RACK 6 ABDOMEN AND CLINICAL ANATOMY

The descending aorta is the longest section of the aorta, running from the T4 vertebra (thoracic) to the T12 vertebra, where it becomes the abdominal aorta, descending to L4 before bifurcating into the right and left common iliac arteries. It supplies the torso, organs, and, through the iliac arteries, the pelvis and lower limbs. 

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Anatomy of the Descending Aorta

The dura mater is the thickest, outermost layer of the meninges surrounding the brain and spinal cord, acting as a protective, fibrous, and inelastic membrane. It consists of a two-layered cranial structure (periosteal and meningeal) and a single-layered spinal structure, with critical functions in venous drainage, compartmentalization of the brain, and support. 

The spinal cord is a cylindrical bundle of nervous tissue and supporting cells, extending from the brainstem's medulla oblongata through the vertebral column to the L1-L2 vertebrae. It is a key component of the central nervous system, characterized by central gray matter (cell bodies) surrounded by white matter (myelinated nerve fibers), and divided into 31 segments that send out paired spinal nerves for movement and sensation. 

Your spinal cord is a cylinder-shaped tube of tissue that runs through the center of your spine, from your brainstem to your lower back. It’s made of nerves and cells that carry messages from your brain to the rest of your body. Your spinal cord is one of the main parts of your nervous system.

The human spinal column is a flexible, S-shaped structure composed of 33 vertebrae divided into five regions—cervical (7), thoracic (12), lumbar (5), sacrum (5 fused), and coccyx (4 fused). It protects the spinal cord, supports the head and upper body, and allows movement. Intervertebral discs act as shock absorbers, while ligaments and muscles provide stability. 

Key Regions of the Spinal Column

The thyroid is a butterfly-shaped endocrine gland in the anterior neck (vertebral levels C5-T1), comprising two lobes connected by an isthmus over the 2nd-4th tracheal rings. It is highly vascular, wrapped around the trachea and larynx, and enclosed in pretracheal fascia. The trachea is a cartilaginous tube extending from the larynx to the bronchi, located posteriorly to the thyroid isthmus. 

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Thyroid Gland Anatomy

 The thyroid is a butterfly-shaped endocrine gland located in the anterior neck, spanning vertebrae C5 to T1, just below the laryngeal prominence (Adam's apple). It consists of two lobes (left and right) connected by an central isthmus that lies over the second and third tracheal rings. Weighing approximately

The tongue is a highly mobile, muscular organ in the oral cavity anchored to the hyoid bone, designed for tasting, mastication, swallowing, and speech. It is divided into an anterior two-thirds (body) and posterior one-third (base) by the V-shaped sulcus terminalis. It is covered in papillae (filiform, fungiform, circumvallate) and comprises intrinsic and extrinsic muscles, primarily innervated by the hypoglossal nerve. 

The tongue, larynx, and esophagus work in concert for speech, digestion, and airway protection. The tongue (oral/pharyngeal parts) connects to the epiglottis, which covers the larynx during swallowing to prevent aspiration, pushing food into the oesophagus. Key structures include the epiglottic valleculae, laryngeal ventricle, and vocal folds. 

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A fibrous liver is characterized by the excessive accumulation of extracellular matrix (ECM) proteins, such as collagen, resulting from chronic injury and