior belly runs forward and medially and is attached to the lower border of the body
of the mandible near the median plane in digastric fossa.
Nerve supply:
The posterior belly is supplied by the facial nerve & The anterior belly is supplied by the
nerve to mylohyoid which is a branch of the inferior alveolar nerve of the mandibular nerve
Action: Depresses the mandible or elevates the hyoid bone.
Mylohyoid Muscle
It is flat and triangular sheet of muscle. It arises from the whole length of the mylohyoid line
of the mandible.
Insertion:
The fibers run downward and forward. The posterior fibers are inserted into the body of the
hyoid bone. The anterior fibers are inserted into a fibrous raphe which extends from the
symphysis menti to the body of the hyoid bone.
Nerve Supply: Mylohyoid branch of the inferior alveolar nerve.
Action: The 2 muscles support the tongue and floor of the mouth ( diaphragma oris ).
When the mandible is fixed, they elevate the floor of the mouth and hyoid during the
1st stage of the swallowing.
When the hyoid bone is fixed, it assists in the depression of the mandible and the
opening of the mouth.
Stylohyoid:
O. Styloid process of the temporal bone.
In. The junction of the body with the greater cornu of the hyoid bone.
Nerve Supply: facial nerve.
Action: Elevates the hyoid bone.
Geniohyoid:
O. inferior mental spine
In . Anterior surface of body of hyoid .
Action: elevates hyoid bone & depresses mandible
Nerve supply: 1st cervical n. through hypoglossal n.
Genioglossus:
O. Superior mental spine
In .Superior fibers pass to tip of tongue ; middle and posterior fibers to dorsum of tongue
and few inferior fibers to body of hyoid bone
Action: 2 ms. Protrude tongue in the midline & one protrudes the tip to the opposite. The
middle & posterior fibers depress the tongue and increase mouth cavity during
swallowing. Lesion of one muscle causes deviation of the tip of the tongue to he
same side of lesion.
styloglossus :
O. Styloid process.
In. Side of tongue.
Action: Draws tongue up & backward
N.B. The 2 muscles are supplied by hypoglossal nerve.
Hyoglossus
middle
O. Upper border of body and greater cornu of
hyoid bone
In. Its fibers mix with those of other muscles at
the side of the tongue.
Action. Depresses the tongue.
Nerve supply: hypoglossal nerve.
styloglossus
Relations of Hyoglossus Muscle
Superficial ( laterally ):
Mylohyoid and styloglossus muscles.
From above downward:
Lingual nerve and its ganglionic branches;
submandibular ganglion ; submandibular duct
and deep part of the submandibular gland and
hypoglossal nerve & its vena comitans and the
suprahyoid artery of the lingual.
Deep ( medially ):
Anteriorly: Genioglossus.
Posteriorly: Stylopharyngeus ; the stylohyoid
ligament and the middle constrictor of the
pharynx. Also, the glossopharyngeal nerve and
the second part of the lingual artery & its dorsal
lingual branches.
Facial Artery
It ascends and grooves posterior
border of submandibular
gland, then hooks around
lower border of body of
mandible , at anterior margin of
masseter.
Branches
1- Ascending palatine: it runs
alongside the pharynx
2- Tonsillar: it perforates superior
constrictor m.
3- Glandular: it supplies
submandibular salivary gland.
4- Submental: it runs along lower
border of the body of The
mandible to supply chin and
lower lip.
Facial vein
It leaves the face behind the facial
artery by crossing the lower
margin of the body of the
mandible.
It is joined by anterior division of
the retromandibular vein and
ends in the internal jugular
vein.
Lingual Artery
It arises from external carotid artery opposite the tip of
the greater cornu of the hyoid bone It runs forward,
forming an upward loop,which is crossed by the
hypoglosal nerve ( the 1st part ).
Then, it passes deep to the hyoglossus muscle along
upper border of greater cornu of the hyoid bone( 2nd
part ).
The 3rd part ascends along anterior border of
hyoglossus. It is crossed by the hypoglossal nerve
submandibular duct and the lingual nerve. Then runs
along the under surface of tongue as deep lingual A. to
reach its tip and anastomoses with artery of opposite
side. It supply the anterior part of the tongue.
Branches :
1- from 1st part :
suprahyoid A. It runs along upper border of
greater cornu of the hyoid bone & superficial to
hyoglossus M and supplying the adjacent Ms.
2- from 2nd part
2 dorsal lingual As. They ascend on the
medial surface of hyoglossus M. to the
posterior part of the dorsum of tongue. They
supply the posterior part of the tongue and the
palatine tonsil.
3- from 3rd part
Sublingual A. that supplies sublingual salivary
Lingual Veins
The dorsal lingual veins drain the dorsum and sides of the tongue . They join to form the
lingual vein, which accompany the lingual artery and lying in the interval between the
hyoglosssus and genioglossus muscles.
The lingual vein passes superficial to the internal and external carotid arteries. Near the
greater cornu of the hyoid bone the lingual vein join the internal jugular vein.
Lymph nodes
They are situated on the superficial surface of the submandibular salivary gland.
Lingual nerve
It passes medially,forward
beneath the lower
border of superior
constrictor muscle
origin which is attached
to the P. border of the
mylohyoid line , here it
is closely related to the
last molar tooth.
Branches
Sensory:
general sensation to
lingual surface of the
gum ; floor of the mouth
and the anterior two
third of tongue
Ganglionic:
secretory parasympathetic
to lingual salivary gland
Communicating with the
hypoglossal n.
Clinical Notes
The lingual nerve
passes forward into the
submandibular region
from the infratemporal
fossa by running
beneath the origin of
the superior constrictor
muscle which is
attached to the
posterior border of the
mylohyoid line on the
mandible.
Here, it is closely
related to the last molar
tooth and is liable to be
damaged in cases of
extraction of an
impacted third molar.
Hypoglossal Nerve
It curves forward, crossing the loop of
the lingual artery just above the tip of
the greater cornu of the hyoid bone.
Then, it runs forward on the lateral
surface of the hyoglossus M. and on the
medial surface of the mylohyoid M.
It lies below the deep part of the
submandibular gland ; the
submandibular duct and the lingual N.
It ends by curving upward toward the tip
of the tongue to supplies its muscles (1 )
except palatoglossus.
2- The nerve to thyrohyiod (1st cervical
N. fibers)
3- The nerve to the geniohyoid ( 1st
cervical N. fibers )
4- Communicating branch with the
lingual nerve on the side of the tongue
Glossopharyngeal Nerve
It passes between the
superior & middle
constrictor muscles
The lingual branch of it
enters the submandibular
region.
The lingual branch enters the
tongue below the
styloglossus muscle.
It supplies:
General sensory & special
taste fibers to the mucous
membrane of the posterior
third of the tongue
( pharyngeal part)
Special taste fibers to the
circumvallate papillae of
the oral part of the tongue.