General Comments.

• The vasculature supply to the thoracic wall travels within the neurovascular plane defined superficially by the internal intercostal muscles and membrane (posterior) and deeply by the subcostal (posterior), innermost intercostal (intermediate), and transversus thoracis (anterior) muscles. The intercostal veins, arteries, and nerves are located inferior to the costal groove of the superior rib defining an intercostal space. From superior to inferior is vein, artery, nerve. Posterior, lateral, and anterior branches of the intercostal vessels and nerves leave the neurovascular plane to supply superficial regions of the thoracic wall. The lateral branches further divide into posterior and anterior branches whereas the anterior branches further divide into medial and lateral branches.

Collateral circulation and structure

• The bulk of the anterior vasculature has the subclavian arteries and brachiocephalic veins as the parent vessels whereas the bulk of the posterior vasculature has the descending aorta (first two intercostal spaces excepted) and azygous system as the parent vessels. The anterior and posterior vasculatures anastomose within the thoracic wall. Thus, the aortic arch can deliver blood directly to the descending aorta or indirectly to the descending aorta by way of the anterior vasculature (subclavian to internal thoracic to anterior intercostals to posterior intercostals to descending). See below.
• Borders
  • anterior - sternum (manubrium, body, xiphoid process), chondral cartilages
  • posterior - vertebral bodies
  • lateral - ribs proper
  • superior - thoracic inlets
  • inferior - thoracic outlet
• Vertebral projections
  • sternal notch - T3
  • sternal angle - T4
  • xiphisternal junction - T9
  • inferior extent of costal margin - L3
• Fascial layers at midaxillary line
  1. skin
  2. telasubcutanea
  3. external intercostal
  4. internal intercostal
  5. neurovascular plane (van)
  6. innermost intercostal
  7. endothoracic fascia
  8. fibrous layer parietal costopleura
  9. serous layer of parietal costopleura
• Intercostal muscles - superficial to deep
  • External intercostals - anterior membrane, downward "V"
  • Internal intercostals - posterior membrane upward "V", superficial to neurovascular plane
  • Innermost intercostals - posterior as subcostals, anterior as transversus thoracis, deep to neurovascular plane
• Innervations
  • Motor innervations by intercostal nerves and posterior rami of spinal nerves T1-11
  • Cutaneous innervation described above in General Comments
    • Skin overlying xyphiod process is by spinal nerve T8
  • Autonomic innervation follows intercostal nerves
    • preganglionic cell bodies in IMLCC T1-11, postganglion cell bodies in thoracic sympathetic trunk ganglia
• Arteries
  • Posterior intercostal spaces
    • 1-2 Supereme (highest) thoracic artery from costocervical trunk of subclavian artery
    • 3-11 Posterior intercostal arteries from the descending aorta
  • Anterior intercostal spaces
    • 1-6 - Internal thoracic artery from subclavian artery
    • 7-9 - Musculophrenic artery from internal thoracic artery
    • 10-11 - Superior epigastric from internal thoracic artery
• Veins
  • Right posterior intercostal spaces
    • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
    • 2-4 - superior intercostal vein from arch of the azygous vein
    • 5-11 - Posterior intercostal veins from azygous vein
  • Left posterior intercostal spaces
    • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
    • 2-4 - superior intercostal vein from accessory hemiazygous vein, or brachiocephalic vein, or coronary sinus
    • 5-11 - Posterior intercostal veins from hemiazygous vein
  • Anterior intercostal spaces
    • 1-6 - Internal thoracic vein
    • 7-9 - Musculophrenic vein
    • 10-11 - Superior epigastric vein

Ribs, Movements and Breathing

• Ribs
  • True ribs
  • False ribs
  • Floating ribs
• Joints
  • costovertebral
  • costotransverse
  • costochondral
  • sternochondral
• Anterior posterior - pump handle and costotransverse joint
  • cupped tubercle of transverse process results in pump handle of upper ribs
  • costochondral and sternochondral joints involved
  • The pump-handle movement of respiration refers to the movements of the upper 6 ribs during breathing. During inspiration there is an increase in the anterior-posterior diameter of the thorax. The sternum moves superiorly and anteriorly in accord with rib movements occurring at the costovertebral, costotransverse, costochondral, and sternochondral joints. Relative to the lower ribs, the costotransverse joint articulation at the transverse process is cupped and accommodates the tubercle of the rib. This articulation permits the rib to rotate on a transverse axis. A slight downward movement at the head of the rib is amplified distally at the sternum. This movement is transferred to the sternum by the costochondral and sternochondral joints. The result is that the sternum raises on inspiration much like the raising of a pump-handle when drawing water from the depths of a well
• transverse - bucket handle and costotransverse joint
  • planar tubercle of transverse process permits an outward sliding of the rib and results in bucket handle of lower ribs
  • costochondral and sternochondral joints involved
• vertical - diaphragmatic
  • phrenic n., pericardiacophrenic vessels, ant. post. intercostal vessels
  • Upon diaphragmatic contraction the height of the diaphragmatic dome drops to increase the vertical extent of the thoracic cavity.
• capillary effect, negative pressure, etc.
  • pneumothorax - air enters and breaks capillary effect, loss of negative pressure, the lung collapses

Lymphatic Drainage

• Laterally, lymph drainage from the anterior thoracic wall (breast) is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove.
• The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left.
• The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.
• axillary notes receive 75% of lymphatic drainage
  • pectoral nodes - lateral border of pectoralis major
  • apical nodes - beneath the clavicle
  • supraclavicular nodes
  • cervical nodes
• parasternal nodes
  • along the internal thoracic artery
• subcutaneous lymphatics
  • distribute to wide area if deep lymphatics are blocked (e.g. cancer)
• intercostal nodes
  • along the azygous veins in the posterior mediastinum
  • drain posterior intercostal spaces
  • left intercostal nodes may drain directly into thoracic duct
  • right intercostal nodes may find their way to the right lymphatic duct
• left/right differences
  • right side into right (subclavian) lymph duct
  • left side into thoracic duct and left subclavian v.
• Summary.
  • Laterally, lymph drainage from the breast is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove.
• The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left.
• The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.
• Posterior intercostal spaces drain into intercostal nodes located in the posterior mediastinum.

General comments

• This hip joint is a synovial "ball and socket" joint

Bones and articulations

• head of femur (ball fits into the acetabulum (socket)
• depth of acetabulum is increased by labrum, labrum overlies the transverse acetabulum ligament at the acetabular notch
  • labrum is non-interrupted
• acetabular notch bridged by the transverse acetabular lig *creates a foramen - posterior branch obturator artery
• articular cartilage on head of femur and on lunate surface of acetabular fossa
• ligamentum teres attaches to acetabular fossa near transverse acetabular ligament
  • Intracapsular and extrasynovial
• synovial reflections and extensions/bursae

Ligaments - capsular thickenings

• pubofemoral - from pectin line to intertrochanteric line, resists abduction
• iliofemoral - from anterior inferior iliac spine (deep to rectus femoris straight head) to intertrochanteric line and lessor trochanter (Y-ligament)
  • fibers spiral from superior anterior medial to inferior posterior lateral - resist extension and shorten on extension to stabilize joint through a "screw home" mechanism that, in turn, leads to close packing of the joint.
• ischiofemoral - from ischium to greater trochanter and intertrochanteric line, resists hyperextension and flexion

Movements, limitation of movement, innervations, and muscle stabilization

• flexion
  • psoas major - lumbar plexus
  • anterior compartment of thigh - femoral nerve
    • rectus femoris - long head
    • sartorius (lateral rotation)
    • tensor fascia lata
  • limited by trunk and hamstrings
• extension
  • posterior compartment of thigh (hamstrings and posterior adductor magnus) - tibial portion of sciatic
  • gluteus maximus - inferior gluteal nerve
  • limited by ligaments of joint capsule (see above)
• adduction
  • medial compartment of thigh and obturator externus - obturator nerve
  • limited by opposite thigh and ligament to the head of the femur
• abduction
  • gluteus minimus and medius and tensor facia lata - superior gluteal nerve
  • limited by pubofemoral ligament and adductors
• lateral rotation
  • short rotators of gluteal region - lumbosacral plexus
  • long head of the biceps - tibial portion of sciatic
  • sartorius - femoral nerve
  • relatively free - limited by neck of femur and pubofemoral ligament
• medial rotation
  • anterior part of gluteus minimus (medius) - superior gluteal nerve
  • gracilis - obturator
  • semitendonosus and semimembranosus - tibial portion sciatic
  • limited by joint capsule
• Muscles - all muscles that cross the joint contribute to stabilization
  • anterior group - flexors: iliopsoas adds major support, rectus femoris, sartorius
  • medial group - all of the adductors
  • posterior group - extensors: the hamstrings
  • gluteal region - rotators and abductors: the five short lateral rotators, gluteus maximus, medius, and minimus, tensor fascia lata
  • fascial specialization - iliotibial tract

Stability

• • The hip joint is maximally stable during extension as is the case during quiet standing. The line of gravity falls behind the axis causing to hip to extend. Capsular thickenings (aforementioned ligaments) spiral from posterior to anterior and from medial on the pelvic girdle to lateral on the femur. As the ligaments tighten the capsule shortens similar to twisting a wet towel. This forces the head of the femur deep securely into the acetabular fossa.

Vascularization

• Cruciate anastomosis - Arteries and key relationships

Innervation

• Hilton's law - all nerves that cross the joint provide innervation to the joint tissues.
  • • Obturator, femoral, and sciatic, and the superior and inferior gluteal nerves

Explicit Statement of Penetrated Structures

1. Skin and plantar aponeurosis
2. Lateral border of abductor hallucis
3. Medial plantar a. and v.
   • The lateral plantar a.v. is posterio-lateral to site of penetration and is spared
   • Deep plantar arch is distal to site of penetration and is spared
4. Medial border of flexor digitorum brevis
5. Tendons of flexor digitorum longus
   • near or immediately distal to crossing of tendons
   • lateral border of tibialis posterior tendon might be damaged
6. Medial border of quadratus plantae
7. Tendon of flexor hallucis longus
8. Spring ligament
9. Head of talus within floor of talocalcaneonavicular joint

Medial Longitudinal Arch

• Bones
  • calcaneus, head of talus, navicular, cuneiforms, and first 3 metatarsals (heads of) - labeled drawing was helpful (with discussion)
  • talocalcaneonavicular joint has the head of the talus of as the "keystone" wedged between the calcaneus and navicular
  • spring ligament is the floor of the talocalcaneonavicular joint and acts as a "staple" to approxmate the navicular to the calcaneus
• Ligaments
  • Spring ligament - plantar calcaneonavicular ligament
    • maintains the head of talus at the peak of the medial longitudinal arch
    • stretching of this ligament allows the navicular bone to move away from the calcaneus; if stretched, the talus falls
  • minor support by long and short plantar
• Muscles
  • Suspends the arch
    • tibialis posterior - suspends the arch
    • tibialis anterior - suspends the arch
    • extensor hallucis longus - suspends the arch
  • Staples the arch
    • peroneus longus - tendinous insertions staple the arch
      • note: peroneus longus is a tie beam for the transverse arch, a vertical support for the lateral longitudinal arch, and a staple for the medial longitudinal arch
    • tibialis posterior - tendinous insertions staple the arch
    • tibialis anterior - tendinous insertions staple the arch
  • "Tie beam" support - structures serving to approximate the bones of the arch
    • intrinsic mm - adductor hallucis oblique head, flexor hallucis, abductor hallucis, flexor digitorum brevis, quadratus plantae, lumbricals
    • extrinsic mm - flexor hallucis longus is key, tibialis posterior, flexor digitorum longus
    • fascia - plantar aponeurosis and septa
    • skin
• Fascial Specializations
  • fascia - plantar aponeurosis and septa
  • skin
• Neural and Vascular Relationships
  • Tibial nerve and posterior tibial artery elaborate medial and lateral plantar arteries and nerves
  • Medial and lateral plantar nerves and vessels pass deep to abductor hallucis to enter plantar region
  • Lateral planter nerve and vessels pass superior to flexor hallucis brevis and inferior to quadratus plantae to reach lateral aspect of sole.
• Consequences of Damage
  • A fallen medial arch indicates failure of the spring ligament to approximate the navicular bone to the calcaneus. As a result, the head of the talus moves inferiorly into the region traversed by the medial and lateral plantar vessels and nerves. Compression of these structures could lead to cold feet (poor circulation) and paraesthesias (compressed nerves).