• This is the posterior curtain-like part, and has no bony support. It does, however, contain a membranous aponeurosis.
• The soft palate, or velum palatinum (L. velum, veil), is a movable, fibromuscular fold that is attached to the posterior edge of the hard palate.
• It extends posteroinferiorly to a curved free margin from which hangs a conical process, the uvula (L. uva, grape).

• The soft palate separates the nasopharynx superiorly and the oropharynx inferiorly.

• During swallowing the soft palate moves posteriorly against the wall of the pharynx, preventing the regurgitation of food into the nasal cavity.

• Laterally, the soft palate is continuous with the wall of the pharynx and is joined to the tongue and pharynx by the palatoglossal and palatopharyngeal folds.

• The soft palate is strengthened by the palatine aponeurosis, formed by the expanded tendon of the tensor veli palatini muscle.
• This aponeurosis attaches to the posterior margin of the hard palate.

ENDOCRINE

Endocrine glands have no ducts

They secrete into the blood from where the secretion (hormone) reaches a target cell

The following is a list of endocrine glands:

• Hypophysis
• Thyroid
• Parathyroid
• Adrenals
• Islets of Langerhans
• Pineal
• Gonads

Hypophysis: Develops from oral ectoderm and nerve tissue,  The oral part forms an upgrowth with an invagination (Rathke's pouch) The nervous part grows from the floor of the diencephalon - staying intact .The oral part separates from the mouth

Ectoderm – adenohypophysis - pars tuberalis

- pars distalis

- pars intermedia .

Diencephalon – neurohypophysis   - pars nervosa .

- infundibulum

- median eminence

Rathke's pouch remains as Rathke's cysts

Pars Distalis: Forms 75% of the gland, The cells form cords,  with fenestrated capillaries in-between

2 Cell types:

Chromophobes :  50% of the cells, do not stain  lie in groups, they are resting chromophils

granules have been used

Chromophils: Stain

They can be subdivided according to their reaction with different stains

Acidophils (40%) :Cells have acidophilic granules in their cytoplasm. The cells are secretory.

They have a well developed EPR and Golgi apparatus.They have secretory granules.

subdivided into:

- Somatotropin cells: secrete somatotropin (growth hormone)

- Mammotropic cells:  secrete prolactin

Basophils (10%) :  These cells have basophilic granules in their cytoplasm and can be subdivided into:

Thyrotropin cells:  secrete thyroid - stimulating hormone (TSH)

Corticotrophin cells:  secrete adrenocorticotropic (ACTH)

Gonadotropic cells:  secrete two hormones:  Follicle stimulating hormone (FSH):

Stimulate follicle development and spermatogenesis

Luteinizing hormone (LH): Stimulate the formation of the corpus luteum and Leydig cells

Pars Tuberalis:  Cells lie around the infundibulum . It is continuous with the pars distalis

Cells are cuboidal with no granules. Their function is unknown

Pars Intermedia:  Poorly developed in the human. Follicles lined by cuboidal cells and filled with colloid are found Known as Rathke's cysts .There are also a few big basophilic cells

Their function is unknown

Pars Nervosa: Contains: - myelinated axons  pituicytes,  blood vessels

Axons:

The cell bodies of the axons lie in the supra-optic and paraventricular nuclei of the hypothalamus .From the cell bodies the axons go through the infundibulum forming the  hypothalamohypophyseal tract to end in the pars nervosa

 The axons have dilated blind endings filled with hormones (Herring bodies) coming from the cell bodies.

Two hormones are secreted:

Oxytoxin: - Cause contraction of the uterus

    - Cause contraction of the myoepithelial cells of the milkgland

    - The hormone is secreted by the paraventricular nuclei

Vasopressin :- Cause reabsorption of H2O in the kidney (also known as antidiuretic hormone ADH)  The hormone is secreted by the supraoptic nuclei.  A hypophyseal portal system exists

A primary capillary plexus of fenestrated capillaries form around the median eminence. Inhibitory hormones are secreted into these capillaries

The capillaries rejoin to form the portal veins that traverse the pituitary stalk

The portal veins break up into a secondary capillary plexus which lies close to the cells of the adenohypophysis

This portal system regulates the functions of the anterior pituitary function.

Pineal

Surrounded by pia which sends septae into the gland Cells are mainly pinealocytes and astroglial cells

Pinealocytes:Irregular shaped cells. with processes ending in flattened dilatations

Have a well developed smooth surfaced endoplasmic reticulum, Also a rough EPR not well developed, Lots of microtubules

Astroglial Cells: Elongated nucleus, Cells have long processes, They perform a supporting function

Hormones:

Melatonin - secreted during the night .suppress the onset of puberty

Serotonin - secreted during the day

In humans the pineal form concretions of calcified material called brain sand

Brain sand vary in size and number with age and is visible on X-rays

Mast cells are also found in the pineal and cause the high histamine contend of the gland

THYROID

Has a CT capsule that sends septae into the gland to divide it up into incomplete lobes and lobules. In the lobules are follicles, Follicles vary in size,  They are surrounded by surrounded by reticular CT and capillaries

Cells of the Follicle:

Follicular Cells :  Single layer of cuboidal cells,  lie around the colloid, Follicular cells can become columnar when very active, Nucleus  central, EPR has wide cisternae ,Golgi present

• microvilli on the free surface

Parafollicular Cells:  Also known as C-cells, Form part of the epithelium or form clusters between the follicles

- They never come into contact with the colloid

- Larger and stain less intensely than the follicular cells, Form 2% of the cells, Secrete calcitonin

Hormones: Thyroxine and thyriodothyronine - stimulate the metabolic rate, Calcitonin - lower the blood calcium

Parathyroid:

Has a CT capsule which send septae into the gland to divide it up into incomplete lobules, The CT contains fat which increase with age - may eventually be 50% of the gland, Glandular cells are arranged in cords

Glandular Cells:

Chief Cells:  Small cells so their nuclei lie close together, Rich in glycogen, Biggest omponent

Secrete parathyroid hormone - essential for life

Oxyphil Cells:Develop at puberty, Bigger than the chief cells, Nuclei are smaller, Acidophilic

Hormones:

Parathyroid hormone - regulate calcium and phosphate ions in the blood

ADRENAL

- Thick CT capsule that do not send septae into the gland

Cortex:

Has 3 layers

Zona glomerulosa: 15% of the cortex, Directly under the capsule, Cells are columnar or pyramidal,  Arranged in small groups or clusters, Wide fenestrated capillaries surround the clusters, Cells have an extensive smooth EPR

Zona Fasciculata: 78% of the cortex, Cells are arranged in cords ,1 to 2 cells wide perpendicular to the surface, Sinusoids lie between the cords, Cells are polyhedral with a central nucleus which is bigger than that of the zona glomerulosa, Lots of lipid in the cytoplasm cause the cells to stain lightly,  Cells have a well developed smooth and rough EPR

The mitochondria in the cells are round with tubular or vesicular cristae

Zona Reticularis:  7% of the cortex, Cells form a network of cords with wide capillaries in-between The mitochondria in the cells are more ofte6n elongated than that in the zona fasciculate  Degenerating cells with pyknotic nuclei are found.  Cells contain numerous large lipofuscin granules. Cells of the cortex do not store their secretions but form and secrete on demand.

Hormones:

3 Groups:

Glucocorticoids (e.g. cortisol) - have an affection on carbohydrate metabolism

Mineralocorticoid (e.g. aldosterone) - control water and electrolyte balans

Androgens (e.g. dehyroepiandrosterone) - not very important

Medulla:

- Cells are big and oval and lie in groups and cords around bloodvessels

- Oxidising agents stain the granules in these cells brown - cells are therefore called chromaffin cells

- Granules contain adrenaline or non-adrernalin

- A few parasympathetic ganglion cells are also present

Hormones:

- Adrenaline - increase oxygen uptake

- increase blood pressure

- Noradrenaline - maintain blood pressure

Blood Supply:

- Blood vessel enter from the capsule to form the wide capillaries

- They flow into venules that form a central vein

- Between the endothelium of the capillaries and the glandular cells there is a subendothelial

- space.

- The glandular cells have microvilli protruding into this space.

ISLES OF LANGERHANS

Endocrine part of pancreas.  The isles are round clusters in the exocrine tissue

- 100 - 200 µm

Islands consists of slightly stained polygonal or rounded cells,  The cells are separated by fenestrated capillaries

- Autonomic nerve fibres innervate the blood vessels and the island cells

- 4 different cell types have been described

A cells : 20% of the cells,  Bigger than B cells, Lie at the periphery, Have secretory granules ,Contain glucagon

B cells :  80%,  Lie in the centre of the island,  The cells are small with granules which are crystals,  Granules are formed by insulin

D cells :  Not numerous, Membrane bound granules, Store somatostatin (inhibit somatotropin)

F cells :  Have membrane bound granules,  Store pancreatic polypeptide, The hormone inhibits pancreatic exocrine secretion

-> Most of the facial skeleton is formed by nine bones: four paired (nasal, zygomatic, maxilla, and palatine) and one unpaired (mandible).
-> The calvaria of the new-born infant is large compared with the relatively small fascial skeleton.
-> This results from the small size of the jaws and the almost complete absence of the maxillary and other paranasal sinuses in the new-born skull.
-> These sinuses form large spaces in the adult facial skeleton. As the teeth and sinuses develop during infancy and childhood, the facial bones enlarge.
-> The growth of the maxillae between the ages of 6 and 12 years accounts for the vertical elongation of the child’s face.

The Nasal Bones 

-> These bones may be felt easily because they form the bridge of the nose.
-> The right and left nasal bones articulate with each other at the internasal suture.
-> They also articulate with the frontal bones, the maxillae, and the ethmoid bones.
-> The mobility of the anteroinferior portion of the nose, supported only by cartilages, serves as a partial protection against injure (e.g., a punch in the nose). However, a hard blow to the anterosuperior bony portion of the nose may fracture the nasal bones (broken nose).
-> Often the bones are displaced sideways and/or posteriorly.

The Maxillae 

-> The skeleton of the face between the mouth and the eyes is formed by the two maxillae.
-> They surround the anterior nasal apertures and are united in the medial plane at the intermaxillary suture to form the maxilla (upper jaw).
-> This suture is also visible in the hard palate, where the palatine processes of the maxillae unite.
-> Each adult maxilla consists of: a hollow body that contains a large maxillary sinus; a zygomatic process that articulates with its mate on the other side to form most of the hard palate; and alveolar processes that form sockets for the maxillary (upper) teeth.
-> The maxillae also articulate with the vomer, lacrimal, sphenoid, and palatine bones.
-> The body of the maxilla has a nasal surface that contributes to the lateral wall of the nasal cavity; an orbital surface that forms most of the floor of the orbit; an infratemporal surface that forms the anterior wall of the infratemporal fossa; and an anterior surface that faces partly anteriorly and partly anterolaterally and is covered buy facial muscles.
-> The relatively large infraorbital foramen, which faces inferomedially, is located about 1 cm inferior to the infraorbital margin; it transmits the infraorbital nerve and vessels.
-> The incisive fossa is a shallow concavity overlying the roots of the incisor teeth, just a shallow concavity overlying the roots of the incisor teeth, just inferior to the nasal cavity. This fossa is the injection site for anaesthesia of the maxillary incisor teeth.
-> If infected maxillary teeth are removed, the bone of the alveolar processes of the maxillae begins to be reabsorbed. As a result, the maxilla becomes smaller and the shape of the face changes.
-> Owing to absorption of the alveolar processes, there is a marked reduction in the height of the lower face, which produces deep creases in the facial skin that pass posteriorly from the corners of the mouth.

The Mandible 

-> This is a U-shaped bone and forms the skeleton of the lower jaw and the inferior part of the face. It is the largest and strongest facial bone.
-> The mandibular (lower) teeth project superiorly from their sockets in the alveolar processes.
-> The mandible (L. mandere, to masticate) consists of two parts: a horizontal part called the body, and two vertical oblong parts, called rami.
-> Each ramus ascends almost vertically from the posterior aspect of the body.
-> The superior part of the ramus has two processes: a posterior condylar process with a head or condyle and a neck, and a sharp anterior coronoid process.
-> The condylar process is separated from the coronoid process by the mandibular notch, which forms the concave superior border of the mandible.
-> Viewed from the superior aspect, the mandible is horseshoe-shaped, whereas each half is L-shaped when viewed laterally.
-> The rami and body meet posteriorly at the angle of the mandible.
-> Inferior to the second premolar tooth on each side of the mandible is a mental foramen (L. mentum, chin) for transmission of the mental vessels and the mental nerve.
-> In the anatomical position, the rami of the mandible are almost vertical, except in infants and in edentulous (toothless) adults.
-> On the internal aspect of the ramus, there is a large mandibular foramen.
-> It is the oblong entrance to the mandibular canal that transmits the inferior alveolar vessels and nerve to the roots of the mandibular teeth.
-> Branches of these vessels and the mental nerve emerge from the mandibular canal at the mental foramen.
-> Running inferiorly and slightly anteriorly on the internal surface of the mandible from the mandibular foramen is a small mylohyoid groove (sulcus), which indicates the course taken by the mylohyoid nerve and vessels.
-> These structures arise from the inferior alveolar nerve and vessels, just before they enter the mandibular foramen.
-> The internal surface of the mandible is divided into two areas by the mylohyoid line, which commences posterior to the third molar tooth. -> Just superior to the anterior end of the mylohyoid line are two small, sharp mental spines (genial tubercles), which serve as attachments for the genioglssus muscles.

The Zygomatic Bones 

-> The prominences of the cheeks (L. mala), the anterolateral rims and much of the infraorbital margins of the orbits, are formed by the zygomatic bones (malar bones, cheekbones).
-> They articulate with the frontal, maxilla, sphenoid, and temporal bones.
-> The frontal process of the zygomatic bone passes superiorly, where it forms the lateral border of the orbit (eye socket) and articulates with the frontal bone at the lateral edge of the supraorbital margin.
-> The zygomatic bones articulate medially with the greater wings of the sphenoid bone. The site of their articulation may be observed on the lateral wall of the orbit.
-> On the anterolateral aspect of the zygomatic bone near the infraorbital margin is a small zygomaticofacial foramen for the nerve and vessels of the same name.
-> The posterior surface of the zygomatic bone near the base of its frontal process is pierced by a small zygomaticotemporal foramen for the nerve of the same name.
-> The zygomaticofacial and zygomaticotemporal nerves, leaving the orbit through the previously named foramina, enter the zygomatic bone through small zygomaticoorbital foramina that pierces it orbital surface.
-> The temporal process of the zygomatic bone unites with the zygomatic process of the temporal bone to form the zygomatic arch.
-> This arch can be easily palpated on the side of the head, posterior to the zygomatic prominence (malar eminence) at the inferior boundary of the temporal fossa (temple).
-> The zygomatic arches form one of the useful landmarks for determining the location of the pterion. These arches are especially prominent in emaciated persons.
-> A horizontal plane passing medially from the zygomatic arch separates the temporal fossa superiorly from the infratemporal fossa inferiorly.

Other Bones

There are several other, very important bones in the skull, including the palatine bone, ethmoid bone, vomer, inferior concha and the ossicles of the ear (malleus, incus and stapes). These, however, are covered to greater detail where they are relevant in the head (e.g., ethmoid bone with the orbit and nasal cavity).

The Arteries of the Face

• The superficial arteries are derived from the external carotid arteries.

The Facial Artery

• This is the chief artery of the face.
• It arises from the external carotid artery and winds its way to the inferior border of the mandible, just anterior to the masseter muscle.
• It hooks around the inferior border of the mandible and grooves the bone. Here the artery is superficial, just beneath the platysma and its pulsation can be felt.

• In its course over the face to the medial angle of the eye, the facial artery crosses the mandible, buccinator muscle, and maxilla.
• It lies deep to the zygomaticus major.

• The facial artery ends by sending branches to the lip and side of the nose.
• The part of the artery that runs along the side of the nose to supply the eyelids is called the angular artery.

The Superficial Temporal Artery

• This artery is the smaller of the two terminal branches of the external carotid artery (the other is the maxillary artery).
• It begins deep to the parotid gland, posterior to the neck of the mandible, and ascends superficial to the posterior end of the zygomatic process of the temporal bone. It then enters the temporal fossa.

• The superficial temporal artery ends in the scalp by dividing into the frontal and parietal branches.

• Pulsation of this artery can be felt by compressing the root of the zygomatic process of the temporal bone.

The Transverse Facial Artery

• This small artery arises from the superficial temporal artery before it emerges from the parotid gland.
• It crosses the face superficial to the masseter muscle, about a fingerbreadth inferior to the zygomatic arch.
• It divides into numerous branches that supply the parotid gland and duct, the masseter muscle, and the skin of the face.

• It anastomoses with branches of the facial artery.

• Long bones (e.g.. femur and humerus)
• Short bones (e.g.. wrist and ankle bones)
• Flat bones (e.g.. ribs)
• Irregular bones (e.g.. vertebrae)

Nerves of the Palate

• The sensory nerves of the palate, which are branches of the pterygopalatine ganglion, are the greater and lesser palatine nerves.
• They accompany the arteries through the greater and lesser palatine foramina, respectively.

• The greater palatine nerve supplies the gingivae, mucous membrane, and glands of the hard palate.

• The lesser palatine nerve supplies the soft palate.

• Another branch of the pterygopalatine ganglion, the nasopalatine nerve, emerges from the incisive foramen and supplies the mucous membrane of the anterior part of the hard palate.