Semitendinosus Muscle – Origin, Nerve Supply, Function

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 4 min read

Patient Tools

Read, save, and share this guide

Use these quick tools to make this medical article easier to read, print, save, or share with a family member.

On this page4 sections

Article Summary

Semitendinosus Muscle is one of the hamstring muscles located in the posterior-medial thigh. It originates from the inferior-medial impression on the superior part of the ischial tuberosity and shares a tendon with the biceps femoris. The long distal tendon of the semitendinosus starts below the mid-thigh on the posterior of the semimembranosus and turns around the medial condyle of the tibia to insert onto the...

Key Takeaways

This article explains Origin of Semitendinosus Muscle in simple medical language.
This article explains Nerve Supply in simple medical language.
This article explains Blood Supply in simple medical language.
This article explains Functions of Semitendinosus Muscle in simple medical language.

Before reading

RX Patient Tools

Use these quick guides before reading the article, or return to them when you need help preparing questions for a doctor.

Start here Choose the right pathway for symptoms, reports, medicines, or urgent warning signs. Disease article roadmap Read this topic step by step: meaning, symptoms, warning signs, diagnosis, treatment, prevention, and follow-up. Treatment planner Prepare questions about treatment choices, benefits, risks, side effects, and follow-up. Family & caregiver guide Organize symptoms, reports, medicines, questions, and follow-up safely. Nutrition & diet guide Prepare food, hydration, supplement, and medicine-timing questions safely. Prevention guide Organize risk factors, protective habits, screening, and warning signs. Recovery guide Prepare a safe plan for activity, rehabilitation, warning signs, and follow-up.

Educational health guideWritten for patient understanding and clinical awareness.

Reviewed content workflowUse writer and reviewer profiles for stronger trust.

Emergency safety firstUrgent warning signs are highlighted below.

Definition

Semitendinosus Muscle is one of the hamstring muscles located in the posterior-medial thigh. It originates from the inferior-medial impression on the superior part of the ischial tuberosity and shares a tendon with the biceps femoris. The long distal tendon of the semitendinosus starts below the mid-thigh on the posterior of the semimembranosus and turns around the medial condyle of the tibia to insert onto the superomedial aspect of the tibia. The tendons of the semitendinosus, sartorius, and gracilis eventually conjoin to form the pes anserinus. The semitendinosus can also attach to the crural fascia of the leg and is usually the only attachment to this fascia [rx].

The semitendinosus muscle is a member of the posterior component of the thigh which also includes the biceps femoris and the semimembranosus muscles. These three muscles together are collectively referred to as the hamstring muscle complex which serves as hip extensors and knee flexors that are integral to gait and running. Injuries to the hamstring muscle complex are commonly seen in athletes and are usually brought on through explosive or high speed running.

Semitendinosus Muscle - Origin, Nerve Supply, Function

Origin of Semitendinosus Muscle

Origin – Tuberosity of ischium by a tendon common with the long head of the biceps femoris.
Semitendinosus muscle attaches between the ischial tuberosity of pelvis and the proximal end of the tibia. This muscle is specific by having almost half of its mass (semi-) made of a rounded tendon (-tendinosis). Semitendinosus shares the origin with the long head of biceps femoris. Both muscles originate with a common tendon from a posteromedial impression on the superior part of the ischial tuberosity.
Insertion – Proximal part of the medial surface of the tibia and deep crural fascia. The tendon of the semitendinosus contributes to the distal fibers of the pes anserinus tendon – a tendon that is comprised of the distal tendons of the semitendinosus, gracilis, and sartorius.
The semitendinosus is a superficial muscle of the posterior thigh, bordered by the long head of the biceps femoris laterally, and the semimembranosus medially (along with portions of the adductor Magnus). All of the hamstring muscles (including the biceps femoris) lay in the posterior compartment of the thigh, with the semitendinosus bordered anteromedially by the posteromedial intermuscular septum.
The semitendinosus can be palpated with relative ease by locating the space between the two large bands that comprise the hamstring tendons just superior to the posterior knee. As you course your fingers up the “valley” created by the division in the hamstrings. You can feel musculotendinous junction invest into the long cylindrical

Nerve Supply

Semitendinosus is innervated by the tibial division of sciatic nerve (L5-S2).
A lower motor neuron exits to the sacral plexus exiting through the spinal levels L5-S2. From the sacral plexus, the lower motor neuron travels down the sciatic nerve.^[rx]

Blood Supply

This muscle is supplied by branches from three large arterial sources;

Femoral artery – via the deep femoral artery and its first perforating branch, and medial femoral circumflex artery
Internal iliac artery – through the inferior gluteal artery
Popliteal artery – via an inferior medial geniculate artery.

Functions of Semitendinosus Muscle

These three muscles work collectively to flex the knee and extend the hip.
The muscle also helps to medially rotate the tibia on the femur when the knee is flexed and medially rotate the femur when the hip is extended. It counteracts forward bending at the hips as well.^[rx]
Attaching between the hip and leg, the semitendinosus produces movements on both hip and knee joints producing thigh extension, internal rotation, pelvis stabilization (hip joint), leg flexion, and internal rotation (knee joint).

There are two functions of semitendinosus related to the hip joint when its tibial attachment is fixed;

When the body’s in the anatomical position, it internally rotates the thigh
If the trunk is flexed anteriorly, this muscle extends the thigh

In case ischial attachment is fixed, semitendinosus has two functions on the knee joint;

When the lower limb is in the anatomical position, it flexes the leg
If the knee is semiflexed, semitendinosus internally rotates the leg acting together with all the hamstring muscles.

Extension of the thigh at the hip

Agonists: gluteus maximus, semimembranosus, biceps femoris (long head), and adductor magnus (posterior part)
Antagonists: psoas major and iliacus

The semitendinosus is also a weak medial rotator of the hip.

Flexion of the leg at the knee

Agonists: biceps femoris (long head), biceps femoris (short head), and semimembranosus
Antagonists: vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris

Gracilis, sartorius, popliteus, gastrocnemius, and plantaris assist with flexion of the knee.

Internal rotation of the knee when the knee is flexed

Agonists: popliteus and semimembranosus
Antagonist: biceps femoris (long head) and biceps femoris (short head)

Sartorius and gracilis assist with internal rotation of the knee.

References

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

Write when the problem started and how it changed.
Bring old prescriptions, investigation reports, and current medicines.
Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

What is the most likely cause of my symptoms?
Which danger signs mean I should go to hospital quickly?
Which tests are necessary now, and which can wait?
How should I take medicines safely and what side effects should I watch for?
When should I come for follow-up?

Tests to discuss

Vital signs: temperature, pulse, blood pressure, oxygen saturation
Basic physical examination by a clinician
CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

Rest, drink safe water, and observe symptoms carefully.
Keep a written note of symptoms, duration, temperature, medicines already taken, and allergy history.
Seek medical care quickly if symptoms are severe, worsening, or unusual for the patient.

OTC medicine safety

For mild pain or fever, ask a registered pharmacist or doctor before using common over-the-counter pain/fever medicines.
Do not combine multiple pain medicines without advice, especially if you have kidney disease, liver disease, stomach ulcer, asthma, pregnancy, or take blood thinners.
Do not give adult medicines to children unless a qualified clinician advises it.

Avoid these mistakes

Do not start antibiotics without a proper medical decision.
Do not use steroid tablets or injections casually for quick relief.
Do not delay emergency care because of home remedies.

Get urgent help if

Severe symptoms, confusion, fainting, breathing difficulty, chest pain, severe dehydration, or sudden weakness need urgent medical care.

Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Doctor / qualified healthcare provider

Tests to discuss with doctor

Basic vital signs: temperature, pulse, blood pressure, oxygen level if needed
Relevant blood, urine, imaging, or specialist tests only after clinical assessment

Questions to ask

What is the most likely cause of my symptoms?
Which warning signs mean I should go to emergency care?
Which tests are really needed now?
Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Go to emergency care if you notice:

Severe or rapidly worsening symptoms
Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration

Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.

Step 1
Check danger signs first

If danger signs are present, seek emergency care and do not wait for online information.
Step 2
Record the symptom story

Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.
Step 3
Visit a qualified clinician

A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.
Step 4
Do only useful tests

Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.
Step 5
Follow up and return early if worse

If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips

Take a written symptom diary and all previous prescriptions/test reports.
Do not hide medicines already taken, even herbal or over-the-counter medicines.
Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.