• Cartilage model is covered with perichondrium that is converted to periosteum

• Diaphysis-central shaft
• Epiphysis-located at either end of the diaphysis
• Growth in length of the bone is provided by the emetaphyseal plate located between the epiphyseal cartilage and the diaphysis

• Blood capillaries and the mesenchymal cells infiltrate the spaces left by the destroyed chondrocytes

• Osteoblasts are derived from the undifferentiated cells; form an osseous matrix in the cartilage
• Bone appears at the site where there was cartilage

      Microscopic structure

• Compact bone is found on the exterior of all bones; canceIlous bone is found in the interior
• Surface of compact bone is covered by periosteum that is attached by Sharpey's fibers
• Blood vessels enter the periosteum via Volkmann's canals and then enter the haversian canals that are formed by the canaliculi and lacunae

•  

• Marrow
  • FiIls spaces of spongy bone
  • Contains blood vessels and blood ceIls in various stages of development
  • Types
• Red bone marrow
  • Formation of red blood ceIls (RBCs) and some white blood cells (WBCs) in this location
  • Predominate type of marrow in newborn
  • Found in spongy bone of adults (sternum, ribs, vertebrae, and proximal epiphyses of long bones)
•  Yellow bone marrow
  • Fatty marrow
  • Generally replaces red bone marrow in the adult, except in areas mentioned above
•  
• Ossification is completed as the proximal epiphysis joins with the diaphysis between the twentieth and twenty-fifth year

The Tongue

• The tongue (L. lingua; G. glossa) is a highly mobile muscular organ that can vary greatly in shape.
• It consists of three parts, a root, body, and tip.

• The tongue is concerned with mastication, taste, deglutition (swallowing), articulation (speech), and oral cleansing.
• Its main functions are squeezing food into the pharynx when swallowing, and forming words during speech.

Gross Features of the Tongue

• The dorsum of the tongue is divided by a V-shaped sulcus terminalis into anterior oral (presulcal) and posterior pharyngeal (postsulcal) parts.
• The apex of the V is posterior and the two limbs diverge anteriorly.
• The oral part forms about 2/3 of the tongue and the pharyngeal part forms about 1/3.

Oral Part of the Tongue

• This part is freely movable, but it is loosely attached to the floor of the mouth by the lingual frenulum.

• On each side of the frenulum is a deep lingual vein, visible as a blue line.
• It begins at the tip of the tongue and runs posteriorly.
• All the veins on one side of the tongue unite at the posterior border of the hyoglossus muscle to form the lingual vein, which joins the facial vein or the internal jugular vein.

• On the dorsum of the oral part of the tongue is a median groove.
• This groove represents the site of fusion of the distal tongue buds during embryonic development.

The Lingual Papillae and Taste Buds

• The filiform papillae (L. filum, thread) are numerous, rough, and thread-like.
• They are arranged in rows parallel to the sulcus terminalis.

• The fungiform papillae are small and mushroom-shaped.
• They usually appear are pink or red spots.

• The vallate (circumvallate) papillae are surrounded by a deep, circular trench (trough), the walls of which are studded with taste buds.

• The foliate papillae are small lateral folds of lingual mucosa that are poorly formed in humans.

• The vallate, foliate and most of the fungiform papillae contain taste receptors, which are located in the taste buds.

The Pharyngeal Part of the Tongue

• This part lies posterior to the sulcus terminalis and palatoglossal arches.
• Its mucous membrane has no papillae.

• The underlying nodules of lymphoid tissue give this part of the tongue a cobblestone appearance.
• The lymphoid nodules (lingual follicles) are collectively known as the lingual tonsil.

The Oropharynx

• The oral part of the pharynx has a digestive function.
• It is continuous with the oral cavity through the oropharyngeal isthmus.
• The oropharynx is bounded by the soft palate superiorly, the base of the tongue inferiorly, and the palatoglossal and palatopharyngeal arches laterally.

• It extends from the soft palate to the superior border of the epiglottis.

The Palatine Tonsils

• These are usually referred to as "the tonsils".
• They are collections of lymphoid tissue the lie on each side of the oropharynx in the triangular interval between the palatine arches.

• The palatine tonsils vary in size from person to person.
• In children, the palatine tonsils tend to be large, whereas in older persons they are usual small and inconspicuous.
• The visible part of the tonsil is no guide to its actual size because much of it may be hidden by the tongue and buried in the soft palate.

A. Anatomic position-erect body position with the arms at the sides and the palms  upward

B. Plane or section

1. Definition-imaginary flat surface formed by an extension through an axis

2. Median plane-a vertical plane. that divides a body into right and left halves

3. Sagittal plane

• Any plane parallel to the median plane
• Divides the body into right and left portions

4. Frontal plane

• Vertical plane that forms at right angles to the sagittal plane
• Divides the body into anterior and posterior sections
• Synonymous with the term coronal plane

5. Transverse plane

• Horizontal plane that forms at right angles to the sagittal and frontal planes
• Divides the body into upper and lower portions
• Synonymous with the term horizontal plane

C. Relative positions

1. Anterior

• Nearest the abdominal surface and the front of the body
• Synonymous with the term ventral
• In referring to hands and forearms, the terms palmar and Volar are used

2. Posterior

• Back of the body
• Synonymous with the term dorsal

3. Superior

• Upper or higher
• Synonymous with the term cranial (head)

4. Inferior

• Below or lower
• Synonymous with the term caudal (tail)
• In referring to the top of the foot and the sole of the foot. the terms dorsal and plantar are used respectively

5. Medial-near to the median plane

6. Lateral-farther away from the median plane

7. Proximal-near the source or attachment

8. Distal-away from the source or. attachment

9. Superficial-near the surface

10. Deep-away from the surface

11. Afferent-conducting toward a structure

12. Efferent-conducting away from a structure

The Hard Palate

• The anterior bony part of the palate is formed by the palatine process of the maxillae and the horizontal plates of the palatine bones.

• Anteriorly and laterally, the hard palate is bounded by the alveolar processes and the gingivae.
• Posteriorly, the hard palate is continuous with the soft palate.

• The incisive foramen is the mouth of the incisive canal.
• This foramen is located posterior to the maxillary central incisor teeth.
• This foramen is the common opening for the right and left incisive canals.
• The incisive canal and foramen transmit the nasopalatine nerve and the terminal branches of the sphenopalatine artery.

• Medial to the third molar tooth, the greater palatine foramen pierces the lateral border of the bony palate.
• The greater palatine vessels and nerve emerge from this foramen and run anteriorly into two grooves on the palate.

• The lesser palatine foramen transmits the lesser palatine nerve and vessels.
• This runs to the soft palate and adjacent structures.

The External Nose

• Noses vary considerably in size and shape, mainly as a result of the differences in the nasal cartilages and the depth of the glabella.

• The inferior surface of the nose is pierced by two apertures, called the anterior nares (L. nostrils).
• These are separated from each other by the nasal septum (septum nasi).
• Each naris is bounded laterally by an ala (L. wing), i.e., the side of the nose.

• The posterior nares apertures or choanae open into the nasopharynx.