Gross Anatomy: Anterior & Medial Thigh PDF 2024

Gross Anatomy: Anterior & Medial Thigh Page 1 of 19 Dr. Paul Walker Session Learning Objectives By the end of this session, students should be able to accurately: 1. Describe the structural relationships of the femoral triangle as related to clinic...

Gross Anatomy: Anterior & Medial Thigh Page 1 of 19 Dr. Paul Walker Session Learning Objectives By the end of this session, students should be able to accurately: 1. Describe the structural relationships of the femoral triangle as related to clinical relevance. A. Define the boundaries, contents, and anatomical relationships of the femoral triangle. B. Discuss the clinical relevance of femoral triangle anatomy. 2. Describe the structure/function relationships of the femoral vessels including lymphatics. A. Describe the origin and course of the femoral artery including its major branches. B. Describe the main tributaries of the femoral vein and discuss its course. C. Summarize the lymphatic vessels and nodes of the proximal thigh region. D. Discuss the clinical relevance of the femoral vessels and lymphatics. 3. Describe the structure/function relationships of the anterior and medial thigh compartment muscles. A. Describe the muscles of the anterior thigh compartment including attachments, actions, and innervation. B. Describe the muscles of the medial thigh compartment including attachments and actions, and innervation. C. Discuss the clinical relevance of compartment syndrome and other injuries affecting the anterior and medial thigh compartments. 4. Summarize the femoral and obturator nerve innervation of the anterior and medial thigh. A. List the spinal origins of the femoral and obturator nerves and describe their sensory and motor functions. B. Predict the clinical outcomes of femoral vs. obturator nerve injuries. Supplemental Reading Gray’s Anatomy for Students, 4thEd (2020) Drake, Vogl, Mitchell (Elsevier) Chapter 6- Lower Limb Clinically Oriented Anatomy, 7thEd (2014) Moore, Dalley, Agur (Wolters Kluwer) Chapter 5- Lower Limb Gross Anatomy: Anterior & Medial Thigh Page 2 of 19 Dr. Paul Walker Session Outline I. Femoral Triangle A. Anatomy of the Femoral Triangle B. Clinical Relevance of Femoral Triangle Anatomy II. Femoral Vessels A. Femoral and Deep Femoral Arteries B. Femoral Vein and Important Tributaries C. Lymphatics D. Clinical Relevance of Femoral Vessels & Lymphatics III. Anterior & Medial Thigh Compartment Muscles A. Muscles of the Anterior Thigh B. Muscles of the Medial Thigh C. Clinical Relevancies of Anterior & Medial Thigh Compartments IV. Innervation of the Anterior & Medial Thigh Compartments A. Sensory and Motor Functions of the Femoral & Obturator Nerves B. Injuries Affecting the Femoral & Obturator Nerves Gross Anatomy: Anterior & Medial Thigh Page 3 of 19 Dr. Paul Walker I. Femoral Triangle Fig 1 (Grays Anatomy for Students) A. Anatomy of the Femoral Triangle The femoral triangle is a transition area for structures to pass between lower abdomen and anterior thigh. 1. Boundaries (Fig 1): inguinal ligament (superior) sartorius m. (lateral) adductor longus m. (medial). Floor contains pectineus m. (medially) and iliopsoas m. (laterally). The inferior apex of the femoral triangle is continuous with the Adductor Canal (Fig 1)- located deep to the sartorius muscle. The femoral artery & vein travel through adductor canal along with the saphenous nerve and the nerve to the vastus medialis muscle (both branches of the femoral nerve). 2. Contents and Relationships (Fig 2) from lateral to medial- NAVL Femoral Nerve Femoral Artery Femoral Vein Fig 2 (Netter 472 left, Acland right) Lymphatics Gross Anatomy: Anterior & Medial Thigh Page 4 of 19 Dr. Paul Walker The Femoral Sheath is an extension of transversalis fascia that surrounds the femoral artery & vein (lateral and intermediate compartments, respectively). The femoral nerve is not contained within the femoral sheath. The Femoral Canal is the medial compartment of the femoral sheath that contains lymphatics. This part of the sheath has a proximal opening into the abdominal cavity called the Femoral Ring. B. Clinical Relevance of the Femoral Triangle 1. Femoral Artery Palpation/Compression: The femoral artery pulsations can be felt in the femoral triangle. Distal femoral artery bleeding can be stopped by compression directly on this area. 2. Femoral Hernia: The femoral ring is a site of potential herniation of abdominal viscera. This is called a femoral hernia. Look for evidence on your cadaver. II. Femoral Vessels Fig 3 (Grays Anatomy for Students) A. Femoral & Deep Femoral Arteries 1. Origin and Course The femoral artery is a continuation of the external iliac artery after it passes deep to the inguinal ligament into the femoral triangle. There are 3 superficial branches of the femoral a. that emerge in the proximal thigh (superficial epigastric, superficial circumflex iliac, superficial external pudendal). You are not responsible for finding these branches in lab. The main branch of the femoral artery is the deep femoral artery (Fig 3) and its main branches. The Deep Femoral Artery (also called deep artery of the thigh or profunda femoris a.) courses parallel to the femoral artery but travels deep to the adductor longus m. Distal to the origin of the deep femoral artery, the femoral artery and vein are found together in the adductor canal deep to the sartorius m. The vessels course toward the adductor hiatus- an opening between the distal attachments of adductor and hamstring parts of the adductor magnus m. The femoral artery and vein travel through the adductor hiatus into the popliteal fossa. Within the popliteal fossa, their names change to popliteal artery and vein. Gross Anatomy: Anterior & Medial Thigh Page 5 of 19 Dr. Paul Walker 2. Branches of Deep Femoral Artery (Profunda femoris artery) (Fig 4) Fig 4 (Netter 491) Lateral Circumflex Femoral a.- passes deep to the rectus femoris m and gives off: Ascending & Transverse Branches- anastomose with arteries around hip joint. Descending Branch- passes between rectus femoris m. and vastus intermedius m. to anastomose with arteries around knee joint (genicular a.) Medial Circumflex Femoral a.- passes posteriorly between pectineus m. and iliopsoas m. Important blood supply to hip joint and to the neck of the femur (supplements weak supply from obturator artery) Gross Anatomy: Anterior & Medial Thigh Page 6 of 19 Dr. Paul Walker The femoral artery (cut and removed in Fig 5 below) provides the main blood supply to the lower extremity. Fig 5 (Grays Anatomy for Students) The distal part of the femoral artery passes from anterior thigh into popliteal fossa via the adductor hiatus and is renamed the popliteal artery. This artery supplies branches to the knee joint and divides into anterior tibial and posterior tibial arteries to supply the 3 leg compartments, ankle joint, and foot. The largest branch of the femoral artery, the deep femoral artery, sends muscular branches to the 3 thigh compartments (Fig 5) as well as important branches to hip & knee joints. Deep Femoral Artery Travels between adductor longus m. and adductor magnus m. Gives several (about 4) perforating branches that supply the posterior compartment of the thigh. Ends in distal thigh. Gross Anatomy: Anterior & Medial Thigh Page 7 of 19 Dr. Paul Walker B. Femoral Vein The femoral vein is continuous with the popliteal vein inferiorly and the external iliac vein superiorly. It runs parallel to the femoral artery and is the main route for blood return to the external iliac vein and subsequent drainage into the inferior vena cava. Most of the femoral vein and its tributaries will be removed during dissection in order to view arterial branches. The great saphenous vein is a tributary of the femoral vein in the proximal anterior thigh. It pierces the saphenous opening as it reaches the femoral vein at the level of the femoral triangle. Fig 6 (Netter 472 left, Grays Anatomy for Students right) Gross Anatomy: Anterior & Medial Thigh Page 8 of 19 Dr. Paul Walker C. Femoral Lymphatic Vessels and Nodes Fig 7 (Netter 472) Vertical and horizontal groups of superficial inguinal lymph nodes are found along the great saphenous vein & inferior to the inguinal ligament, respectively. These nodes receive lymphatic drainage from the lower limb, anterior abdominal wall, perineum, and external genitalia. They drain into the deep inguinal nodes located along the femoral and external iliac veins (Fig 7) There are also popliteal nodes located deeply along the popliteal vein in the popliteal fossa. These receive lymphatic drainage from the leg and foot. D. Clinical Relevance of Femoral Vessels & Lymphatics 1. Saphenous Vein Graft The great saphenous vein is commonly used as a coronary bypass vessel. It is harvested distally from its position in the medial leg region. 2. Femoral Vessel Catheterization: A catheter into the femoral artery or vein can be advanced to the heart for the purposes of non-invasive surgery. This avoids opening the chest cavity. 3. Femoral Lymphatics Inguinal nodes may swell during minor infections of the lower extremities in otherwise healthy people. Reproductive organs of the pelvis (e.g. uterus) have Gross Anatomy: Anterior & Medial Thigh Page 9 of 19 Dr. Paul Walker some drainage to the inguinal nodes, and these may enlarge in more serious diseases such as cancer. As such, swelling of the inguinal nodes must be further investigated as a potential sign of serious, life-threatening disease. III. Anterior and Medial Thigh Compartments There are 3 compartments of the thigh containing muscles that move the lower extremity at the hip & knee joints: Fig 8 (Grays Anatomy for Students) A. Muscles of the Anterior Thigh 1. Iliopsoas (Fig 8): Psoas major and iliacus muscles have separate proximal attachments but combine distally to attach to the lesser trochanter of the femur. The combined iliopsoas m. passes into the anterior thigh compartment through the lateral half of the gap between inguinal ligament and pelvic bone. The iliopsoas m. comprises the lateral floor of the femoral triangle. Innervation: Iliacus Femoral nerve (L2-4) Psoas Ventral rami (L1-3) Actions of the Iliopsoas: Thigh flexion at the hip joint Promotes flexion of the thigh at the hip joint during swing phase of walking. This is when the distal attachment moves toward proximal attachment (normal action). Promotes flexion of the trunk at the hip joint to sit- up from supine position. This is when the proximal attachment moves toward the distal attachment (reverse action). Gross Anatomy: Anterior & Medial Thigh Page 10 of 19 Dr. Paul Walker Fig 9 (Netter 479) 2. Sartorius (L: sartor, a tailor) has proximal attachment on the ASIS and distal attachment onto the anteromedial tibia as part of pes anserinus. Clinical Note: Pes anserinus (L: goose foot) is the term given to the conjoined distal tendons of the sartorius, gracilis, and semitendinosus muscles attaching to the anteromedial tibia. The appearance of the 3 tendons resembles the webbed foot of a goose. There is a small bursa (anserine bursa) deep to the tendon that can become inflamed (anserine bursitis) with overuse injuries. It is a source of knee pain extrinsic to knee joint pathology in some patients. Innervation: Femoral nerve Actions of Sartorius: Produces movement to cross the legs in a sitting position. At the hip joint, it produces thigh flexion and lateral rotation. At the knee joint, it produces leg flexion (and slight medial rotation). Figure 10 (Netter 497) Gross Anatomy: Anterior & Medial Thigh Page 11 of 19 Dr. Paul Walker Fig 11 (Netter 484) 3. Tensor of the Fascia Lata (Tensor Fasciae Latae, TFL): Proximal attachment is from ASIS. The muscle attaches distally to the iliotibial (IT) tract (band). The IT tract (band) itself, is a lateral thickening of the fascia lata that attaches distally to the anterolateral surface of the proximal tibia. This attachment site is also known as Gerdy’s tubercle- an anatomical landmark for surgical approaches to the distal femur and proximal tibia. Innervation: Superior Gluteal nerve Actions of TFL Hip joint: Thigh flexion (assists iliopsoas), abduction, and medial rotation. Knee joint: Stabilizes knee joint during leg extension (via IT tract) Clinical note: Inflammation of the distal attachment of the IT band to the anterolateral surface of the proximal tibia (Gerdy’s tubercle) can be a source of pain in some patients extrinsic to knee joint pathology. Gross Anatomy: Anterior & Medial Thigh Page 12 of 19 Dr. Paul Walker Fig 12 (Netter 479) 4. Quadriceps femoris: 4 muscles of anterior thigh All have different proximal attachments and the same converging distal attachment. Proximal Attachments: Rectus femoris Proximal attachment- anterior inferior iliac spine (AIIS) of pelvis Vastus lateralis Proximal attachment- lateral lip of linea aspera & greater trochanter of femur Vastus medialis Proximal attachment- medial lip of linea aspera & intertrochanteric line of femur Vastus intermedius Proximal attachment- anterior & lateral surfaces of femur Distal Attachment: The 4 quadriceps femoris muscles coverge distally at the quadriceps femoris tendon, which inserts on the tibial tuberosity via the patellar ligament (tendon). Innervation: Femoral nerve Action of Quadriceps Hip Joint: Thigh flexion (rectus femoris only) Knee Joint: Leg extension (all 4 heads) Gross Anatomy: Anterior & Medial Thigh Page 13 of 19 Dr. Paul Walker Muscle tables from Grant’s Dissector (17th Ed) are included for students who prefer muscle attachments, actions, and innervation listed in table format. The anterior thigh muscle table is below, and the medial thigh muscle table is on p 15. There are 2 amendments made to the Grant’s Dissector (17th Ed) Anterior Thigh Muscle table: The pectineus muscle was listed on the anterior thigh muscle chart in Grant’s Dissector. It is blocked out by a gray rectangle in the below amended table since this muscle is technically in the medial thigh compartment. The pectineus is included in the medial thigh muscle table on p 15. The psoas major part of the iliopsoas muscle is innervated by nerve branches that arise directly from the ventral rami of L1-L3 spinal nerves proximal to the formation of the femoral nerve. In contrast, direct branches from the femoral nerve innervate the iliacus muscle. As such, both sources are included on the amended table. Ventral rami L1-3 and Femoral n. Femoral n. Gross Anatomy: Anterior & Medial Thigh Page 14 of 19 Dr. Paul Walker 2. Muscles of the Medial Thigh Fig 13 (Grays Anatomy for Students) Pectineus: Proximal attachment on the superior pubic ramus. Distal attachment on the pectineal line of femur (inferior to lesser trochanter). Innervation: Femoral n. Actions of Pectineus: Hip Joint: Thigh adduction Adductor Longus: Proximal attachment from body of pubis inferior to pubic crest. Distal attachment on middle third of the linea aspera. Innervation: Obturator n. Action of Adductor Longus: Hip Joint: Thigh adduction Adductor Brevis: Located deep to pectineus and adductor longus. Proximal attachment from body of pubis and inferior ramus (superior to origin of gracilis). Distal attachment on pectineal line of femur and proximal part of linea aspera. Innervation: Obturator n. Action of Adductor Brevis: Hip Joint: Thigh adduction Gross Anatomy: Anterior & Medial Thigh Page 15 of 19 Dr. Paul Walker Fig 14 (Grays Anatomy for Students) Adductor Magnus: Has adductor part and hamstring part. Both have proximal attachment from the ischiopubic ramus and ischial tuberosity. The adductor part has a broad distal attachment on the gluteal tuberosity, linea aspera, and supracondylar line of the femur. The hamstring part has distal attachment on the adductor tubercle of femur. Innervation: Obturator n. (adductor part) Tibial division of sciatic n. (hamstring part) Action of Adductor Magnus Thigh adduction (adductor part) & thigh extension (hamstring part) Obturator Externus: Proximal attachment from the margins of the obturator foramen and obturator membrane. Distal attachment on trochanteric fossa of femur (tendon runs posterior to neck of femur). Innervation: Obturator n. Action of Obturator Externus Hip Joint: Thigh lateral (external) rotation Gross Anatomy: Anterior & Medial Thigh Page 16 of 19 Dr. Paul Walker Fig 15 (Netter 479) Gracilis (L. slender): Proximal attachment from the body of pubis & inferior ramus. Distal attachment on medial tibia as part of pes anserinus. Innervation: Obturator n. Actions of Gracilis: Hip Joint: Thigh adduction (weak) Knee Joint: Leg flexion & internal (medial) rotation Gross Anatomy: Anterior & Medial Thigh Page 17 of 19 Dr. Paul Walker There are 2 amendments made to the Grant’s Dissector (17th Ed) Medial Thigh Muscle table: Added ‘of femur’ to the distal attachment of pectineus muscle. It now reads ‘pectineal line of femur’. There is a ‘pectin pubis’ term of the pubic bone that is a different pectineal line (so to avoid confusion). Removed obturator nerve as a source of innervation to the pectineus. This muscle is mostly innervated by the femoral nerve. of femur C. Clinical Relevancies of Anterior & Medial Thigh Compartments Psoas Abscess: Tuberculosis of the vertebral column can cause an abdominal abscess that passes between the psoas and its fascia into the proximal thigh causing severe pain. Patient will have difficult flexing the thigh at the hip joint when laying in supine position. Patellar Tendon Reflex: Tapping the patellar tendon causes a brief stretch of the quadriceps muscle and activates a L2-L4 spinal reflex arc (afferent- efferent) via the femoral nerve. This produces immediate contraction of the quadriceps femoris muscle and leg extension- a way to test the integrity of the femoral n. and L2-L4 spinal levels. Gracilis Transplantation: Because of its weak effect on thigh adduction, the gracilis m. can be harvested for transplantation into another body region (e.g. to replace damaged hand muscle). Gross Anatomy: Anterior & Medial Thigh Page 18 of 19 Dr. Paul Walker IV. Femoral and Obturator Nerves A. Sensory and Motor Functions of Femoral & Obturator Nerves Femoral Nerve (Fig 15) Obturator Nerve (Fig 16) Originates L2-L4 ventral rami Enters medial thigh via obturator Enters anterior thigh via femoral foramen. triangle deep to inguinal ligament Cutaneous supply to medial thigh Cutaneous supply to anterior thigh Motor branches to medial Motor branches to anterior compartment muscles (except compartment muscles (except psoas pectineus and hamstring portion of & TFL) adductor magnus) Saphenous nerve: large sensory Divides into anterior and posterior branch travels in adductor canal and branches, which travel superficial passes between sartorius and and deep to the adductor brevis m. gracilis muscles to innervate skin of medial leg, foot, ankle. Fig 17 below (Grays Anatomy for Students) Fig 16 below (Grays Anatomy for Students) O r i g i n a t e s L 2 - L 4 v e n t r a l r a m i Gross Anatomy Prep: Anterior & Medial Thigh Page 19 of 19 Dr. Paul Walker B. Injuries Affecting the Femoral & Obturator Nerves Femoral Nerve Injury: Causes paralysis (or paresis) of the quadriceps femoris m. and weakening of leg extension against resistance. Patients may press on the distal thigh during rising from chair to standing position to prevent inadvertent leg flexion at the knee. Obturator Nerve Injury: causes paralysis (or paresis) of the medial compartment adductors. Patients would have difficulty with gait and any thigh movements that involve adduction.