Anatomy Bones and Muscles · MU Pleven

5. Thorax - bony connections and thorax as a whole

Covers the bony parts of the thorax, including the sternum, the twelve ribs grouped as true, false and floating, and the thoracic vertebrae. It then describes how these bones connect: costovertebral and costotransverse joints, costochondral, sternocostal and interchondral joints, and the manubriosternal and xiphisternal joints. It closes with the thorax as a whole, its walls, superior and inferior apertures, contents and respiratory function.

Inside: 5 sections · 5 labelled pictures · 19 flashcards · 2 min

Topic 5 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 5 sections, about 267 words (2 min of reading), with 19 flashcards.

In this note

  1. THORAX-BONY CONNECTIONS AND THORAX AS A WHOLE
  2. BONY ELEMENTS OF THE THORAX
  3. CONNECTIONS BETWEEN BONY ELEMENTS
  4. THORAX AS A WHOLE
  5. FUNCTION OF THORAX

BONY ELEMENTS OF THE THORAX

  • → STERNUM (MANUBRIUM, BODY, XIPHOID, PROCESS)
  • → RIBS (12 P)
  • → 1-7 = TRUE RIBS (ATTACH DIRECTLY TO STERNUM VIA COSTAL CARTILAGES)
  • → 8-10 = FALSE RIBS (JOIN ABOVE RIB'S CARTILAGE, THEN STERNUM INDIRECTLY)
  • → 11-12 = FLOATING RIBS (NO STERNAL CONNECTION)

THORACIC VERTEBRAE (T₁ · T₂)

CONNECTIONS BETWEEN BONY ELEMENTS

(a) VERTEBRA-RIB CONNECTIONS

  • COSTOVERTEBRAL JOINTS: RIB HEAD ↔ BODY OF VERTEBRAE (SUPERIOR + INFERIOR COSTAL FACETS).
  • COSTOTRANSVERSE JOINTS: RIB TUBERCLE ↔ TRANSVERSE PROCESS OF VERTEBRA

(b) RIB - STERNUM CONNECTIONS

  • COSTOCHONDRAL JOINTS: RIBS ↔ COSTAL CARTILAGE (SYNCHONDROSIS, IMMOVABLE).
  • STERNOCOSTAL JOINTS: COSTAL CARTILAGE ↔ STERNUM (SYNOVIAL, EXCEPT 1st RIB = SYNCHONDROSIS)
  • INTERCHONDRAL JOINTS: BETWEEN COSTAL CARTILAGES OF RIB 6-9 (SOMETIMES 9-10).

(c) STERNUM - STERNUM CONNECTIONS

  • MANUBRIOSTERNAL JOINT (MANUBRIUM ↔ BODY → FIBROCARTILAGINOUS, FORMS STERNAL ANGLE (angle of LOUIS).
  • XIPHISTERNAL JOINT (BODY ↔ XIPHOID → CARTILAGINOUS, MARKS INFERIOR LIMIT OF THORACIC CAVITY

THORAX AS A WHOLE

(a) SHAPE: CONE/ TRUNCATED CONE → NARROW AT TOP (THORACIC INLET), WIDE AT BOTTOM (THORACIC INLET), WIDE AT BOTTOM

(b) BOUNDARIES

ANT. WALL : STERNUM + COSTAL CARTILAGES

POST. WALL : THORACIC VERTEBRAE + RIBS.

LAT. WALL : RIBS + INTERCOSTAL MUSCLES

(c) OPENINGS

SUPERIOR THORACIC APERTURE (THORACIC INLET)

BOUNDARIES → T1 VERTEBRAE, 1st RIB, MANUBRIUM

STRUCTURES PASSING → TRACHEA, ESOPHAGUS, VESSELS (SUBCLAVIAN A/V), NERVES

INFERIOR THORACIC APERTURE (THORACIC OUTLET)

BOUNDARIES → T12 VERTEBRA, 12th RIBS, COSTAL MARGIN, XIPHISTERNAL JOINT.

CLOSED BY DIAPHRAGM (MAIN RESPIRATORY MUSCLE).

(d) CONTENTS

THORACIC CAVITY

  • RIGHT AND LEFT PLEURAL CAVITIES (LUNGS)
  • MEDIASTINUM (HEART TRACHEA, ESOPHAGUS, THYMUS, VESSELS, NERVES)

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