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
The Medial Wall of the Orbit
- This wall is paper-thin and is formed by the orbital lamina or lamina papyracea of the ethmoid bone, along with contributions from the frontal, lacrimal, and sphenoid bones (L. papyraceus, "made of papyrus" or parchment paper).
- There is a vertical lacrimal groove in the medial wall, which is formed anteriorly by the maxilla and posteriorly by the lacrimal bone.
- It forms a fossa for the lacrimal sac and the adjacent part of the nasolacrimal duct.
- Along the suture between the ethmoid and frontal bones are two small foramina; the anterior and posterior ethmoidal foramina.
- These transmit nerves and vessels of the same name.
-> This bone forms much of the base and posterior aspect of the skull.
-> It has a large opening called the foramen magnum, through which the cranial cavity communicates with the vertebral canal.
-> It is also where the spinal cord becomes continuous with the medulla (oblongata) of the brain stem.
-> The occipital bone is saucer-shaped and can be divided into four parts: a squamous part (squama), a basilar part (basioccipital part), and two lateral parts (condylar parts).
-> These four parts develop separately around the foramen magnum and unite at about the age of 6 years to form one bone.
-> On the inferior surfaces of the lateral parts of the occipital bone are occipital condyles, where the skull articulates with C1 vertebra (the atlas) at the atlanto-occipital joints.
-> The internal aspect of the squamous part of the occipital bone is divided into four fossae: the superior two for the occipital poles of the cerebral hemispheres, and the inferior two, called cerebellar fossae, for the cerebellar hemispheres.
Muscles of the Soft Palate
The Levator Veli Palatini (Levator Palati)
- Superior attachment: cartilage of the auditory tube and petrous part of temporal bone.
- Inferior attachment: palatine aponeurosis.
- Innervation: pharyngeal branch of vagus via pharyngeal plexus.
- This cylindrical muscle runs inferoanteriorly, spreading out in the soft palate, where it attaches to the superior surface of the palatine aponeurosis.
- It elevates the soft palate, drawing it superiorly and posteriorly.
- It also opens the auditory tube to equalise air pressure in the middle ear and pharynx.
The Tensor Veli Palatini (Tensor Palati)
- Superior attachment: scaphoid fossa of medial pterygoid plate, spine of sphenoid bone, and cartilage of auditory tube.
- Inferior attachment: palatine aponeurosis.
- Innervation: medial pterygoid nerve (a branch of the mandibular nerve).
- This thin, triangular muscle passes inferiorly, and hooks around the hamulus of the medial pterygoid plate.
- It then inserts into the palatine aponeurosis.
- This muscle tenses the soft palate by using the hamulus as a pulley.
- It also pulls the membranous portion of the auditory tube open to equalise air pressure of the middle ear and pharynx.
The Palatoglossus Muscle
- Superior attachment: palatine aponeurosis.
- Inferior attachment: side of tongue.
- Innervation: cranial part of accessory nerve (CN XI) through the pharyngeal branch of vagus (CN X) via the pharyngeal plexus.
- This muscle, covered by mucous membrane, forms the palatoglossal arch.
- The palatoglossus elevates the posterior part of the tongue and draws the soft palate inferiorly onto the tongue.
The Palatopharyngeus Muscle
- Superior attachment: hard palate and palatine aponeurosis.
- Inferior attachment: lateral wall of pharynx.
- Innervation: cranial part of accessory nerve (CN XI) through the pharyngeal branch of vagus (CN X) via the pharyngeal plexus.
- This thin, flat muscle is covered with mucous membrane to form the palatopharyngeal arch.
- It passes posteroinferiorly in this arch.
- This muscle tenses the soft palate and pulls the walls of the pharynx superiorly, anteriorly and medially during swallowing.
The Musculus Uvulae
- Superior attachment: posterior nasal spine and palatine aponeurosis.
- Inferior attachment: mucosa of uvula.
- Innervation: cranial part of accessory through the pharyngeal branch of vagus, via the pharyngeal plexus.
- It passes posteriorly on each side of the median plane and inserts into the mucosa of the uvula.
- When the muscle contracts, it shortens the uvula and pulls it superiorly.
|
Pharyngeal Arch |
Arch Artery |
Cranial Nerve |
Skeletal elements |
Muscles |
|
1 |
Terminal Branch of maxillary artery |
Maxillary and mandibular division of trigemenial (V) |
Derived from arch cartilages (originating from neural crest): From maxillary cartilages: Alispenoid, incus From mandibular: Mackel’s cartilage, malleus
Upper portion of external ear (auricle) is derived from dorsal aspect of 1st pharyngeal arch.
Derived by direct ossification from arch dermal mesenchyme: Maxilla, zygomatic, squamous portion of temporal bone, mandible
|
Muscles of mastication (temporalis, masseter, and pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini (originate from cranial somitomere 4) |
|
2 |
Stapedius artery (embryologic) and cortiotympanic artery (adult) |
Facial nerve (VII) |
Stapes, styloid process, stylohyoid ligament, lesser horns and upper rim of hyoid (derived from the second arch cartilage; originate from neural crest).
Lower portion of external ear (auricle) is derived from 2nd pharyngeal arch. |
Muscles of facial expression (orbicularis oculi, orbicularis oris, auricularis, platysma, fronto-ooccipitalis, buccinator), posterior belly of digastric, stylohyoid, stapedius (originate from cranial somitomere 6) |
|
3 |
Common carotid artery, most of internal carotid |
Glossopharyngeal (IX) |
Lower rim and greater horn of hyoid (derived from the third arch cartilage; originate from neural crest cells) |
Sytlopharyngeus (originate from cranial somitomere 7) |
|
4 |
Left: Arch of aorta; Right: Right subclavian artery; Original sprouts of pulmonary arteries |
Superior laryngeal branch of vagus (X) |
Laryngeal cartilages (Derived from the 4th arch cartilage, originate from lateral plate mesoderm) |
Constrictors of pharynx, cricothyroid, levator veli palatine (originate from occipital somites 2-4) |
|
6 |
Ductus arteriosus; roots of definitive pulmonary arteries |
Recurrent laryngeal branch of vagus (X) |
Laryngeal cartilages (derived from the 6th-arch cartilage; originate from lateral plate mesoderm) |
Intrinsic muscles of larynx (originate from occipital somites 1 and 2) |
The Salivary Glands
- There are three large, paired salivary glands: the parotid, submandibular, and sublingual glands.
- In addition to the main salivary glands, there are numerous small accessory salivary glands scattered over the palate, lips, cheeks, tonsils, and tongue.
Classified on functional Basis
Secretion ,Protection and waterproofing, Absorbtion, Transport, Sensory
Secretion
Glandular epithelium’s 3 types:
- Exocrine - with ducts
- endocrine - without ducts
- mixed exo-endocrine
Exocrine glands: One cell
- goblet cells
- In lining epitheliums of respiratory tract and GIT
- Secretes musin (protein) Musin + water = mucus, Mucus is a lubricant
More than one cell
Simple: Has a single duct,
- Acinar - mucus glands of the penile urethra
- Tubular - cripts of Lieberkuhn
- Coiled tubular - sweat gland
- Spiral tubular - Gland of Moll
- Branched tubular - mucous glands of the pyloric region
- Branched acinar - sebaceous gland in the skin
Compound
- Consists of a branched duct with numerous secretory end organs
- Compound tubular - Brünners glands
- Compound alveolar - mammary, prostate, pancreas, parotid
- Compound tubuloalveolar - submandibular-, sublingual salivary glands
Endocrine glands
Secrete directly into the blood
One cell : mast cells, in soft CT, near capillaries,
secrete - heparin - histamine
More than one cell
Cells can be arranged in the following ways:
- Cords - adrenal glands, parathyroid, anterior pituitary
- anastomosing cords with dilated blood capillaries in-between
- Isles - pancreas
- Follicles - thyroid
- cells line a follicle filled with non-cellular material