Download anatomy_lec12_21_3_2011

Anatomy lec# 12
21-3-2011

sternocleidomastoid (SCM) divide the neck into two triangles :
posteriorly posterior triangle.
anteriorly  anterior triangle.
anterior triangle of the neck

boundaries :
anterior  by midline of the neck (which extending from symphysis menti to supra sternum
notch )
posterior by anterior border of SCM muscle.
superior  by inferior border of mandible.

Roof :
skin  superficial fascia (platysma muscle within it ) deep fascia

nerve supply :
transverse cervical nerve that comes from C2,C3 which supply the skin of the neck.

subdivisions :
the anterior triangle is subdivided into 4 subdivisions (triangles) by 3 muscles :
1. Anterior belly of digastrics muscle.
2. posterior belly of digastrics muscle .
3. superior belly of omohyoid muscle.
 so these three muscles divide the anterior Triangle into :

sub mental triangle (anterior).

digastrics triangle or sub mandibular triangle .

carotid triangle.

muscular triangle.
platysma muscle





a)
b)
c)
d)
e)
it is within superficial fascia.
origin : DEEP fascia over deltoid & pectoralis major.
insertion : body of the mandible & angle of the mouth.
NS : facial nerve.
Action : depress angle of mandible & angle of the mouth. And its one of the muscles of facial
expression.
 Note : the resistant points ,which are found on the midline of the neck, are :
symphysis menti.
hyoid bone.
Larynx(thyroid cartilage)
Cricoids cartila
Manubrium (supra sternal notch).
Hyoid bone







U-shaped mobile (not attached to any bone ) single bone.
2nd resistant point at midline of the neck.
Located at C3 level.
Gives attachment to muscles .
Parts : body anterior
Two lesser horn  anterior
Two greater horn  posterior.
It is a small image of mandible bone.
Hyoid bone held in place by several muscles :
>>supra hyoid muscles : a. Anter. & postr. Belly of digastrics muscle.
b. mylohyoid muscle.
c. geniohyoid (it is new & will be discussed later ).
d. stylohyoid muscle.
>> infra hyoid muscles :

a. Omohyoid muscle.
b. sternohyoid muscle.
c. thyrohyoid muscle.
d. sternothyroid muscle.
All these muscles action are : steadying , or moving hyoid and larynx during swallowing or
speaking.
Digastrics muscle (anterior belly)




Origin: digastrics fossa of mandible.
Insertion : intermediate tendon which is anchored to hyoid bone through a facial sling.
NS : mylohyoid nerve which is branch from inferior alveolar nerve.
Action: elevate hyoid & depress mandible.
Digastrics muscle (posterior belly)




Origin: Inner surface of mastoid notch.
Insertion : intermediate tendon attached to hyoid.
NS : Facial nerve .
Action : Elevate hyoid & retract mandible .
Mylohyoid muscle






Triangular in shape with apex forward.
Has a free posterior border.
Origin : mylohyoid line.
Insertion : median fibrous raphe & body of hyoid bone.
NS : mylohyoid nerve .
Action : support & elevate floor of oral cavity.
Geniohyoid muscle





Origin : inferior mental spine.
Insertion : body of hyoid bone.
NS : C1 nerve via hypoglossal N.
Action : Elevate hyoid bone & tongue
Paired in either side of midline.
 Hypo glossal nerve : On emerging from the hypoglossal canal, it gives off a small
meningeal branch and picks up a branch from the anterior ramus of C1. After passing
deep to the posterior belly of the digastric muscle, it passes to the submandibular
region to enter the tongue.(from Wikipedia, just for explanation).
Stylohyoid muscle





Origin : styloid process.
Insertion : body of hyoid.
NS : facial nerve.
Action : elevate & retract the mandible.
So we have now two muscles that elevate and retract mandible : stylohyoid & posterior belly
of digastrics.
 Subdivisions of anterior triangle :
sub mental triangle (lymph node triangle)

Boundaries :
right and left by  anterior belly of digastrics.
Inferiorly  body of hyoid.
Apex  symphysis menti.


Roof : skin , superficial fascia (platysma ) , deep fascia.
Contents : submental lymph node.
Submental lymph node


Drains lymph from :
 Tip of tongue.
 Lower mandible incisors & associated gingiva.
 Central part of lower lip.
 Skin of the chin.
After taking lymph from all these areas , it will drains lymph into  submandibular lymph
node  cervical lymph node.
Dedicated to my beloved brothers : Abd el-raheem yaseen , Ahmad taiseer ,
Rami al-shayeb , Omar Fode , Omar rshdan .
Done by : Khaled AL-Khatib.