NEET MDS Lessons
Anatomy
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
Appendicular Skeleton
Upper extremity
• Shoulder-clavicle and scapula
Clavicle
Articulates with the manubrium at the sternal end
Articulates with the scapula at the lateral end
Slender S-shaped bone that extends horizontally across the upper part of the thorax
Scapula
Triangular bone with the base upward and the apex downward
Lateral aspect contains the glenoid cavity that articulates with the head of the humerus
Spine extends across the upper part of the posterior surface; expands laterally and
forms the acromion (forms point of shoulder)
Coracoid process projects anteriorly from the upper part of the neck of the scapula
Arm (humerus)
Consists of a shaft (diaphysis) and two ends (epiphyses)
Proximal end has a head that articulates with the glenoid fossa of the scapula
Greater and lesser tubercles lie below the head
Intertubercular groove is located between them; long tendon of the biceps attaches here
Surgical neck is located below the tubercles
o Radial groove runs obliquely on the posterior surface; radial nerve is located here
o Deltoid muscles attaches in a V-shaped area in the middle of the shaft. called the deltoid tuberosity
Distal end has two projections. the medial and lateral epicondyles
Capitulum-articulates with the radius
Trochlea-articulates with the ulqa
Forearm
Radius
Lateral bone of the forearm
Radial tuberosity is located below the head on the medial side
Distal end is broad for articulation with the wrist: has a styloid process on its lateral side
Ulna
Medial side of the forearm
Conspicuous part of the elbow joint (olecranon)
Curved surface that articulates with the trochlea of the humerus is the trochlearnotch
Lateral ide is concave (radial notch); articulates with the head of the radius Distal end contains the styloid process
Distal end contains the styloid process
Hand
Carpal bones (8)
Aranged in two rows of four
Scaphoid. lunate. triquetral. and pisiform proximal row); trapezium. trapezoid.
capitate. and hamate (distal row)
Metacarpal bones (5)
Framework of the hand
Numbered 1 to 5 beginning on the lateral side
Phalanges (14)
Fingers
Three phalanges in each finger; two phalanges in the thumb
The Lips
- These are mobile muscular folds that surround the mouth, the entrance of the oral cavity.
- The lips (L. labia) are covered externally by skin and internally by mucous membrane.
- In between these are layers of muscles, especially the orbicularis oris muscle.
- The upper and lower lips are attached to the gingivae in the median plane by raised folds of mucous membrane, called the labial frenula.
Sensory Nerves of the Lips
- The sensory nerves of the upper and lower lips are from the infraorbital and mental nerves, which are branches of the maxillary (CN V2) and mandibular (CN V3) nerves.
The Medial Pterygoid Muscle
- This is a thick, quadrilateral muscle that also has two heads or origin.
- It embraces the inferior head of the lateral pterygoid muscle.
- It is located deep to the ramus of the mandible.
- Origin: deep head—medial surface of lateral pterygoid plate and pyramidal process of palatine bone, superficial head—tuberosity of maxilla.
- Insertion: medial surface of ramus of mandible, inferior to mandibular foramen.
- Innervation: mandibular nerve via medial pterygoid nerve.
- It helps to elevate the mandible and closes the jaws.
- Acting together, they help to protrude the mandible.
- Acting alone, it protrudes the side of the jaw.
- Acting alternately, they produce a grinding motion.
- 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.
Muscles Moving the Auditory Ossicles
The Tensor Tympani Muscle
- This muscle is about 2 cm long.
- Origin: superior surface of the cartilaginous part of the auditory tube, the greater wing of the sphenoid bone, and the petrous part of the temporal bone.
- Insertion: handle of the malleus.
- Innervation: mandibular nerve (CN V3) through the nerve to medial pterygoid.
- The tensor tympani muscle pulls the handle of the malleus medially, tensing the tympanic membrane, and reducing the amplitude of its oscillations.
- This tends to prevent damage to the internal ear when one is exposed to load sounds.
The Stapedius Muscle
- This tiny muscle is in the pyramidal eminence or the pyramid.
- Origin: pyramidal eminence on the posterior wall of the tympanic cavity. Its tendon enters the tympanic cavity by traversing a pinpoint foramen in the apex of the pyramid.
- Insertion: neck of the stapes.
- Innervation: nerve to the stapedius muscle, which arises from the facial nerve (CN VII).
- The stapedius muscle pulls the stapes posteriorly and tilts its base in the fenestra vestibuli or oval window, thereby tightening the anular ligament and reducing the oscillatory range.
- It also prevents excessive movement of the stapes.
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