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Anatomy - NEETMDS- courses
NEET MDS Lessons
Anatomy

Ligaments of the Joint

  • The fibrous capsule is thickened laterally to form the lateral (temporomandibular) ligament. It reinforces the lateral part of this capsule.
  • The base of this triangular ligament is attached to the zygomatic process of the temporal bone and the articular tubercle.
  • Its apex is fixed to the lateral side of the neck of the mandible.
  • Two other ligaments connect the mandible to the cranium but neither provides much strength.
  • The stylomandibular ligament is a thickened band of deep cervical fascia.
  • It runs from the styloid process of the temporal bone to the angle of the mandible and separates the parotid and submandibular salivary glands.
  • The sphenomandibular ligament is a long membranous band that lies medial to the joint.
  • This ligament runs from the spine of the sphenoid bone to the lingula on the medial aspect of the mandible.

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

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.

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

 

  • Articulations

    Classified according to their structure, composition,and movability
    •    Fibrous joints-surfaces of bones almost in direct contact with limited movement
        o    Syndesmosis-two bones united by interosseous ligaments
        o    Sutures-serrated margins of bones united by a thin layer of fibrous tissue
        o    Gomphosis-insertion of a cone-shaped process into a socket

    •    Cartilaginous joints-no joint cavity and contiguous bones united by cartilage
        o    Synchondrosis-ends of two bones approximated by hyaline cartilage
        o    Symphyses-approximating bone surfaces connected by fibrocartilage

    •    Synovial joints-approximating bone surfaces covered with cartilage; may be separated by a disk; attached by ligaments 
        o    Hinge-permits motion in one plane only
        o    Pivot-permits rotary movement in which a ring rotates around a central axis
        o    Saddle-opposing surfaces are convexconcave. allowing great freedom of motion
        o    Ball and socket - capable of movement in an infinite number of axes; rounded head of one bone moves in a cuplike cavity of the approximating bone

    Bursae
    •    Sacs filled with synovial fluid that are present where tendons rub against bone or where skjn rubs across bone
    •    Some bursae communicate with a joint cavity 
    •    Prominent bursae found at the elbow. hip, and knee'

    Movements
    •    Gliding
        o    Simplest kind of motion in a joint
        o    Movement on a joint that does not involve any angular or rotary motions
    •    Flexion-decreases the angle formed by the union of two bones
    •    Extension-increases the angle formed by the union of two bones
    •    Abduction-occurs by moving part of the appendicular skeleton away from the median plane of the body
    •    Adduction-occurs by moving part of the appendicular skeleton toward the median plane of the body
    •    Circumduction
        o    Occurs in ball-and-socket joints
        o    Circumscribes the conic space of one bone by the other bone
    •    Rotation-turning on an axis without being displaced from that axis
     

Nerve Supply of the Muscles of the Orbit (pp. 715-6)

  • Three cranial nerves supply the muscles of the eyeball; the oculomotor (CN III), trochlear (CN IV) and abducent (CN IV) nerves.
  • All three enter the orbit via the superior orbital fissure.
  • The trochlear nerve supplies the superior oblique muscle.
  • The abducent nerve supplies the lateral rectus muscle.
  • The oculomotor nerve supplies everything else.
  • A mnemonic that is used is this formula for this strange sulfate: SO4(LR6)3

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

 

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