Sciatic Nerve – Anatomy

The Sciatic nerve is the largest nerve in the human body. The nerve originates in the lower spine and travels all the way down to the feet in both legs. Throughout its course, the nerve gives numerous branches that supply the muscles and carry sensations from different regions of the legs. The compression of the sciatic nerve roots may cause symptoms of low back pain that radiates down to the leg known as sciatica.

Sciatic Nerve Origin 

The Sciatic nerve originates from the nerve roots of the lower lumbar and upper sacral spine. The L4, L5, S1, S2, and S3 nerve roots join together to form the Sciatic nerve. The nerve roots exit the neural foramen in the vertebral column. The roots originate from the spinal cord carrying transmissions to and from the brain.

MRI image of the lumbosacral spine in sagittal section showing herniated intervertebral disc at L4-L5 level.

MRI image of the lumbosacral spine in sagittal section showing herniated intervertebral disc at L4-L5 level.

At its maximum width, the Sciatic nerve is about 2cms in width. The rope-like nerve is protected by a fatty sheath that runs throughout its course. The nerve receives its blood supply both from outside the nerve and through a network of blood vessels running in its outer layer.

Sciatic Nerve Course

The Sciatic nerve exits the pelvis along with some blood vessels through the greater sciatic notch. The greater sciatic opening lies in the back of the pelvis under the piriformis muscle.

The nerve courses under the piriformis muscle and lies to rest on a small group of muscles responsible for external rotation of the hip joint. The nerve lies under the large buttock muscle (gluteus maximus).

The nerve after crossing the gluteus maximus enters the upper thigh and comes to lie under the large muscle in the back of the thigh (bicep femoris).

The nerve continues down the back of the thigh and divides into two branches in the back of the knee. The back of the knee joint known as the popliteal fossa is a conduit for various structures from the thigh to the lower leg.

The two divisions of the Sciatic nerve, the tibial nerve, and the common peroneal nerve continue down the leg. The tibial nerve continues in the back of the leg and supplies the calf and the soles of the feet.

The common peroneal nerve travels to the outer leg and the feet. The nerve divides into two branches, the deep peroneal nerve, and the superficial peroneal nerve. Together they supply the muscles in the front and the outer side of the leg.

Although the largest nerve, the Sciatic nerve throughout its course lies deep in the thigh and the buttock and cannot be felt on palpation.

Motor Function

The Sciatic nerve controls the major muscle groups in the thigh, leg, and feet. The muscle groups help the human body to perform activities such as walking, running, sitting, climbing stairs, etc.

The Sciatic nerve supplies the four hamstring muscles namely the semitendinosus, semimembranosus, bicep femoris – long head, and bicep femoris – short head. The Sciatic nerve also supplies a part of adductor magnus muscles.

The hamstring muscles help the body to bend the knee and coordinate activities such as walking, climbing stairs, etc.

The tibial division of the Sciatic nerve supplies the muscles of the calf. The muscles include gastrocnemius, plantaris, soleus, flexor digitorum longus, and hallucis longus. Together these muscles help us to stand on our toes and move the toes down.

The peroneal part of the Sciatic nerve divides to supply the major muscles on the outer side and the front of the leg. The muscles include tibialis anterior, peroneus longus, peroneus brevis, extensor digitorum longus, and hallucis longus.

The muscles on the front and the side of the leg help us to move the foot and the toes up and outwards. The muscles of the calf and the front of the legs together function to help us to walk in a coordinated manner.

Besides the major muscles, both the tibial and the peroneal division supply a number of small muscles in the feet. The small muscles in the feet help us to walk with stability.

Sensory function

Besides the motor function, the Sciatic nerve carries sensory signals from the legs and feet through its branches. The sensation from the back of the leg (calf) and the outer sole is carried by the tibial nerve.

The sensory input from the front and the outer aspect of the leg is carried by the common peroneal division. The sensation from the top of the feet is carried by the superficial peroneal nerve, whereas the sensation from the 1st and the 2nd webspace is carried by the deep peroneal nerve.

Blood Supply

The blood supply of the nerve is vital in maintaining the Sciatic nerve’s function. The blood supply may be compromised in systemic diseases such as diabetes mellitus and in cases of external pressure over the nerve.

Call Us Now!

4.9
Based on 93 reviews
Dr Vaksha, is a great doctor very professional knows what he talking about. Treat patient with upmost respect. Thank You
Troy Spencer
16:46 19 Jan 23
Dr. Karkare is an amazing doctor, very caring and attentive, the girl at the front desk is very kind and helpful. .elizabeth .thank you so much .
blanca ventura
21:32 26 Oct 22
Been going to this place before my accident and after I had my knee surgery. So happy how I been treated and how well I am getting. Thank you all and specially Dr. VAKSHA for everything and getting back on track.
Ita Opico
19:01 25 Oct 22
Love this place From the minute I called I was treated kindly. When I arrived The Dr saw me right away he was compassionate and ordered the appropriate tests for me. I came back in for my follow up and had the same great experience.
Christine Rostock
21:28 23 May 22
Dr Vaksha and Dr karkare are 2 of the best orthopedic doctors around my wife Susan had a very serious broken ankle in March of 2019 she didn't think she was going to walk again Dr vaksha did an excellent surgery on her ankle he said it was his toughest he ever did he put a lot of hardware in her ankle and told her she would be alright she made remarkable recovery thanks to his surgery as of now she regained 100 percent use of her ankle she would highly recommend him to anyone. My own experience with Dr karkare has been wonderful he takes his time with you listens to what you have to say and prescribes various treatments and is very caring I would highly recommend him to anyone I would give both doctors a 10 plus rating we are very happy with them the best.
Harry Jones
23:31 19 May 22
Complete orthopedics is a wonderful place to go when you hurt or injured a great staff and wonderful doctors very knowledgeable and helpful I would recommend this place to all of my family and friends that is in me of orthopedic care I give them 10 thumbs up
Wayne Pemberton
17:39 18 May 22
The staff is very professional and helpful. Dr. Vaksha is excellent. He takes time to listen and offer suggestions to help you get better. I’m very thankful and happy to be a patient here at Complete Orthopedics.
Phoenix Rising
19:54 16 May 22
Dr.Karkare is the best. He listens to everything and explains everything I recommend him to everyone. I am so happy he is my doctor.
Myrna James
00:48 13 May 22
Dr.Kuo is amazing very attentive,caring,and passionate and staff is awsome too.Thank you for everything Dr.kuo.
Erick Murillo
23:17 12 May 22
I was in a car accident November 1 I was referred to Dr. Vaksha For shoulder surgery . I he was amazing he made me feel very comfortable and explained everything that was going to happen from surgery all the way through my physical therapy highly recommend Dr. Vaksha
Yolanda Ojeda
19:37 09 May 22
My appointment with Dr. Vaksha was amazing. Dr. Vaksha was very thorough and kind. I would refer this office to anyone who needs a great orthopedic doctor.
John Senechal
19:54 05 May 22
Scheduling my appointment was quick and easy. The staff was super friendly and down to earth. I was seen on time. The appropriate test, “x-rays” were taken before the conversation with doctor, something I really liked, test for analysis and conversation was done upfront. Dr. V had a great personality and was no BS, straight forward diagnosis and a play on next steps. I am happy I found them and would refer them to friends and family.
Sam
00:46 03 May 22
I have seen Dr. Kuo two times already and he's awesome along with his staff. Very friendly office and I'm glad to be a patient here.
Camaris A
20:01 28 Apr 22
Amazing team!! Very caring, profesional, and friendly!! Dr. Kevin Kuo, you are the best, very passionate, caring, and helping thank you for getting me better and being so kind to me! Elizabeth you the best thank you for you help always and you big smile and positive actitud❤️🙏🏼
breidy valerio
19:01 22 Apr 22
The staff is truly exceptional, they make you feel comfortable and welcomed. The doctors are amazing,always professional, compassionate and great listeners.
Elizabeth Collado
03:25 09 Apr 22
What a great place! The place is clean and organized.The staff is wonderful. Setting up physical therapy is right there as well.I'm so glad I found this place.
Donna Anne
22:45 05 Apr 22
This was my 1st time breaking something in my 27 years on this planet. I was recommended here by a friend Dr. Vashka helped me from day 1 and still continues to check in on me and my healing ankle. Would highly recommend
tyron davis
16:06 01 Apr 22
Brand new office, same great doctors! Rooms are clean, plenty of parking, physical therapy attached, Dr. Karkare and his staff are awesome. Thank you!
Emily B
02:49 24 Mar 22
Dr.VAksha is the best, I love the way he treats me as his patient, he is caring,understanding and very attentive to my needs
Mirna Caballero
14:53 03 Mar 22
Great staff. Dr. Vaksha is awesome and takes the time to listen to his patients. He is very compassionate. I would highly recommend this office.
Bebe Doyle
01:24 23 Feb 22
After suffering from a severe ankle injury Dr. V was able to help me heal and return back to work completely to a job where I stand for 12 hours a day. The office is very clean and I appreciated the reminders of my appointments via phone call and through text. The patient portal made it easy for me to access all my documents including work notes. The office staff is wonderful and Rebecca was able to schedule me with a busy schedule and awesome at answering all of my questions including referring me to a great physical therapy office. I highly recommend this office to anyone who’s looking for knowledgeable and kind orthopedic office.
Elizabeth Birchwell
21:31 28 Jan 21
The staff here are great, I was seen at the time of my appointment and was well taken care of!
Shaun Berry
18:14 07 Jan 21
They are an excellent practice. The front and back office people are amazing and so helpful. Rebecca is such a kind and understanding person. I had an issue with paperwork and she cleared it right up. Dr. Karkare is very knowledgeable, helpful, and caring.
Matt S.
19:31 18 Nov 20
Rebecca K. - What a true burst of sunshine. Very friendly and definitely an asset to the practice!
Laura Aston
18:17 17 Nov 20
Great experience, the Doctor is nice but the staff is incredible. I worked with Linda, who was profession and assisted me beyond what any person has done at other practices. Complete Ortho should be complimented for having such a person on their staff.I highly recommend this place!!!
Joe Allen
17:26 17 Nov 20
Linda and Becca they are so good ever time I come they are very nice I would tell everyone I no to come to this office..
Barbara Victor
16:45 17 Nov 20
I was rear ended in an auto accident , Dr Vashka was recommended by a friend of mine .I was experiencing Back , neck , and shoulder pain . After a thorough examination and given exercises to do at home , I am feeling much better , and I ended up avoiding surgery . The staff at Complete Ortho is extremely attentive and show great care when making an appointment and are very friendly and i never waited more than 5 minutes for my appointment . So I would strongly recommend Complete Orthopedics for any aches and pains that one might be experiencing.....
Bill Becht
04:44 17 Nov 20
It was the afternoon of Friday Sept. 24. We were in Pt. Jefferson and my wife, Mary Ann, broke her hip. We went to Mather Hospital and it was determined that she would have to have an operation to have it repaired. This would be her third time under the knife in the past year. It just so happened that we were very fortunate enough to have Dr. Karkare, who was on standby, perform the surgery. He put in a rod and two screws in her hip. She spent a few days in the hospital and then went to Gurwin rehabilitee for another few weeks.It has now been almost six weeks and we both worked the election the other day. If it wasn’t for Dr. Karkare’s expertise she never would have been able to work. She is able to walk with a walker and is doing physical therapy three times a week.We can not thank the doctor enough for the compassion and dedication that he puts into his work. It allows Mary Ann do the things that she likes to do, even on a limited basis for a while. I know that with her will, perseverance and the great work that the surgeon performed she will be back on her feet in no time.Sincerely:John V. PlumpEast Northport, NY 11731
Jack Harris
14:36 06 Nov 20
In the year of 2018 I was referred to Dr. Karkare because I was experiencing severe knee joint pain. After exhausting physical therapy and trying to labor through the pain, I had to make a quality of life decision. Total knee replacement was the only viable option. Dr. Karkare made my decision easy as he walked me through the whole process from surgery to recovery.On 12/13/19 ( Friday the 13th) I enter Lenox Hill Hospital in great hands. From the time I entered Dr. Karkare’s office for the first time until now, his staff has been amazing. Andrea the medical coordinator walked me through all the paper work and necessary preparations for the surgery. Courtesy and kind would be an understatement. Dr. Karkare went over and beyond from the wellness checks and phone calls all to assure me that I was important to him. This was the right decision no pain and no limp. Complete Orthopedics should be your choice!
Kenneth Randolph
22:18 25 Sep 20
Dr. Vadshka has a great bedside manner. He really takes his time and explains treatment options.
T Lee
12:33 09 Sep 20
I suffered with pain in both knees for years. My orthopedic doctor kept recommending knee replacement . I fought it for years, as I was just afraid. When I had no choice and could barely walk , it was recommended I see Dr. Karkare. We set up a consultation and my wife and I left his office feeling totally confident and comfortable with moving ahead with the surgery. He explained everything to us, and the office staff set everything up for us and made the process easy. So about one month after our initial meeting I had the first knee done. I was up walking mere hours after the surgery, and on the workout machines the next morning. I went home two days after the surgery, and yes walked my daughter down the aisle at her wedding only one week after the surgery without even a cane! Three months later I had the other knee done and went home the very next day. Dr. Karkare put my fears to rest . I would highly recommend him. His expertise gave me my life back. Thank you Dr. Karkare.SincerelyVito Congro
Ethel Congo
23:58 12 Aug 20
Dr Rhodin really cares for his patients. When I see him he makes sure to review my progress in detail.
Micki Cahill
15:03 08 Feb 20
My mom had a total hip replacement by dr karkare. He is the BEST orthopedic doctor.Her incision is almost invisable.She is going back for her other hip next week. The office staff is the best, love Andrea.You wont find a better doctor.
Ryan Brigandi
21:06 13 Jul 18
There is no better Orthopedic doctor you will find. Broke my ankle three places on a Saturday. Called Dr. Karkare. He had is team ready at the hospital and operated on me within 6 hours after my injury. Now After 3 months of great care by him and his staff, I am walking to normalcy.
Spacecom Tel
04:13 23 Mar 18
js_loader

My name is Dr. Suhirad Khokhar, and am an orthopaedic surgeon. I completed my MBBS (Bachelor of Medicine & Bachelor of Surgery) at Govt. Medical College, Patiala, India.

I specialize in musculoskeletal disorders and their management, and have personally approved of and written this content.

My profile page has all of my educational information, work experience, and all the pages on this site that I've contributed to.