NEET MDS Lessons
Anatomy
EPITHELIUMS
Epithelial Tissue Epithelial tissue covers surfaces, usually has a basement membrane, has little extracellular material, and has no blood vessels. A basement membrane attaches the epithelial cells to underlying tissues. Most epithelia have a free surface, which is not in contact with other cells. Epithelia are classified according to the number of cell layers and the shape of the cells.
- Epitheliums contain no blood vessels. There is normally an underlying layer of connective tissue
- Almost all epitheliums lie on a basement membrane.The basement membrane consists of a basal lamina and reticular lamina. The reticular lamina is connected to the basal lamina by anchoring fibrils. The reticular lamina may be absent in which case the basement membrane consist only of a basal lamina. The basal lamina consists of a - lamina densa in the middle (physical barrier) with a lamina lucida on both sides (+charge barrier),The basement membrane is absent in ependymal cells.The basement membrane is not continuous in sinusoidal capillaries.
- Epitheliums always line or cover something
- Epithelial cells lie close together with little intercellular space
- Epithelial cells are strongly connected to one another especially those epitheliums that are subjected to mechanical forces.
Functions of Epithelium:
→ Simple epithelium involved with diffusion, filtration, secretion, or absorption
→ Stratified epithelium protects from abrasion
→ Squamous cells function in diffusion or filtration
Hip
Constitutes the pelvic girdle
United with the vertebral column
Union of three parts that is marked by a cup shaped cavity (acetabulum) Ilium
• Prominence of the hip
• Superior border is the crest
• Anterosuperior spine-projection at the anterior tip of the crest
• Corresponding projections on the posterior part are the posterosuperior and posteroinferior iliac spines
• Greater sciatic notch-located beneath the posterior part
• Most is a smooth concavity (iliac fossa)
• Posteriorly it is rough and articulates with the sacrum in the formation of the sacroiliac joint
Pubic bone
Anterior part of the innominate bone
Symphysis pubic-joining of the two pubic bones at the midline
Body and two rami
• Body forms one fifth of the acetabulum
• Superior ramis extends from the body to the median plane: superior border forms the pubic crest
• Inferior ramus extends downward and meets with the ischium
• Pubic arch is formed by the inferior rami of both pubic hones
Ischium
Forms the lower and back part of the innominate bone
Body
• Forms two fifths of the accrabulum
• Ischial tuberosiry-supports the body in a sitting position
• Ramus-passes upward to join the inferior ramus of rhe pubis; known as rhe obturator foramen
Pelvis
Fanned by the right and left hip bones, sacrum, and coccyx
Greater pelvis
o Bounded by the ilia and lower lumbar vertebrae
o Gives support to the abdominal viscera
Lesser pelvis
o Brim of the pelvis corresponds to the sacral promontory
o Inferior outlet is bounded by the tip of the coccyx, ischial tuberosities, and inferior rami of the pubic bones
Female pelvis
o Shows adaptations related to functions as a birth canal Wide outlet
o Angle of the pubic arch is obtuse
Male pelvis
o Shows adaptations that contribute to power and speed
o Heart-shaped outlet
o Angle of the pubic arch is acute
Thigh
Femur-longest and strongest bone of the body
Proximal end has a rounded head that articulates with the acetabulum
Constricted portion-the neck
Greater and lesser trochanters
Slightly arched shaft; is concave posteriorly
o Linea aspera-strengthened by this prominent ridge
o Site of attachment for several muscles
Distal end has two condyles separated on the posterior side by the intercondyloid notch
Knee cap
Patella-sesamoid bone
Embedded in the tendon of the quadriceps muscle
Articulates with the femur
Leg
Tibia-medial bone
o Proximal end has two condyles that articulate with the femur
o Triangular shaft
Anterior-shin
Posterior-soleal line
Distal-medial malleolus that articulates with the latus to form the ankle joint
Fibula-lateral bone
o Articulates with the lateral condyle of the tibia but does not enter the knee joint
o Distal end projects as the lateral malleolus
Ankle, foot, and toes
Adapted for supporting weight but similar in structure to the hand
Talus
o Occupies the uppennost and central position in the tarsus
o Distributes the body weight from the tibia above to the other tarsal bones
Calcaneus (heel)-Iocated beneath the talus
Navicular-located in front of the talus on the medial side; articulates with three cuneifonn bones distally
Cuboid-lies along the lateral border of the navicular bone
Metatarsals
o First, second, and third p1etatarsals lie in front of the three cuneifonn bones
o (2) Fourth and fifth metatarsals lie in front of the cuboid bone
Phalanges
o Distal to the metatarsals
o (2) Two in the great toe; three in each of the other four toes .
Longitudinal arches in the foot (2)
o Lateral-fonned by the calcaneus, talus, cuboid, and fourth and fifth metatarsal bones
o Medial-fonned by the calcaneus, talus, navicular, cuneifonn, and first, second, and third metatarsal bones
Transverse arches-formed by the tarsal and metatarsal bones
o English: all speech sounds produced by making exhaled air audible
o Two ways of producing sound
at larynx
further up in vocal tract (tongue, lips)
o How to produce sound at larynx
changes in breathing: regulate airstream from lungs to atmosphere by changing movements of vocal folds, pharynx, soft-palate, tongue, lips and jaws
• inhalation: take in greater volume more quickly, abduct folds
• expiration: variable force; use muscles of inhalation to control rate of expiration, adduct
How to vibrate vocal cords
• NOT rhythmic contraction of laryngeal muscles: would be impossible b/c frequenceies of virbration
• Changes in air pressure cause vibrations
o Adduct folds increase in subglottal pressure force folds apart folds sucked back together (Bernouilli effect)
• The vibration of vocal cords disturbs airareas of low pressure (rarefaction) alternating with areas of high pressure (compression)
• Changes in pressure sound at ears
• Sine waves
o Changes in amplitudes: loudness
o Changes in frequency: pitch
o Normal sounds have fundamental frequency, overtones or harmonics
o Mass of folds: critical in voice
Low pitch of lion’s roar: due to massive fibrous pad that forms part of vocal cords
Men: more massive vocal cords
Larger foldsslow vibrationdeeper voice
o Producing vowels and constants
Most vowels are “voiced”: vocal folds produce sounds
Consonants: can be “voiced” (Z) or “non-voiced” (S)
• Use higher regions of vocal tract to control by stopping, restricting airflow from vocal folds; use lips, teethaperiodic sound
o Vocal folds and resonators emphasize and deemphasize certain frequencies
Never hear sounds produced at vocal foldsevery sound changed by passage thru vocal tract: sinuses/resonating chambers
Howling monkeys: large hyoid bonepowerful resonator
o Age-related changes in voice
Infant larynx is smaller, different proportions
• Arytenoids are proportionately larger
• Smaller vocal apparatushigher pitch
• Larynx sits higher easier to breathe thru nose
Abrupt change in larynx at pubertycan’t control voice
Older adult: normal degenerative changes in lamina propria, ossification of thyroid cartilagechanges in fundamental frequency
Lose your voice vocal fold are irritated
• Can’t adduct foldsair escapes
o Singing v. speaking
Singing: greater thoracic pressure and uneven breathing with changes in resonators
o Whispering
Intercartilaginous portions of vocal folds: open to allow air to escapelesser subglottal pressureslittle vibration of foldslittle tonal quality, low volume
o Falsetto
Allowing only part of vocal folds to vibrate
Increase range by training which part of vocal folds to vibrate
o Colds
Mucus secretions add mass to folds—decrease in pitch, can’t adduct folds as well
o Surgeryscars, fibrotic changes can interfere with voice
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 Layers of the Pharyngeal Wall
- The pharyngeal wall is composed of 5 layers. From internal to external, they are as follows.
- Mucous membrane: this lines the pharynx and is continuous with all chambers with which it communicates.
- Submucosa
- Pharyngobasilar fascia: this is a fibrous layer that is attached to the skull.
- Muscular layer: this is composed of inner longitudinal and outer circular parts.
- Buccopharyngeal fascia: this is a loose connective tissue layer.
- This fascia is continuous with the fascia covering the buccinator and pharyngeal muscle.
- It contains the pharyngeal plexus of nerves and veins.
-
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 Parotid Glands
- The parotid glands are the largest of the three pairs of salivary glands.
- Each gland is wedged between the mandible and the sternocleidomastoid muscle and partly covers them.
- The parotid gland is wrapped with a fibrous capsule (parotid fascia) that is continuous with the deep investing fascia of the neck.
- Viewed superficially, the parotid gland is somewhat triangular in shape.
- Its apex is posterior to the angle of the mandible and its base is along the zygomatic arch.
- The parotid gland overlaps the posterior part of the masseter muscle.
- The parotid duct (Stensen's duct) is about 5 cm long and 5 mm in diameter.
- It passes horizontally from the anterior edge of the gland.
- At the anterior border of the masseter muscle, the parotid duct turns medially and pierces the buccinator muscle.
- It enters the oral cavity opposite the second maxillary molar.
Blood Vessels of the Parotid Gland
- This gland is supplied by branches of the external carotid artery.
- The veins from the parotid gland drains into the retromandibular vein, which enters the internal jugular vein.
Lymphatic Drainage of the Parotid Gland
- The lymph vessels of this gland end in the superficial and deep cervical lymph nodes.
Nerves of the Parotid Gland
- These nerves are derived from the auriculotemporal nerve and from the sympathetic and parasympathetic systems.
- The parasympathetic fibres are derived from the glossopharyngeal nerve (CN IX) through the otic ganglion.
- Stimulation of these fibres produces a thin watery (serous) saliva to flow from the parotid duct.
- The sympathetic fibres are derived from the cervical ganglia through the external carotid plexus.
- Stimulation of these fibres produces a thick mucous saliva.