Gastrointestinal SystemAnatomy

By

Dr. THAAER MOHAMMED DAHER ALSAAD

M.B.Ch.B.(MBBS) F.I.B.M.S.(Ph.D.)

SPECIALIST IN GENERAL SURGERY

SENIOR LECTURER

IMS MSU

Highlights

• Mouth

• Esophagus

• Stomach

• Small intestine

• Large intestine

• Rectum and Anal canal

• Liver, Pancreas, Salivary glands

Mouth or Oral Cavity

• lies below the nasal cavity.

• It has floor and roof ,and lateral walls,

• it open to the face through the oral fissure, and is continuous with the cavity of the pharynx to form the oropharynx( the oral part of the pharynx).

Mouth or Oral Cavity

Function of the oral cavity

1-it is the inlet for the digestive system involved with the initial processing of food, which is aided by secretions of the salivary gland.

2- it manipulates sounds produced by larynx and one out come of this is speech.

3-it can be used for breathing because it open in the pharynx, which a common pathway for food and air.

http://upload.wikimedia.org/wikipedia/commons/d/d4/Illu01_head_neck.jpg

The Teeth

Alligators are known for their large mouths and sharp teeth.

Illustration of the inside of a human mouth

A closed human mouth

cavitas oris

Models of human teeth as they exist within the alveolar bone

http://upload.wikimedia.org/wikipedia/commons/5/5d/Denticao.jpg

http://en.wikipedia.org/wiki/File:Teeth_by_David_Shankbone.jpg

Section of a human molar

Histologic slide of tooth erupting into the mouth.

A: ToothB: Gingiva

C: BoneD: Periodontal ligaments

Radiograph of lowerdifferent stages right third, second, and first molars in of development

Deciduous teethFront Teeth:

A. Central incisorB. Lateral incisorC. Canine or eye tooth

Back Teeth:D. First molarE. Second molar

Permanent teeth

Front Teeth:

1. Central incisor2. Lateral incisor3. Canine or eye tooth

Back Teeth:

4. First premolar5. Second premolar6. First Molar7. Second Molar8. Third Molar Or Wisdom Tooth

The Teeth

• I, C, P, and M (incisors, canines, premolars, and molars).

• The permanent or adult dental formula of humans is I (2/2, C 1/1, P 2/2, M 3/3) x2= 32.

• The dental formula for humans following the format for would be;

• 2:1:2:3/2:1:2:3,• where the numbers correspond to• I:C:P:M (upper)/I:C:P:M (lower).

• Deciduous teeth

• Central incisor 6 month

• Lateral incisor +2 8 month

• First molar +4 12 month

• Canine +4 16 month

• Second molar +4 20 months

The 1st deciduous molar appears before the canine.

The Teeth

• Permanent teeth• First molar 6 years• Central incisor +1 7 years• Lateral incisor +1 8 years• Canine +1 9 years• Premolar +1 10 years• Second molar +1 11 years• Third molar ------------------ 17 years +• 3rd molar = wisdom tooth, it is no infrequently

one or more 3rd molars may fail to erupt.

The Teeth

Differences in Structure of Different Teeth• The teeth are arranged in arch,

• Terms like anterior, posterior, medial and lateral are confusing.

• Buccal (labial) surface =

• the surface of the tooth facing the lip or cheek.

• Lingual (or palatal) surface =

• the surface of the tooth facing towards the tongue.

• Mesial surface =

• the surface of the tooth nearest the middle line.

• Distal surface =

• the surface of the tooth opposite to the mesial surface.

• Occlusal surface =

• the upper surfaces of the lower teeth and the lower surfaces of the upper teeth.

• Occlusal surface of the incisor teeth forms a sharp cutting edge.

• In the canine it is pointed.

• In the premolars and molars the occlusal surface bears rounded elevations or cusps.

• In fact all lower teeth lie slightly anterior (and mesial)

• To their upper counterpart.

Differences in Structure of Different Teeth

Blood and Nerve Supply to the Teeth

• The lower teeth

• are supplied by branches from the inferior alveolar artery (branch of maxillary artery); and by

• the inferior alveolar nerve (branch of mandibular nerve).

• The upper teeth• Are supplied by the anterior and posterior superior alveolar

branches of the maxillary artery, and by the

• Anterior, middle and posterior superior alveolar nerves (branches of the maxillary nerve and infraorbital continuation).

The Tongue

. Tongue--Musculature

Genioglossus –

depresses the tongue; posterior part protrudes tongue.

Hyoglossus –depresses and retracts the tongue. Styolglossus –retracts tongue and draws its edges up to create a trough for swallowing. Palatoglossus –

elevates the posterior part of tongue. Intrinsic muscles of tongue –

are confined to the tongue and do not attach to bone.(SLM =superior longitudinal muscle, ILM = inferior longitudinal muscle,

transverse muscle fibers, vertical muscle fibers)-

Vascular supply The lingual artery, a branch of the external carotid artery is the major arterial blood supply to the tongue .

Tongue innervation.

The posterior one-third of the tongue receives both generalsensory and special sensory from CN IX innervation.

A small posterior region of the tongue receives sensory innervation from CN X.The tongue receives general sensory innervation from the lingual branch of CN V for the anterior two-thirds,and special sensory (taste) from the chorda tympani nerve, a branch of CN VII.

Motor innervation from CN XII.

The Palate• Soft palate and hard palate

• Soft palate muscles:

1. Tensor palati

2. Levator palati

3. Musculus uvelae

4. Palatopharyngeus

• Action of palatine muscle: the muscle are responsible for the movement of the palate with deglutition and with speech.

• The levator palate helps to close the pharyngeal isthmus by elevating the palate and bringing it in contact with the posterior wall of the pharynx.

• Nerve supply

• All muscles oa the palate, except tensor palati, are supplied by the cranial part of the accessory nerve through the pharyngeal branch of the vagus.

• The tensor palati is supplied by the mandibular nerve.

The Palate

Anatomy of The pharynx

Site

Midline of the neckFrom skull base to esophagusIn front of upper 6 Cervical vertebra

Behind :The Nose

The MouthThe larynx

Seen from behind

Anatomy of The pharynx

Shape

Irregular Fibromuscular tube lined by mucous membrane

Length: 15 cm

Anatomy of The pharynx

Structure

The wall is formed of 4 layers

1-Mucous membrane

2- pharyngeal aponeurosis

3-muscle layer

4-Bucco-pharyngeal fascia

Stratified squamous epithelium except the nasopharynx, it is pseudo-stratified with goblet cells

Loose connective tissue which contains lymphoid tissue that aggregates in some areas forming tonsils (Waldayer’s ring) Formed of 3 muscles, superior middle and inferior constrictor muscles

A thin coat of connective tissue

• Three constrictors:

• Superior constrictor

• Middle constrictor

• Inferior constrictor; consist of two part:

1. Thyropharyngeus

2. Cricopharyngeus

Pharyngeal muscles

Pharyngeal muscles

• In addition to the constrictors, the pharynx has three muscles the fibers of which run longitudinally.

• These are the:1. Stylopharyngeus

2. Palatopharyngeus

3. salpingopharyngeus

What is Waldeyer’s ring?

The lymphoid tissue in the

pharyngeal aponeurosis

aggregates in some areas

forming tonsils:

1-one nasopharyngeal tonsil

2- two palatine tonsils

3- two lingual tonsils

Anatomy of the pharynxCompartments

• Nasopharynx

• Oropharynx

• Laryngopharynx

(Hypopharynx)

Seen from behind

• Nasopharynx

• Oropharynx

• Laryngopharynx

(Hypopharynx)

Seen from lateral

Nasopharynx

-Behind the nasal cavity

-Extends from skull

Base superiorly to the

soft palate inferiorly

- Communicates inferiorly with the oropharynx through the velo-pharyngeal sphincter

- The nasopharyngeal tonsil lies in the roof

- The pharyngeal opening of ET lies in the lateral wall

Oropharynx

Behind the oral cavity (in front of 2nd&3rd

Cervical vertebra)

From the soft palate superiorly to tip of epiglottis inferiorly

Communicates:

Anteriorly with the oral cavity

Superiorly with the nasopharynx

Inferiorly with the hypopharynx

The palatine tonsils lie laterally

between the anterior and posterior

pilars

The tonsils lie between the Two pillars

Hypopharynx

Behind the Larynx (in front of 3rd to

6th Cervical vertebra)

From the tip of epiglottis superiorly to

the lower border of cricoid cartilage

Inferiorly

Communicates:

- Anteriorly with the Larynx

- Superiorly with the oropharynx

- Inferiorly with the esophagus

The hypopharynx does not only

lie behind the larynx BUT also

Projects laterally on each side of the larynx

So it is formed of :

- Postcricoid region ( behind the larynx)

- Two pyriform fossa (on each side of the larynx

Seen from behind

Cross section

Blood supply

From the External Carotid Artery & its branches

1- Tonsillar artery (from Facial Artery)

2-Ascending palatine artery (from Facial Artery)

3-Ascending pharyngeal Artery (from external carotid)

4-Descending palatine artery ( from Maxillary artery.

5-Dorsalis lingulae artery (from Lingual artery)

Nerve Supply

Motor ---► X Except :

Stylopharyngeus --►IX

Tensor palati --►V

Sensory --►

- Nasopharynx: V

- Oropharynx: IX

- Laryngopharynx: X

Autonomic:- sympathetic: SCG- Parasympathetic: through VII