Thoracic Wall and Diaphragm Anatomy

Comprehensive vocabulary flashcards covering the anatomy, joints, neurovascular structures, clinical conditions, and mechanical function of the thoracic wall and diaphragm.

True Ribs (Vertebrosternal Ribs)

The first $7$ pairs of ribs (ribs $1\text{--}7$) that articulate directly with the sternum anteriorly through their costal cartilages.

False Ribs (Vertebrochondral Ribs)

Ribs $8$ through $10$, whose costal cartilages articulate anteriorly with the costal cartilage of the rib immediately above rather than directly with the sternum.

Floating Ribs (Vertebral Ribs)

Ribs $11$ and $12$, which have no anterior connection to the sternum or adjacent costal cartilages and end in the abdominal musculature.

Thoracic Inlet

The superior aperture of the thorax bounded anteriorly by the upper border of the manubrium sterni, posteriorly by the anterior border of the superior surface of the $T1$ vertebra, and laterally by the medial border of the first rib and its costal cartilage.

Sibson's Fascia (Suprapleural Membrane)

A tent-like fascial structure attached to the transverse process of the $C7$ vertebra and the medial border of the first rib, which covers and protects the cervical dome of the pleura and apex of the lung.

Thoracic Inlet Syndrome

A clinical condition caused by compression of the subclavian artery and the lower trunk of the brachial plexus ($T1$) as they cross over the first rib, often due to a cervical rib or a hypertrophied scalenus anterior muscle.

Sternal Angle (Angle of Louis)

A palpable transverse ridge located around $5\,\text{cm}$ below the suprasternal notch where the manubrium joins the body of the sternum, lying opposite the $T4\text{--}T5$ intervertebral disc.

Sternal Puncture

A procedure involving bone marrow aspiration from the upper part of the manubrium sterni because it is subcutaneous and accessible; avoided in children due to thin sternal bone.

Mid-sternotomy

A median longitudinal surgical division of the sternum used to gain access to the heart and great blood vessels.

Funnel Chest (Pectus Excavatum)

A thoracic deformity in which the chest is compressed anteroposteriorly and the sternum is pushed backward by overgrowth of the ribs, potentially compressing the heart.

Pigeon Chest (Pectus Carinatum)

A chest wall deformity where the chest is compressed laterally and the sternum projects forward and downward like the keel of a boat.

Cleft Sternum

A congenital defect caused by failure of the sternebrae to fuse in the midline, often associated with ectopia cordis.

Typical Thoracic Vertebrae

Vertebrae $T2$ through $T8$, characterized by heart-shaped bodies, circular vertebral foramina, long downward-directed spinous processes, and costal facets for rib articulation.

Atypical Thoracic Vertebrae

Vertebrae $T1$ and $T9$ through $T12$, which possess unique articular facet arrangements and distinct features setting them apart from typical thoracic vertebrae.

Intervertebral Disc

A secondary cartilaginous joint structure composed of an outer fibrous ring (annulus fibrosus) and a soft inner gel-like center (nucleus pulposus) situated between adjacent vertebral bodies.

Typical Ribs

Ribs $3$ through $9$, which share identical general structural features classified as Curved, Angulated, and Twisted (CAT).

Costal Groove

A groove along the lower border of the inner surface of a rib shaft that lodges, from above downward, the intercostal vein, intercostal artery, and intercostal nerve (VAN).

Scalene Tubercle

A prominent tubercle on the inner border of the first rib that provides insertion for the scalenus anterior muscle and separates the anterior groove for the subclavian vein from the posterior groove for the subclavian artery.

Cervical Rib

An anomalous extra rib arising from an elongated costal element of the $C7$ vertebra, occurring in $5\%$ of individuals, which can cause thoracic inlet syndrome.

Lumbar Rib (Gorilla Rib)

An accessory rib developing from the costal element of the $L1$ vertebra, which is usually asymptomatic but can be misdiagnosed as an $L1$ transverse process fracture.

Flail Chest (Stove-in-Chest)

A traumatic condition that occurs when multiple adjacent ribs are fractured in two separate places (anteriorly and at the angle), creating an unattached, paradoxically moving chest wall segment.

External Intercostal Muscle

Eleven pairs of intercostal muscles running downwards, forwards, and medially that extend from the rib tubercles to the costochondral junction and elevate the ribs during inspiration.

Internal Intercostal Muscle

Eleven pairs of intercostal muscles running downwards, forwards, and laterally that extend from the sternum to the rib angles and act primarily to depress the ribs during expiration.

Sternocostalis

A muscle originating from the posterior surface of the lower body of the sternum and xiphoid process that inserts into costal cartilages $2$ through $6$ to draw them downward.

Typical Intercostal Nerves

Intercostal nerves $3$ through $6$ (ventral rami of thoracic spinal nerves), which remain entirely restricted to their corresponding intercostal spaces.

Herpes Zoster (Shingles)

A viral infection of the thoracic spinal ganglia presenting with severe pain and a rash of cutaneous vesicles localized along the dermatomal area supplied by an intercostal nerve.

Coarctation of Aorta

A congenital narrowing of the aortic arch that leads to compensatory enlargement of posterior intercostal arteries, causing characteristic erosion and notching of the lower borders of the ribs.

Internal Thoracic Artery

A branch of the subclavian artery that runs vertically down the inner chest wall behind the costal cartilages, supplying the upper $6$ intercostal spaces before terminating as the superior epigastric and musculophrenic arteries.

Right Crus of Diaphragm

A musculotendinous slip arising from the anterior surfaces of the bodies of the upper three lumbar vertebrae ($L1\text{--}L3$) and their intervertebral discs.

Left Crus of Diaphragm

A musculotendinous slip arising from the anterior surfaces of the bodies of the upper two lumbar vertebrae ($L1\text{--}L2$) and their intervertebral discs.

Medial Arcuate Ligament (Medial Lumbocostal Arch)

A thickening of fascia extending over the upper psoas major muscle from the body of $L1$ or $L2$ to the transverse process of $L1$, transmitting the sympathetic trunk beneath it.

Lateral Arcuate Ligament (Lateral Lumbocostal Arch)

A thickening of fascia extending over the upper quadratus lumborum muscle from the transverse process of $L1$ to the twelfth rib, transmitting the subcostal nerve and vessels beneath it.

Vena Caval Opening

A major opening in the central tendon of the diaphragm situated at the level of the $T8$ vertebra that transmits the inferior vena cava and the right phrenic nerve.

Esophageal Opening

An aperture located within the right crus of the diaphragm at the level of the $T10$ vertebra that transmits the esophagus, anterior and posterior vagal trunks, and esophageal branches of the left gastric artery.

Aortic Opening

An osseo-aponeurotic opening situated posterior to the median arcuate ligament at the level of the $T12$ vertebra that transmits the abdominal aorta, thoracic duct, and azygos vein.

Phrenic Nerves

Spinal nerves ($C3\text{--}C5$) providing the sole motor innervation to the entire diaphragm as well as sensory innervation to its central tendinous region.

Foramen of Bochdalek (Pleuroperitoneal Hiatus)

A posterolateral defect between the costal and vertebral origins of the diaphragm resulting from non-closure of the pleuroperitoneal canal, representing the most common site for congenital diaphragmatic hernia.

Space of Larrey (Foramen of Morgagni)

A retrosternal gap between the sternal and costal slips of origin of the diaphragm through which retrosternal hernias and superior epigastric vessels pass.

Sliding Hiatal Hernia

The most common internal hernia in which the gastroesophageal junction and upper stomach protrude upward through the esophageal hiatus into the thoracic cavity.

Pump-Handle Movement

A movement during respiration involving elevation of vertebrosternal ribs (ribs $2\text{--}6$) that increases the anteroposterior diameter of the thoracic cavity.

Bucket-Handle Movement

A movement during respiration involving elevation and outward eversion of vertebrochondral ribs (ribs $7\text{--}10$) that increases the transverse diameter of the thoracic cavity.