NEET MDS Lessons
Anatomy
Sternum
o Forms the medial part of the anterior chest wall
o Manubrium (upper part)-clavicle and first rib articulate with the manubrium .
o Body (middle blade)-second and tenth ribs articulate with the body via the costal cartilages
o Xiphoid (blunt cartilaginous tip)
Ribs (12 pairs)
o Each rib articulates with both the body and the transverse process of its corresponding
o thoracic vertebra
o The second to ninth ribs articulate with the body of the vertebra above'
o Ribs curve outward, forward, and then downward
o Anteriorly, each of the first seven ribs joins a costal cartilage that attaches to the sternum
o Next three ribs (eighth to tenth) join the cartilage of the rib above
o Eleventh and twelfth ribs do not attach to the sternum; are called "floating ribs"
The Nose
- The nose is the superior part of the respiratory tract and contains the peripheral organ of smell.
- It is divided into right and left nasal cavities by the nasal septum.
- The nasal cavity is divided into the olfactory area and the respiratory area.
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.
The Nasal Mucosa
- Mucosa lines the entire nasal cavities except for the vestibule of the nose.
- The nasal mucosa is firmly bound to the periosteum and perichondrium of the supporting structures of the nose.
- It is continuous with the adjoining cavities to which the nasal cavity communicates (e.g., the nasopharynx and paranasal sinuses).
- The inferior 2/3 of the nasal mucosa is called the respiratory area and air passing over this is warmed and moistened before it passes into the lungs.
- The superior 1/3 is called the olfactory area.
The Olfactory Area of Nasal Mucosa
- This area contains the peripheral organ of smell.
- Sniffing draws air into this area
- Olfactory receptor cells (from the olfactory nerve, CN I, are located in the mucosa of this area in the nose.
Nerves to the Respiratory Area of Nasal Mucosa
- The inferior 2/3 of the nasal mucosa are supplied chiefly by the trigeminal nerve (CN V).
- The mucous membrane of the nasal septum is supplied chiefly by the nasopalatine nerve, a branch of the maxillary nerve (CN V2).
- Its anterior portion is supplied by the anterior ethmoidal nerve (a branch of the nasociliary nerve) which is derived from the ophthalmic nerve (CN V1).
- The lateral walls of the nasal cavity are supplied by branches of the maxillary nerve (CN V2); the greater palatine nerve, and the anterior ethmoidal nerve.
Arteries of the Nasal Mucosa
- The blood supply of the mucosa of the nasal septum is derived mainly from the maxillary artery.
- The sphenopalatine artery, a branch of the maxillary, supplies most of the blood of the nasal mucosa.
- It enters by the sphenopalatine foramen and sends branches to the posterior regions of the lateral wall and to the nasal septum.
- The greater palatine artery, also a branch of the maxillary, passes through the incisive foramen to supply the nasal septum.
- The anterior and posterior ethmoidal arteries, branches of the ophthalmic artery, supply the anterosuperior part of the mucosa of the lateral wall of the nasal cavity and nasal septum.
- Three branches of the facial artery (superior labial, ascending palatine, and lateral nasal) also supply the anterior parts of the nasal mucosa.
Veins of the Nasal Mucosa
- The veins of the nasal mucosa form a venous network of plexus in the connective tissue of the nasal mucosa.
- Some of the veins open into the sphenopalatine vein and drain to the pterygoid plexus.
- Others join the facial and infraorbital veins.
- Some empty into the ophthalmic veins and drain into the cavernous sinus.
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Pharyngeal Arch |
Arch Artery |
Cranial Nerve |
Skeletal elements |
Muscles |
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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
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Muscles of mastication (temporalis, masseter, and pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini (originate from cranial somitomere 4) |
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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) |
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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) |
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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) |
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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) |
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Muscle
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Emotion
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Epicranius
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Surprise
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Orbicularisoculi
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Squinting
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Orbicularisoris |
Pouting |
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Nasalis
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Smelling
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Zygomaticus
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Smiling
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Buccinator
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Chewing
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Mentalis
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Doubt
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Triangularis
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Sadness
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Platysma
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Sadness
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Masseter
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Chewing
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Temporalis
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Sternness
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Pterygoid
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Conternation
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Genioglossus and Styloglossus
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Swallowing, Speaking, Chewing
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Ossification
- Intramembranous-found in the flat bones of the face
- Mesenchymal cells cluster and form strands
- Strands are cemented in a uniform network. Which is known as osteoid
- Calcium salts are deposited; osteoid is converted to bone
- Trabeculae are formed and make cancellous bone with open spaces known as marrow cavities
- Periosteum forms on the inner and outer surfaces of the ossification centers
- Surface bone becomes compact bone
- Endochondral-primary type of ossification In the human